188-418: Laughter is a pleasant physical reaction and emotion consisting usually of rhythmical, usually audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli . Laughter can rise from such activities as being tickled , or from humorous stories, imagery , videos or thoughts. Most commonly, it is considered an auditory expression of
376-457: A multiple-systems model , suggesting that some effects may not be simply mediated by one portion of the brain. Studies on freely moving rats and mice have shown many hippocampal neurons to act as place cells that cluster in place fields , and these fire bursts of action potentials when the animal passes through a particular location. This place-related neural activity in the hippocampus has also been reported in monkeys that were moved around
564-536: A positive feedback . The study of humor and laughter, and its psychological and physiological effects on the human body, is called gelotology . Laughter might be thought of as an audible expression or appearance of excitement, an inward feeling of joy and happiness. It may ensue from jokes , tickling , and other stimuli completely unrelated to psychological state, such as nitrous oxide . One group of researchers speculated that noises from infants as early as 16 days old may be vocal laughing sounds or laughter. However,
752-421: A beautifully tragic story. We take pleasure from many things that are not beautiful, which is why beauty is usually defined in terms of a special type of pleasure: aesthetic or disinterested pleasure. A pleasure is disinterested if it is indifferent to the existence of the beautiful object. For example, the joy of looking at a beautiful landscape would still be valuable if it turned out that this experience
940-502: A better knowledge of society. One of the theories of the essay is that laughter, as a collective activity, has a social and moral role, in forcing people to eliminate their vices. It is a factor of uniformity of behaviours, as it condemns ludicrous and eccentric behaviours. Anthony Ludovici developed the thoughts of Hobbes even further in The Secret of Laughter . His conviction is that there's something sinister in laughter, and that
1128-418: A broader system that incorporates both the memory and the spatial perspectives in its role that involves the use of a wide scope of cognitive maps. This relates to the purposive behaviorism born of Tolman's original goal of identifying the complex cognitive mechanisms and purposes that guided behaviour. It has also been proposed that the spiking activity of hippocampal neurons is associated spatially, and it
1316-636: A candidate mechanism for long-term memory , LTP has since been studied intensively, and a great deal has been learned about it. However, the complexity and variety of the intracellular signalling cascades that can trigger LTP is acknowledged as preventing a more complete understanding. The hippocampus is a particularly favorable site for studying LTP because of its densely packed and sharply defined layers of neurons, but similar types of activity-dependent synaptic change have also been observed in many other brain areas. The best-studied form of LTP has been seen in CA1 of
1504-452: A central role in theories from various areas of philosophy . Such theories are usually grouped together under the label "hedonism". Pleasure is related not just to how we actually act, but also to how we ought to act, which belongs to the field of ethics . Ethical hedonism takes the strongest position on this relation in stating that considerations of increasing pleasure and decreasing pain fully determine what we should do or which action
1692-496: A certain type of experience while well-being is about what is good for a person. Many philosophers agree that pleasure is good for a person and therefore is a form of well-being . But there may be other things besides or instead of pleasure that constitute well-being , like health, virtue, knowledge or the fulfillment of desires. On some conceptions, happiness is identified with "the individual's balance of pleasant over unpleasant experience". Life satisfaction theories , on
1880-418: A comparison with the shape of the folded back forelimbs and webbed feet of the mythological hippocampus , a sea monster with a horse's forequarters and a fish's tail. The hippocampus was then described as pes hippocampi major , with an adjacent bulge in the occipital horn , described as the pes hippocampi minor and later renamed as the calcar avis . The renaming of the hippocampus as hippocampus major, and
2068-487: A daily laughter record, and found they laughed an average of 18 times per day. However, their study also found a wide range, with some people laughing as many as 89 times per day, and others laughing as few as 0 times per day. Thomas Hobbes wrote, "The passion of laughter is nothing else but sudden glory arising from sudden conception of some eminency in ourselves, by comparison with the infirmity of others, or with our own formerly." Philosopher Arthur Schopenhauer devotes
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#17328022946822256-597: A dimension going from positive degrees through a neutral point to negative degrees. This assumption is important for the possibility of comparing and aggregating the degrees of pleasure of different experiences, for example, in order to perform the Utilitarian calculus . The concept of pleasure is similar but not identical to the concepts of well-being and of happiness . These terms are used in overlapping ways, but their meanings tend to come apart in technical contexts like philosophy or psychology. Pleasure refers to
2444-532: A distinct pattern of neural population activity and waves of electrical activity as measured by an electroencephalogram (EEG). These modes are named after the EEG patterns associated with them: theta and large irregular activity (LIA). The main characteristics described below are for the rat, which is the animal most extensively studied. The theta mode appears during states of active, alert behavior (especially locomotion), and also during REM (dreaming) sleep. In
2632-417: A full-fledged theory of the role of the hippocampus in anxiety. The inhibition theory is currently the least popular of the three. The second major line of thought relates the hippocampus to memory. Although it had historical precursors, this idea derived its main impetus from a famous report by American neurosurgeon William Beecher Scoville and British-Canadian neuropsychologist Brenda Milner describing
2820-555: A good name, power, piety, benevolence, malevolence, memory, imagination, expectation, pleasures dependent on association, and the pleasures of relief. Some commentators see 'complex pleasures' including wit and sudden realisation, and some see a wide range of pleasurable feelings. Pleasure comes in various forms, for example, in the enjoyment of food, sex, sports, seeing a beautiful sunset or engaging in an intellectually satisfying activity. Theories of pleasure try to determine what all these pleasurable experiences have in common, what
3008-603: A hedonic coldspot. In rats, microinjections of opioids , endocannabinoids , and orexin are capable of enhancing liking reactions in these hotspots. The hedonic hotspots located in the anterior OFC and posterior insula have been demonstrated to respond to orexin and opioids in rats, as has the overlapping hedonic coldspot in the anterior insula and posterior OFC. On the other hand, the parabrachial nucleus hotspot has only been demonstrated to respond to benzodiazepine receptor agonists. While all pleasurable stimuli can be seen as rewards, some rewards do not evoke pleasure. Based upon
3196-449: A hidden goal. Other cells have been discovered since the finding of the place cells in the rodent brain that are either in the hippocampus or the entorhinal cortex. These have been assigned as head direction cells , grid cells and boundary cells . Speed cells are thought to provide input to the hippocampal grid cells. Approach-avoidance conflict happens when a situation is presented that can either be rewarding or punishing, and
3384-478: A laugh despite individual variants. It has also been determined that eyes moisten during laughter as a reflex from the tear glands. Laughter is not always a pleasant experience and is associated with several negative phenomena. Excessive laughter can lead to cataplexy , and unpleasant laughter spells, excessive elation, and fits of laughter can all be considered negative aspects of laughter. Unpleasant laughter spells, or "sham mirth", usually occur in people who have
3572-412: A learned capacity to delay immediate gratification in order to take the real consequences of our actions into account. Freud also described the pleasure principle as a positive feedback mechanism that motivates the organism to recreate the situation it has just found pleasurable, and to avoid past situations that caused pain . A cognitive bias is a systematic tendency of thinking and judging in
3760-405: A life-long memory of the event even after a single training session. The memory of such an event appears to be first stored in the hippocampus, but this storage is transient. Much of the long-term storage of the memory seems to take place in the anterior cingulate cortex . When such an intense learning event was experimentally applied, more than 5,000 differently methylated DNA regions appeared in
3948-474: A line of work that eventually led to their very influential 1978 book The Hippocampus as a Cognitive Map . There is now almost universal agreement that hippocampal function plays an important role in spatial coding, but the details are widely debated. Later research has focused on trying to bridge the disconnect between the two main views of hippocampal function as being split between memory and spatial cognition. In some studies, these areas have been expanded to
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#17328022946824136-436: A negative sensation, one that negates the usual existential condition of suffering. Pleasure is often regarded as a bipolar construct, meaning that the two ends of the spectrum from pleasure to suffering are mutually exclusive. That is part of the circumplex model of affect. Yet, some lines of research suggest that people do experience pleasure and suffering at the same time, giving rise to so-called mixed feelings. Pleasure
4324-426: A neurological condition, including patients with pseudobulbar palsy , multiple sclerosis and Parkinson's disease . These patients appear to be laughing out of amusement but report that they are feeling undesirable sensations "at the time of the punch line". Excessive elation is a common symptom associated with bipolar disorder psychoses and mania / hypomania . Those with schizophrenic psychoses seem to experience
