Abstract

Event-related potentials (ERPs) reflect the hierarchy of regional brain activity during the information processing sequence. Reductions of early ERP components in schizophrenia have been inconsistently observed, which may stem from differences in patients' symptoms. Importantly, N1 reductions to tones over left temporal cortex have been reported for psychotic patients during periods of auditory hallucinations. Taking advantage of two 67-channel ERP data sets recorded during recognition memory (RM) and working memory (WM) paradigms using words and faces, we compared right-handed patients who either reported experiencing auditory hallucinations (n = 19/16 for RM/WM) or not (n = 32/35) and healthy adults (n = 44/40). ERPs were transformed into reference-free current source density (CSD) waveforms (spherical spline surface Laplacian), which included a distinct N1 sink (approximate peak latency 150 ms) at inferior lateral-parietal sites (P7/8, P9/10), which was right-lateralized for faces (N170) but strongly left-lateralized for words. CSDs were submitted to unrestricted Varimax-PCA separately for each paradigm to quantify N1 sink activity. In both paradigms, N1 sink was substantially reduced in hallucinators compared with controls and non-hallucinators, who did not differ from each other. These N1 sink reductions were most robust for words over the left hemisphere, suggesting an interference of activity in temporoparietal language regions of hallucinators during early visual processing of words, which may contribute to their verbal memory deficits during RM and WM tasks. [Supported by NIMH grant MH066597].