|MadSci Network: Neuroscience|
This reply comes from Dr. J. Horowitz, Professor Emeritus of the University of California At the cellular level, memory is often associated with long-term-potentiation, LTP (although this is still an area of debate). LTP can occur at all the synapses in the trisynaptic circuit, and hence the transmission of signals along the circuit can be modified as new "memories" are laid down. The "function" of the trisynaptic circuit is thus, as noted in the question, to get signals into, through, and out of the hippocampus. Actually, the circuits are a good deal more complex, e.g. there are recurrent collatorals and many inhibitory interneurons modify activity. In the intact animal, the theta rhythm (driven by signals from the septum) excites cells synchronouosly, thus, the situation is even more complex. The bottom line is that the exact relationship between memory and the basic trisynaptic hippocampal network is unkown, although since the Hebbian synapses have been identified all along the trisynaptic circuit one can speculate that modification of synaptic strength somehow may play a role in mnemonic mechanisms.
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