PROMETHEUS An Exploration of Learning and Memory in the Mouse Primary Visual Cortex

Abstract

Intelligence relies on more than just perception and decision-making; it also requires the capability to recognize patterns in current events and project these patterns into the future. Intelligent behaviors such as learning and memory ought therefore to require animals to make predictions about their environment, and to change their actions based on spatial or temporal cues. We test this hypothesis both behaviorally and physiologically by studying the mouse primary visual cortex (V1) while the animal views repeating temporal patterns of visual stimuli. Prior to experimentation the mice are surgically modified to allow for head-fixed experimentation, with a cranial window over V1 and a metal headplate installed. The results of the behavioral test confirm that the mice are capable of recognizing violations in temporal sequences up to five frames in length. The imaging data, meanwhile, show a strong violation response in almost all the visible cells from Layer 2/3 of V1, and reveal novel firing properties in the form of sustained cells that lock to the normal stimulus. A study of the violation and sustained responses over several days of training demonstrates a significant increase in response probability and amplitude from the first day to the last day of training. Whether this response modulation in V1 drives the mouse’s behavioral learning, however, remains unclear.