A quantitative description of short-term plasticity at excitatory synapses in layer 2/3 of rat primary visual cortex

Juan A. Varela, Kamal Sen, Jay Gibson, Joshua Fost, L. F. Abbott, Sacha B. Nelson

Research output: Contribution to journalArticle

417 Citations (Scopus)

Abstract

Cortical synapses exhibit several forms of short-term plasticity, but the contribution of this plasticity to visual response dynamics is unknown. In part, this is because the simple patterns of stimulation used to probe plasticity in vitro do not correspond to patterns of activity that occur in vivo. We have developed a method of quantitatively characterizing short-term plasticity at cortical synapses that permits prediction of responses to arbitrary patterns of stimulation. Synaptic responses were recorded intracellularly as EPSCs and extracellularly as local field potentials in layer 2/3 of rat primary visual cortical slices during stimulation of layer 4 with trains of electrical stimuli containing random mixtures of frequencies. Responses exhibited complex dynamics that were well described by a simple three-component model consisting of facilitation and two forms of depression, a stronger form that decayed exponentially with a time constant of several hundred milliseconds and a weaker, but more persistent, form that decayed with a time constant of several seconds. Parameters obtained from fits to one train were used to predict accurately responses to other random and constant frequency trains. Control experiments revealed that depression was not caused by a decrease in the effectiveness of extracellular stimulation or by a buildup of inhibition. Pharmacological manipulations of transmitter release and postsynaptic sensitivity suggested that both forms of depression are mediated presynaptically. These results indicate that firing evoked by visual stimuli is likely to cause significant depression at cortical synapses. Hence synaptic depression may be an important determinant of the temporal features of visual cortical responses.

Original languageEnglish (US)
Pages (from-to)7926-7940
Number of pages15
JournalJournal of Neuroscience
Volume17
Issue number20
StatePublished - 1997

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Visual Cortex
Synapses
Pharmacology

Keywords

  • Contrast adaptation
  • Depression
  • EPSC
  • Facilitation
  • Field potential
  • Neocortex
  • Nonlinearity
  • Presynaptic
  • Temporal filtering
  • Temporal integration

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

A quantitative description of short-term plasticity at excitatory synapses in layer 2/3 of rat primary visual cortex. / Varela, Juan A.; Sen, Kamal; Gibson, Jay; Fost, Joshua; Abbott, L. F.; Nelson, Sacha B.

In: Journal of Neuroscience, Vol. 17, No. 20, 1997, p. 7926-7940.

Research output: Contribution to journalArticle

Varela, Juan A. ; Sen, Kamal ; Gibson, Jay ; Fost, Joshua ; Abbott, L. F. ; Nelson, Sacha B. / A quantitative description of short-term plasticity at excitatory synapses in layer 2/3 of rat primary visual cortex. In: Journal of Neuroscience. 1997 ; Vol. 17, No. 20. pp. 7926-7940.
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