Glossary
Long-term potentiation
What is long-term potentiation?
Long-term potentiation (LTP) is a lasting increase in the strength of communication at a synapse following particular patterns of activity. It is a major experimental model for studying the synaptic basis of learning and memory.
How it works
In a well-studied NMDA-dependent form of LTP in the hippocampal CA1 region, glutamate released by the sending neuron coincides with sufficient depolarization of the receiving neuron. Depolarization relieves a magnesium block of the NMDA receptor channel, allowing calcium to enter the receiving cell. The calcium rise activates signaling processes that support stronger transmission.
Changes in AMPA receptors help express that strengthening: more receptors can be delivered to the postsynaptic membrane, and receptors already there can change their activity. The result is a larger response to subsequent input. These steps are described in Purves and colleagues’ account of LTP induction and a review of NMDA receptor activation. LTP mechanisms vary; the properties of this form should not be assumed to describe every synapse or every kind of learning.
Applied example
Imagine recording responses to two separate inputs, A and B, onto the same neuron. Researchers first test both, then give A an LTP-inducing stimulation pattern while B does not receive that pattern. If later test pulses show a persistent increase for A but not B, that illustrates input specificity: strengthening is selective rather than shared by every input to the cell.
This selectivity helps explain interest in LTP as a memory model, because learning must distinguish particular inputs. The comparison is an illustration of an experimental property, not proof that either input stores a particular everyday memory.
Why it matters
LTP provides a way to test cellular models of memory. It does not mean every learned association is permanent or that all behavior change has a single synaptic mechanism.
Evidence note: Bliss and Collingridge (1993) describe LTP as an experimental model of memory.