Attenuated GBRs were not related to positive or negative symptoms in young schizophrenia or CHR patients. This finding is consistent with some (Haig et al., 2000b), but not all (Hall et al., 2011b; Leicht et al., 2010b), prior efforts to relate abnormal oscillations in the gamma frequency range to symptoms. It is worth noting, however, that some studies have found relationships between diminished gamma response and “treatment-resistant” symptoms including disorganization (Gordon, 2001) and psychomotor poverty (Gordon, 2001; Lee, 2003). Additional studies have reported associations between reductions in gamma and disrupted perceptual (Johannesen et al., 2008) and cognitive ability (Uhlhaas et al., 2006), including impaired working memory (Light et al., 2006; Winterer et al., 2004). However, other studies have reported unexpected correlations between enlarged gamma-band response and positive symptoms (Hirano et al., 2008; Lee, 2003; Spencer et al., 2008a; Spencer et al., 2009; Spencer et al., 2004; Uhlhaas et al., 2006). Further clarification is needed about whether the same clinical and cognitive abnormalities are associated with different gamma measures (e.g., total power vs. evoked power vs. intertrial phase coherence). Thus, whether the gamma-band abnormalities are a general characteristic of schizophrenia or are more specifically associated with certain symptom domains remains unclear.
