Merging CSD and PCA methods into a generic ERP strategy and applying it to both stimulus- and response-locked activity has again been found to be a potent approach in advancing knowledge of cognitive dysfunction in schizophrenia. The present findings establish robust reductions of the ERP old/new effects over left lateral temporoparietal, but not mid-parietal, sites as an electrophysiologic correlate of word recognition memory deficits in schizophrenia, implicating impaired stimulus representation involving posterior regions. Marked reductions of stimulus-related vertex N2 sinks preceded and response-related mid-frontal sink activity followed these impairments, indicating additional deficits in word classification (i.e., stimulus categorization) and performance monitoring in schizophrenia involving anterior cingulate cortex. These impairments, while essentially present for both visual and auditory recognition memory tasks, were clearly more robust for spoken words, suggesting a specific impairment of temporal integration and retrieval of semantic information by means of a phonological code (cf. Baddeley, 1983; see also Kayser et al., 2003, p. 12) involving left parietal-temporal regions typically associated with language-related processing.
