Tuesday, May 10, 2011

When Your Brain Rejects Your Body

The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human
V.S. Ramachandran has produced a fascinating book: The Tell-Tale Brain: A Neuroscientist’s Quest for What Makes Us Human. He provides us with a description of the brain that delves into its complexity, but focuses on illuminating areas where recent research has generated increased understanding. One thing he emphasis throughout is that there are many human behaviors that have traditionally been attributed psychological issues that can be better explained as neurological issues. We will consider an explanation for why people might have an intense desire to amputate a limb, or to change the sexual orientation of their body.

The brain has evolved by adding new structures on top of old structures. If this addition is consistent with or enhances survival it is likely to survive and be passed on to progeny and enter the gene pool. This is not engineering. The brain will try to use whatever capability this new feature might provide, but what emerges is a complex interweaving of functions and connectivities. For example, the author states that there are at least thirty areas in the brain that contribute to visualization. Not all have a known function, but evolution seems to have arrived at multiple levels of sophistication and time-urgency. What one might call the unconscious brain analyzes all the visual sensory information, sends messages up to other constructs that combine it with other data available and finally send up a response to the conscious brain. The conscious brain only sees what the unconscious brain allows it to see.

Many of the structures and connections that determine sensory perception and analysis are defined during fetal growth. Given the complexity of the brain it is not surprising that in some cases the connections will not be made appropriately. This can lead to some strange and unusual behaviors. We will begin with a harmless example of how the wiring imprinted in the fetus produces confusion. We will then discuss two severe examples where wiring abnormalities lead to a conscious wish to reject parts of the body, or a wish to reject the sexual identity of the body.

Ramchandran tells us that while the appendix is positioned at the lower right of the abdomen, that is not where we first feel pain when that organ becomes inflamed.

“In the fetus the appendix first starts growing under the navel, but as the intestines lengthen and become convoluted the appendix gets pushed into the lower right quadrant of the abdomen. But the brain remembers its original location, so that is where it experiences the initial pain—under the belly button. Soon the inflammation spreads to the abdominal wall overlying it. That’s when the pain migrates to the right.”

This is a simple case of the brain feeding faulty information to the consciousness and perhaps delaying response to a potentially life-threatening situation.

The author describes a more complex condition called apotemnophilia, a term from the Greek that essentially translates to something like: “to cut away emotional attachment to.”

“....a curious disorder in which a completely normal individual has an intense and ever-present desire to amputate an arm or a leg....He may describe his body as being ‘overcomplete’ or his arm as being ‘intrusive.’ You get the feeling that the subject is trying to convey something ineffable. For instance he might say, ‘It’s not as if I feel it does not belong to me Doctor. On the contrary it feels like it’s too present.’ More than half the patients go on and have the limb removed.”

Ramachandran provides data to convince the reader that this is truly neurological in origin. Sometimes patients will pinpoint a precise point where they want the amputation to occur. Brain and other response measurements indicate that patients have emotional reactions to being touched on the offending region of the limb that they do not have on other sections.

The author’s explanation for this phenomenon is that there are specific locations in the brain where sensory information is accumulated and processed. This processing takes place at multiple levels again. It would appear that these individuals can see and sense their limbs, but when that information gets sent up to higher levels for processing a connection is not correctly made and all or part of the limb is not recognized as being a valid body part. Since the brain seems to abhor discrepancies it generates a feeling of emotional stress over which the individual has no conscious control.

“The answer....lies in the key concept of mismatch aversion, which....plays a crucial role in many forms of mental illness. The general idea is that lack of coherence, or mismatch, between outputs of brain modules can create alienation, discomfort, delusion, or paranoia.”

Transsexuality has always been a difficult phenomenon to deal with intellectually—if it is viewed as a psychological issue. What could make a person consciously wish to go through the pain and expense of reforming their body to that of the opposite sex?

Consider the author’s description of the emotional states of transsexuals.

“Many male-to-female transsexuals report feeling that their penis seems to be redundant or, again, overpresent and intrusive. Many female-to-male transsexuals report feeling like a man in a woman’s body, and a majority of them have had a phantom penis since early childhood. Many of these women also report having phantom erections. In both kinds of transsexuals the discrepancy between internally specified sexual body image—which, surprisingly, includes details of sexual anatomy—and external anatomy leads to an intense discomfort and, again, a yearning to reduce the mismatch.”

Ramachandran suggests that a misconnection produces a mismatch between sensory detection centers and higher level brain functions creates these feelings of discomfort in much the same way that people feel compelled to eliminate an offending limb.

It is possible that Ramachandran’s description of what is causing these two phenomena is not entirely correct. What seems incontrovertible is that something in the brains of those suffering from apotemnophilia is compelling them to amputate an arm or a leg to escape emotional discomfort. We would normally feel compassion for such individuals. It seems obvious that transsexuals have felt a similar compulsion and have felt the same need to take drastic measures to find relief from emotional discomfort. Perhaps we should grant them the same understanding and compassion.

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