title: Cortical spatio-temporal dynamics underlying phonological target detection in humans.
abstract: Selective processing of task-relevant stimuli is critical for goal-directed behavior. We used electrocorticography to assess the spatio-temporal dynamics of cortical activation during a simple phonological target detection task, in which subjects press a button when a prespecified target syllable sound is heard. Simultaneous surface potential recordings during this task revealed a highly ordered temporal progression of high gamma (HG, 70-200 Hz) activity across the lateral hemisphere in less than 1 sec. The sequence demonstrated concurrent regional sensory processing of speech syllables in the posterior superior temporal gyrus (STG) and speech motor cortex, and then transitioned to sequential task-dependent processing from prefrontal cortex (PFC), to the final motor response in the hand sensorimotor cortex. STG activation was modestly enhanced for target over nontarget sounds, supporting a selective gain mechanism in early sensory processing, whereas PFC was entirely selective to targets, supporting its role in guiding response behavior. These results reveal that target detection is not a single cognitive event, but rather a process of progressive target selectivity that involves large-scale rapid parallel and serial processing in sensory, cognitive, and motor structures to support goal-directed human behavior.
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, San Francisco, CA 94143, USA. ChangEd@neurosurg.ucsf.edu
authors.forename: Edward F
authors.initials: EF
authors.lastname: Chang
authors.forename: Erik
authors.initials: E
authors.lastname: Edwards
authors.forename: Srikantan S
authors.initials: SS
authors.lastname: Nagarajan
authors.forename: Noa
authors.initials: N
authors.lastname: Fogelson
authors.forename: Sarang S
authors.initials: SS
authors.lastname: Dalal
authors.forename: Ryan T
authors.initials: RT
authors.lastname: Canolty
authors.forename: Heidi E
authors.initials: HE
authors.lastname: Kirsch
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Barbaro
authors.forename: Robert T
authors.initials: RT
authors.lastname: Knight
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D002540:Cerebral Cortex / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D006040:Goals; D006801:Humans; D009044:Motor Cortex / Q000502:physiology; D010700:Phonetics; D010775:Photic Stimulation / Q000379:methods; D017397:Prefrontal Cortex / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000502:physiology; D013997:Time Factors
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