EVENT-RELATED POTENTIALS IN APHASIC PATIE NTS - AN N400 STUDY

In 10 patients with fluent aphasia (Wernicke's aphasia/anomic aphasia) event-related potentials (ERP) were recorded during a lexical decisio n task. 10 normal volunteers served as controls. An acoustic paired-wo rd N400 paradigm was applied, where patients and controls had to disti nguish words from nonwords and respond manually using a two-button rea ction time device. ERP in controls resembled those described in tachis toscopic N400 studies. Recordings in aphasics disclosed three specific alterations of the late components, namely (1) increased latencies, ( 2) decreased amplitude or loss of the N400 component, and (3) temporal dyscorrelation as revealed by topographical analysis. The P3-wave was preserved in most cases. In five patients, the patterns of ERP change s was well correlated to the localization of the lesion as confirmed b y CCT or MRI. ERP alterations were present in cases with merely subcli nical language impairments. These results suggest that the acoustic ER P paradigm applied in this study is a sensitive method for the detecti on of functional impairments of the cerebral language system. The prog nostic value of this method with respect to neuropsychological outcome remains to be explored in further studies.