Abstract
Disruption in the visual field before the critical period can change how the neurons in the primary visual cortex integrate binocular inputs. Strabismus (ocular misalignment) during development leads to cortical neurons that are almost exclusively monocular when measured by spike rate.The traditional interpretation for this phenomenon is an underlying reduction, or even elimination, of the synaptic input to the cortical neuron from the non-preferred eye via activity-dependent competition. Since this interpretation has relied almost exclusively on recording of suprathreshold activity (spiking), which is indirectly related to synaptic input, we measured subthreshold membrane potential responses to assess the changes in functional selectivity following ocular misalignment. Following surgically-induced strabismus in cats before the critical period (p12) we used whole-cell recordings in vivo to measure the activities of the cortical neurons in adult animals. We compared each neurons preference for orientation, spatial frequency, and contrast sensitivity for both the right and left eyes. We find a surprising match between these selectivity of the neurons for the right and left eyes at the level of membrane potential. Right and left eye inputs in strabismus animals share orientation preference, spatial frequency preference, and contrast sensitivity despite the increased degree of monocularity in these neurons. While we do uncover some variance in selectivity between the right and left eye inputs, this degree of variances matches that found in normal animals. These direct measurements of input selectivity following strabismus reveal that despite the lack of correlation between the images that the left and right eyes provide, the underlying selectivity of the neurons is maintained.
Meeting abstract presented at VSS 2015