Stimulus competition by inhibitory interference

When two stimuli are present in the receptive field of a V4 neuron, the firing rate response is between the weakest and strongest response elicited by each of the stimuli alone. When attention is directed towards the stimulus eliciting the strongest response (preferred stimulus), the response to the pair is increased, whereas the response decreases when attention is directed to the poor stimulus. We reproduced these results in a V4 model neuron. The model suggests that top-down attention biases the competition between V2 columns for control of V4 neurons by changing the relative timing of inhibition rather than by changes in synchrony of interneuron networks.