4512-600: A number of positive emotional states, such as joy, mirth, happiness or relief. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, surprise, or confusion such as nervous laughter or courtesy laugh . Age, gender, education, language and culture are all indicators as to whether a person will experience laughter in a given situation. Other than humans, some other species of primate ( chimpanzees , gorillas and orangutans ) show laughter-like vocalizations in response to physical contact such as wrestling, play chasing or tickling. Laughter
4700-415: A number of studies that show the involvement of the hippocampus in conflict tasks. The authors suggest that one challenge is to understand how conflict processing relates to the functions of spatial navigation and memory and how all of these functions need not be mutually exclusive. The hippocampus has received renewed attention for its role in social memory. Epileptic human subjects with depth electrodes in
4888-450: A person is trying to cope with a terminal illness or just trying to manage their stress or anxiety levels, laughter therapy can be a significant enhancement to their life. Ramon Mora-Ripoll in his study on The Therapeutic Value Of Laughter In Medicine, stated that laughter therapy is an inexpensive and simple tool that can be used in patient care. It is a tool that is only beneficial when experienced and shared. Care givers need to recognize
5076-534: A positive character for Nietzsche." Laughter can, however, also have a negative connotation when it is used for the expression of social conflict. This is expressed, for instance, in The Gay Science : "Laughter – Laughter means to be schadenfroh , but with clear conscience." "Possibly Nietzsche's works would have had a totally different effect, if the playful, ironical and joking in his writings would have been factored in better." In Laughter: An Essay on
5264-511: A proportion of the claimed CA1 cells in the study. The dorsal CA2 and ventral CA1 subregions of the hippocampus have been implicated in social memory processing. Genetic inactivation of CA2 pyramidal neurons leads to pronounced loss of social memory, while maintaining intact sociability in mice. Similarly, ventral CA1 pyramidal neurons have also been demonstrated as critical for social memory under optogenetic control in mice. The hippocampus shows two major "modes" of activity, each associated with
5452-411: A rat's location to be reconstructed with high confidence. The size of place fields varies in a gradient along the length of the hippocampus, with cells at the dorsal end showing the smallest fields, cells near the center showing larger fields, and cells at the ventral tip showing fields that cover the entire environment. In some cases, the firing rate of hippocampal cells depends not only on place but also
5640-468: A result of a learned association with an intrinsic reward. In other words, extrinsic rewards function as motivational magnets that elicit "wanting", but not "liking" reactions once they have been acquired. The reward system contains pleasure centers or hedonic hotspots – i.e., brain structures that mediate pleasure or "liking" reactions from intrinsic rewards. As of October 2017, hedonic hotspots have been identified in subcompartments within
5828-541: A result of depression, but this can be stopped with anti-depressants even if they are not effective in relieving other symptoms. Chronic stress resulting in elevated levels of glucocorticoids , notably of cortisol , is seen to be a cause of neuronal atrophy in the hippocampus. This atrophy results in a smaller hippocampal volume which is also seen in Cushing's syndrome . The higher levels of cortisol in Cushing's syndrome
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6016-579: A room whilst in a restraint chair. However, the place cells may have fired in relation to where the monkey was looking rather than to its actual location in the room. Over many years, many studies have been carried out on place-responses in rodents, which have given a large amount of information. Place cell responses are shown by pyramidal cells in the hippocampus and by granule cells in the dentate gyrus . Other cells in smaller proportion are inhibitory interneurons , and these often show place-related variations in their firing rate that are much weaker. There
6204-400: A sensation but as an aspect qualifying sensations or other mental phenomena. As an aspect, pleasure is dependent on the mental phenomenon it qualifies, it cannot be present on its own. Since the link to the enjoyed phenomenon is already built into the pleasure, it solves the problem faced by sensation theories to explain how this link comes about. It also captures the intuition that pleasure
6392-477: A severe impact on many types of cognition including memory . Even normal aging is associated with a gradual decline in some types of memory, including episodic memory and working memory (or short-term memory ). Because the hippocampus is thought to play a central role in memory, there has been considerable interest in the possibility that age-related declines could be caused by hippocampal deterioration. Some early studies reported substantial loss of neurons in
6580-444: A sharp wave, there is a dramatic increase in firing rate in up to 10% of the hippocampal population These two hippocampal activity modes can be seen in primates as well as rats, with the exception that it has been difficult to see robust theta rhythmicity in the primate hippocampus. There are, however, qualitatively similar sharp waves and similar state-dependent changes in neural population activity. The underlying currents producing
6768-526: A three-step process. First, it needs a situation that seems odd and induces a sense of incongruity (bewilderment or panic). Second, the worry or stress the incongruous situation has provoked must be worked out and overcome (resolution). Third, the actual release of laughter acts as an all-clear siren to alert bystanders (relief) that they are safe. Chimpanzees and other great apes perform laugh-like vocalizations, and some ultrasonic noises made by rats have been interpreted as laughter. Pleasure Pleasure
6956-502: A treatment program for his ankylosing spondylitis and collagen disease consisting of large doses of Vitamin C alongside laughter induced by comic films, including those of the Marx Brothers . "I made the joyous discovery that ten minutes of genuine belly laughter had an anesthetic effect and would give me at least two hours of pain-free sleep," he reported. "When the pain-killing effect of the laughter wore off, we would switch on
7144-610: A very irregular temporal pattern. Sharp waves are less frequent during inactive waking states and are usually smaller. Sharp waves have also been observed in humans and monkeys. In macaques, sharp waves are robust but do not occur as frequently as in rats. One of the most interesting aspects of sharp waves is that they appear to be associated with memory. Wilson and McNaughton 1994, and numerous later studies, reported that when hippocampal place cells have overlapping spatial firing fields (and therefore often fire in near-simultaneity), they tend to show correlated activity during sleep following
7332-405: A way that deviates from a normative criterion, especially from the demands of rationality . Cognitive biases in regard to pleasure include the peak–end rule , the focusing illusion , the nearness bias and the future bias . The peak–end rule affects how we remember the pleasantness or unpleasantness of experiences. It states that our overall impression of past events is determined for
7520-482: Is good in itself . This position entails that things other than pleasure, like knowledge, virtue or money, only have instrumental value : they are valuable because or to the extent that they produce pleasure but lack value otherwise. Within the scope of axiological hedonism, there are two competing theories about the exact relation between pleasure and value: quantitative hedonism and qualitative hedonism . Quantitative hedonists, following Jeremy Bentham , hold that
7708-405: Is a part of human behavior regulated by the brain , helping humans clarify their intentions in social interaction and providing an emotional context to conversations. Laughter is used as a signal for being part of a group—it signals acceptance and positive interactions with others. Laughter is sometimes seen as contagious and the laughter of one person can itself provoke laughter from others as
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7896-406: Is activated by quite diverse pleasures, suggesting a common neural currency. Some commentators opine that our current understanding of how pleasure happens within us remains poor, but that scientific advance gives optimism for future progress. In the past, there has been debate as to whether pleasure is experienced by other animals rather than being an exclusive property of humankind; however, it
8084-462: Is also substantial evidence that it makes a contribution to memory, which can be distinguished from the contribution of the hippocampus. It is apparent that complete amnesia occurs only when both the hippocampus and the parahippocampus are damaged. The major input to the hippocampus is through the entorhinal cortex (EC), whereas its major output is via CA1 to the subiculum. Information reaches CA1 via two main pathways, direct and indirect. Axons from
8272-423: Is available to everyone and it provides benefits to a person's physical, emotional, and social well being. Some of the benefits of using laughter therapy are that it can relieve stress and relax the whole body. It can also boost the immune system and release endorphins to relieve pain. Additionally, laughter can help prevent heart disease by increasing blood flow and improving the function of blood vessels. Some of
8460-402: Is by pointing out that the hedonic tone of pleasure-experiences is not a regular quality but a higher-order quality. As an analogy, a vividly green thing and a vividly red thing do not share a regular color property but they share "vividness" as a higher-order property. Attitude theories propose to analyze pleasure in terms of attitudes to experiences. So to enjoy the taste of chocolate it
8648-406: Is called anhedonia . An active aversion to obtaining pleasure is called hedonophobia . The degree to which something or someone is experienced as pleasurable not only depends on its objective attributes (appearance, sound, taste, texture, etc.), but on beliefs about its history, about the circumstances of its creation, about its rarity, fame, or price, and on other non-intrinsic attributes, such as
