Temporal coherence in the perceptual organization and cortical representation of auditory scenes.
Just as the visual system parses complex scenes into identifiable objects, the auditory system must organize sound elements scattered in frequency and time into coherent "streams." Current neurocomputational theories of auditory streaming rely on tonotopic organization of the auditory system to explain the observation that sequential spectrally distant sound elements tend to form separate perceptual streams. Here, we show that spectral components that are well separated in frequency are no longer heard as separate streams if presented synchronously rather than consecutively. In contrast, responses from neurons in primary auditory cortex of ferrets show that both synchronous and asynchronous tone sequences produce comparably segregated responses along the tonotopic axis. The results argue against tonotopic separation per se as a neural correlate of stream segregation. Instead we propose a computational model of stream segregation that can account for the data by using temporal coherence as the primary criterion for predicting stream formation.
Elhilali
Mounya
M
Department of Electrical and Computer Engineering, Johns Hopkins University, Barton Hall 105, 3400 North Charles Street, Baltimore, MD 21218, USA. mounya@jhu.edu
Ma
Ling
L
Micheyl
Christophe
C
Oxenham
Andrew J
AJ
Shamma
Shihab A
SA
D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001303:Auditory Cortex / Q000033:anatomy & histology / Q000502:physiology*; D001306:Auditory Pathways / Q000033:anatomy & histology / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D003198:Computer Simulation; D004594:Electrophysiology; D005289:Ferrets; D006801:Humans; D009474:Neurons / Q000502:physiology; D009483:Neuropsychological Tests; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors