SYNAPTIC DEPRESSION AND THE TEMPORAL RESPONSE CHARACTERISTICS OF V1 CELLS

We explore the effects of short-term synaptic depression on the tempor al dynamics of VI responses to visual images by constructing a model s imple cell. Synaptic depression is modeled on the basis of previous de tailed fits to experimental data. A component of synaptic depression o perating in the range of hundreds of milliseconds can account for a nu mber of the unique temporal characteristics of cortical neurons, inclu ding the bandpass nature of frequency-response curves, increases in re sponse amplitude and in cutoff frequency for transient stimuli, nonlin ear temporal summation, and contrast-dependent shifts in response phas e. Synaptic depression also provides a mechanism for generating the te mporal phase shifts needed to produce direction selectivity, and a mod el constructed along these lines matches both extracellular and intrac ellular data. A slower component of depression can reproduce the effec ts of contrast adaptation.