The Effects of Feedback Signals Mediated by NMDA-Type Synapses for Modulating Border-Ownership Selective Neurons in Visual Cortex

摘要

The mean firing rate of a Border-Ownership Selective (BOS) neuron in intermediate-level visual areas represents where a figure direction from its classical receptive field. Recent neurophysiological and computational studies implied that slow modulatory feedback signals mediated by NMDA synaptic currents played an important role for modulating the responses and dynamics of BOS neurons. In order to understand the effects of modulatory feedback signals for modulating the responses of BOS neurons in more detail, we analyzed the simulation data of BOS model neurons through the jitter methods for computing tight synchrony with various ranges of jitter window. In the millisecond range of the jitter window, tight synchrony for the pairs of BOS model neurons was not modulated by selective attention. However, when the jitter window was widened, attention markedly decreased the magnitude of the tight synchrony for BOS model neurons. These behaviors of model neurons were in good agreement with the characteristics of neurophysiological BOS neurons, supporting a critical role of the modulatory feedback signals for modulating the responses of BOS neurons in intermediate-level visual areas. These results provide testable predictions for understanding the neural mechanism of figure-ground segregation and object perception.