Subcortical neural correlates of behavior in the auditory system

Abstract

One of the biggest open questions in neuroscience is the relationship between neuronal activity and behavior. Little is known in the auditory system about the nature of the relationship between stimulus encoding and perception. To shed light on this topic, we recorded responses of single neurons in the central nucleus of the inferior colliculus (CNIC) and cochlear nucleus (CN) of macaques that were trained to detect tones or vowels during behavioral performance. Using signal detection theoretic methods, we determined that neurometric tone and vowel detection thresholds based on rate measures in CNIC matched behavioral thresholds, while thresholds of CN neurons were higher than behavior. Additionally, the response magnitudes of a majority of the CNIC neurons varied significantly depending on the behavioral accuracy, compared to a much smaller proportion of CN neurons. Analysis of temporal patterns of response (e.g., phase locking) suggests that neurometric thresholds of all CN and most CNIC neurons matched behavioral thresholds during vowel detection. Additionally, every CNIC and CN neuron showed significant response pattern differences based on behavioral accuracy. These results suggest that behaviorally relevant coding early in the pathway is temporal in nature and is transformed to more rate based measures at higher levels of processing.One of the biggest open questions in neuroscience is the relationship between neuronal activity and behavior. Little is known in the auditory system about the nature of the relationship between stimulus encoding and perception. To shed light on this topic, we recorded responses of single neurons in the central nucleus of the inferior colliculus (CNIC) and cochlear nucleus (CN) of macaques that were trained to detect tones or vowels during behavioral performance. Using signal detection theoretic methods, we determined that neurometric tone and vowel detection thresholds based on rate measures in CNIC matched behavioral thresholds, while thresholds of CN neurons were higher than behavior. Additionally, the response magnitudes of a majority of the CNIC neurons varied significantly depending on the behavioral accuracy, compared to a much smaller proportion of CN neurons. Analysis of temporal patterns of response (e.g., phase locking) suggests that neurometric thresholds of all CN and most CNIC neurons matched...