These findings support the value of a symptom-based approach for dealing with the heterogeneity of schizophrenia, and suggest that visual N1 reductions may not represent a biological marker for schizophrenia per se. Although reduced visual N1 may be dependent on presence of auditory hallucinations during testing (i.e., a marker of current clinical state), it may also represent a stable trait in patients prone to auditory hallucinations. Additional research is required to address this state vs. trait issue, and whether the observed N1 sink reductions for auditory hallucinators are specific to the visual modality, or are also present, and perhaps even more robust, for auditory stimuli (Foxe et al., 2011; Salisbury et al., 2010).
