Auditory frequency and intensity discrimination explained using a cortical population rate code.
The nature of the neural codes for pitch and loudness, two basic auditory attributes, has been a key question in neuroscience for over century. A currently widespread view is that sound intensity (subjectively, loudness) is encoded in spike rates, whereas sound frequency (subjectively, pitch) is encoded in precise spike timing. Here, using information-theoretic analyses, we show that the spike rates of a population of virtual neural units with frequency-tuning and spike-count correlation characteristics similar to those measured in the primary auditory cortex of primates, contain sufficient statistical information to account for the smallest frequency-discrimination thresholds measured in human listeners. The same population, and the same spike-rate code, can also account for the intensity-discrimination thresholds of humans. These results demonstrate the viability of a unified rate-based cortical population code for both sound frequency (pitch) and sound intensity (loudness), and thus suggest a resolution to a long-standing puzzle in auditory neuroscience.
Department of Psychology, University of Minnesota, Minneapolis, Minnesota, United States of America.
Christophe
C
Micheyl
Paul R
PR
Schrater
Andrew J
AJ
Oxenham
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D019295:Computational Biology; D006801:Humans; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D011323:Primates