Artificial Consciousness/Neural Correlates/Neural Groups/Center Surround Function

The Center Surround Function
As I mentioned in the Neural Groups page, One of the reasons why we study neural groups is because of the tendency of neurons at least in the Left hemisphere of the cerebral cortex to self-organize into groups where hundreds of neurons act to influence the output of a few selected neurons.

The problem is that we don't know enough about other areas of the brain to be able to be sure that they don't also self-organize, nor enough about how the Left Hemisphere does, to be able to prove that they shouldn't. One theory, exists however which might shed light on this function, and that is the theory that the center surround mechanism is managed by the sixth layer Pyramidal Neurons of the Cerebral cortex, and that therefore we shouldn't expect the same self-organization in other ares of the brain, unless they have a similar function.

Center Surround Function might be a very important cortex function, in that it gathers together a large field of data, to produce a single signal. This partitioning of knowledge into clusters, might be extremely important in that it allows for recognition of fields of responses as being germane to a single signal. This also might speed the discrimination of signals, since if they trigger different neural groups they must be different.

In some theories of the bicameral mind, it is the ability of the brain to both cluster the signals thus recognizing the simularity of certain types of signals, and the ability to have a representation of the same signals, that is not so differentiated, that gives the human mind more sophistication.

One interpretation is that the undifferentiated form, allows us to model ranges of signals while the other allows us to recognize groups of signals as being the same type. It has long been thought that the strategy by which we pick the more general modeling mechanism, or the more specialized differentialized form at some stages in our mental processing, is related to some extent to the dominance of the one hemisphere over the other. The greater majority of people are left dominant brainwise, and thus tend to use the differentiated form preferentially to the undifferentiated form.

Thus, it is thought that Left handed people tend to be more artistic, while Right handed people tend to be more specialized. Recently work has been done on mixed handedness, that suggests that strategies that make use of both sides of the brain may make understanding of things like evolution more likely, in that the differentiated form and the undifferentiated form are more easily fused if the processing strategy compares them more often. One way of looking at this, is that people with balanced brain dominance tend to see the larger picture because they can compare the model to the specialized recognition system, and thus see where one is more useful than the other.

While we don't know exactly how the Sixth layer Pyramidal Neurons operate, one thought is that they cluster the neural group together by sensing pre-threshold signals, suppressing the surrounding neurons to keep them from actually firing, and promoting the centroid of the set so that it fires. Evidence that the centroid shifts over time, might indicate that because of its dependence on the prefiring potential of the second and third layers of the cerebral cortex, the highest value pre-firing is allowed to fire, while the rest of the neurons are suppressed. As one neuron becomes fatigued, or habituated, and can no longer fire, the next most enervated neuron, takes over, thus keeping the neural group active longer.

The Sixth layer pyramidal neuron, has been associated with the Column structure in the cerebral cortex, where it has been seen that stimulation at different levels within the column causes the column as a whole to fire, suggesting that the column, at least in the Left Hemisphere of the brain is the most likely signal level to be transferred outside the cortex.