Temporal Characteristics of V1 Cells Arising from Synaptic Depression
Neurons in the primary visual cortex (VI) exhibit response characteristics qualitatively different from their LGN afferents. Some of these characteristics, such as the oriented structure of simple cell receptive fields, can be explained as arising from linear combinations of LGN receptive fields.1 However, many aspects of VI responses, especially in the temporal domain, reflect underlying nonlinear mechanisms. Here we study the idea that synaptic depression may give rise to many of these nonlinearities. Synaptic depression is observed in intracortical3–5 as well as thalamocortical6,7 synapses and has been proposed as a possible mechanism for contrast adaptation and direction selectivity.2,9 We construct a model VI simple cell and explore the effects of synaptic depression on the temporal dynamics of its responses. Our results indicate that synaptic depression may play an important role in the enhancement of responses to transient stimuli, direction selectivity, and contrast adaptation.
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