Temporal Strategies in Visual Cortex

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DESCRIPTION (provided by applicant): Behavior relies on the reliable interpretation of sensory information and the flexible association of that information with actions. It therefore depends on the both the accurate encoding of information by sensory neurons and the appropriate decoding of these sensory signals according to task constraints. In circumstances involving rapid changes in the sensory environment, the speed of these processes can be of paramount importance: an inability to quickly respond to a looming threat can be fatal. Evidence acquired in the previous grant submission demonstrates that the activity of single neurons over tens of milliseconds can accurately and precisely encode motion information. The same brief periods of activity were also strongly predictive of behavioral choice when animals were engaged in a natural foveation task, and therefore potentially play a pivotal role in rapid decision making. The proposed experiments will explore how such precision is distributed among neural populations and how it is altered by training or task demands. Animals will be trained in tasks requiring the rapid analysis of motion information. Simultaneous recording of neuronal activity and behavior will be analyzed to infer the precision and reliability of sensory signals and their influence on behavioral choice. In the first specific aim, the distribution of reliable sensory information over a cortical population will be investigated. In the first experiment, nearby neurons will be simultaneously activated by a motion stimulus in order to examine how activity correlations might improve or degrade sensory information and its association with behavioral outcome. In the second experiment, the stimulus dependence of precision and reliability will be used to infer how these factors vary across a broad population of activated neurons. In the second specific aim, recordings of individual neurons will be made during the acquisition of proficiency in rapid motion detection to study the extent to which this precision is learned. In the third specific aim, stimulus and probability manipulations will be used to reveal the specific task parameters responsible for such precise neuronal activity. Because all of these tasks are highly challenging, they will help reveal the underlying constraints on the accuracy and speed of decision making. By simultaneously addressing the reliability and precision of sensory encoding and decoding within the brain, these studies could also provide valuable information for the development of effective neural interfaces for prosthetics.