NEUROPERCEPTUAL DIFFERENCES IN CONSONANT AND VOWEL DISCRIMINATION - AS REVEALED BY DIRECT CORTICAL ELECTRICAL INTERFERENCE

The effects of direct cortical electrical interference on consonant an d vowel discrimination were investigated in five patients with implant ed subdural electrode arrays. Without electrical interference, patient s' performance discriminating consonants and vowels was intact. With e lectrical interference, consonant discrimination was impaired at one e lectrode site in each patient on the superior temporal gyrus of the la teral left perisylvian cortex. Conversely, vowel and tone discriminati on remained relatively intact when tested with electrical interference at the same site. Analysis of patients' consonant discrimination erro rs revealed that neither differences in acoustic temporal structure no r syllable position fully account for the consonant-vowel perceptual d issociations elicited. Our data suggest that at the cortical level con sonant and vowel perception are intrinsically distinct perceptual phen omena. The selective impairment of consonant, but not vowel, discrimin ation further suggests that consonant and vowel perception are disting uished by differences in relative dependence on the functional - perha ps integrative - resources of the left lateral superior temporal gyrus .