Electroencephalographic activity over temporal brain areas during phonological encoding in picture naming

Objectives: The present study examined electroencephalographic (EEG) correlates of phonological encoding during picture naming with special emphasis on hemispheric asymmetries of these EEG correlates. We also examined whether a small set of stimuli was sufficient to study the phonological encoding, and to what extent the complexity of the produced message affects the EEG responses. Methods: Event-related electrical brain activity during the covert and overt production of names and nominal phrases derived from 16 Variants from 3 different pictures was compared with that during passive viewing of the same pictures. Results: Topographical and source analyses of the differential EEG activity (naming versus passive viewing) indicated that the N1 and P2 components of the visual evoked potential resulted from the same brain areas, but were activated stronger during naming as compared to passive viewing. In contrast, the differential EEG activity from 275 to 400 ms suggested the involvement of additional brain areas during naming with more pronounced left- than right-hemispheric activation in middle and posterior temporal regions for both overt and covert naming. Conclusions: Results suggest the involvement of Wernicke's area in the phonological encoding of a message during speech production, which can even be obtained with a small set of pictures and a large number of repetitions. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.