Evidence for Normalization as a Fundamental Operation Across the Human Visual Cortex

Abstract

Divisive normalization of the neural responses by the activity of the neighboring neurons has been proposed as a fundamental operation in the nervous system. Nevertheless, experimental evidence for this operation is still scant. Here, using functional MRI, we explored the role of normalization across the visual hierarchy in the human visual cortex. Presenting objects in isolation or in clutter and asking subjects to attend or ignore the presented stimuli, we modeled single voxel responses and demonstrated that the response to multiple stimuli as well as attentional modulations could be captured by a model that takes normalization into account. Our results provide compelling evidence for normalization as a canonical computation operating in the human brain.