by Dr. Christoph Kellendonk and Dr.Gael Mallet
Center For Neurobiology and Behaviour Columbia University New York
In the early part of the 19th century Franz Joseph Gall, a physician at the University of Vienna, stated that mental processes are biological and arise from the brain. Thereby, he rejected the dualist thinking which separated the body from the mind, an idea that was discussed by the French philosopher Rene Descartes and that was in line with the current thinking of the church. This was of course a revolutionary hypothesis not only for the scientific field but also for society in general. Until the beginning of the nineteenth century, the study of mind was part of philosophy, and the chief method for understanding the mind was introspection. By the middle of the nineteenth century, introspection began to give way to experimental approaches that eventually led to the independent discipline of experimental psychology. In its early years, experimental psychology was concerned primarily with the study of sensation, but later psychologists turned to behavior itself including learning, memory, attention, perception, and voluntary action. Gall and his followers realized that the brain and specifically the cerebral cortex – a brain area that is most developed in humans – are subdivided into various centers that are responsible for distinct mental functions. Today we know that these centers or functional sites are interconnected systems controlling complicated processes such as language, memory or emotional thinking. For example, in the cerebral cortex there are two distinct areas responsible for the processing of language. The first, known as Wernicke area, is required to understand language, the second, the Broca area is required to express language. A patient with an impaired Wernicke area can speak but has an impaired comprehension, whereas a patient with a destroyed Broca area can understand simple sentences but cannot formulate grammatically correct or complete sentences. However, although both areas are necessary for language processing they are not sufficient because finally a large network of interacting brain areas are additionally recruited. How large networks of neurons or systems mediate complex behavior is one of the major and most fascinating fields in neuroscience today.
Yet, despite all scientific achievements, it is still hard to believe that mental processes should simply be the consequence of electrical and chemical reactions in the brain. This holds true in particular for emotions that are often unconscious and therefore even harder to understand by logical reasoning. However, it is widely believed that the complexity of the human brain – independent of our understanding of this complexity – is sufficient to organize these processes. The complexity itself arises partly from the indefinite possibilities of interconnections between billions of nerve cells or neurons that are the simple units of the brain.
Bodo Korsig’s work explores the limits of philosophy and science by asking questions about personal identity and the matter of the mind, and how we artificially can affect them. Nowadays we can buy everything in the shopping mall, why not buy a new brain? A “head transplant” could solve a lot of problems such as erasing bad memories – “erase your past” or getting rid of a life-threatening brain tumor. However, most biologists will agree that we are not able to exchange our brains because: we are our brains. For scientists, mind, identity and emotions are generated by the brain. Korsig’s “Where can I buy a new brain” is therefore a contradiction in itself.
Nevertheless, in the early 1970s, cephalic exchange or head transplantations have been performed in monkeys but with little success. Viability ranged from 6 to 30 hours. There are two major challenges to cephalic transplantation. First, the brain has to be connected to the cardio-vascular system of the body and second, the body may reject the new organ. In addition, the body will have a totally different experience than the brain. Although cognitive processes and emotions are mediated by the brain the inter-play between body and brain strongly affects brain activity and therefore the state of the mind. Body and brain usually experience and learn together. When we learn to ride a bicycle, brain and muscles are learning the task together. Try transplanting a brain of a professional cyclist into the body of someone who never rode a bike before, and see what happens.
To consider another example: We know that intense feelings trigger the release of hormones into the body. Best known is the adrenaline rush we feel in a stressful situation. Adrenalin is secreted into the body from small endocrine glands closely located to the kidney. From there it is transported to the brain and modulates the activity of the brain, thereby affecting our level of attention. In consequence, the interaction between mind and body affects not only basic processes such as motor coordination, but also higher cognitive functions that affect our very true way of thinking.
Although a transplantation of a whole brain is luckily out of interest, brain tissue transplantations are currently being developed as a clinical-therateupic tool for neurodegenerative disorders such as Parkinson’s or Alzheimer disease. In Parkinson disease neurons producing the neurotransmitter dopamine degenerate in a specific brain structure called substantia nigra. As a consequence patients have severe problems with movements including a paucity and slowness of movement and involuntary tremulous motions. In addition, patients suffer from cognitive deficits such as decreased working memory. Patients are usually treated with drugs that increase the amount of dopamine in the brain. But, even with the newest antiparkinsonian drugs the benefits of drug therapy usually begin to wane after five years and troublesome side effects such as uncontrolled movements develop. One new therapeutical approach is to transplant fetal or embryonic stem cells producing dopamine into the target areas of the degenerated neurons. This approach is still in its beginning but despite largely negative results promising because it would reconstitute the brain’s ability to produce its own dopamine. However, it opens the ethical question whether the transplantation of foreign tissue alters the personal identity of the patient. Do we preserve the personal identity of the patient by ameliorating the symptoms of Parkinson or do we alter it? If the brain is the substrate of the mind and if we replace parts of that substrate we may theoretically change the mind. What affects personal identity more, the disease or the transplant? And the end, we have to be practical. If transplantation reduces suffering and if it improves the prognosis of the disease a slight change in the personal identity will most likely be the smaller problem.
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One of the great remaining mysteries of biology is the nature of consciousness. The study of consciousness is a highly debated field among philosophers and biologists because consciousness cannot be easily explained in reductionist physical terms. A major problem in the study of consciousness is that one defining characteristic is subjectivity. Each of us experiences a world of private and unique sensations. Our own ideas, moods, and sensations we experience directly, whereas we can only appreciate other people’s ideas, moods, and sensations by referring to our own direct experience. How can we measure subjective processes by objective measures, when we don’t even know if we all see the same color when we look on a blue monochrom? Another problem is that we have a single conscious experience. Consciousness comes as a unified whole. When we look at and listen to a person, we do not hear this person independently from seeing this person. Both sensory experiences come together as a single experience. At one moment, all external and internal stimuli will be experienced as one unified perception. Since it is impossible to measure all variables affecting our brain, it will be difficult to measure the unified whole of consciousness. Therefore many philosophers and scientists believe that we will not be able to study consciousness. However, as the philosopher Patricia Churchland points out, scientists have made major progress in understanding the neural basis of color perception without knowing whether each of us sees the same blue. Besides, the perception of color is in itself a conscious process and by studying this process we are studying consciousness.
Will we ever completely understand the mind? We don’t know. But already what is known today about the mind and its substrate, the brain, is deeply fascinating. Bodo Korsigs paintings and sculptures reflect this fascination.