Mitchell Sutter - US grants

DESCRIPTION: (Adapted from applicant's abstract): The goal of this work is to elucidate the relationship between neural activity in auditory cortex and sound perception. The applicant will determine 1) the abilities of humans and nonhuman primates to perceive and integrate spectral and temporal features of sounds, and 2) the relationship of single neuron responses in auditory cortex to psychophysical performance. For Aim 1, human and nonhuman subjects will be trained to discriminate sounds that vary along temporal or spectral dimensions, and for Aim 2, neurons will be recorded in nonhuman primate auditory cortex during behavioral discriminations. Signal detection methods will be used to determine the discriminative capabilities of single neurons, and whether their firing is more closely associated with the physical attributes of sound or the higher level decision to respond to the sound. The data will provide information for understanding the effects of cortical disruptions, as well as basic understanding of temporal acoustic processing. The results are of potential use for treating stroke and dyslexia.

The general goal of the proposed research is to illuminate the relationship between neuronal activity and auditory function. Specifically we are interested (1) what are the psychophysical abilities of human and non- human subjects in integrating spectral and temporal features of sounds, and (2) how do auditory cortical single neuron responses relate to this ability as measured through psychophysical performance. Psychophysical measurements will be made from human and non-human subjects to determine their ability to discriminate temporally or spectrally complex sounds. We will then record single unit responses from non- human subjects while they discriminate sounds used in the psychophysical experiments. For one aim, we will investigate amplitude modulation as a function of sound duration and AM frequency and for the other aim investigate complex sound spectra. Using novel modifications of signal detection theory, we will determine the discriminative capabilities of neurons, and whether the firing of individual neurons is more closely associated with the physical attributes of sound or to the pscyhophysicaljudgement. These results will provide critical direct links between single neuron physiological function and psychophysical perfrormance. This data will add knowledge about the effects of cortical disruptions due to strokes trauma, and other degenerative diseases of the brain on hearing. Additionally, this study should add to the understanding of temporal acoustical processing which appears related to many of the effects of dyslexia and other developmental disorders. These results accordingly are of potential use for understanding and treating strokes and developmental disorders. Achieving the three aims will allow us to rigorously assess: (1) how spectral and temporal information is integrated and combined by the auditory central nervous system.

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. A fundamental question is: How can one segregate and analyze a sound-producing object in a complex acoustic environment? By combining behavior and physiology, carefully framing the behavioral question, and using signal detection theory based analyses we will achieve three aims. Aim 1: To measure and compare macaque and human perceptions of fill-in. Aim 1 will be achieved by measuring macaques'and humans'abilities to detect the continuity of foreground sounds as a function of the duration of gaps inserted into them and the intensity of an interrupting noise. Aim 2: To determine neural correlates of fill-in using analyses that allow for direct comparisons of auditory cortical neurons'responses to the results of Aim 1. Aim 3: To determine the strength of association between neural responses and behavioral performance and decisions in multiple cortical fields. To achieve Aims 2 nd 3, signal detection theory based analyses--similar to analyses referred to in the previous paragraph about the visual system--will be used. Achieving the aims will significantly advance the understanding of neural responses contributions to auditory perceptions and decision-making.