The effect of concussion history on relevancy-based gating of visual and tactile stimuli

Abstract

At the cortical level, incoming sensory inputs are subject to interruption as they are transmitted to modality-specific cortical areas, in order to prevent excessive processing of task-irrelevant sensory information and aid in planning appropriate responses. This interruption of stimulus transmission is known as sensory gating, and it is an important component of attentional orienting: effective gating allows attention to be oriented only to stimuli which are task-relevant. Concussion is a condition in which attentional orienting processes appear to be disrupted, but the details of this disruption and its underlying mechanisms are unknown. The experiments contained within this thesis address questions related to the effects of concussion on sensory processing. This thesis aimed to characterize the electrophysiological and behavioural correlates of attentional orienting and sensory gating on a sensory selection task; to build an understanding of the cortical mechanisms involved in sensory selection under conditions of varying task-relevance and in the presence of distractor stimuli; and to address the clinical hypothesis that a history of concussion injury leads to problems gating irrelevant sensory information out of the processing stream. The results provide insight into the process of sensory gating based on task-relevance, the top-down and bottom-up factors that modulate attentional orienting, the cortical networks involved, and the disruption to these processes that can occur with concussion.