Abnormal Spontaneous Gamma Power Is Associated With Verbal Learning and Memory Dysfunction in Schizophrenia

Abstract

Background: Schizophrenia patients exhibit cognitive deficits across multiple domains, including verbal memory, working memory, and executive function, which substantially contribute to psychosocial disability. Gamma oscillations are associated with a wide range of cognitive operations, and are important for cortico-cortical transmission and the integration of information across neural networks. While previous reports have shown that schizophrenia patients have selective impairments in the ability to support gamma oscillations in response to 40-Hz auditory stimulation, it is unclear if patients show abnormalities in gamma power at rest, or whether resting-state activity in other frequency bands is associated with cognitive functioning in schizophrenia patients. Methods: Resting-state electroencephalogram (EEG) was assessed over 3 min in 145 healthy comparison subjects and 157 schizophrenia patients. Single-word reading ability was measured via the reading subtest of the Wide Range Achievement Test-3 (WRAT). Auditory attention and working memory were evaluated using Letter-Number Span and Letter-Number Sequencing. Executive function was assessed via perseverative responses on the Wisconsin Card Sorting Test (WCST). Verbal learning performance was measured using the California Verbal Learning Test second edition (CVLT-II). Results: Schizophrenia patients showed normal levels of delta-band power but abnormally elevated EEG power in theta, alpha, beta, and gamma bands. An exploratory correlation analysis showed a significant negative correlation of gammaband power and verbal learning performance in schizophrenia patients. Conclusions: Patients with schizophrenia have abnormal resting-state EEG power across multiple frequency bands; gamma-band abnormalities were selectively and

Neurophysiologic Characterization of Resting State Connectivity Abnormalities in Schizophrenia Patients

“…Increased functional connectivity of alpha band activity at the superior parietal and the occipital lobe area at scalp levels of EEG in schizophrenia patients (N = 28) were previously reported by Liu et al 49; we successfully replicate and extended the results showing the involvement of frontotemporal regions. We also previously reported that abnormal spontaneous gamma band activity measured via a spatial PCA of scalp channel data was associated with verbal memory performance (24). Although the PCA method used in the prior study provides a data-driven approach for characterizing macroscale/global oscillatory effects at the scalp, the neural interactions among sources were not assessed.…”

“…Therefore, we removed the subjects of extreme value of age and sex, and used a final sample of n = 126 healthy comparison subjects and n = 139 schizophrenia patients in the effective connectivity analysis (Supplementary Method 1, Supplementary Table 1). Resting-state spectral characteristics assessed at a single principal component analysis (PCA)-based composite scalp sensor level were previously reported (24). Antipsychotics, anxiolytics, and anticholinergics were prescribed for 125, 27, and 42 schizophrenia patients, respectively.…”

Do NMDA-R antagonists re-create patterns of spontaneous gamma-band activity in schizophrenia? A systematic review and perspective

“…and 7 studies had a clinical sample smaller than n = 10. During the preparation of the manuscript, 5 additional studies meeting our inclusion criteria were included after the initial selection (Krukow et al, 2019;Lottman et al, 2019;Tanaka-Koshiyama et al, 2020;Zeev-Wolf et al, 2018) (see Figure 3). N = 6 studies that employed only visual artefact correction procedures were excluded (Mitra et al, 2015;Tikka et al, 2013Tikka et al, , 2015Tikka et al, , 2016Umesh et al, 2018;Winterer et al, 2001).…”

High‐power gamma‐related delta phase alteration in schizophrenia patients at rest

“…Our prior studies showed that (i) resting‐state gamma‐band EEG power at the frontal and temporal scalp electrodes is increased in schizophrenia patients relative to healthy subjects 44 ; and (ii) that significantly increased directed connectivities in the gamma band are observed between estimated frontal and temporal source regions in schizophrenia patients relative to healthy subjects 45 . However, the underlying neural mechanisms of abnormal higher gamma‐band EEG activity in schizophrenia patients remains unclear 44,46–49 . Identification of the contributing lower frequently neural synchronization such as delta‐ and theta‐band EEG to gamma‐band EEG power abnormality at rest (i.e.…”

“…45 However, the underlying neural mechanisms of abnormal higher gamma-band EEG activity in schizophrenia patients remains unclear. 44,[46][47][48][49] Identification of the contributing lower frequently neural synchronization such as delta-and theta-band EEG to gamma-band EEG power abnormality at rest (i.e. spontaneous gamma oscillation) may elucidate fundamental pathophysiologic abnormalities associated with the illness and ultimately yield clinically relevant applications.…”