Split-Brain and Suicidal Tendencies
While reading through some psychology texts, trying to focus through a wine-induced haze, I read something which absolutely fascinated me. But to talk about it we’ll need to do a crash course in neuro-psychology. Don’t worry, it’s not as bad as it sounds, in fact you might even like it.
The brain is split into two hemispheres, the left and the right. The left side processes all stimuli and motor activities for the right-hand side of the body, and the right hemisphere does the same for the left-hand side of the body. Further to this, certain sides of the brain are generally responsible for certain patterns of thought, such as the left hemisphere being the rational side and the right hemisphere being the emotional side. The corpus callosum is the structure of the brain that links the two hemispheres and is a conduit for the two to communicate with each other.
Now, it is possible for someone to exist with impairment to the corpus callosum, and this has been observed in particular in certain surgeries which intentionally sever the link between the two hemispheres in a last-ditch attempt to help people suffering from serious and regular epileptic seizures that have not responded to other therapies (this contains the brainstorm activity to the hemisphere on which it starts). People who have had this surgery can seem perfectly fine and normal most of the time, however Roger Sperry et. al. performed some experiments in 1968 which showed behaviour in such individuals which was far from normal. In these experiments / tests it was shown that a blindfolded participant who has undergone the aforementioned surgery will be able to recognise objects they touch with their left hand, but are unable to say what the object is. This seems to be because the left hand is linked to the right hemisphere of the brain, however the part of the brain that deals with speech is in the left hemisphere and the brain is no longer able to pass messages between the two sides. Further to this, once the participants touched the object with their right hand they were able to say what it was.
While that is plenty fascinating enough, it is the (1998) description by V. S. Ramachandran of a 1950s case study that really caught my eye. A woman who had part of her corpus callosum damaged by a stroke found that although most of the time she appeared normal, occasionally she would attempt to strangle herself with her left hand. She had to use her right hand to fight off the left hand (is everyone else getting the Dr Strangelove image here too?).
Ramachandran proposed that the woman had suicidal tendencies in the right hemisphere of her brain (remember this is where the emotional stuff happens) but that was normally kept under control by the logical and rational left hemisphere. After the stroke destroyed the link between the two hemispheres, however, the emotional side was free to do as it wished, including sending impulses to the arm to attempt to end her own life!
The thoughts this opens up could keep me busy for days, but I’ll let you mull them over yourselves. I will say, however, that it does raise interesting questions about affective (to do with emotional state) disorders, especially since people who have damage to the left (rational) side of the brain exhibit much more concern / worry / etc. over what has happened to them than people who have suffered damage to the right (emotional) side, who generally appear to be a lot more blasé about their experience.
Could it be that those of us who suffer from things like depression and bipolar disorder are experiencing an inequality between the hemispheres of the brain? A kind of brainy power-struggle? Could we possibly combat this by doing certain things to improve left-hemisphere dominance? I don’t know, I haven’t read enough about it yet. But it sure is interesting to think about.