Experience-dependent modification of synaptic plasticity in visual cortex

A. Kirkwood, M. G. Rioult, M. F. Bear

Research output: Contribution to journalArticlepeer-review

451 Scopus citations


In many regions of the cerebral cortex, Ca2+ influx through NMDA (N-methyl-D-aspartate) sensitive glutamate receptors (NMDA receptors) can trigger two forms of synaptic plasticity: long-term depression (LTD) and long-term potentiation (LTP). LTD is induced by low levels of postsynaptic NMDA-receptor activation, for instance in response to low-frequency stimulation, whereas LTP is induced by the stronger activation that occurs following high-frequency stimulation. Theoretical studies have shown that the properties of synaptic LTD and LTP can account for many aspects of experience-dependent plasticity in the developing visual cortex, provided that the LTD-LTP crossover point (the modification threshold, θ(m)) varies as a function of the history of cortical activity. Here we provide direct experimental evidence that the value of θ(m) depends on sensory experience. We find in visual cortex of light-deprived rats that LTP is enhanced and LTD diminished over a range of stimulation frequencies, and that these effects can be reversed by as little as two days of light exposure. Our findings support the idea that a variable synaptic-modification threshold allows synaptic weights in neural networks to achieve a stable equilibrium.

Original languageEnglish (US)
Pages (from-to)526-528
Number of pages3
Issue number6582
StatePublished - 1996
Externally publishedYes

ASJC Scopus subject areas

  • General


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