8836-413: Is concealed by the parahippocampal gyrus . The cortex thins from six layers to the three or four layers that make up the hippocampus. The term hippocampal formation is used to refer to the hippocampus proper and its related parts. However, there is no consensus as to what parts are included. Sometimes the hippocampus is said to include the dentate gyrus and the subiculum . Some references include
9024-399: Is considered one of the core dimensions of emotion. It can be described as the positive evaluation that forms the basis for several more elaborate evaluations such as "agreeable" or "nice". As such, pleasure is an affect and not an emotion , as it forms one component of several different emotions. The clinical condition of being unable to experience pleasure from usually enjoyable activities
9212-399: Is described as having an anterior and posterior part (in primates ) or a ventral and dorsal part in other animals. Both parts are of similar composition but belong to different neural circuits . In the rat, the two hippocampi resemble a pair of bananas, joined at the stems by the commissure of fornix (also called the hippocampal commissure). In primates , the part of the hippocampus at
9400-414: Is essential to them. They are traditionally divided into quality theories and attitude theories. An alternative terminology refers to these theories as phenomenalism and intentionalism . Quality theories hold that pleasure is a quality of pleasurable experiences themselves while attitude theories state that pleasure is in some sense external to the experience since it depends on the subject's attitude to
9588-429: Is experience that feels good, that involves the enjoyment of something. It contrasts with pain or suffering , which are forms of feeling bad. It is closely related to value, desire and action: humans and other conscious animals find pleasure enjoyable, positive or worthy of seeking. A great variety of activities may be experienced as pleasurable, like eating, having sex, listening to music or playing games. Pleasure
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#17328022946829776-461: Is happening. This variant, originally held by Henry Sidgwick , has recently been defended by Chris Heathwood, who holds that an experience is pleasurable if the subject of the experience wants the experience to occur for its own sake while it is occurring. But this version faces a related problem akin to the Euthyphro dilemma : it seems that we usually desire things because they are enjoyable, not
9964-414: Is highly communicative and helps accomplish actions and regulate relationships. Common causes for laughter are sensations of joy and humor ; however, other situations may cause laughter as well. A general theory that explains laughter is called the relief theory . Sigmund Freud summarized it in his theory that laughter releases tension and "psychic energy". This theory is one of the justifications of
10152-437: Is how to explain the relation between beauty and pleasure. This problem is akin to the Euthyphro dilemma : is something beautiful because we enjoy it or do we enjoy it because it is beautiful? Identity theorists solve this problem by denying that there is a difference between beauty and pleasure: they identify beauty, or the appearance of it, with the experience of aesthetic pleasure. The ancient Cyrenaics posited pleasure as
10340-515: Is involved in emotions and helps us with functions necessary for humans' survival. The structures in the limbic system that are involved in laughter are the hippocampus and the amygdala . The December 7, 1984, Journal of the American Medical Association describes the neurological causes of laughter as follows: Some drugs are well known for their laughter-facilitating properties (e. g. ethanol and cannabis ), while
10528-437: Is little, if any, spatial topography in the representation; in general, cells lying next to each other in the hippocampus have uncorrelated spatial firing patterns. Place cells are typically almost silent when a rat is moving around outside the place field but reach sustained rates as high as 40 Hz when the rat is near the center. Neural activity sampled from 30 to 40 randomly chosen place cells carries enough information to allow
10716-408: Is no laugh, as Mack Sennett pointed out: "when the audience is confused, it doesn't laugh." This is one of the basic laws of a comedian , referred to as "exactness". It is important to note that sometimes the inconsistency may be resolved and there may still be no laugh. Because laughter is a social mechanism, an audience may not feel as if they are in danger, and the laugh may not occur. In addition,
10904-421: Is not sufficient to have the corresponding experience of the taste. Instead, the subject has to have the right attitude to this taste for pleasure to arise. This approach captures the intuition that a second person may have exactly the same taste-experience but not enjoy it since the relevant attitude is lacking. Various attitudes have been proposed for the type of attitude responsible for pleasure, but historically
11092-458: Is not yet clear. In rats (the animals that have been the most extensively studied), theta is seen mainly in two conditions: first, when an animal is walking or in some other way actively interacting with its surroundings; second, during REM sleep . The function of theta has not yet been convincingly explained although numerous theories have been proposed. The most popular hypothesis has been to relate it to learning and memory. An example would be
11280-424: Is now known that animals do experience pleasure, as measured by objective behavioral and neural hedonic responses to pleasurable stimuli. Hippocampus The hippocampus ( pl. : hippocampi ; via Latin from Greek ἱππόκαμπος , ' seahorse ') is a major component of the brain of humans and other vertebrates . Humans and other mammals have two hippocampi, one in each side of the brain . The hippocampus
11468-516: Is occasionally interrupted by large surges called sharp waves . These events are associated with bursts of spike activity lasting 50 to 100 milliseconds in pyramidal cells of CA3 and CA1. They are also associated with short-lived high-frequency EEG oscillations called "ripples", with frequencies in the range 150 to 200 Hz in rats, and together they are known as sharp waves and ripples . Sharp waves are most frequent during sleep when they occur at an average rate of around 1 per second (in rats) but in
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#173280229468211656-466: Is part of the limbic system , and plays important roles in the consolidation of information from short-term memory to long-term memory , and in spatial memory that enables navigation. The hippocampus is located in the allocortex , with neural projections into the neocortex , in humans as well as other primates. The hippocampus, as the medial pallium , is a structure found in all vertebrates . In humans, it contains two main interlocking parts:
11844-484: Is part of various other mental states such as ecstasy , euphoria and flow . Happiness and well-being are closely related to pleasure but not identical with it. There is no general agreement as to whether pleasure should be understood as a sensation, a quality of experiences, an attitude to experiences or otherwise. Pleasure plays a central role in the family of philosophical theories known as hedonism . "Pleasure" refers to experience that feels good, that involves
12032-445: Is partly why returning to a location where an emotional event occurred may evoke that emotion. There is a deep emotional connection between episodic memories and places. Due to bilateral symmetry the brain has a hippocampus in each cerebral hemisphere . If damage to the hippocampus occurs in only one hemisphere, leaving the structure intact in the other hemisphere, the brain can retain near-normal memory functioning. Severe damage to
12220-675: Is related to the anterior parts of the right and left hippocampus. The right head of the hippocampus is more involved in executive functions and regulation during verbal memory recall. The tail of the left hippocampus tends to be closely related to verbal memory capacity. Damage to the hippocampus does not affect some types of memory, such as the ability to learn new skills (playing a musical instrument or solving certain types of puzzles, for example). This fact suggests that such abilities depend on different types of memory ( procedural memory ) and different brain regions. Furthermore, amnesic patients frequently show "implicit" memory for experiences even in
12408-458: Is remembered less negatively due to the reduced pain at the end. This even increases the likelihood for the patient to return for subsequent procedures. Daniel Kahneman explains this distortion in terms of the difference between two selves : the experiencing self , which is aware of pleasure and pain as they are happening, and the remembering self , which shows the aggregate pleasure and pain over an extended period of time. The distortions due to
12596-439: Is right. Ethical hedonist theories can be classified in relation to whose pleasure should be increased. According to the egoist version, each agent should only aim at maximizing her own pleasure. This position is usually not held in very high esteem. Utilitarianism , on the other hand, is a family of altruist theories that are more respectable in the philosophical community. Within this family, classical utilitarianism draws
12784-433: Is self-defeating in the sense that it leads to less actual pleasure than following other motives. Sigmund Freud formulated his pleasure principle in order to account for the effect pleasure has on our behavior. It states that there is a strong, inborn tendency of our mental life to seek immediate gratification whenever an opportunity presents itself. This tendency is opposed by the reality principle , which constitutes
12972-401: Is suggested that the memory, spatial cognition, and conflict processing functions may be seen as working together and not mutually exclusive. Psychologists and neuroscientists generally agree that the hippocampus plays an important role in the formation of new memories about experienced events ( episodic or autobiographical memory ). Part of this function is hippocampal involvement in
13160-399: Is the thesis that all our actions aim at increasing pleasure and avoiding pain. Freud 's pleasure principle ties pleasure to motivation and action by holding that there is a strong psychological tendency to seek pleasure and to avoid pain. Classical utilitarianism connects pleasure to ethics in stating that whether an action is right depends on the pleasure it produces: it should maximize
13348-425: Is unnatural, and one is physically unable, to have a laugh structure of "ha-ho-ha-ho". The usual variations of a laugh most often occur in the first or final note in a sequence- therefore, "ho-ha-ha" or "ha-ha-ho" laughs are possible. Normal note durations with unusually long or short "inter-note intervals" do not happen due to the result of the limitations of our vocal cords. This basic structure allows one to recognize
13536-405: Is usually pleasure of something: enjoyment of drinking a milkshake or of playing chess but not just pure or object-less enjoyment. According to this approach, pleasurable experiences differ in content (drinking a milkshake, playing chess) but agree in feeling or hedonic tone. Pleasure can be localized, but only to the extent that the impression it qualifies is localized. One objection to both
13724-447: Is usually the result of medications taken for other conditions. Neuronal loss also occurs as a result of impaired neurogenesis. Another factor that contributes to a smaller hippocampal volume is that of dendritic retraction where dendrites are shortened in length and reduced in number, in response to increased glucocorticoids. This dendritic retraction is reversible. After treatment with medication to reduce cortisol in Cushing's syndrome,
13912-499: Is usually understood in combination with egoism , i.e. that each person only aims at her own happiness. Our actions rely on beliefs about what causes pleasure. False beliefs may mislead us and thus our actions may fail to result in pleasure, but even failed actions are motivated by considerations of pleasure, according to psychological hedonism . The paradox of hedonism states that pleasure-seeking behavior commonly fails also in another way. It asserts that being motivated by pleasure
14100-560: The Great Hippocampus Question . The term hippocampus minor fell from use in anatomy textbooks and was officially removed in the Nomina Anatomica of 1895. Today, the structure is just called the hippocampus, with the term cornu Ammonis (that is, 'Ammon's horn') surviving in the names of the hippocampal subfields CA1-CA4 . The term limbic system was introduced in 1952 by Paul MacLean to describe
14288-712: The Iliad and Odyssey ) has been studied and analyzed by many thinkers and writers, from the Ancient Greek philosophers onward. Henri Bergson 's Laughter: An Essay on the Meaning of the Comic ( Le rire , 1901) is a notable 20th-century contribution. For Herodotus , laughers can be distinguished into three types: According to Donald Lateiner , Herodotus reports about laughter for valid literary and historiological reasons. "Herodotus believes either that both nature (better,
14476-423: The entorhinal cortex via the perforant path . The entorhinal cortex (EC) is strongly and reciprocally connected with many cortical and subcortical structures as well as with the brainstem. Different thalamic nuclei , (from the anterior and midline groups), the medial septal nucleus , the supramammillary nucleus of the hypothalamus, and the raphe nuclei and locus coeruleus of the brainstem all send axons to
14664-522: The hippocampus proper (also called Ammon's horn ), and the dentate gyrus . In Alzheimer's disease (and other forms of dementia ), the hippocampus is one of the first regions of the brain to suffer damage; short-term memory loss and disorientation are included among the early symptoms. Damage to the hippocampus can also result from oxygen starvation ( hypoxia ), encephalitis , or medial temporal lobe epilepsy . People with extensive, bilateral hippocampal damage may experience anterograde amnesia :
14852-475: The hypothalamic mammillary body , and the anterior nuclear complex in the thalamus , and is generally accepted to be part of the limbic system. The hippocampus can be seen as a ridge of gray matter tissue , elevating from the floor of each lateral ventricle in the region of the inferior or temporal horn. This ridge can also be seen as an inward fold of the archicortex into the medial temporal lobe . The hippocampus can only be seen in dissections as it
15040-424: The incentive salience model of reward – the attractive and motivational property of a stimulus that induces approach behavior and consummatory behavior – an intrinsic reward has two components: a "wanting" or desire component that is reflected in approach behavior, and a "liking" or pleasure component that is reflected in consummatory behavior. Some research indicates that similar mesocorticolimbic circuitry
15228-412: The nucleus accumbens shell , ventral pallidum , parabrachial nucleus , orbitofrontal cortex (OFC), and insular cortex . The hotspot within the nucleus accumbens shell is located in the rostrodorsal quadrant of the medial shell, while the hedonic coldspot is located in a more posterior region. The posterior ventral pallidum also contains a hedonic hotspot, while the anterior ventral pallidum contains
15416-440: The peak–end rule happen on the level of the remembering self . Our tendency to rely on the remembering self can often lead us to pursue courses of action that are not in our best self-interest. A closely related bias is the focusing illusion . The "illusion" occurs when people consider the impact of one specific factor on their overall happiness. They tend to greatly exaggerate the importance of that factor, while overlooking
15604-474: The thalamus to field CA1. A very important projection comes from the medial septal nucleus, which sends cholinergic , and gamma amino butyric acid (GABA) stimulating fibers (GABAergic fibers) to all parts of the hippocampus. The inputs from the medial septal nucleus play a key role in controlling the physiological state of the hippocampus; destruction of this nucleus abolishes the hippocampal theta rhythm and severely impairs certain types of memory. Areas of
15792-505: The 12th century, Razi 's Treatise of the Self and the Spirit ( Kitab al Nafs Wa’l Ruh ) analyzed different types of pleasure- sensuous and intellectual , and explained their relations with one another. He concludes that human needs and desires are endless, and "their satisfaction is by definition impossible." The 19th-century German philosopher Arthur Schopenhauer understood pleasure as
15980-415: The 13th chapter of the first part of his major work, The World as Will and Representation , to laughter. Friedrich Nietzsche distinguishes two different purposes for the use of laughter. In a positive sense, "man uses the comical as a therapy against the restraining jacket of logic, morality and reason. He needs from time to time a harmless demotion from reason and hardship and in this sense laughter has
16168-510: The DH were shown to cause spatial memory impairment while VH lesions did not. Its projecting pathways include the medial septal nucleus and supramammillary nucleus . The dorsal hippocampus also has more place cells than both the ventral and intermediate hippocampal regions. The intermediate hippocampus has overlapping characteristics with both the ventral and dorsal hippocampus. Using anterograde tracing methods, Cenquizca and Swanson (2007) located
16356-513: The DNA base excision repair pathway (see Epigenetics in learning and memory ). The between-systems memory interference model describes the inhibition of non-hippocampal systems of memory during concurrent hippocampal activity. Specifically, Fraser Sparks, Hugo Lehmann, and Robert Sutherland found that when the hippocampus was inactive, non-hippocampal systems located elsewhere in the brain were found to consolidate memory in its place. However, when
16544-451: The EC that originate in layer III are the origin of the direct perforant pathway and form synapses on the very distal apical dendrites of CA1 neurons. Conversely, axons originating from layer II are the origin of the indirect pathway, and information reaches CA1 via the trisynaptic circuit . In the initial part of this pathway, the axons project through the perforant pathway to the granule cells of
16732-403: The EC, so that it serves as the interface between the neocortex and the other connections, and the hippocampus. The EC is located in the parahippocampal gyrus , a cortical region adjacent to the hippocampus. This gyrus conceals the hippocampus. The parahippocampal gyrus is adjacent to the perirhinal cortex , which plays an important role in the visual recognition of complex objects. There
16920-501: The LIA mode, the EEG is dominated by sharp waves that are randomly timed large deflections of the EEG signal lasting for 25–50 milliseconds. Sharp waves are frequently generated in sets, with sets containing up to 5 or more individual sharp waves and lasting up to 500 ms. The spiking activity of neurons within the hippocampus is highly correlated with sharp wave activity. Most neurons decrease their firing rate between sharp waves; however, during
17108-445: The Meaning of the Comic , French philosopher Henri Bergson , renowned for his philosophical studies on materiality, memory, life and consciousness , tries to determine the laws of the comic and to understand the fundamental causes of comic situations. His method consists in determining the causes of the comic instead of analyzing its effects. He also deals with laughter in relation to human life, collective imagination and art , to have
17296-558: The ability to laugh. Provine argues that "Laughter is primitive, an unconscious vocalization." Provine argues that it probably is genetic. In a study of the "Giggle Twins", two happy twins who were separated at birth and only reunited 43 years later, Provine reports that "until they met each other, neither of these exceptionally happy ladies had known anyone who laughed as much as they did." They reported this even though they had been brought together by their adoptive parents, who they indicated were "undemonstrative and dour". He indicates that
17484-481: The absence of conscious knowledge. For example, patients asked to guess which of two faces they have seen most recently may give the correct answer most of the time in spite of stating that they have never seen either of the faces before. Some researchers distinguish between conscious recollection , which depends on the hippocampus, and familiarity , which depends on portions of the medial temporal lobe. When rats are exposed to an intense learning event, they may retain
17672-432: The ancient Egyptian god often portrayed as such takes the name c ornu A mmonis . Its abbreviation CA is used in naming the hippocampal subfields CA1, CA2, CA3, and CA4 . It can be distinguished as an area where the cortex narrows into a single layer of densely packed pyramidal neurons , which curl into a tight U shape. One edge of the "U," – CA4, is embedded into the backward-facing, flexed dentate gyrus. The hippocampus
17860-525: The area of depression, anxiety and stress levels. There were limited harmful side effects. Laughter therapy should be used in conjunction with other cancer treatment. Laughter in literature, although considered understudied by some, is a subject that has received attention in the written word for millennia. The use of humor and laughter in literary works (for example the homeric laughter (ἄσβεστος γέλως, ásbestos gélōs, “unceasing laughter”) in Greek epics like
18048-493: The behavioral session. This enhancement of correlation, commonly known as reactivation , has been found to occur mainly during sharp waves. It has been proposed that sharp waves are, in fact, reactivations of neural activity patterns that were memorized during behavior, driven by strengthening of synaptic connections within the hippocampus. This idea forms a key component of the "two-stage memory" theory, advocated by Buzsáki and others, which proposes that memories are stored within
18236-400: The beliefs that laughter is beneficial for one's health. This theory explains why laughter can be used as a coping mechanism when one is upset, angry or sad . Philosopher John Morreall theorizes that human laughter may have its biological origins as a kind of shared expression of relief at the passing of danger. Friedrich Nietzsche , by contrast, suggested laughter to be a reaction to
18424-428: The bottom, near the base of the temporal lobe , is much broader than the part at the top. This means that in cross-section the hippocampus can show a number of different shapes, depending on the angle and location of the cut. In a cross-section of the hippocampus, including the dentate gyrus, several layers will be shown. The dentate gyrus has three layers of cells (or four if the hilus is included). The layers are from
18612-484: The brain releases endorphins that can relieve some physical pain. Laughter also boosts the number of antibody-producing cells and enhances the effectiveness of T-cells, leading to a stronger immune system. A 2000 study found that people with heart disease were 40 percent less likely to laugh and be able to recognize humor in a variety of situations, compared to people of the same age without heart disease. Anecdotally, journalist and author Norman Cousins developed in 1964
18800-417: The brain that are either in the hippocampus itself or are strongly connected to it, such as the speed cells present in the medial entorhinal cortex . Together these cells form a network that serves as spatial memory. The first of such cells discovered in the 1970s were the place cells, which led to the idea of the hippocampus acting to give a neural representation of the environment in a cognitive map . When
18988-470: The brakes!") was very popular up to the 1960s. It derived much of its justification from two observations: first, that animals with hippocampal damage tend to be hyperactive ; second, that animals with hippocampal damage often have difficulty learning to inhibit responses that they have previously been taught, especially if the response requires remaining quiet as in a passive avoidance test. British psychologist Jeffrey Gray developed this line of thought into
19176-441: The calcar avis as hippocampus minor, has been attributed to Félix Vicq-d'Azyr systematizing nomenclature of parts of the brain in 1786. Mayer mistakenly used the term hippopotamus in 1779, and was followed by some other authors until Karl Friedrich Burdach resolved this error in 1829. In 1861 the hippocampus minor became the center of a dispute over human evolution between Thomas Henry Huxley and Richard Owen , satirized as
19364-406: The case that we desire something first and then enjoy it, this cannot always be the case. In fact, often the opposite seems to be true: we have to learn first that something is enjoyable before we start to desire it. This objection can be partially avoided by holding that it does not matter whether the desire was there before the experience but that it only matters what we desire while the experience
19552-468: The chocolate. But this account cannot explain why the enjoyment is linked to the taste of the chocolate and not to the itch. Another problem is due to the fact that sensations are usually thought of as localized somewhere in the body. But considering the pleasure of seeing a beautiful sunset, there seems to be no specific region in the body at which we experience this pleasure. These problems can be avoided by felt-quality-theories, which see pleasure not as
19740-414: The closest connection between pleasure and right action by holding that the agent should maximize the sum-total of everyone's happiness. This sum-total includes the agent's pleasure as well, but only as one factor among many. Pleasure is intimately connected to value as something that is desirable and worth seeking. According to axiological hedonism , it is the only thing that has intrinsic value or
19928-408: The definition of beauty by holding that there is a necessary connection between pleasure and beauty, e.g. that for an object to be beautiful is for it to cause pleasure or that the experience of beauty is always accompanied by pleasure. The pleasure due to beauty does not need to be pure , i.e. exclude all unpleasant elements. Instead, beauty can involve mixed pleasure, for example, in the case of
20116-474: The dentate gyrus (first synapse). From then, the information follows via the mossy fibres to CA3 (second synapse). From there, CA3 axons called Schaffer collaterals leave the deep part of the cell body and loop up to the apical dendrites and then extend to CA1 (third synapse). Axons from CA1 then project back to the entorhinal cortex, completing the circuit. Basket cells in CA3 receive excitatory input from
20304-404: The dentate gyrus and the subiculum in the hippocampal formation, and others also include the presubiculum, parasubiculum , and entorhinal cortex . The neural layout and pathways within the hippocampal formation are very similar in all mammals. The hippocampus, including the dentate gyrus, has the shape of a curved tube, which has been compared to a seahorse, and to a horn of a ram, which after
20492-412: The detection of new events, places and stimuli. Some researchers regard the hippocampus as part of a larger medial temporal lobe memory system responsible for general declarative memory (memories that can be explicitly verbalized – these would include, for example, memory for facts in addition to episodic memory). The hippocampus also encodes emotional context from the amygdala . This
20680-651: The dilatation of the inner lining of blood vessels, the endothelium , and increases blood flow. Drs. Michael Miller (University of Maryland) and William Fry (Stanford) theorize that beta-endorphin-like compounds released by the hypothalamus activate receptors on the endothelial surface to release nitric oxide , thereby resulting in dilation of vessels. Other cardioprotective properties of nitric oxide include reduction of inflammation and decreased platelet aggregation. Laughter has various proven beneficial biochemical effects. It has been shown to lead to reductions in stress hormones such as cortisol and epinephrine . When laughing,
20868-410: The direction a rat is moving, the destination toward which it is traveling, or other task-related variables. The firing of place cells is timed in relation to local theta waves , a process termed phase precession . In humans, cells with location-specific firing patterns have been reported during a study of patients with drug-resistant epilepsy . They were undergoing an invasive procedure to localize
21056-658: The direction of time. On the positive side, we prefer pleasurable experiences to be in the future rather than in the past. On the negative side, we prefer painful experiences to be in the past rather than in the future. Pleasure is a component of reward, but not all rewards are pleasurable (e.g., money does not elicit pleasure unless this response is conditioned). Stimuli that are naturally pleasurable, and therefore attractive, are known as intrinsic rewards , whereas stimuli that are attractive and motivate approach behavior, but are not inherently pleasurable, are termed extrinsic rewards . Extrinsic rewards (e.g., money) are rewarding as
21244-422: The earliest widely held hypothesis was that the hippocampus is involved in olfaction . This idea was cast into doubt by a series of anatomical studies that did not find any direct projections to the hippocampus from the olfactory bulb . However, later work did confirm that the olfactory bulb does project into the ventral part of the lateral entorhinal cortex, and field CA1 in the ventral hippocampus sends axons to
21432-480: The elderly than in the young. Furthermore, a randomized control trial published in 2011 found that aerobic exercise could increase the size of the hippocampus in adults aged 55 to 80 and also improve spatial memory. The hippocampus contains high levels of glucocorticoid receptors , which make it more vulnerable to long-term stress than most other brain areas . There is evidence that humans having experienced severe, long-lasting traumatic stress show atrophy of
21620-427: The emotional benefits include diminishing anxiety or fear, improving overall mood, and adding joy to one's life. Laughter is also known to reduce allergic reactions in a preliminary study related to dust mite allergy sufferers. Laughter therapy also has some social benefits, such as strengthening relationships, improving teamwork and reducing conflicts, and making oneself more attractive to others. Therefore, whether
21808-481: The enjoyment of something. The term is primarily used in association with sensory pleasures like the enjoyment of sex or food. But in its most general sense, it includes all types of positive or pleasant experiences including the enjoyment of sports, seeing a beautiful sunset or engaging in an intellectually satisfying activity. Pleasure contrasts with pain or suffering, which are forms of feeling bad. Both pleasure and pain come in degrees and have been thought of as
21996-482: The ensuing decision-making has been associated with anxiety . fMRI findings from studies in approach-avoidance decision-making found evidence for a functional role that is not explained by either long-term memory or spatial cognition. Overall findings showed that the anterior hippocampus is sensitive to conflict, and that it may be part of a larger cortical and subcortical network seen to be important in decision-making in uncertain conditions. A review makes reference to
22184-409: The experience. More recently, dispositional theories have been proposed that incorporate elements of both traditional approaches. In everyday language, the term "pleasure" is primarily associated with sensory pleasures like the enjoyment of food or sex. One traditionally important quality-theory closely follows this association by holding that pleasure is a sensation. On the simplest version of
22372-419: The extent of the inconsistency (and aspects of its timing and rhythm) has to do with the amount of danger the audience feels, and how hard or long they laugh. Laughter can also be brought on by tickling . Although most people find it unpleasant, being tickled often causes heavy laughter, thought to be an (often uncontrollable) reflex of the body. A normal laugh has the structure of "ha-ha-ha" or "ho-ho-ho". It
22560-407: The fastest routes between them in order to pass a strict test known as The Knowledge in order to gain a license to operate. A study showed that the posterior part of the hippocampus is larger in these drivers than in the general public, and that a positive correlation exists between the length of time served as a driver and the increase in the volume of this part. It was also found the total volume of
22748-518: The first to illustrate the structure, also wavered between "seahorse" and "silkworm". "Ram's horn" was proposed by the Danish anatomist Jacob Winsløw in 1732; and a decade later his fellow Parisian, the surgeon de Garengeot, used cornu Ammonis – horn of Amun , the ancient Egyptian god who was often represented as having a ram's head. Another reference appeared with the term pes hippocampi , which may date back to Diemerbroeck in 1672, introducing
22936-415: The gods' direction of it) and human nature coincide sufficiently, or that the latter is but an aspect or analogue of the former, so that to the recipient the outcome is suggested." When reporting laughter, Herodotus does so in the conviction that it tells the reader something about the future and/or the character of the person laughing. It is also in this sense that it is not coincidental that in about 80% of
23124-440: The grounds that it threatens to turn axiological hedonism into a "philosophy of swine". Instead, they argue that the quality is another factor relevant to the value of a pleasure-experience, for example, that the lower pleasures of the body are less valuable than the higher pleasures of the mind. A very common element in many conceptions of beauty is its relation to pleasure. Aesthetic hedonism makes this relation part of
23312-422: The hippocampi in both hemispheres results in profound difficulties in forming new memories ( anterograde amnesia ) and often also affects memories formed before the damage occurred ( retrograde amnesia ). Although the retrograde effect normally extends many years back before the brain damage, in some cases older memories remain. This retention of older memories leads to the idea that consolidation over time involves
23500-618: The hippocampus neuronal genome of the rats at one hour and at 24 hours after training. These alterations in methylation pattern occurred at many genes that were down-regulated , often due to the formation of new 5-methylcytosine sites in CpG rich regions of the genome. Furthermore, many other genes were upregulated , likely often due to the removal of methyl groups from previously existing 5-methylcytosines (5mCs) in DNA. Demethylation of 5mC can be carried out by several proteins acting in concert, including TET enzymes as well as enzymes of
23688-422: The hippocampus and occurs at synapses that terminate on dendritic spines and use the neurotransmitter glutamate . The synaptic changes depend on a special type of glutamate receptor , the N -methyl-D-aspartate (NMDA) receptor , a cell surface receptor which has the special property of allowing calcium to enter the postsynaptic spine only when presynaptic activation and postsynaptic depolarization occur at
23876-401: The hippocampus are shown to be functionally and anatomically distinct. The dorsal hippocampus (DH), ventral hippocampus (VH) and intermediate hippocampus serve different functions, project with differing pathways, and have varying degrees of place cells. The dorsal hippocampus serves for spatial memory, verbal memory, and learning of conceptual information. Using the radial arm maze , lesions in
24064-480: The hippocampus during behavior and then later transferred to the neocortex during sleep. Sharp waves in Hebbian theory are seen as persistently repeated stimulations by presynaptic cells, of postsynaptic cells that are suggested to drive synaptic changes in the cortical targets of hippocampal output pathways. Suppression of sharp waves and ripples in sleep or during immobility can interfere with memories expressed at
24252-404: The hippocampus is dysfunctional, orientation is affected; people may have difficulty in remembering how they arrived at a location and how to proceed further. Getting lost is a common symptom of amnesia. Studies with animals have shown that an intact hippocampus is required for initial learning and long-term retention of some spatial memory tasks, in particular ones that require finding the way to
24440-432: The hippocampus more than of other parts of the brain. These effects show up in post-traumatic stress disorder , and they may contribute to the hippocampal atrophy reported in schizophrenia and severe depression . Anterior hippocampal volume in children is positively correlated with parental family income and this correlation is thought to be mediated by income related stress. A recent study has also revealed atrophy as
24628-542: The hippocampus of elderly people , but later studies using more precise techniques found only minimal differences. Similarly, some MRI studies have reported shrinkage of the hippocampus in elderly people, but other studies have failed to reproduce this finding. There is, however, a reliable relationship between the size of the hippocampus and memory performance; so that where there is age-related shrinkage, memory performance will be impaired. There are also reports that memory tasks tend to produce less hippocampal activation in
24816-530: The hippocampus to space. The spatial theory was originally championed by O'Keefe and Nadel, who were influenced by American psychologist E.C. Tolman's theories about " cognitive maps " in humans and animals. O'Keefe and his student Dostrovsky in 1971 discovered neurons in the rat hippocampus that appeared to them to show activity related to the rat's location within its environment. Despite skepticism from other investigators, O'Keefe and his co-workers, especially Lynn Nadel, continued to investigate this question, in
25004-453: The hippocampus was reactivated, memory traces consolidated by non-hippocampal systems were not recalled, suggesting that the hippocampus interferes with long-term memory consolidation in other memory-related systems. One of the major implications that this model illustrates is the dominant effects of the hippocampus on non-hippocampal networks when information is incongruent. With this information in mind, future directions could lead towards
25192-485: The hippocampus was unchanged, as the increase seen in the posterior part was made at the expense of the anterior part, which showed a relative decrease in size. There have been no reported adverse effects from this disparity in hippocampal proportions. Another study showed opposite findings in blind individuals. The anterior part of the right hippocampus was larger and the posterior part was smaller, compared with sighted individuals. There are several navigational cells in
25380-405: The importance of laughter and possess the right attitude to pass it on. He went on to say that since this type of therapy is not widely practiced, health care providers will have to learn how to effectively use it. In another survey, researchers looked at how Occupational Therapists and other care givers viewed and used humor with patients as a means of therapy. Many agreed that while they believed it
25568-428: The inability to form and retain new memories . Since different neuronal cell types are neatly organized into layers in the hippocampus, it has frequently been used as a model system for studying neurophysiology . The form of neural plasticity known as long-term potentiation (LTP) was initially discovered to occur in the hippocampus and has often been studied in this structure. LTP is widely believed to be one of
25756-425: The labels " present bias " or " temporal discounting ", refers to our tendency to violate temporal neutrality in regards to temporal distance from the present. On the positive side, we prefer pleasurable experiences to be near rather than distant. On the negative side, we prefer painful experiences to be distant rather than near. The future bias refers to our tendency to violate temporal neutrality in regards to
25944-433: The left posterior, left anterior or right anterior hippocampus demonstrate distinct, individual cell responses when presented with faces of presumably recognizable famous people. Associations among facial and vocal identity were similarly mapped to the hippocampus of rheseus monkeys. Single neurons in the CA1 and CA3 responded strongly to social stimulus recognition by MRI. The CA2 was not distinguished, and may likely comprise
26132-402: The level of the behavior, nonetheless, the newly formed CA1 place cell code can re-emerge even after a sleep with abolished sharp waves and ripples, in spatially non-demanding tasks. Since at least the time of Ramon y Cajal (1852–1934), psychologists have speculated that the brain stores memory by altering the strength of connections between neurons that are simultaneously active. This idea
26320-577: The main neural mechanisms by which memories are stored in the brain. In rodents as model organisms , the hippocampus has been studied extensively as part of a brain system responsible for spatial memory and navigation. Many neurons in the rat and mouse hippocampus respond as place cells : that is, they fire bursts of action potentials when the animal passes through a specific part of its environment. Hippocampal place cells interact extensively with head direction cells , whose activity acts as an inertial compass, and conjecturally with grid cells in
