Oscillatory mechanism of auditory stream segregation in primary auditory cortex
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1
Nathan Kline Institute for Psychiatric Research, Cognitive Neuroscience and Schizophrenia Program, United States
Earlier studies show that neuronal oscillations reflecting rhythmic excitability fluctuations of neuronal ensembles can track rhythmic stimulus streams by entraining to their temporal structure. When stimuli are most likely to occur, neuronal ensembles are consistently in high excitability phases resulting in an amplification of neuronal responses to events. At the same time, entrained oscillations also serve as temporal filters, in that their low excitability phases suppress neuronal responses to events that are "out of phase" with the attended stream. In theory, this makes entrained oscillations ideal candidates to separate attended rhythmic streams from the background in complex auditory scenes. We examined laminar profiles of synaptic activity and action potentials obtained through multielectrode recordings in monkey A1. We presented two concurrent streams of pure tones that differed in their rhythm and frequency. Subjects responded to deviants in only one of the streams, while ignoring deviants in the other. We found that neuronal oscillations across A1 entrained to the rhythm of the attended stream, even in regions whose best frequency (BF) matched that of pure tones in the ignored stream. We also found that entrainment was frequency specific: if the frequency of pure tones in the attended stream corresponded to the BF of a given A1 region, oscillations entrained with their high, while outside this region oscillations entrained with their low excitability phases. This indicates that entrained oscillations across A1 act as a complex spectral-temporal filter mechanism, making them ideal candidates for the segregation of relevant rhythmic auditory stimulus streams along arguably the most fundamental organizing dimensions in auditory processing, frequency and time.
Keywords:
auditory processing,
neuronal oscillations
Conference:
XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011.
Presentation Type:
Symposium: Oral Presentation
Topic:
Symposium 3: The role of neuronal oscillations in computation and communication in multi-scale brain networks
Citation:
Lakatos
P,
OConnell
N,
Falchier
A and
Schroeder
CE
(2011). Oscillatory mechanism of auditory stream segregation in primary auditory cortex.
Conference Abstract:
XI International Conference on Cognitive Neuroscience (ICON XI).
doi: 10.3389/conf.fnhum.2011.207.00021
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Received:
04 Nov 2011;
Published Online:
15 Nov 2011.
*
Correspondence:
Dr. Peter Lakatos, Nathan Kline Institute for Psychiatric Research, Cognitive Neuroscience and Schizophrenia Program, Orangeburg, NY, 10962, United States, plakatos@nki.rfmh.org