title: Population responses in primary auditory cortex simultaneously represent the temporal envelope and periodicity features in natural speech.
abstract: Speech perception relies on a listener's ability to simultaneously resolve multiple temporal features in the speech signal. Little is known regarding neural mechanisms that enable the simultaneous coding of concurrent temporal features in speech. Here we show that two categories of temporal features in speech, the low-frequency speech envelope and periodicity cues, are processed by distinct neural mechanisms within the same population of cortical neurons. We measured population activity in primary auditory cortex of anesthetized guinea pig in response to three variants of a naturally produced sentence. Results show that the envelope of population responses closely tracks the speech envelope, and this cortical activity more closely reflects wider bandwidths of the speech envelope compared to narrow bands. Additionally, neuronal populations represent the fundamental frequency of speech robustly with phase-locked responses. Importantly, these two temporal features of speech are simultaneously observed within neuronal ensembles in auditory cortex in response to clear, conversation, and compressed speech exemplars. Results show that auditory cortical neurons are adept at simultaneously resolving multiple temporal features in extended speech sentences using discrete coding mechanisms.
authors.affiliation: Auditory Neuroscience Laboratory, The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA. Electronic address: daa@stanford.edu.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Abrams
authors.affiliation: Auditory Neuroscience Laboratory, The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA.
authors.forename: Trent
authors.initials: T
authors.lastname: Nicol
authors.affiliation: Auditory Neuroscience Laboratory, The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: White-Schwoch
authors.affiliation: Auditory Neuroscience Laboratory, The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Zecker
authors.affiliation: Auditory Neuroscience Laboratory, The Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA; Departments of Neurobiology and Physiology, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA; Department of Otolaryngology, Northwestern University, 2240 Campus Drive, Evanston, IL, 60208, USA.
authors.forename: Nina
authors.initials: N
authors.lastname: Kraus
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001303:Auditory Cortex / Q000502:physiology*; D001307:Auditory Perception / Q000502:physiology; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009482:Neurophysiology; D013060:Speech; D013701:Temporal Bone / Q000502:physiology*
keywords: Auditory cortex; Auditory thalamus; Guinea pig; Temporal coding