Interaction of feedforward and feedback streams in visual cortex in a firing-rate model of columnar computations.

Abstract

Visual sensory input stimuli are rapidly processed along bottom-up feedforward cortical streams. Beyond such driving streams neurons in higher areas provide information that is re-entered into the representations and responses at the earlier stages of processing. The precise mechanisms and underlying functionality of such associative feedforward/feedback interactions are not resolved. This work develops a neuronal circuit at a level mimicking cortical columns with response properties linked to single cell recordings. The proposed model constitutes a coarse-grained model with gradual firing-rate responses which accounts for physiological in vitro recordings from mammalian cortical cells. It is shown that the proposed population-based circuit with gradual firing-rate dynamics generates responses like those of detailed biophysically realistic multi-compartment spiking models. The results motivate using a coarse-grained mechanism for large-scale neural network modeling and simulations of visual cortical mechanisms. They further provide insights about how local recurrent loops change the gain of modulating feedback signals.