Perhaps the most fundamental of these is the mind-body problem—how the workings of the brain can give rise to perception, memory, feelings, and consciousness. For a long time, problems in these areas were considered to be unsolvable or even to be outside the proper domain of scientific exploration. Indeed, as A. N. Whitehead first noted, since the very beginning of Western science, the mind was removed from nature. Galileo, quite properly, felt it was not necessary to consider the mind in pursuing his physics. And with his dualism, Descartes quite explicitly considered the mind to be a thinking substance, not an extended substance examinable by physics. By the end of the nineteenth century, however, the rise of experimental physiology and psychology made it clear that the mind had to be put back into nature by scientific means. This remains a formidable task and the path to its accomplishment has not been a smooth one. In the present century, we have seen, for example, the rise and fall of introspectionism, of behaviorism, and, more recently, of the computer model of the mind. But now the task of understanding the relationship between the mind and the brain appears achievable.
What is different now is the remarkable explosion of knowledge in neuroscience over the last several decades. A confluence of multiple disciplines and a still unabated swell of interest are almost certainly major contributors to this remarkable growth. The implications for matters of human concern are obvious: Neurological disease, psychological exploration, psychiatry, the human sciences, and even art are all likely to be strongly influenced by the findings of neuroscience…
Modern neuroscience began in connection with medicine, and the contemporary neurology that grew out of this connection is a superbly precise diagnostic engine. But, largely because of the fact that central nervous system neurons do not regenerate, the formation in many diseases of what amounts to scar tissue after cell death prevents the formation of new connections. Modern advances in early diagnosis by techniques of brain imaging and molecular biological characterization of basic cellular processes of the neuron promise to change this picture. Moreover, transplantation methods and implantation of electrodes by modern neurosurgery show great promise in treating diseases such as Parkinsonism. For these reasons, the somewhat gloomy forecasts of a decade ago have been replaced by guarded optimism. Within the next decade, we can expect the same kind of happy transformation to occur in neurology as was experienced in cardiology after World War II.
As significant as this is, the resolution by neuroscientific research of some of the deep problems of psychology will be even more significant. It has now become clear, for example, that a major mechanism underlying learning and memory is a biochemical change in the strengths of neural connections in the brain known as synapses. The intricacy of these structures is stunning and their numbers are hyperastronomical—there are approximately 1 million billion synapses in the cerebral cortex alone. Through studies of synaptic changes, the likelihood of understanding memory and even improving it has recently been enhanced. The mechanisms by which we perceive events and objects and the means by which we control movement are also becoming better understood.
These advances stem in part from new technologies ranging from molecular biological assays, through the use of multiple recording electrodes, to imaging methods applied to the brains of living subjects doing various tasks. It is now possible, for example, to visualize the neural correlates of conscious states. But perhaps more important than any single technical application is the ability to observe a living and behaving animal or human by means of a multilevel approach. A robust theoretical framework that goes well beyond facile comparisons of the brain to a digital computer is now available to make sense of the enormous amounts of data that will emerge. Although much of modern biology is pursued without strong dependence on theory, if brain science is to deal with the very bases of our sentience, it must not take such a stance. There is now an increasing interest in consolidating intermediate range theories involving perception, memory, and consciousness into a global theory of brain function…
What are the unmet challenges to this vigorous and fruitful program of research? Above all, we need to resolve some outstanding mysteries. One is consciousness itself—a problem whose solution, William James suggested, would mark the greatest scientific achievement of all times. A second problem is a related one—why do we sleep? Much progress has been made in this arena but the actual function of sleep remains a mystery. Another area of deep social significance relates to drug abuse. How can we meet the challenge to human integrity that is posed by addiction? And, of course, there remains the vast field of mental disease that is connected in one way or another to all of these extraordinary problems.
A key area to be addressed by neuroscience concerns the expressive or emotive aspects of brain function. These aspects are seen and experienced as feelings, and, in language, as the communication of feelings. Analogies to physics and computationally based brain theories either do not address the origin of feelings or fail abysmally to account for them. This stands as a major criticism of those aspects of cognitive psychology that are based on the computer model. There is a suggestion that the so-called selectional brain theories… may be able to address this issue. Such theories depend on the workings of evolved value systems of the brain and their task is to connect these basic neural systems to emotion and meaning. If they succeed, the insights that emerge will greatly affect approaches to improving the development and education of children.
--The Brain, Gerald M. Edelman, Jean-Pierre Changeux
