Temporal sorting of neural components underlying phonological processing

EVENT-RELATED haemodynamic responses (EHRs) were recorded in subjects perfo rming phonological tasks to test whether distinguishable temporal involveme nt of corresponding neural components would show through. A sequence of act ivation leading from auditory cortices to premotor regions emerged in the f ast repetition and the phoneme monitoring tasks used. EHRs peaked significa ntly earlier in Wernicke's area (phonological decoding) than in Broca's are a, the left supramarginal gyrus and the precentral gyrus (phonological rehe arsal). Moreover, the sensitivity of within cluster temporal gradients to t he nature of the tasks indicated either sensory to association cortex synch ronization for fast repetition or delayed analysis for phoneme monitoring. These results are consistent with previous findings on working memory and s how that fMRI permits temporal tracking of cognitive activations. (C) 1999 Lippincott Williams & Wilkins.