Michael S. Osmanski - US grants

[unreadable] DESCRIPTION (provided by applicant): Budgerigars are small parrots that, like songbirds, have a complex, learned vocal repertoire. Previous findings in the Dooling lab have indicated that budgerigars, like humans, exhibit the Lombard effect - altering the intensity of their vocalizations in response to an increase in ambient noise level (Manabe et al., 1998). Pilot work that I have completed extends these findings in the frequency domain and suggests that budgerigars may only be able to alter the pitch of their vocalizations by a few hundred Hz or less. Here I propose to explore the potential mechanisms underlying vocal production in budgerigars using operant conditioning methods. Specifically, I will examine the typical range of acoustic variation (especially in the frequency, duration, and amplitude domains) measured in the contact calls of these birds and whether these birds can alter the various acoustic parameters of their calls. I am especially interested in determining the limits of acoustic change in contact call production. Results of these studies will contribute greatly to our understanding of the mechanisms underlying vocal production in this species and also offer insights into vocal behavior generally through comparisons with both songbirds and humans. [unreadable] [unreadable]

DESCRIPTION (provided by applicant): A fundamental question in auditory neuroscience is how neural activity in the cerebral cortex gives rise to perception and how changes in brain activity relate to different behavioral states. Activity in primary auditory cortex has been shown to be modulated by engagement in a psychophysical task, but relatively little is known about the causal links between neural activity and perception and how different behavioral states modulate various cortical areas at both the single neuron and population level - especially for non-primary auditory areas. The experiments in this proposal will use a powerful combination of multi-channel neurophysiological techniques and behavioral testing to examine the links between neural activity in auditory cortex and perception at both the individual neuron and population levels in marmosets. Specific Aim 1 examines and compares behavioral modulation of neural responses between two auditory cortical areas. Specific Aim 2 focuses on the correlation between neural responses and marmoset's perception of pitch-bearing harmonic complex tones in the pitch region of auditory cortex. Results of the experiments described here will contribute greatly to our understanding of the perceptual organization of complex sounds and their physiological underpinnings in marmosets. These experiments will also help to elucidate the functional organization of different levels of the auditory cortical hierarchy. Finaly, because of the close phylogenetic relationship between human and nonhuman primates, these results will provide a better understanding of complex sound processing, including speech perception, in human auditory cortex.