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This Article Full Text Full Text (PDF) All Versions of this Article: 96/3/1105    most recent 00124.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Fishman, Y. I. Articles by Steinschneider, M. Search for Related Content PubMed PubMed Citation Articles by Fishman, Y. I. Articles by Steinschneider, M.

Spectral Resolution of Monkey Primary Auditory Cortex (A1) Revealed With Two-Noise Masking

¹Department of Neurology and ²Department of Neuroscience, Albert Einstein College of Medicine, Rose F. Kennedy Center, Bronx, New York

Submitted 2 March 2006; accepted in final form 30 May 2006

An important function of the auditory nervous system is to analyze the frequency content of environmental sounds. The neural structures involved in determining psychophysical frequency resolution remain unclear. Using a two-noise masking paradigm, the present study investigates the spectral resolution of neural populations in primary auditory cortex (A1) of awake macaques and the degree to which it matches psychophysical frequency resolution. Neural ensemble responses (auditory evoked potentials, multiunit activity, and current source density) evoked by a pulsed 60-dB SPL pure-tone signal fixed at the best frequency (BF) of the recorded neural populations were examined as a function of the frequency separation (F) between the tone and two symmetrically flanking continuous 80-dB SPL, 50-Hz-wide bands of noise. Fs ranged from 0 to 50% of the BF, encompassing the range typically examined in psychoacoustic experiments. Responses to the signal were minimal for F = 0% and progressively increased with F, reaching a maximum at F = 50%. Rounded exponential functions, used to model auditory filter shapes in psychoacoustic studies of frequency resolution, provided excellent fits to neural masking functions. Goodness-of-fit was greatest for response components in lamina 4 and lower lamina 3 and least for components recorded in more superficial cortical laminae. Physiological equivalent rectangular bandwidths (ERBs) increased with BF, measuring nearly 15% of the BF. These findings parallel results of psychoacoustic studies in both monkeys and humans, and thus indicate that a representation of perceptual frequency resolution is available at the level of A1.