Synaptic depression and the temporal response characteristics of V1 cells.
We explore the effects of short-term synaptic depression on the temporal dynamics of V1 responses to visual images by constructing a model simple cell. Synaptic depression is modeled on the basis of previous detailed fits to experimental data. A component of synaptic depression operating in the range of hundreds of milliseconds can account for a number of the unique temporal characteristics of cortical neurons, including the bandpass nature of frequency-response curves, increases in response amplitude and in cutoff frequency for transient stimuli, nonlinear temporal summation, and contrast-dependent shifts in response phase. Synaptic depression also provides a mechanism for generating the temporal phase shifts needed to produce direction selectivity, and a model constructed along these lines matches both extracellular and intracellular data. A slower component of depression can reproduce the effects of contrast adaptation.
Chance
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FS
Volen Center and Department of Biology, Brandeis University, Waltham, Massachusetts 02254-9110, USA.
Nelson
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SB
Abbott
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LF
D000222:Adaptation, Physiological / Q000502:physiology; D000818:Animals; D015350:Contrast Sensitivity / Q000502:physiology; D006801:Humans; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D013569:Synapses / Q000502:physiology*; D013997:Time Factors; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*