An introduction to the defence against neurobiological reductionism

It was whilst studying neuroanatomy during my third semester at medical school that I first came across the problem of neurobiological reductionism. We had three weeks to prepare for this fourth and final part of the cadaver dissection course, and so I delved into the realms of our brain and spinal chord, the ‘central part’ of our nervous system, learning about the various lobes, the basal ganglia, the limbic system, the brain stem and so on. It wasn’t until learning about the frontal lobe, which includes the prefrontal cortex – a structure that’s widely held responsible for many of the characteristics that separate human beings from all other living things- that I began to think about the meaning of such understanding for the concepts about our own actions, and indeed for free will in itself. An often used example when explaining the functions of the prefrontal cortex is the tragic story of the young American railroad construction worker Phineas Gage. He was the head of a small unit of men within the rail company, described by those who knew him as extremely capable; an excellent worker as well as a respected leader. During an accidental explosion in 1848, an iron rod was knocked into Mr. Gage in such a way that it ‘entered on the side of his face, shattering the upper jaw, and passing back of the left eye, and out at the top of the head’1, cutting in its path through the connections between limbic system (held responsible for motivation and human drives) and the prefrontal cortex. It didn’t, however, damage his brain stem, and he was thus left alive. To the general astonishment of medics at the time, Phineas Gage recovered fully from the accident. He was able to see with his other eye, his vital organs worked normally, he was able to walk, talk, eat, drink and appear generally like a well-functioning human being. Yet emotionally, Mr. Gage changed. He became erratic and uninhibited in his behaviour. He lost his job and his friends. His post-accident behaviour was compared to that of a child. Anatomically, everything still worked the way that it should do, except for the damaged connections within his brain. The prefrontal cortex was cut off from the limbic system, and this showed in his behaviour. Interestingly, it has often been claimed that Mr. Gage later managed to relearn some of his social capacity- the changes were apparently not permanent.

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