In this chapter, we transitioned from thinking about LTP as a straightforward activity-dependent form of synaptic plasticity. We saw, for example, that LTP induction is subject to a great number of modulatory influences. Also, temporal integration mechanisms are key to regulating LTP induction. In addition to these issues, we discussed the fact that regulating membrane excitability, directly by modulating membrane ion channels and indirectly through local GABAergic circuits, can play a pronounced role in regulating LTP induction. Finally, we noted the existence of altered probability of action potential firing as a persisting effect superimposed upon synaptic potentiation. All these issues are key to thinking about the roles for LTP in memory formation in the behaving animal. The synapse integrates a wide variety of signals in order to make a biochemical decision whether to trigger lasting change. In the next three chapters we will take our analysis to the next level of detail and discuss the molecular mechanisms that allow for this complex physiologic information processing to occur.


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LTP Induction Biochemistry J. David Sweatt, Acrylic on canvas, 2002

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