Recurrent Cortical Amplification Produces Complex Cell Responses

Cortical amplification has been proposed as a mechanism for enhancing the selectivity of neurons in the primary visual cortex. Less appreciated is the fact that the same form of amplification can also be used to de-tune or broaden selectivity. Using a network model with recurrent cortical circuitry, we propose that the spatial phase invariance of complex cell responses arises through recurrent amplification of feedforward input. Neurons in the network respond like simple cells at low gain and complex cells at high gain. Similar recurrent mechanisms may play a role in generating invariant representations of feedforward input elsewhere in the visual processing pathway.