TY - JOUR
T1 - Neural representation of concurrent harmonic sounds in monkey primary auditory cortex
T2 - implications for models of auditory scene analysis
AU - Fishman, Yonatan I.
AU - Steinschneider, Mitchell
AU - Micheyl, Christophe
AU - Micheyl, Christophe
N1 - Publisher Copyright:
© 2014 by the Society for Neuroscience. All rights reserved.
PY - 2014/9/10
Y1 - 2014/9/10
N2 - The ability to attend to a particular sound in a noisy environment is an essential aspect of hearing. To accomplish this feat, the auditory system must segregate sounds that overlap in frequency and time. Many natural sounds, such as human voices, consist of harmonics of a common fundamental frequency (F0). Such harmonic complex tones (HCTs) evoke a pitch corresponding to their F0. A difference in pitch between simultaneous HCTs provides a powerful cue for their segregation. The neural mechanisms underlying concurrent sound segregation based on pitch differences are poorly understood. Here, we examined neural responses in monkey primary auditory cortex (A1) to two concurrentHCTsthat differed in F0 such that they are heard as two separate “auditory objects” with distinct pitches.Wefound that A1 can resolve, via a rate-place code, the lower harmonics of both HCTs, a prerequisite for deriving their pitches and for their perceptual segregation. Onset asynchrony between the HCTs enhanced the neural representation of their harmonics, paralleling their improved perceptual segregation in humans. Pitches of the concurrent HCTs could also be temporally represented by neuronal phaselocking at their respective F0s. Furthermore, a model of A1 responses using harmonic templates could qualitatively reproduce psychophysical data on concurrent sound segregation in humans. Finally, we identified a possible intracortical homolog of the “object-related negativity” recorded noninvasively in humans, which correlates with the perceptual segregation of concurrent sounds. Findings indicate that A1 contains sufficient spectral and temporal information for segregating concurrent sounds based on differences in pitch.
AB - The ability to attend to a particular sound in a noisy environment is an essential aspect of hearing. To accomplish this feat, the auditory system must segregate sounds that overlap in frequency and time. Many natural sounds, such as human voices, consist of harmonics of a common fundamental frequency (F0). Such harmonic complex tones (HCTs) evoke a pitch corresponding to their F0. A difference in pitch between simultaneous HCTs provides a powerful cue for their segregation. The neural mechanisms underlying concurrent sound segregation based on pitch differences are poorly understood. Here, we examined neural responses in monkey primary auditory cortex (A1) to two concurrentHCTsthat differed in F0 such that they are heard as two separate “auditory objects” with distinct pitches.Wefound that A1 can resolve, via a rate-place code, the lower harmonics of both HCTs, a prerequisite for deriving their pitches and for their perceptual segregation. Onset asynchrony between the HCTs enhanced the neural representation of their harmonics, paralleling their improved perceptual segregation in humans. Pitches of the concurrent HCTs could also be temporally represented by neuronal phaselocking at their respective F0s. Furthermore, a model of A1 responses using harmonic templates could qualitatively reproduce psychophysical data on concurrent sound segregation in humans. Finally, we identified a possible intracortical homolog of the “object-related negativity” recorded noninvasively in humans, which correlates with the perceptual segregation of concurrent sounds. Findings indicate that A1 contains sufficient spectral and temporal information for segregating concurrent sounds based on differences in pitch.
KW - Auditory evoked potentials
KW - Concurrent sound segregation
KW - Current source density
KW - Multiunit activity
KW - ORN
KW - Pitch perception
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U2 - 10.1523/JNEUROSCI.0025-14.2014
DO - 10.1523/JNEUROSCI.0025-14.2014
M3 - Article
C2 - 25209282
AN - SCOPUS:84907013306
SN - 0270-6474
VL - 34
SP - 12425
EP - 12443
JO - Journal of Neuroscience
JF - Journal of Neuroscience
IS - 37
ER -