26508-554: The main olfactory bulb, the anterior olfactory nucleus, and to the primary olfactory cortex. There continues to be some interest in hippocampal olfactory responses, in particular, the role of the hippocampus in memory for odors, but few specialists today believe that olfaction is its primary function. Over the years, three main ideas of hippocampal function have dominated the literature: response inhibition , episodic memory , and spatial cognition. The behavioral inhibition theory (caricatured by John O'Keefe and Lynn Nadel as "slam on
26696-460: The medial septum is more than just the controller of theta; it is also the main source of cholinergic projections to the hippocampus. It has not been established that septal lesions exert their effects specifically by eliminating the theta rhythm. During sleep or during resting, when an animal is not engaged with its surroundings, the hippocampal EEG shows a pattern of irregular slow waves, somewhat larger in amplitude than theta waves. This pattern
26884-490: The moderate projections to two primary olfactory cortical areas and prelimbic areas of the medial prefrontal cortex . This region has the smallest number of place cells. The ventral hippocampus functions in fear conditioning and affective processes. Anagnostaras et al. (2002) showed that alterations to the ventral hippocampus reduced the amount of information sent to the amygdala by the dorsal and ventral hippocampus, consequently altering fear conditioning in rats. Historically,
27072-579: The modern omnipresence of humour and the idolatry of it are signs of societal weakness, as instinctive resort to humour became a sort of escapism from responsibility and action. Ludovici considered laughter to be an evolutionary trait and he offered many examples of different triggers for laughter with their own distinct explanations. Carlo Bellieni examined laughter in an essay published in New Ideas in Psychology. He wrote we can strip back laughter to
27260-542: The most active of them. An active cell typically stays active for half a second to a few seconds. As the rat behaves, the active cells fall silent and new cells become active, but the overall percentage of active cells remains more or less constant. In many situations, cell activity is determined largely by the spatial location of the animal, but other behavioral variables also clearly influence it. The LIA mode appears during slow-wave (non-dreaming) sleep, and also during states of waking immobility such as resting or eating. In
27448-404: The most influential version assigns this role to desires . On this account, pleasure is linked to experiences that fulfill a desire had by the experiencer. So the difference between the first and the second person in the example above is that only the first person has a corresponding desire directed at the taste of chocolate. One important argument against this version is that while it is often
27636-440: The most intensively studied subject in medical history. In the ensuing years, other patients with similar levels of hippocampal damage and amnesia (caused by accident or disease) have also been studied, and thousands of experiments have studied the physiology of activity-driven changes in synaptic connections in the hippocampus. There is now universal agreement that the hippocampi play some sort of important role in memory; however,
27824-403: The most part not by the total pleasure and suffering it contained but by how it felt at its peaks and at its end . For example, the memory of a painful colonoscopy is improved if the examination is extended by three minutes in which the scope is still inside but not moved anymore, resulting in a moderately uncomfortable sensation. This extended colonoscopy, despite involving more pain overall,
28012-450: The motion picture projector again and not infrequently, it would lead to another pain-free interval." A number of studies using methods of conversation analysis and discourse analysis have documented the systematic workings of laughter in a variety of interactions, from casual conversations to interviews, meetings, and therapy sessions. Working with recorded interactions, researchers have created detailed transcripts that indicate not only
28200-465: The neighboring entorhinal cortex . The earliest description of the ridge running along the floor of the temporal horn of the lateral ventricle comes from the Venetian anatomist Julius Caesar Aranzi (1587), who likened it first to a silkworm and then to a seahorse ( Latin hippocampus , from Greek ἱππόκαμπος, from ἵππος, 'horse' + κάμπος, 'sea monster'). The German anatomist Duvernoy (1729),
28388-440: The numerous other factors that would in most cases have a greater impact. The nearness bias and the future bias are two different forms of violating the principle of temporal neutrality . This principle states that the temporal location of a benefit or a harm is not important for its normative significance: a rational agent should care to the same extent about all parts of their life. The nearness bias , also discussed under
28576-402: The opposite—they do not understand humor or get any joy out of it. A fit describes an abnormal time when one cannot control the laughter or one's body, sometimes leading to seizures or a brief period of unconsciousness. Some believe that fits of laughter represent a form of epilepsy . Laughter has been used as a therapeutic tool for many years because it is a natural form of medicine. Laughter
28764-496: The other hand, hold that happiness involves having the right attitude towards one's life as a whole . Pleasure may have a role to play in this attitude, but it is not identical to happiness . Pleasure is closely related to value, desire, motivation and right action. There is broad agreement that pleasure is valuable in some sense. Axiological hedonists hold that pleasure is the only thing that has intrinsic value . Many desires are concerned with pleasure. Psychological hedonism
28952-409: The other way round. So desire theories would be mistaken about the direction of explanation. Another argument against desire theories is that desire and pleasure can come apart: we can have a desire for things that are not enjoyable and we can enjoy things without desiring to do so. Dispositional theories try to account for pleasure in terms of dispositions , often by including insights from both
29140-482: The others, like salvinorin A (the active ingredient of Salvia divinorum ), can even induce bursts of uncontrollable laughter. A research article was published December 1, 2000, on the psycho-evolution of laughter (Panksepp 2000). A link between laughter and healthy function of blood vessels was first reported in 2005 by researchers at the University of Maryland Medical Center with the fact that laughter causes
29328-410: The outer in – the molecular layer , the inner molecular layer , the granular layer , and the hilus . The CA3 in the hippocampus proper has the following cell layers known as strata: lacunosum-moleculare, radiatum, lucidum, pyramidal, and oriens. CA2 and CA1 also have these layers except the lucidum stratum . The input to the hippocampus (from varying cortical and subcortical structures) comes from
29516-422: The output to the EC, additional output pathways go to other cortical areas including the prefrontal cortex . A major output goes via the fornix to the lateral septal area and to the mammillary body of the hypothalamus (which the fornix interconnects with the hippocampus). The hippocampus receives modulatory input from the serotonin , norepinephrine , and dopamine systems, and from the nucleus reuniens of
29704-444: The phase with which theta rhythms, at the time of stimulation of a neuron, shape the effect of that stimulation upon its synapses. What is meant here is that theta rhythms may affect those aspects of learning and memory that are dependent upon synaptic plasticity . It is well established that lesions of the medial septum – the central node of the theta system – cause severe disruptions of memory. However,
29892-430: The point of near convergence. In an attempt to reconcile the two disparate views, it is suggested that a broader view of the hippocampal function is taken and seen to have a role that encompasses both the organisation of experience ( mental mapping , as per Tolman's original concept in 1948) and the directional behaviour seen as being involved in all areas of cognition, so that the function of the hippocampus can be viewed as
30080-520: The precise nature of this role remains widely debated. A recent theory proposed – without questioning its role in spatial cognition – that the hippocampus encodes new episodic memories by associating representations in the newborn granule cells of the dentate gyrus and arranging those representations sequentially in the CA3 by relying on the phase precession generated in the entorhinal cortex . The third important theory of hippocampal function relates
30268-511: The presence of laughter but also features of its production and placement. These studies challenge several widely held assumptions about the nature of laughter. Contrary to notions that it is spontaneous and involuntary, research documents that laughter is sequentially organized and precisely placed relative to surrounding talk. Far more than merely a response to humor, laughter often works to manage delicate and serious moments. More than simply an external behavior "caused" by an inner state, laughter
30456-408: The pyramidal cells and then give an inhibitory feedback to the pyramidal cells. This recurrent inhibition is a simple feedback circuit that can dampen excitatory responses in the hippocampus. The pyramidal cells give a recurrent excitation which is an important mechanism found in some memory processing microcircuits. Several other connections play important roles in hippocampal function. Beyond
30644-448: The quality theories and the attitude theories. One way to combine these elements is to hold that pleasure consists in being disposed to desire an experience in virtue of the qualities of this experience. Some of the problems of the regular desire theory can be avoided this way since the disposition does not need to be realized for there to be pleasure, thereby taking into account that desire and pleasure can come apart. Pleasure plays
30832-607: The results of surgical destruction of the hippocampi when trying to relieve epileptic seizures in an American man Henry Molaison , known until his death in 2008 as "Patient H.M." The unexpected outcome of the surgery was severe anterograde and partial retrograde amnesia ; Molaison was unable to form new episodic memories after his surgery and could not remember any events that occurred just before his surgery, but he did retain memories of events that occurred many years earlier extending back into his childhood. This case attracted such widespread professional interest that Molaison became
