metonymy4u

When I was in graduate school studying neuroanatomy I realized one day that the paradigm of brain mapping being taught was not intellectually satisfying to me in one very important way. Here’s the paradigm: peripheral nerve group A is stimulated by an event and fires signals which travel to brain cell group A which are then stimulated into activity which is different than peripheral nerve group B being stimulated and sending electrochemical impulses to brain cell group B, so that’s why we experience different sensory events as different. For example, if I see the color “green” this stimulates certain cells in my retina which sends impulses to various regions of my brain in the back of my head so I see green, whereas when I hear the note middle C on the piano, other brain cells in other parts of my brain are stimulated, so that’s why I don’t confuse green with middle C.

Neuroanatomy comes down to brain mapping—a description of which events end up stimulating which groups of cells in your peripheral and central nervous system.

The problem I had with this was that one day I suddenly realized that the model didn’t explain anything at all! How do we, the sensing creature, know that group A’s neurons being stimulated corresponds to “green” events and that group B neurons being stimulated corresponds to “middle C” events? Is there some master control center somewhere else in the brain where cells know that A neurons mean “green” and B neurons mean “middle C?” But if that were the case, then we would just end up with yet another extension of the brain mapping. So is there yet another neural center of representation to code the first representational center? Of course, this could quickly become an infinite regress…

It quickly became clear to me that the neuroanatomical model provided no explanation whatsoever for what I named “the subjective character” of human experience. (Which is the fact that I clearly experience green as distinct from middle C). Based on this model of brain mapping, how could I ever know the difference between middle C and green, since they all seemed to reduce to one group of neurons or another when mapped onto my central nervous system?
I asked all my professors to clear up this paradox. All but one had no idea what I was talking about. The one professor who understood the question also understood that he did not have the answer.

Philosophers of mind call this the “anesthesia problem.” In order to give an objective account of the human mind, they claim, one must feign anesthesia about all of these so called subjective experiences, since the objective neuroanatomical models provide no way of locating a neuroanatomical cause of subjectivity. Since to feign anesthesia is clearly ridiculous, they therefore claim that the objective models must commit the fallacy of trying to reduce something that is irreducible. Call it “subjectivity” or “intentionality” or “mind,” the objection to the neuroanatomical model is still the same, and it is misguided.

The problem is that we have forgotten what Kant taught us about models of human experience. In brief, what Kant said was that we are contingent beings trying to understand the world from the perspective of the uncontingent. He cautioned that though this may be a useful approach to many of life’s problems, it is ultimately doomed to fail, because it is clear that we cannot, at least in this life, transcend the contingencies of an existence in a physical body. Thus, he said, we should not be surprised if we constantly come up against the limits of our knowledge, which Wittgenstein said were the limits of language.

What does this have to do with modern neuroanatomy? The mistake that I made as a student was to follow my professor’s lead in assuming that events create distinct and discreetly localizable responses in the brain. Certainly at the level of resolution that most modern imagining techniques allow, it looks as though responses to distinct events can be localized with some degree of certainty. However, we also know that the brain is a much more interdependent organ than was previously thought, and that there really is no such thing as a completely isolatable event. The body impacts the brain and the brain impacts the body in a continuous dance of mutuality. For example, cortisol levels released in response to stress damage the hippocampus and may be implicated in depression and anxiety. Brain deficiencies in prefrontal executive circuits can impede activities of daily living and result in increases in stress hormones and subjective experiences of anxiety and depression. The list could go on from there, and no doubt will as our science refines its level of resolution. The point is that it is no longer appropriate to think about discrete brain regions but rather we need to think about the state of the entire brain as it is situated in the body at any given moment.

From this perspective, it is no longer appropriate to think about “knowing” the difference between middle C and green. To say that we “know” the difference between middle C and green becomes a non-sequitor, unless by “know” we are simply describing a propensity for future actions, which seems as preposterous to me as the argument from anesthesia. Because to know the difference between C and green would seem to imply that there is something added to the complete description of the whole brain in response to C. But this just recapitulates the mistake that Kant was trying to warn us about. It represents the effort to go beyond a contingent description of the facts and hypothesize an object that can never be given in experience. Kant destroyed this endeavor in his critique of rational psychology but we clearly still see it cropping up in our cultural habits of experiential description. I think that the answer Kant would have proposed to my student question would be something like this:

            “The answer is that the whole brain experiences C and green, and the whole brain is in a different electrochemical configuration when stimulated by C as opposed to when it is stimulated by green. What we call ‘knowing the difference between C and green’ is nothing more than the fact that our brains are in a different state at different points in time. There is nothing else to add to the description. You have exhausted all the facts available to your contingent brain. To try to move beyond these facts is to entertain an experience of the uncontingent, and that, my son, you will never achieve in this life.”