Contextual Modulation of Naturalistic Behavior and Sensory Processing

Abstract

Forming representations of the sensory world and navigating within it require an animal to actively interact and sample key aspects of the environment. In the olfactory system, many organisms search for food by actively sensing the odor environment, employing search programs to successfully navigate across turbulent odor plumes to the source. In the visual system, we effortlessly perceive the world of light, shadow, color, and movement as a stable, predictable, and unified percept. We use this perception to extract information about the outside world we live in, to move our eyes across a line of text, and critically, to move through our environment. Here, we present three studies investigating how animal behavior and sensory processing interact to produce the complex dynamics we observe in behavioral and neural data.

In Chapter II, we characterized the dynamics of olfactory search behavior in freely moving mice using latent state space modelling. We identified behavioral motifs that constitute the overall search strategy of the mouse. By segmenting the behavior into these identifiable and reoccurring motifs, we determined that mice actively sample the environment in a sniff-synchronized, two-state strategy to gain information about concentration gradient cues.

In Chapter III, we linked theoretical predictions from a spiking neural network model to observations from electrophysiological recordings in mouse visual cortex and to the behavioral state of the animal. We connect mechanisms in our model to neural activity by modeling the locomotion-induced perturbations in cortex as an increase in variance of the input currents to excitatory neurons, which decreases the gain of single neurons and an acceleration of stimulus-processing speed.

In Chapter IV, we quantified the effects of temporal context and expectation on the sensory processing of natural images in mouse visual cortex. We found that all areas we recorded from predominately encode for the temporal context in which the images were presented in. In other words, it matters how and when a stimulus is presented to an animal. Overall, the conjunctive encoding of representations of natural scenes and temporal context was modulated by the expectation about sequential events.

This dissertation consists of previously published co-authored material.