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Curr Biol. 2018 Jun 18;28(12):1860-1871.e4. doi: 10.1016/j.cub.2018.04.033. Epub 2018 May 31.

A Spatial Map of Onset and Sustained Responses to Speech in the Human Superior Temporal Gyrus.

Author information

1
Department of Neurological Surgery and Center for Integrative Neuroscience, University of California, San Francisco, 675 Nelson Rising Lane, San Francisco, CA 94158, USA; Department of Communication Sciences and Disorders, Moody College of Communication, The University of Texas at Austin, 2504A Whitis Avenue (Stop A1100), Austin, TX 78712, USA; Department of Neurology, Dell Medical School, The University of Texas at Austin, 1701 Trinity Street, Austin, TX 78705, USA.
2
Department of Neurological Surgery and Center for Integrative Neuroscience, University of California, San Francisco, 675 Nelson Rising Lane, San Francisco, CA 94158, USA.
3
Department of Neurological Surgery and Center for Integrative Neuroscience, University of California, San Francisco, 675 Nelson Rising Lane, San Francisco, CA 94158, USA. Electronic address: edward.chang@ucsf.edu.

Abstract

To derive meaning from speech, we must extract multiple dimensions of concurrent information from incoming speech signals. That is, equally important to processing phonetic features is the detection of acoustic cues that give structure and context to the information we hear. How the brain organizes this information is unknown. Using data-driven computational methods on high-density intracranial recordings from 27 human participants, we reveal the functional distinction of neural responses to speech in the posterior superior temporal gyrus according to either onset or sustained response profiles. Though similar response types have been observed throughout the auditory system, we found novel evidence for a major spatial parcellation in which a distinct caudal zone detects acoustic onsets and a rostral-surround zone shows sustained, relatively delayed responses to ongoing speech stimuli. While posterior onset and anterior sustained responses are used substantially during natural speech perception, they are not limited to speech stimuli and are seen even for reversed or spectrally rotated speech. Single-electrode encoding of phonetic features in each zone depended upon whether the sound occurred at sentence onset, suggesting joint encoding of phonetic features and their temporal context. Onset responses in the caudal zone could accurately decode sentence and phrase onset boundaries, providing a potentially important internal mechanism for detecting temporal landmarks in speech and other natural sounds. These findings suggest that onset and sustained responses not only define the basic spatial organization of high-order auditory cortex but also have direct implications for how speech information is parsed in the cortex. VIDEO ABSTRACT.

KEYWORDS:

ECoG; auditory; electrocorticography; intracranial recordings; natural speech; neurolinguistics; spectrotemporal receptive field; unsupervised learning

PMID:
29861132
DOI:
10.1016/j.cub.2018.04.033
[Indexed for MEDLINE]
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