Glossary
Synaptic plasticity
What is synaptic plasticity?
Synaptic plasticity is a change in how effectively a synapse transmits a signal. It is an important mechanism studied in learning, memory, and adaptation.
Long-Term Potentiation and Long-Term Depression
Long-term potentiation and long-term depression are forms of lasting strengthening and weakening. Hebbian learning describes an influential activity-dependent principle, but synaptic plasticity has several mechanisms.
How it is studied
Researchers can measure synaptic responses before and after a specified stimulation or learning procedure. A musician getting better with practice raises questions about changes in the relevant circuits; performance alone does not reveal what happened at each synapse.
A classic experimental example
In 1973, Bliss and Lømo stimulated the perforant pathway in anesthetized rabbits and recorded electrical responses from the dentate region of the hippocampus. After brief trains of repeated stimulation, responses to subsequent single inputs remained potentiated for 30 minutes to 10 hours in 15 of 18 rabbits.
The recordings included population synaptic potentials and neuronal firing measures; these did not always change together. The authors distinguished increased synaptic transmission from increased excitability of the receiving cells. This is evidence from a controlled stimulation experiment, not a direct recording of a human memory or proof that every individual synapse became stronger.
Why it matters
Experience can change how circuits work. Synaptic plasticity explains part of that capacity, but it should not be used as a catch-all explanation for every change in the brain or behavior.