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10/25/11

Can the Brain Explain Your Mind? On V.S. Ramachandran

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"Is studying the brain a good way to understand the mind? Does psychology stand to brain anatomy as physiology stands to body anatomy? In the case of the body, physiological functions—walking, breathing, digesting, reproducing, and so on—are closely mapped onto discrete bodily organs, and it would be misguided to study such functions independently of the bodily anatomy that implements them. If you want to understand what walking is, you should take a look at the legs, since walking is what legs do. Is it likewise true that if you want to understand thinking you should look at the parts of the brain responsible for thinking?

Is thinking what the brain does in the way that walking is what the body does? V.S. Ramachandran, director of the Center for Brain and Cognition at the University of California, San Diego, thinks the answer is definitely yes. He is a brain psychologist: he scrutinizes the underlying anatomy of the brain to understand the manifest process of the mind. He approvingly quotes Freud’s remark “Anatomy is destiny”—only he means brain anatomy, not the anatomy of the rest of the body.

But there is a prima facie hitch with this approach: the relationship between mental function and brain anatomy is nowhere near as transparent as in the case of the body—we can’t just look and see what does what. The brain has an anatomy, to be sure, though it is boneless and relatively homogeneous in its tissues; but how does its anatomy map onto psychological functions? Are there discrete areas for specific mental faculties or is the mapping more diffuse (“holistic”)?

The consensus today is that there is a good deal of specialization in the brain, even down to very fine-grained capacities, such as our ability to detect color, shape, and motion—though there is also a degree of plasticity. The way a neurologist like Ramachandran investigates the anatomy–psychology connection is mainly to consider abnormal cases: patients with brain damage due to stroke, trauma, genetic abnormality, etc. If damage to area A leads to disruption of function F, then A is (or is likely to be) the anatomical basis of F.

This is not the usual way that biologists investigate function and structure, but it is certainly one way—if damage to the lungs hinders breathing, then the lungs are very likely the organ for breathing. The method, then, is to understand the normal mind by investigating the abnormal brain. Brain pathology is the key to understanding the healthy mind. It is as if we set out to understand political systems by investigating corruption and incompetence—a skewed vision, perhaps, but not an impossible venture. We should judge the method by the results it achieves.

Ramachandran discusses an enormous range of syndromes and topics in The Tell-Tale Brain. His writing is generally lucid, charming, and informative, with much humor to lighten the load of Latinate brain disquisitions. He is a leader in his field and is certainly an ingenious and tireless researcher.  . . .

We begin with phantom limbs—the sensation that an amputated or missing limb is still attached to the body. Such limbs can arrange themselves intransigently into painful positions. The doctor touches the patient’s body in different parts with a cotton swab, eliciting normal responses; then he touches the patient’s face and elicits sensations in the patient’s phantom hand, finding an entire map of the absent hand on the patient’s face. Why? Because in the strip of cortex called the postcentral gyrus the areas that deal with nerve inputs from the hand and face happen to be adjacent, so that in the case of amputation some sort of neighborly cross-activation occurs—the facial inputs spill over to the area that maps the phantom hand.

A contingency of anatomy therefore gets reflected in a psychological association; if the hand area of the brain had been next to the foot area, then tickling the foot might have caused a tickling sensation in the phantom hand. In another patient, amputation of the foot leads to sensations from the penis being felt in the phantom foot, including orgasm. Ramachandran devises a method to enable patients to move their paralyzed phantom arms, by using a mirror that simulates seeing the absent arm by reflecting the remaining arm: the brain is fooled into believing that the arm is still there and lets the patient regain control of its position. There are even cases in which the mirror device enables a patient to amputate a phantom arm, so that he no longer suffers the illusion of possessing it."  More
(Review by Colin McGinn of V.S. Ramachandran's The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human)
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