Evaluation of resting state gamma power as a response marker in schizophrenia

Abstract

Aims: An abnormal activity in the electroencephalography (EEG) gamma band (>30 Hz) has been demonstrated in schizophrenia and this has been suggested to be reflecting a deficit in the development and maturation of the basic cognitive functions of attention, working memory and sensory processing. Hypothesizing gamma oscillatory activity as a potential EEG biomarker to antipsychotic response in schizophrenia, the present study aimed at measuring baseline spontaneous gamma activity in schizophrenia patients, and evaluating its response to antipsychotic treatment over 8 weeks.Methods: Fifteen drug-free/naïve patients were recruited, compared at baseline with 15 age-, sex-and education-matched healthy controls, and were followed up for 8 weeks' treatment on antipsychotics. Resting state EEG waves were recorded using high (192-channel) resolution EEG at admission, 4 weeks and 8 weeks. Spectral power was calculated using fast Fourier transformation, Hanning window. The power was averaged region-wise over nine regions in three frequency ranges (30-50 Hz, 50-70 Hz, 70-100 Hz).Results: Patients and controls differed significantly at intake in terms of left temporal and parietal high (70-100 Hz) gamma power. Consequently, no significant differences were seen over the course of antipsychotic treatment on gamma spectral power in any of the regions. Conclusions:Lack of significant effect of treatment on gamma power suggests that these gamma oscillations may be trait markers in schizophrenia.

Neural synchronization deficits linked to cortical hyper-excitability and auditory hypersensitivity in fragile X syndrome

“…Four patients were receiving atypical antipsychotics (2 aripiprazole, 2 risperidone), two antidepressants, (paroxetine, citalopram) and one both an atypical antipsychotic (aripiprazole) and an antidepressant (citalopram), all on a stable dose for at least 4 weeks. EEG studies of these drugs in psychiatric research suggest they do not significantly alter electrophysiology in a way that would confound data interpretation, consistent with our analyses, which only found one difference in EEG measures based on whether patients were taking these psychiatric medications [19, 20]. …”

“…It is not possible to determine whether psychiatric medications were causing EEG alterations or if the medications were prescribed to treat particularly severe behavioral problems associated with the EEG alterations (medicated patients also had more abnormal clinical ratings on the Sensory Profile and SCQ— p  < .01). However, in studies of multiple psychiatric disorders, gamma power remains relatively unaffected in patients treated with these medications [19, 20]. FXS patients showed a significant correlation between age and gamma ITC during the ERP to stimulus onset (rho = .59, p  = .01) and age and theta ITC during the ERP to stimulus offset (rho = .52, p  = .03), while these correlations were not significant in the age-matched controls.…”

Schneiderian first rank symptoms in schizophrenia: A developmental neuroscience evaluation

“…However, a recent meta‐analysis reveals no influence of medication status or gender on reduced BDNF levels in schizophrenia (Green et al, 2011). Moreover, acute phase antipsychotic treatment has been shown to have no influence on resting state gamma oscillations as well (Mitra et al, 2015). More importantly, the limited sample size is an inevitable limitation in generalizing the study results.…”

Decoding Saccadic Directions Using Epidural ECoG in Non-Human Primates

“…The length of the wavelets was 5 cycles of the lowest frequency (i.e., 625 ms). For each channel and each 100 ms time period, the normalized average power spectral densities were computed in 4 different frequency bands; the α-band (8–13 Hz), β-band (18–26 Hz), low γ-band (30–50 Hz), and high γ-band (70–100 Hz) (18-20). Then, we selected the data in four time bins after the TG in the TG condition and 5 time bins before the SS time in the SS condition.…”