Archive for September, 2012


“Everybody laughs the same in every language because laughter is a universal connection. ”
Yakov Smirnoff

I went two years without cable, relying on Netflix and Hulu+ for most of what I wanted to watch.  With a presidential election looming, however, I simply couldn’t resist the siren song of endless punditry paraded out in front of me on every cable and broadcast channel for the next couple of weeks.  I knew if I got cable for that purpose, I’d also once again lose hours in front of the television laughing as people pawn their family heirlooms and useless junk, try to survive on a remote tropical island, and speculate about ancient astronauts, UFO conspiracies, and the end of the world.  I think I love watching that stuff almost as much as I love watching straight up documentaries about the origins of the universe or animal behavior, even when (and maybe especially because) it makes me lament the lack of critical thinking skills from some of the people on these shows.

So I gave in and got cable again.

And, true to form, if I am home the television is on.  So, unsurprisingly, I was doing some work one morning last week with the TV on when my attention was caught by the sound of laughter.  I looked up in time to see this commercial:

This may be just a commercial, but it is delightful  I found myself laughing along with it as I watched.  I laughed again when I tracked the video down on YouTube.   Laughter, as we see from this ad, knows virtually no boundaries.  Not age.  Not race.  Not gender.  We are all capable of laughter, from the beginning of our life until the end.  This means it is an integral part of our nervous system, as well as an important behavior.

When do we begin laughing, and how does our laughter change as we grow older?  I’d originally thought to write about development of laughter, but I got sidetracked by the fact that the answer to these questions, and indeed the questions themselves are anything but simple since laughter is such a complicated subject.  For example, Meyer, Baumanne, Wildgruber, and Alter (2007) mention an intriguing point about laughter and why it is of interest to researchers.  They report on a widely held opinion that laughter may be a link between animal vocalizations and human speech, with the focus on the affective component of vocalizations across species.  Because laughter takes advantage of our vocal apparatus, and is presumed to have a social and communicative function, understanding laughter is tied to understanding how it is similar and how it is different from speech.  This was one of the surprises as I was looking into this, and in retrospect I guess it shouldn’t have been.  But I always simply considered that we speak, and that we laugh, and never stopped to realize that we often do both together.  Or that the same structures we use to speak are also used to laugh.  It wasn’t until I was writing up my last blog entry, and reviewing Darwin’s book on emotions that it occurred to me that they are probably very related in the brain.

Interestingly, according to Meyer, et al (2007), there is no “laughing center” in the brain.  While the same might be said of language, there are clear areas associated with language in the brain, most notably Broca’s area and Wernicke’s area.

The insular cortex.  Click the picture to read an interesting blog entry about the insular cortex.

They say that laughter seems to be more distributed in the brain.  Major emotion centers of the brain, particularly structures found in the limbic system (such as the amygdala, the thalamus, and the hypothalamus) become active when we laugh, along with many structures from the frontal lobes to the brainstem that mediate motor behavior (for the physical behavior of laughing).  When participants were exposed to laughter, backwards laughter, and silence, the amygdala only became active to the sound of regular laughter.  They suggest that the amygdala, the insula, and areas of the superior temporal lobe particularly mediate the perception and affective responses to laughter (Meyer, et al).  Incidentally, this blog has made me very curious about the insular cortex, since it seems to play a special role in socially mediated emotions, such as embarrassment, among other things.

So I think it’s kind of fitting that an advertisement became the inspiration for this blog entry.  An ad is nothing if not an attempt to communicate, to evoke some kind of emotion from the person viewing it.  In this case, the makers of the ad want to sell you a car, but they chose to go about it without ever once showing you a picture of said car or using much in the way of language (and in fact, no spoken language at all).  Instead, they use a fundamental human behavior, one that taps quickly into the emotion centers of our brain, such as the amygdala and the insula, to evoke an emotional state in us that they undoubtedly hope you will associate with their product.

Most importantly, however, I like to think that the makers of this particular ad also wanted to remind us how integral laughter is to the human condition.

References

Meyer, M., Baumanne, S., Wildgruber, D., & Alter, K. (2007). How the brain laughs: Comparative evidence from behavioral, electrophysiological and neuroimaging studies in human and monkey. Behavioral Brain Research, 182, 245-260.

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I recently visited my mother, who has been in a nursing home with Alzheimer’s Disease since July 2008. Her health is very good, but she has lost nearly all ability to speak, and mutters incoherently a lot, with a recognizable word here and there. She can’t walk, or care for herself at all.  In many ways, the progression of the disorder has been about as typical as can be expected.

I was struck, however, by a new set of behaviors I saw on this visit that have recently emerged. Though she cannot walk, she moves her legs all the time, crossing and uncrossing them, even in her sleep. Her tongue also moves in and out of her mouth, over and over again, involuntarily. But the most interesting new behavior to me was laughter. She laughs all the time. She just bursts out with a chuckle, or sustained laughter interspersed with a mix of muttering and the occasional word. We would say something to her and she would laugh. My sister would ask her a question and she would chuckle. We would sing to her and she would giggle. We would wheel her outside, and she’d laugh as we moved through the corridors into the elevator.  I don’t know whether these new behaviors are part of the dementia or indicative of something else; her doctors are currently assessing them.

This has piqued an interest in laughter on my part. It bears some similarities to yawning, a topic I recently wrote about in this blog. Like yawning, laughter is a common, highly stereotypical behavior that is phylogenetically older and far more complex than it appears at first blush. Naturally, it is of interest to scientists, particularly evolutionary psychologists and neuroscientists. Not only are we interested in the physiological and perceptual activity that provokes laughter, we are also interested in the evolution of such a behavior.  I thought this was a great opportunity to explore the behavior of laughter.

