CENTRO DE RECONCILIACION FAMILIAR--CONSEJERIA CRISTOCENTRICA
LAUGHTER AND THE HUMAN BRAIN
Imagine that you are sitting with a friend and suddenly, your friend's face starts to convulse involuntary. Her facial muscles, particularly her lips, stretch and she has a peculiar expression in her eyes. Her vocal organs vibrate and she is making a sequence of rhythmic expiratory sounds. Oddly enough, nobody around you even turns his head to look as your friend chokes, trying to take broken, sudden inhalations, while her shoulders jerk and her entire body twists and shakes.
Call the paramedics? Not necessary. Actually, this has happened to you many times, and yes, it was probably something you said. This sequence of events is defined in medical dictionaries as laughter. And if the above description sounds like an account of a neurological disorder, you are right. Analyzing the physiological manifestation of laughter reveals striking similarities to seizures and even to some types of epilepsy.
Why do we laugh? What function does laughter have? Laughter is one of the most poorly understood of human behaviors. While we know, for example, that certain parts of the brain are responsible for certain functions and tasks, it seems that laughter cannot be traced to one specific area of the brain. Furthermore, the relationships between laughter and humor, or even laughter and mirth are not understood, despite their evident interconnection.
Some clues for the physiological basis of laughter have come from people who suffered brain injuries, strokes or neurological diseases. C.B., a landscaper in Iowa, is one of them. Three years ago, at the age of 48, C.B. suffered a stroke. Fortunately, he recovered quite well and was expected to return to his normal life. However, since the stroke, C.B. and those around him, have been perplexed by certain changes in his behavior. Though he seems healthy, and doesn't suffer any pain, occasionally, for no noticeable reason, he bursts out into uncontrollable, wild laughter. In other cases, out of the blue, he is swept into tears in a similar attack.
C.B. has joined a long list of clinical cases that are described in medical literature as pathological laughter and crying (PLC). All of these patients suffer from brain damage that has destroyed or impaired small areas in their brains. Usually, the lesions are no bigger than a few cubic millimeters. However, since the lesions do not always occur exactly in the same spot in the brain, it is hard to determine based on these cases, which brain areas are in charge of laughter. Nevertheless, PLC suggests an interesting linkage; the same tiny lesion can cause both laughter and crying. That means that the same brain regions are involved in both laughter and crying. But most surprisingly, these laughter and crying are not associated with mirth or sadness. PLC patients suffer from "mechanical laughter". The pleasant feelings, happiness, amusement or joy that usually accompany laughter are absent. Patients like C.B. often even suffer anxiety and fear with their laughter.
The case of a French woman who suffered from Parkinson's disease sheds more light on the association between laughter, crying and emotions. Trying to ease the symptoms of her disease, the doctors implanted electrodes in the woman's brain. This type of Apparatus sends electric pulses to the brain region that is in charge of motor activity, causing, in most patients, a significant improvement in the motor condition. However, this time something very odd happened. Immediately after the first pulse, the patient started crying. The alarmed doctors thought they might have hurt her. But upon inquiring, the woman responded with a different explanation. "I no longer wish to live, to see anything, hear anything, feel anything. I'm fed up with life", she wept, "I'm hopeless". The doctors stopped the current right away. Then, suddenly, the woman became happy, even manic. Laughing and joking, she playfully pulled the tie of one of the doctors. A few minutes later, her normal mood was restored, as if nothing had happened. When the doctors resumed the electric current a few days later, the same scenario repeated itself.
The region that was stimulated in the woman's brain was far away from the region that caused mechanical laughter in PLC cases. This time the crying and laughing were associated with emotions; the patient believed she was laughing or crying in response to something funny or sad.
These two cases suggest that there are certain parts of the brain that associate laughter with emotions, while others just operate the physical mechanism of laughter.
Pathological cases have shown associations between laughter and crying, and have implied a connection between laughter and motor activity. However, we can learn a lot about laughter not just from pathological cases, but also from its normal manifestations.
Tickling causes laughter. Perhaps laughter is merely a reflexive reaction to some types of physical irritation? Apparently, this is not the case. A person can stick his finger into his own throat and operate the gag reflex. But no matter how hard one tries, self-tickling will not cause laughter.
Laughter is unique to human beings. Like language, we don't share it even with our closest cousins, the apes. Produced only by the most evolutionarily mature and complicated brain, many theorists hypothesize that laughter and language must be associated. The relationship between the two does not end with their coordinated appearance on the stage of evolution. Laughter can be evoked by language, causing many neuroscientists to search for a functional connection between the two.
It seems that laughter is connected to a myriad of physiological and behavioral functions, but only recently have scientists begun to bring all the parts of this jigsaw puzzle together. It will be a long time before we fully understand why C.B. laughs without being happy, why an electrical stimulation to a motor control center causes the French woman to ride an emotional roller coaster, and why certain stories or situations cause ridiculous, uncontrollable convulsions.
References:
1.Pathological laughter and crying, Parvizi et al. (2001), Brain, Vol. 124: 1708-1719.
2.Transient Acute Depression Induced by High-Frequency Deep-Brain Stimulation, Bejjani et al. (1999), NEJM Vol. 340:1476-1480.
Written by Yanay Ofran.
http://www.pbs.org/wnet/brain/episode4/laughter/page2.html
Call the paramedics? Not necessary. Actually, this has happened to you many times, and yes, it was probably something you said. This sequence of events is defined in medical dictionaries as laughter. And if the above description sounds like an account of a neurological disorder, you are right. Analyzing the physiological manifestation of laughter reveals striking similarities to seizures and even to some types of epilepsy.
Why do we laugh? What function does laughter have? Laughter is one of the most poorly understood of human behaviors. While we know, for example, that certain parts of the brain are responsible for certain functions and tasks, it seems that laughter cannot be traced to one specific area of the brain. Furthermore, the relationships between laughter and humor, or even laughter and mirth are not understood, despite their evident interconnection.
Some clues for the physiological basis of laughter have come from people who suffered brain injuries, strokes or neurological diseases. C.B., a landscaper in Iowa, is one of them. Three years ago, at the age of 48, C.B. suffered a stroke. Fortunately, he recovered quite well and was expected to return to his normal life. However, since the stroke, C.B. and those around him, have been perplexed by certain changes in his behavior. Though he seems healthy, and doesn't suffer any pain, occasionally, for no noticeable reason, he bursts out into uncontrollable, wild laughter. In other cases, out of the blue, he is swept into tears in a similar attack.
C.B. has joined a long list of clinical cases that are described in medical literature as pathological laughter and crying (PLC). All of these patients suffer from brain damage that has destroyed or impaired small areas in their brains. Usually, the lesions are no bigger than a few cubic millimeters. However, since the lesions do not always occur exactly in the same spot in the brain, it is hard to determine based on these cases, which brain areas are in charge of laughter. Nevertheless, PLC suggests an interesting linkage; the same tiny lesion can cause both laughter and crying. That means that the same brain regions are involved in both laughter and crying. But most surprisingly, these laughter and crying are not associated with mirth or sadness. PLC patients suffer from "mechanical laughter". The pleasant feelings, happiness, amusement or joy that usually accompany laughter are absent. Patients like C.B. often even suffer anxiety and fear with their laughter.
The case of a French woman who suffered from Parkinson's disease sheds more light on the association between laughter, crying and emotions. Trying to ease the symptoms of her disease, the doctors implanted electrodes in the woman's brain. This type of Apparatus sends electric pulses to the brain region that is in charge of motor activity, causing, in most patients, a significant improvement in the motor condition. However, this time something very odd happened. Immediately after the first pulse, the patient started crying. The alarmed doctors thought they might have hurt her. But upon inquiring, the woman responded with a different explanation. "I no longer wish to live, to see anything, hear anything, feel anything. I'm fed up with life", she wept, "I'm hopeless". The doctors stopped the current right away. Then, suddenly, the woman became happy, even manic. Laughing and joking, she playfully pulled the tie of one of the doctors. A few minutes later, her normal mood was restored, as if nothing had happened. When the doctors resumed the electric current a few days later, the same scenario repeated itself.
The region that was stimulated in the woman's brain was far away from the region that caused mechanical laughter in PLC cases. This time the crying and laughing were associated with emotions; the patient believed she was laughing or crying in response to something funny or sad.
These two cases suggest that there are certain parts of the brain that associate laughter with emotions, while others just operate the physical mechanism of laughter.
Pathological cases have shown associations between laughter and crying, and have implied a connection between laughter and motor activity. However, we can learn a lot about laughter not just from pathological cases, but also from its normal manifestations.
Tickling causes laughter. Perhaps laughter is merely a reflexive reaction to some types of physical irritation? Apparently, this is not the case. A person can stick his finger into his own throat and operate the gag reflex. But no matter how hard one tries, self-tickling will not cause laughter.
Laughter is unique to human beings. Like language, we don't share it even with our closest cousins, the apes. Produced only by the most evolutionarily mature and complicated brain, many theorists hypothesize that laughter and language must be associated. The relationship between the two does not end with their coordinated appearance on the stage of evolution. Laughter can be evoked by language, causing many neuroscientists to search for a functional connection between the two.
It seems that laughter is connected to a myriad of physiological and behavioral functions, but only recently have scientists begun to bring all the parts of this jigsaw puzzle together. It will be a long time before we fully understand why C.B. laughs without being happy, why an electrical stimulation to a motor control center causes the French woman to ride an emotional roller coaster, and why certain stories or situations cause ridiculous, uncontrollable convulsions.
References:
1.Pathological laughter and crying, Parvizi et al. (2001), Brain, Vol. 124: 1708-1719.
2.Transient Acute Depression Induced by High-Frequency Deep-Brain Stimulation, Bejjani et al. (1999), NEJM Vol. 340:1476-1480.
Written by Yanay Ofran.
http://www.pbs.org/wnet/brain/episode4/laughter/page2.html
Tags: laughter
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Christian in Recovery
National Mental Health Assoc.
Narcotics Anonimous
Adult Children
RAINN-Rape, Sexual and Incest Abuse
National Depression and Manic Depression Assoc.
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