31 Evidence is also available that dopamine and 5-HT modulate the prevalence of oscillations in different frequency bands.32-35 High-frequency oscillations in schizophrenia

Because of the close relations with underlying physiological parameters and evidence for the functional involvement of oscillatory networks in cognitive processes, there is increasing interest in the possibility that neural oscillations in SCZ may be informative for revealing the causes of cognitive deficits as well as establish potential links to the pathophysiology. Indeed, a large body of work has examined rhythmic activity during both spontaneous and task-related activity in SCZ patients Inhibitors,research,lifescience,medical with electroencephalography (EEG)/magnetoencephalography (MEG). Because of the prominent role of gamma-band activity in cognition during normal brain functioning, a particular focus has been on the investigation of high-frequency activity in patient populations. Gamma band (30-100 Hz) The overwhelming evidence Inhibitors,research,lifescience,medical points to a reduction of gamma-band oscillations during the execution of cognitive tasks in SCZ patients relative to controls(click here Figure 1).36 Reductions

in gamma-band amplitude have been demonstrated for a wide range of cognitive and perceptual paradigms, including working memory,37 executive control,38 and perceptual processing.39,40 There is preliminary evidence Inhibitors,research,lifescience,medical that the decrease in gamma-band spectral power is independent of medication status.38 Figure 1. Mechanisms underlying the generation of gamma oscillations and synchrony, Inhibitors,research,lifescience,medical a) A neocortical circuit involved in the generation of gammaband oscillations. Generation of synchronized neural activity in neocortical circuits is dependent on negative feedback … Recent studies have also examined the contribution of high (> 60 Hz) gamma-band oscillations to perceptual and cognitive deficits in schizophrenia. In a recent

study by our group41 (Figure 2), impaired task performance during a perceptual organization task was accompanied by a widespread deficit in the power of gamma-band oscillations between 60 and Inhibitors,research,lifescience,medical 120 Hz. This deficit was associated with an effect size of d=1.26 which is in the range and above of effect sizes for event-related potentials during (ERPs) that have been frequently investigated in SCZ, such as the Mismatch Match Negativity (MMN).42 Similar results supporting the relevance of dysfunctions in oscillatory activity > 60 Hz have been reported by Tsuchimoto et al43 and Hamm and colleagues44 who examined high gamma-band activity during an auditory steady state (ASS) paradigm. Figure 2. High-frequency oscillations in schizophrenia patients. a) TMS-elicited high-frequency oscillations in controls and SCZ patients: single-pulse transcranial magnetic stimulation over 4 cortical areas was associated with peak frequencies between 20 and 30 …