In recent years, there has also been an increasing interest in abnormal neural oscillations in schizophrenia (e.g., Uhlhaas et al., 2008; Uhlhaas & Singer, 2010). Stimulus-induced or event-related changes in ongoing rhythmic EEG activity substantially contribute to the observed ERP components (e.g., Gruber et al., 2005; Makeig et al., 2002; Sauseng et al., 2007). Neurophysiologic techniques involving EEG or magnetoencephalography (MEG) provide high-temporal resolution and are therefore ideal for assessing oscillatory activation. However, the averaging process underlying ERPs generally prevents the study of neural oscillations (e.g., Pfurtscheller & Lopes da Silva, 1999). Several spectral decomposition approaches allow the study of event-related EEG oscillations that are poorly represented or absent in ERPs (e.g., Roach & Mathalon, 2008, for a review). Most of the time-frequency EEG research in schizophrenia has focused on high-frequency (i.e., beta and gamma) modulations (e.g, Ford et al., 2008; Spencer et al., 2003, 2004; Uhlhaas & Singer, 2010). Nonetheless, low-frequency modulations involving alpha and theta bands are associated with working memory, attention, inhibition and top-down cognitive control (Uhlhaas & Singer, 2010, for a review), functional domains that are the hallmark of cognitive impairments in schizophrenia (e.g., Barch & Smith, 2008).
