The Geometry of Masking in Neural Populations

We introduce a geometric approach to study the representation of orientation by populations of neurons in primary visual cortex in the presence and absence of an additive mask. Despite heterogeneous effects at the single cell level, a simple geometric model explains how population responses are transformed by the mask and reveals how changes in discriminability and bias relate to each other. We propose that studying the geometry of neural populations can yield insights into the role of contextual modulation in the processing of sensory signals.