| | |
Summary: 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, and Sacha B. Nelson
Department of Biology and Center for Complex Systems, Brandeis University, Waltham, Massachusetts 02254
Cortical synapses exhibit several forms of short-term plasticity,
but the contribution of this plasticity to visual response dynam-
ics 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 arbi-
trary patterns of stimulation. Synaptic responses were recorded
intracellularly as EPSCs and extracellularly as local field poten-
tials 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,
|
