In the NYRB, Colin McGinn reviews Oliver Sacks’ Musicophilia: Tales of Music and the Brain:
Sacks generally eschews theoretical speculation in Musicophilia, but he does raise one theoretical possibility that has influenced thinking about mind and brain from the great British neuroscientist Hughlings Jackson on, namely the notion of disinhibition. Sacks writes:
Normally there is a balance in each individual, an equilibrium between excitatory and inhibitory forces. But if there is damage to the (more recently evolved) anterior temporal lobe of the dominant hemisphere, then this equilibrium may be upset, and there may be a disinhibition or release of the perceptual powers associated with the posterior parietal and temporal areas of the non-dominant hemisphere.
This is an extremely intriguing theory, because it suggests that the brain contains untapped potential that is released only in unusual conditions. With damage to the left hemisphere, in which language is primarily located, the right hemisphere tends to come into its own. Blindness and deafness can result in an access of musical achievement, as the brain devotes itself to activities other than seeing and hearing. Strokes can result in newfound talents precisely because they turn off the inhibitory mechanisms in the brain. Synesthesia may be lurking within all of us, if only our brain weren’t tamping it down all the time. Savants may get the way they are simply because they don’t have the brain circuits that put clamps on the natural abilities we all share.
In other words, the brain is forever reining itself in, slowing itself down, suppressing its natural powers—all in order to preserve that precious equilibrium. Remove the abstract rational and linguistic structures and the suppressed portions of the brain can break free and flower. I