Last month during the holidays, I took a shuttle home from the airport and there was another passenger sitting at the back. The driver must have been exposed to another foreign culture and was making comments about other drivers on the road, some of which could be funny. This other passenger, kept laughing, at every instance the silence in the cab was disturbed. Eventually it was pretty clear that the passenger was having problems adjusting to behavior so heavily influenced by a foreign culture, but wasn’t disagreeable to the occasional humor and so was resorting to making the laugh-like noise. My introductory Hi was replied by a high pitched ha..ha Hi..! I was anticipating some ha..ha.. when the vehicle stopped in front of my place; there was none. I purposely didn’t say anything while leaving just to check if it would result in a spontaneous ha..ha..bye; it didn’t.
Around that time, I was reading
’s The Expression of the Emotions in Man and Animals, which was probably why I was a little bit too curious of these things. Based on his observations, Darwin formulated three categories of expressions: Darwin
1) The perception of certain stimuli generates muscle movement;
2) Perception of the opposite stimuli generates the opposite movements;
In both of these, the muscle movement, which results in our expressions, may or may not be necessary, that is, these are habits, involuntary.
3) Sometimes, perception leads to expressions that do not involve muscles.
A small part of expressions is learnt, most of it is transmitted. So if you decide something is funny and laughable, whether you want it or not, your facial muscles will move, like when you laugh.
George Washington Crile in 1915 related these emotions to the energy transduction pathway between the various organs, in The Origin and Nature of Emotions. His observations (once again meticulous considering the existing technology at that time and I wonder if these experiments have now been repeated using scanning probe microscopy) were that in animals exposed to various kinds of shocking emotions like anger, fear and even in surgical trauma, damage could be observed in the Brain, Kidney and Liver tissue. Besides establishing that functionally these organs are dependent, he also proposed that conversion of potential energy to kinetic energy (motion and heat) was the common denominator in their functions.
Crile’s recording of body temperature(human body temperature was first systematically documented by Carl Reinhold August Wunderlich in 1861) was what I found most intriguing. The diurnal variation of our body temperature (starts getting warm around and starts cooling down around ) is now known to be controlled by the superchiasmatic nucleus (SCN). The SCN is also the main site receiving nerve signals from our eyes.
I had been trying to find a link between the HPA axis and our visual signal processing pathway for quite sometime.