Artificial Consciousness/Neural Correlates/Synaptic Models/Complex Ion Channel Model

Complex Ion Channel Model

It is tempting to think of Ion channels as either filters that allow one type of ion into the channel, and thus filter all others out, or pumps that pump one type of ion across the membrane against the electrostatic gradient. And at one time, that was probably all that ion channels were, however, some ion channels evolved into multi-function mechanisms that are much more complex, and interact at a much more intimate level with the chemistry inside the neuron. Some ion channels pump different ions in different directions and some ion channels have secondary messengers that trigger chemical responses inside the cell. And some have it all, the NMDA ion channel for instance pumps potassium out of the cell, Calcium into the cell, and attracts Magnesium Ions to the outside of the ion channel when the cell it is in isn't near firing. These have the effect of blocking the ion channel so that it only works when the cell is near firing. As well, although it is primarily a Glutamate detector triggered ion channel, the ion channel can be blocked open by the presence of a second Neuro-Transmitter essentially sustaining firing long after the other synapses quit triggering it. Finally, the NMDA ion channel releases a chemical called cAMP that together with the calcium, triggers a chemical cascade reaction that involves parallel chemical cascades happening simultaneously, triggers DNA expression, and Protein Regulation mechanisms, and any number of other things that haven't been detected yet.

Eric R. Kandel of Columbia University, another Nobel Laureate, studied the operation of the NMDA ion channel, and extracted from it, a theory of long-term memory formation at the cellular level.

Although the S synapse is not quite as complicated, it may share some of the aspects of the NMDA ion channel including the linkage to long-term memory.

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Artificial Consciousness/Neural Correlates/Synaptic Models

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