As is often the case with me, when I become interested in something I try to start at the beginning. Those of you who have taken courses from me know I have a great fondness for the history of the discipline of psychology, and talk about it often. It’s fairly common to find that the ancient Greeks wrote about various phenomenon. Such was the case with yawning, with both Aristotle and Hippocrates writing about it. The same is undoubtedly true of laughter, though my research begins with sources more recent than those from ancient Greece. Darwin (1872) published an entire book on emotional expression, and included a chapter (Chapter VIII) entitled “Joy, High Spirits, Love, Tender Feelings, Devotion.”  What I enjoy so much about these older references is the Victorian-era tendency toward excessive description of behavior, and other natural phenomena. In that chapter Darwin brought together many contemporary sources to provide a detailed description of the facial expressions that accompany laughter and smiling across species (yes, other species besides humans smile and laugh), as well as the musculature involved. He talked extensively about the contraction of the zygomaticus (upper cheeks) muscles which pull the ends of the orbicularis oris (mouth) muscles out and up for smiling and laughing.

Duchenne smile

Duchenne artificially stimulates the muscles of a man with facial paralysis.

Most importantly, Darwin and others (including a pioneer of this work, Duchenne) talk about the role of the eyes in smiling.  Duchenne (1862, as cited by Darwin 1872) found he could produce a smile by applying electrical stimulation to the zygomatic muscles.  However, when photographs of that type of smile were compared to genuine smiles, as Darwin himself ascertained, people readily picked the genuine smiles out from the artifical ones created by the stimulation.  This led many to talk about social smiles, those smiles that never quite reach the muscles of the eyes, which we do not have voluntary control over when expressing emotion (unlike the zygomaticus).  In fact, Duchenne advocated that the muscles of the eyes, which contract when we smile causing the skin around the eyes to crinkle, are only involved when the emotion behind the smile is real.  A recent study, however, suggests that people are capable of producing fake smiles that are indistinguishable from fake or social smiles (Krumhuber & Manstead, 2009), but more often than not when they are looking at dynamic, video stimuli, which probably involves other cues.

My guitar

My guitar, which I don’t play often enough anymore.

Darwin (1872) also talked at length about the sound of laughter, and speculates that it is the expression and communication of joy, such as might occur between a parent and their offspring being reunited.  This fits in well with his hypothesis that the expression of emotion serves a communicative function.  He found the peculiarities of the sound of laughter interesting, and speculated that, since it uses the same physiological mechanisms that produce screaming and crying and other forms of vocal communication, that it needed to sound as different from those as possible.  This idea, which I think he’s right about, always makes me think of musical instruments, which can produce a myriad of auditory combinations from the same, limited set of available sounds.  Imagine a guitar, which has a mere six strings, each with a different pitch attached.  Then think about all the different songs you have ever heard played on a guitar, some slow and sad, some fast and joyful, all produced from those same six strings.

It probably hasn’t been lost on you that I’m sticking mainly with a description of laughter (and smiling).  This is on purpose, and it goes back to Mom.  Do I think Mom’s laughter is the result of her being happy all the time and finding everything funny? I wish that was the case. But, while it would be at least a little comforting to think that her general emotional state is one of happiness, I doubt there is much genuine emotion or awareness behind the laughter. When I look into her eyes while she is laughing, all I see is a kind of benign bewilderment, and I think the world must be a very confusing place for her now.  What is more likely, though I cannot know for certain, is that the cortex in her frontal lobes has degenerated so significantly that their inhibitory effect on some of these behaviors is almost nonexistent. Still, it is curious that she laughs rather than other, more negative expressions.  So I take comfort in that, as well as the fact that she does not appear to be fearful.  While Duchenne did not really study laughter, the first time I saw her involuntarily smiling and laughing made me immediately think of the gentleman with facial paralysis in the research by Duchenne.  Here, however, there is no man administering a mild electrical shock to the muscles of my mother’s face to make them contract.  Instead, something far more terrible has happened inside of her to the parts of her brain that make her who she is.

In future entries, I think I will continue with the laughter topic.  I want to talk about brain structures involved in laughter for the next entry, since we now understand more about that. And I want to delve into the evolution of laughter.  I have also looked a little into the pathology of laughter, because I want to find out more about my mother’s condition, but there is surprisingly little information about dementia and laughter.  I will report on anything I find out about that here, however.  As always, my interests lie less in abnormal behavior and pathology and more in everyday, normal behavior, so that’s what I will likely focus on.  My mother’s involuntary laughter is the impetus for my curiosity, but I realized that I have never once really thought about the behavior of laughter, or taken a moment to really appreciate it as an important and complex behavior.

Maybe this is yet one more gift from my mother.

Note

The title of this blog entry is from The Illiad by Homer, describing the laughter of the gods.

References

Darwin, C. (1872). The expression of emotion in man and animals. London: John Murray.

Duchenne (de Boulogne), G. B. (1862). Mécanisme de la physionomie humaine ou analyse électro-physiologique de l’expression des passions. Texte: Première partie. Deuxième édition. Paris: Librairie J.-B. Bailliere et Fils.

Krumhuber, E. G. and Manstead, A. S. R. (2009). Can Duchenne smiles be feigned? New evidence on felt and false smiles.  Emotion, 9(6), 807-820.