This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Biology 202, Spring 2005
First Web Papers
What is the consciousness? How should it be defined? Where does come from? People have a notion of what consciousness is, simply by virtue their own experiences, but do we account for in exploration our neurobiological anatomy? There debate being waged scientific community about whether or not traditional tools and language used neurobiology can consciousness. Some believe that articulated through methods brain behavior engagement, while others beyond scope those new needs to developed phenomenon In looking at the source of consciousness, we must first decide how to define consciousness. I believe that one logical way to do this is to see consciousness as a spectrum, ranging from states of heightened awareness to states of drowsiness, sleep, and coma (1). This interpretation of consciousness is employed by today's scientists and its origins go back to William James, who was one of the first to delve into questions concerning questions of conscious and unconscious states (2). When thinking about consciousness, we realize that consciousness can vary significantly depending upon the amount of attention we owe a particular process. We can control how we focus our attention when we try to recognize a face in a crowd, memorize new vocabulary words, or play an instrument.
Now that we have a working definition of what consciousness is, we must determine how we will go about identifying it in the brain. One place to start is to locate what has been called the neuronal correlates of consciousness (NCC). That is, to find the neurons that are responsible for processes that are directly involved in conscious activities (3). An example of a process that would be highly correlated with consciousness is vision. Vision is used for recognition, a common process in our conscious lives. We use visual recognition to read, determine where to move, recognize familiar faces, and so on.
Work has been done to establish a biological account for the distinction between perception and awareness. While attempts to locate the NCCs responsible for this distinction have been done, further investigation is needed to map the differences. Some reports believe that the barrier lies in the complexity of the part of the brain where NCCs are thought to be (4). Others have found limitations in the kinds of subjects that can be tested on. Animals such as monkeys have been used because their brains are similar to human brains and because scientists can control their experiments by intentionally damaging certain parts of the brain to gain insight about the functioning of it. However, since animals cannot describe what they are experiencing, it is difficult to determine if the targeted brain area is affecting their motor visual processes or their experiential visual processes (3). There is also the possibility that NCCs are not static and that any neuron can take on the function of a NCC at any place (in the neocortex) at any time (3).
While NCC mapping is still in stages of infancy, certain areas of the brain that are thought to contribute most to consciousness have been identified. Research has found that in those areas of the brain, neuromodulating occurs, a process by which chemicals affect the speed of cortical neurons synapses. Neuromodulating requires more time than a regular synapse would take thus, some believe it is there that consciousness occurs (1). These approximately one second intervals account for the extra time it takes to think about and perceive the process that is occurring. It is also interesting to note that as a conscious task is repeated, the synaptic connections between the cortical neurons occur more easily, and in parallel, the task takes less concentration to do. This could suggest a biological account of the economy of consciousness: the more I do something, the easier it becomes, and the less concentration I must spend on it to do it. While this brings us a step closer to understanding how neurons work in the systems that seem to give rise to consciousness, there are still problems to deal with.
Above, we laid the foundations for the time gap it takes for thinking to occur, but we inferred that the time gap was somehow associated with consciousness, without finding a direct accounting of it. Similarly, any mapping of NCCs could explain which neurons make consciousness possible, but it would fail to explain how they do so. David Chalmers has criticized the NCC approach to finding consciousness because he believes that such an approach can only solve part of the puzzle. In looking at a process that is associated with consciousness, we are merely explaining a cognitive function. That function can be explained using a mechanistic model, but it fails to relate that model to conscious awareness (5). Koch and Crick have a theory that neural oscillations occurring at 40 hertz bind and integrate information in such a way that makes consciousness possible (6). However, this theory, while a good account of the binding of information, still fails to explain why the bound material is experienced as conscious experience (5).
Chalmers' puts forth a theory that since the traditional reductive method of explaining consciousness has failed to answer the hard questions, a non-reductive theory should be employed. There are several scientific findings that have required non-reductive methods of explanation. For example, when electromagnetic fields were first discovered, the language used to account for a theory of physics had to be expanded. He believes that if we take experience as a fundamental, we can accomplish more to account for consciousness, as it relates to the rest of the world (5). A set of psychophysical principles that would supplement physical principles would help to explain the consciousness in a way that would be shed more insight on it than current reductive theories do. Chalmers' principles of structural coherence, organizational invariance, and the double aspect theory of information would create a new definition of consciousness that could be expanded to a number of entities that previously would not be considered conscious.
His third principle of the double aspect theory of information suggests that information consists of two parts: information states and information space, in which the former is embedded in the latter (5). This would mean that information has two aspects: a physical and a phenomenal, or experiential. If we say that information has an experiential aspect, then the binding of information through 40-hertz oscillations in neurons could give an account of consciousness. However, this would also imply that a thermostat could have experience and consciousness at some very basic level (7).
Chalmers seems to be looking for a silver bullet that will explain consciousness immediately, without having to search for something new. While there is a certain allure to his theory, it seems to be too easy. While it would help account for the gap between NCC behavior and consciousness itself, it does not explain why information is experiential.
Whether or not we want to grant a thermostat consciousness is not an issue to be taken lightly. His hypothesis means that a computer, which has great capacity to process information, has consciousness on some level. Granted, that the human nervous system is more complex and processes more information than any computer to date, but it would seem that if one were complex enough, perhaps a supercomputer, it could have a consciousness equal to, or even superior to our own. Perhaps if it is true that information is experiential, then it could be the patterns and structures that give rise to consciousness. There may not be a missing or unmapped biological element we have not accounted for, but rather a physical pattern of information that gives rise to consciousness, by virtue of the pattern and not the substance. This, however, would seem to be a reductionist theory, if it were possible to reduce consciousness to a pattern of information. The difference between a reductionist approach to this possibility and a non-reductionist approach is the proof. Reductionists would require an account of how the pattern of information gives rise to consciousness while the non-reductionist would take this on faith.
I think that either is a distinct possibility, but I find myself more skeptical of the non-reductionist approach to this matter. While electromagnetic fields required a new vocabulary for physics, it is the kind of simplistic, 'take it as fundamental' thinking that reinforced the notion of a geocentric universe for so long (8). Furthermore, I am skeptical of Chalmers' jump between physical and experiential information. Such a jump requires further explanation and evidence to make it a strong and convincing theory.
I began this research as open to both reductionist and non-reductionist possibilities. However, I am more skeptical of the non-reductionist theory, despite the difficulties that the reductionist approaches have faced. I believe it is far too soon to discount the reductionist approach as being unable to bridge the gap between neural behavior and consciousness. Given what I have seen, I believe that further research into NCCs will reveal more about how consciousness is created by the brain.
2) William James on Serendip; a resource on William James' work, written by Eugene Taylor of Harvard University Medical School.
3) Crick, F. and Kock, C. "Some Thoughts on Consciousness and Neuroscience", The New Cognitive Neurosciences. Cambridge: MIT, 2000. pp 1285-1294.
4) Perception Without Awareness; a paper by Fred Dretske of NYU.
5) Chalmers, D.J. "Facing up to the Problem of Consciousness", Explaining Consciousness, The 'Hard Problem'. Cambridge: MIT, 1997. pp 9-30.
6) Crick, F. and Koch, C. "Toward a neurobiological theory of consciousness", Seminars in the Neurosciences (1990), 2, pp. 263-75.
7) Chalmers, D.J. "The Puzzle of Conscious Experience". Scientific American (2002).
8) Can Neurobiology Teach us Anything about Consciousness?; a paper against non-reductive theories of consciousness, by Patricia Smith Churchland of University of California, San Diego.
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