Contribution of a corticofugal pathway to auditory perception

点击翻译按钮获取中文摘要

SUMMARY Auditory perception is mediated by both bottom-up (feedforward) and top-down (feedback or corticofugal) mechanisms. Top-down mechanisms filter the ascending bottom-up stream, which improves auditory perception by enhancing the neuronal representations of behaviorally relevant stimuli, while simultaneously suppressing neuronal representations of behaviorally irrelevant stimuli. As a consequence of this interaction between bottom-up and top-down mechanisms, a listener can flexibly direct their perceptual and cognitive resources in the pursuit of goal-directed behavior. Yet, despite their critical importance, we do not fully understand the contribution of corticofugal activity to auditory perception, especially in primate models of hearing. This R21 proposal begins to fill this knowledge gap by identifying a contribution of a corticothalamic pathway (i.e., a pathway from the primary auditory cortex to the auditory thalamus) to primate auditory perception. We identify contributions of a corticothalamic pathway to auditory perception by examining how its functional connectivity is modulated during a monkey's performance on a neuroethologically relevant task, the “vocalization-in-chorus” task. In this vocalization-in-chorus task, monkeys covertly attend to one of two speakers' locations and detect a “target” vocalization that is embedded in a background “chorus” of vocalizations; the target vocalization may or may not be presented at the attended location. We manipulate the listening environment by (1) changing the sound level of the target vocalization relative to the background chorus and (2) changing the locus of the monkeys' spatial attention. We have three hypotheses. We hypothesize that task-related changes in AC-to-MGB functional connectivity will increase in low signal-to-noise regimes. We also hypothesize that this functional connectivity will increase when the monkey attends to the location of the target vocalization than when they do not. Finally, we hypothesize that task-related changes in AC-to-MGB functional connectivity will be greater between AC and lemniscal components of the MGB than between AC and non-lemniscal MGB components. Individually and collectively, the findings of this proposal provide valuable, quantitative insights into the role of corticothalamic circuits in primate auditory behavior.