Auditory perceptual processing in the primate superior colliculus

PROJECT SUMMARY/ABSTRACT Auditory perception and communication, in particular in natural settings, involves the transformation of noisy, ambiguous, or uncertain auditory cues into categorical auditory percepts. Contemporary models of hearing suggest that this process can be conceptualized computationally in terms of decision-making under uncertainty. By this view, the perception of an acoustic stimulus involves a sequence of computational steps, whereby the external acoustic input is transformed into an internal decision variable, which, in turn, is transformed into an auditory percept by way of a comparison to a decision criterion. Despite the fundamental nature of this process to contemporary models of hearing, however, relatively little is known about the neural mechanisms that support it in the primate brain. That is, while previous studies have identified brain areas involved in computing decision variables for auditory perception, very little is known about where or how in the primate brain the relevant decision criteria are established. The broad goal of the work proposed here is to fill this knowledge gap and determine the mechanisms in the primate brain that support decision criteria for auditory perception. The proposed research is focused on the primate superior colliculus (SC), a midbrain sensorimotor structure that receives extensive auditory input and has been shown to play an important role in decision criteria for visual perception. A series of experiments are proposed in which novel and innovative psychophysical techniques that provide rigorous experimental control over decision criteria are combined with neural recordings and causal manipulations of brain activity in a nonhuman primate model of hearing. The first aim of these experiments is to determine the role of the SC in decision criteria for spatial perception, whereas the second aim is to determine the role of the SC in decision criteria for nonspatial perception. Taken together, therefore, the results will paint a comprehensive picture of the SC's role in decision criteria for auditory perception (i.e., in different decision-making contexts involving different acoustic stimuli) and provide fundamental insights into the brain bases of normal hearing in healthy primates, setting the stage for future studies of disordered hearing in the primate brain. As such, the proposed work is directly in line with NIDCD's mission and strategic plan. The PI of this fellowship application is a Postdoctoral Associate at the State University of New York College of Optometry, where the work will be conducted. A sponsorship team consisting of world-renowned experts on the role of the primate SC in higher- order perceptual and cognitive functions and the neural mechanisms of auditory perception and auditory perceptual decision-making has been assembled to provide the applicant with research training on a variety of topics relevant to nonhuman primate auditory research. This training, together with additional, targeted training focused on the applicant's career development, will prepare the applicant for the transition to research independence and a productive research career studying the neural mechanisms of auditory perception.