1 Psychology and human development1.4 Memory
1.4.2 Long-term potentiation
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Written by Resident Doctor Committee · Published
New in the 2027 syllabus
The College added this topic for exams from January 2027.
What it is
Long-term potentiation is a lasting increase in how strongly a synapse responds, after a particular pattern of activity has triggered it. It is a model of the plasticity that underlies memory. It is not memory itself.
It fits the idea of Hebbian learning. When presynaptic activity repeatedly happens at the same time as the postsynaptic neuron is activated, the connection between them gets stronger.
How it works: the hippocampal model
The best-studied model is in the hippocampus. It depends on two types of glutamate receptor: alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and N-methyl-D-aspartate (NMDA) receptors.
Step | What happens |
|---|---|
Glutamate release | Glutamate activates AMPA and NMDA receptors |
Postsynaptic depolarisation | Depolarisation removes the magnesium block from NMDA receptors |
Calcium entry | Calcium flows in and switches on signalling pathways inside the cell |
Early strengthening | AMPA receptors change in how they work and in number |
Longer-lasting change | May need gene expression, protein synthesis and structural change |
Three properties
Input specificity: strengthening mainly affects the synapses that were active.
Associativity: a weak input can be strengthened if it is paired with a strong enough input converging on the same neuron.
Cooperativity: several active inputs together can produce enough depolarisation to trigger potentiation.
Traps
Long-term depression weakens transmission under other patterns of activity. Learning involves plasticity in both directions, not strengthening everywhere.
Mechanisms differ between synapses. Do not treat NMDA-dependent hippocampal potentiation as the only form of learning.