LAUGHTER

Laughter is a physical reaction in humans and some other species of primate, consisting typically of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli

Laughter is a physical reaction in humans and some other species of primate, consisting typically of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli. Laughter can arise from such activities as being tickled,[1] or fromhumorous stories or thoughts.[2] Most commonly, it is considered a visual expression of a number of positive emotional states, such as joy, mirth,happiness, relief, etc. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, apology, or confusion such asnervous laughter or courtesy laugh. Age, gender, education, language, and culture are all factors[3] as to whether a person will experience laughter in a given situation.

Laughter 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 a positive feedback.[4] This may account in part for the popularity oflaugh tracks in situation comedy television shows.

THE BRAIN

Neurophysiology indicates that laughter is linked with the activation of the ventromedialprefrontal cortex, that produces endorphins.[13] Scientists have shown that parts of the limbic system are involved in laughter. This system is involved in emotions and helps us with functions necessary for humans' survival. The structures in the limbic system that are involved in laughter: the hippocampus and the amygdala.[14]

The December 7, 1984, Journal of the American Medical Association describes the neurological causes of laughter as follows:

"Although there is no known 'laugh center' in the brain, its neural mechanism has been the subject of much, albeit inconclusive, speculation. It is evident that its expression depends on neural paths arising in close association with the telencephalic and diencephalic centers concerned with respiration. Wilson considered the mechanism to be in the region of the mesial thalamus, hypothalamus, and subthalamus. Kelly and co-workers, in turn, postulated that the tegmentum near theperiaqueductal grey contains the integrating mechanism for emotional expression. Thus, supranuclear pathways, including those from the limbic system that Papez hypothesised to mediate emotional expressions such as laughter, probably come into synaptic relation in the reticular core of the brain stem. So while purely emotional responses such as laughter are mediated by subcortical structures, especially the hypothalamus, and are stereotyped, the cerebral cortex can modulate or suppress them."

HEALTH

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 the dilatation of the inner lining of blood vessels, the endothelium, and increases blood flow.[15] 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. [16][17]

Laughter has proven beneficial effects on various other aspects of biochemistry. It has been shown to lead to reductions in stress hormones such as cortisol and epinephrine. When laughing the brain also releases endorphins that can relieve some physical pain.[18] Laughter also boosts the number of antibody-producing cells and enhances the effectiveness of T-cells, leading to a stronger immune system.[19] 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

CAUSES

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 Freudsummarized it in his theory that laughter releases tension and "psychic energy". This theory is one of the justifications of the beliefs that laughter is beneficial for one's health.[22] 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 the sense of existential loneliness and mortality that only humans feel.

For example: a joke creates an inconsistency and the audience automatically try to understand what the inconsistency means; if they are successful in solving this 'cognitive riddle' and they realize that thesurprise was not dangerous, they laugh with relief. Otherwise, if the inconsistency is not resolved, there 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 "exactness". It is important to note that sometimes the inconsistency may be resolved and there may still be no laugh.[citation needed] 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, the extent of the inconsistency (and aspects of it 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. [23][24]

LAUGHTER THERAPHY

Laughter has been used as a therapeutic tool for many years because it is a natural form of medicine. Laughter 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.[29] It can also boost the immune system and releaseendorphins to relieve pain.[30] Additionally, laughter can help prevent heart disease by increasing blood flow and improving the function of blood vessels. Some of 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.[31]

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 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. [32][33]