31020-468: The same time. Drugs that interfere with NMDA receptors block LTP and have major effects on some types of memory, especially spatial memory. Genetically modified mice that are modified to disable the LTP mechanism, also generally show severe memory deficits. Age-related conditions such as Alzheimer's disease and other forms of dementia (for which hippocampal disruption is one of the earliest signs ) have
31208-416: The sensation theory and the felt-quality theory is that there is no one quality shared by all pleasure-experiences. The force of this objection comes from the intuition that the variety of pleasure-experiences is just too wide to point out one quality shared by all, for example, the quality shared by enjoying a milkshake and enjoying a chess game . One way for quality theorists to respond to this objection
31396-404: The sensation theory, whenever we experience pleasure there is a distinctive pleasure-sensation present. So a pleasurable experience of eating chocolate involves a sensation of the taste of chocolate together with a pleasure-sensation. An obvious shortcoming of this theory is that many impressions may be present at the same time. For example, there may be an itching sensation as well while eating
31584-403: The sense of existential loneliness and mortality that only humans feel. For example: a joke creates an inconsistency and the audience automatically tries to understand what the inconsistency means; if they are successful in solving this 'cognitive riddle ' and they realize that the surprise was not dangerous, they laugh with relief . Otherwise, if the inconsistency is not resolved, there
31772-412: The set of structures that line the deep edge of the cortex (Latin limbus meaning border ): These include the hippocampus, cingulate cortex , olfactory cortex , and amygdala . Paul MacLean later suggested that the limbic structures comprise the neural basis of emotion. The hippocampus is anatomically connected to parts of the brain that are involved with emotional behavior – the septum ,
31960-465: The social status or identity it conveys. For example, a sweater that has been worn by a celebrity is more desired than an otherwise identical sweater that has not, though considerably less so if it has been washed. Pleasure-seeking behavior is a common phenomenon and may indeed dominate our conduct at times. The thesis of psychological hedonism generalizes this insight by holding that all our actions aim at increasing pleasure and avoiding pain. This
32148-424: The source of their seizures , with a view to surgical resection. The patients had diagnostic electrodes implanted in their hippocampus and then used a computer to move around in a virtual reality town. Similar brain imaging studies in navigation have shown the hippocampus to be active. A study was carried out on taxi drivers. London's black cab drivers need to learn the locations of a large number of places and
32336-454: The specific content or quality of a pleasure-experience is not relevant to its value, which only depends on its quantitative features: intensity and duration. On this account, an experience of intense pleasure of indulging in food and sex is worth more than an experience of subtle pleasure of looking at fine art or of engaging in a stimulating intellectual conversation. Qualitative hedonists, following John Stuart Mill , object to this version on
32524-476: The spiking of hippocampal neurons and synchronise across the hippocampus in a travelling wave pattern. The trisynaptic circuit is a relay of neurotransmission in the hippocampus that interacts with many brain regions. From rodent studies it has been proposed that the trisynaptic circuit generates the hippocampal theta rhythm. Theta rhythmicity is very obvious in rabbits and rodents and also clearly present in cats and dogs. Whether theta can be seen in primates
32712-445: The study of these non-hippocampal memory systems through hippocampal inactivation, further expanding the labile constructs of memory. Additionally, many theories of memory are holistically based around the hippocampus. This model could add beneficial information to hippocampal research and memory theories such as the multiple trace theory . Lastly, the between-system memory interference model allows researchers to evaluate their results on
32900-566: The sum-total of pleasure. Many pleasurable experiences are associated with satisfying basic biological drives, such as eating , exercise , hygiene , sleep , and sex . The appreciation of cultural artifacts and activities such as art , music , dancing , and literature is often pleasurable. Pleasure is sometimes subdivided into fundamental pleasures that are closely related to survival (food, sex, and social belonging) and higher-order pleasures (e.g., viewing art and altruism). Bentham listed 14 kinds of pleasure; sense, wealth, skill, amity,
33088-483: The therapeutic efficacy of laughter." In 2017, an institution in Japan conducted an open-label randomized controlled trial to evaluate the effects of laughter therapy on quality of life in patients with cancer. The study used laughter yoga, comedy, clown and jokes. The result showed that laughter therapy was helpful in improving quality of life and cancer symptoms in some areas for cancer survivors. Improvements were seen in
33276-401: The theta mode, the EEG is dominated by large regular waves with a frequency range of 6 to 9 Hz , and the main groups of hippocampal neurons ( pyramidal cells and granule cells ) show sparse population activity, which means that in any short time interval, the great majority of cells are silent, while the small remaining fraction fire at relatively high rates, up to 50 spikes in one second for
33464-426: The theta wave are generated mainly by densely packed neural layers of the entorhinal cortex, CA3, and the dendrites of pyramidal cells. The theta wave is one of the largest signals seen on EEG, and is known as the hippocampal theta rhythm . In some situations the EEG is dominated by regular waves at 3 to 10 Hz, often continuing for many seconds. These reflect subthreshold membrane potentials and strongly modulate
33652-403: The times when Herodotus speaks about laughter it is followed by a retribution. "Men whose laughter deserves report are marked, because laughter connotes scornful disdain, disdain feeling of superiority, and this feeling and the actions which stem from it attract the wrath of the gods." There is a wide range of experiences with laughter. A 1999 study by two humor researchers asked 80 people to keep
33840-499: The transfer of memories out of the hippocampus to other parts of the brain. Experiments using intrahippocampal transplantation of hippocampal cells in primates with neurotoxic lesions of the hippocampus have shown that the hippocampus is required for the formation and recall, but not the storage, of memories. It has been shown that a decrease in the volume of various parts of the hippocampus in people leads to specific memory impairments. In particular, efficiency of verbal memory retention
34028-404: The twins "inherited some aspects of their laugh sound and pattern, readiness to laugh, and maybe even taste in humor". Scientists have noted the similarity in forms of laughter induced by tickling among various primates , which suggests that laughter derives from a common origin among primate species. The spotted hyena , another species of animal, was also known as the laughing hyena because of
34216-494: The universal aim for all people. Later, Epicurus defined the highest pleasure as aponia (the absence of pain), and pleasure as "freedom from pain in the body and freedom from turmoil in the soul". According to Cicero (or rather his character Torquatus) Epicurus also believed that pleasure was the chief good and pain the chief evil. The Pyrrhonist philosopher Aenesidemus claimed that following Pyrrhonism's prescriptions for philosophical skepticism produced pleasure. In
34404-417: The way it sounds when it communicates. A very rare neurological condition has been observed whereby the sufferer is unable to laugh out loud, a condition known as aphonogelia . Neurophysiology indicates that laughter is linked with the activation of the ventromedial prefrontal cortex , that produces endorphins . Scientists have shown that parts of the limbic system are involved in laughter. This system
34592-491: The weight of the evidence supports the appearance of such sounds at 15 weeks to four months of age. Laughter researcher Robert Provine [ es ] said: "Laughter is a mechanism everyone has; laughter is part of universal human vocabulary. There are thousands of languages, hundreds of thousands of dialects, but everyone speaks laughter in pretty much the same way." Babies have the ability to laugh before they ever speak. Children who are born blind and deaf still retain
34780-450: Was an illusion, which would not be true if this joy was due to seeing the landscape as a valuable real estate opportunity. Opponents of aesthetic hedonism have pointed out that despite commonly occurring together, there are cases of beauty without pleasure. For example, a cold jaded critic may still be a good judge of beauty due to her years of experience but lack the joy that initially accompanied her work. A further question for hedonists
34968-462: Was beneficial to the patients, the proper training was lacking in order to effectively use It. Even though laughter and humor has been used therapeutically in medical conditions, according to Mora-Ripoll, there was not enough data to clearly establish that laughter could be used as an overall means of healing. It did suggest that additional research was still needed since "well-designed randomized controlled trials have not been conducted to date validating
35156-402: Was formalized by Donald Hebb in 1949, but for many years remained unexplained. In 1973, Tim Bliss and Terje Lømo described a phenomenon in the rabbit hippocampus that appeared to meet Hebb's specifications: a change in synaptic responsiveness induced by brief strong activation and lasting for hours or days or longer. This phenomenon was soon referred to as long-term potentiation (LTP). As
35344-461: Was suggested that the mechanisms of memory and planning both evolved from mechanisms of navigation and that their neuronal algorithms were basically the same. Many studies have made use of neuroimaging techniques such as functional magnetic resonance imaging (fMRI), and a functional role in approach-avoidance conflict has been noted. The anterior hippocampus is seen to be involved in decision-making under approach-avoidance conflict processing. It
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