Just what is consciousness The answer I believe is that

consciousness is an instinct—a built-in property of brains. Like all instincts, it is just there. You do not learn to be conscious and you cannot unlearn the reality of conscious experience. Someday we will achieve a more mechanistic understanding of its operation, but I warn you now: That won't be especially fulfilling on a personal level. We have to shed our expectation that a scientific understanding of consciousness will sweep away our sense of strangeness, like finding out how ships get in bottles. Take our reproductive instinct. Does it help our sense of desire to understand the role of testosterone when we see a shapely figure across the room? Or take the human instinct for language. Does it help us to enjoy language if we understand that grammar is a universal built-in reflex but that our lexicon is learned? Understanding the problem of consciousness may be essential to our ultimate ability to deal with some mental disorders. Disorders of conscious experience, whether autism or schizophrenia or dementia, will be illuminated by a mechanistic understanding of personal conscious experience.

My own thinking on this topic started early, in Roger Sperry's laboratory at the California Institute of Technology on an afternoon almost 40 years ago, when I first tested a split-brain patient. It seemed that,

This article is reproduced from Gazzaniga, M. S. (1999). The interpreter within: The glue of conscious experience. Cerebrum 1(1). with permission of the Dana Foundation.

whatever consciousness was, you could have two of them after the surgical severy of the corpus callosum connecting the two cerebral hemispheres. Mind Left did not appear to know about Mind Right and vice versa. Those first impressions, which still endure, nevertheless left much to be desired as a sophisticated perspective on the question of consciousness. My plight as a researcher echoed Tom Wolfe's admonition to practice writing for 20 years before you seek a publisher.

Classic split-brain research highlighted how the left brain and the right brain serve distinctive functions and led us to believe that the brain is a collection of modules. The left brain (or hemisphere) is specialized not only for language and speech but also for intelligent behavior. After the human cerebral hemispheres are disconnected, the patient's verbal IQ remains intact and his problem-solving capacity (as observed in hypothesis formation tasks) remains unchanged for the left hemisphere. Indeed, that hemisphere seems to remain unchanged from its presurgical capacity. Yet the largely disconnected right hemisphere, which is the same size as the left, becomes seriously impoverished for many cognitive tasks. While it remains superior to the left hemisphere in certain activities (in recognizing upright faces, having better skills in paying attention, and perhaps in expressing emotions), it is poorer after separation at problem solving and many other mental activities.

Apparently the left brain has modules specialized for higher cognitive functions, while the right has modules specialized for other functions. Visuospatial function, for example, is generally more acute in the right hemisphere, but left hemisphere integration may be needed to perform higher order tasks. The use of tactile information to build spatial representations of abstract shapes appears to be better developed in the right hemisphere, but tasks such as the Block Design test, which are typically associated with the right parietal lobe, appear to require integration between the hemispheres in some patients. Furthermore, even though the right hemisphere is better able to analyze unfamiliar facial information than is the left hemisphere, and the left is better able to generate voluntary facial expressions, both hemispheres can generate facial expression when spontaneous emotions are expressed.

In addition to the skills named previously, our big human brains have hundreds if not thousands more individual capacities. Our uniquely human skills may well be produced by minute, circumscribed neuronal networks, sometimes referred to as "modules," but our highly modularized brain generates a feeling in all of us that we are integrated and unified. If we are merely a collection of specialized modules, how does that powerful, almost self-evident feeling come about?

Anxiety and Depression 101

Anxiety and Depression 101

Everything you ever wanted to know about. We have been discussing depression and anxiety and how different information that is out on the market only seems to target one particular cure for these two common conditions that seem to walk hand in hand.

Get My Free Ebook


Post a comment