Cortical Spatio-temporal Dynamics Underlying Phonological Target Detection in Humans

摘要

Selective processing of task-relevant stimuli is critical for goaldirectednbehavior. We used electrocorticography to assess thenspatio-temporal dynamics of cortical activation during a simplenphonological target detection task, in which subjects press a buttonnwhen a prespecified target syllable sound is heard. Simultaneousnsurface potential recordings during this task revealed anhighly ordered temporal progression of high gamma (HG, 70–n200 Hz) activity across the lateral hemisphere in less thann1 sec. The sequence demonstrated concurrent regional sensorynprocessing of speech syllables in the posterior superior temporalngyrus (STG) and speech motor cortex, and then transitioned tonsequential task-dependent processing from prefrontal cortexn(PFC), to the final motor response in the hand sensorimotor cortex.nSTG activation was modestly enhanced for target over nontargetnsounds, supporting a selective gain mechanism in earlynsensory processing, whereas PFC was entirely selective to targets,nsupporting its role in guiding response behavior. These resultsnreveal that target detection is not a single cognitive event, butnrather a process of progressive target selectivity that involvesnlarge-scale rapid parallel and serial processing in sensory, cognitive,nand motor structures to support goal-directed humannbehavior. ■