Lexical processing of vocabulary class in patients with Broca's aphasia: an event-related brain potential study on agrammatic comprehension.
This paper presents electrophysiological evidence of an impairment in the on-line processing of word class information in patients with Broca's aphasia with agrammatic comprehension. Event-related brain potentials (ERPs) were recorded from the scalp while Broca patients and non-aphasic control subjects read open- and closed-class words that appeared one at a time on a PC screen. Separate waveforms were computed for open- and closed-class words. The non-aphasic control subjects showed a modulation of an early left anterior negativity in the 210-325ms as a function of vocabulary class (VC), and a late left anterior negative shift to closed-class words in the 400-700ms epoch. An N400 effect was present in both control subjects and Broca patients. We have taken the early electrophysiological differences to reflect the first availability of word-category information from the mental lexicon. The late differences can be related to post-lexical processing. In contrast to the control subjects, the Broca patients showed no early VC effect and no late anterior shift to closed-class words. The results support the view that an incomplete and/or delayed availability of word-class information might be an important factor in Broca's agrammatic comprehension.
ter Keurs
Mariken
M
Neurocognition of Language Processing Research Group, Max Planck Institute for Psycholinguistics, Nijmegen, The Netherlands. terkeurs.dewit@consunet.nl
Brown
Colin M
CM
Hagoort
Peter
P
D000328:Adult; D000368:Aged; D001039:Aphasia, Broca / Q000175:diagnosis / Q000503:physiopathology*; D001288:Attention / Q000502:physiology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology; D004292:Dominance, Cerebral / Q000502:physiology; D004410:Dyslexia / Q000175:diagnosis / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011932:Reading; D012660:Semantics; D014825:Vocabulary