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In this paper, we provide guidance for the organization and implementation of EEG studies. This work was inspired by our experience conducting a large-scale, multi-site study, but many elements could be applied to any EEG project. Section 1 focuses on study activities that take place before data collection begins. Topics covered include: establishing and training study teams, considerations for task design and piloting, setting up equipment and software, development of formal protocol documents, and planning communication strategy with all study team members. Section 2 focuses on what to do once data collection has already begun. Topics covered include: (1) how to effectively monitor and maintain EEG data quality, (2) how to ensure consistent implementation of experimental protocols, and (3) how to develop rigorous preprocessing procedures that are feasible for use in a large-scale study. Links to resources are also provided, including sample protocols, sample equipment and software tracking forms, sample code, and tutorial videos (to access resources, please visit: https://osf.io/wdrj3/).

A growing body of literature suggests that cognitive impairment in people with schizophrenia (PSZ) results from disrupted cortical excitatory/inhibitory (E-I) balance, which may be linked to gamma entrainment and can be measured noninvasively using electroencephalography (EEG). However, it is not yet known the degree to which these entrainment abnormalities covary within subjects across sensory modalities. Furthermore, the degree to which cross-modal gamma entrainment reflects variation in biological processes associated with cognitive performance remains unclear. We used EEG to measure entrainment to repetitive auditory and visual stimulation at beta (20 Hz) and gamma (30 and 40 Hz) frequencies in PSZ (n = 78) and healthy control subjects (HCS; n = 80). Three indices were measured for each frequency and modality: event-related spectral perturbation (ERSP), intertrial coherence (ITC), and phase-lag angle (PLA). Cognition and symptom severity were also assessed. We found little evidence that gamma entrainment covaried across sensory modalities. PSZ exhibited a modest correlation between modalities at 40 Hz for ERSP and ITC measures (r = 0.23-0.24); however, no other significant correlations between modalities emerged for either HCS or PSZ. Both univariate and multivariate analyses revealed that (a) the pattern of entrainment abnormalities in PSZ differed across modalities, and (b) modality rather than frequency band was the main source of variance. Finally, we observed a significant association between cognition and gamma entrainment in the auditory domain only in HCS. Gamma-band EEG entrainment does not reflect a unitary transcortical mechanism but is instead modality specific. To the extent that entrainment reflects the integrity of cortical E-I balance, the deficits observed in PSZ appear to be modality specific and not consistently associated with cognitive impairment. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Although people with schizophrenia (PSZ) exhibit robust and reliable deficits in working memory (WM) capacity, the neural processes that give rise to this impairment remain poorly understood. One reason for this lack of clarity is that most studies employ a single neural recording modality-each with strengths and weaknesses-with few examples of integrating results across modalities. To address this gap, we conducted a secondary analysis that combined data from an overlapping set of subjects in previously published electroencephalographic and functional magnetic resonance imaging studies that used nearly identical working memory tasks (visual change detection). The prior studies found similar patterns of results for both posterior parietal BOLD activation and suppression of the alpha frequency band within the EEG. Specifically, both signals exhibited abnormally shallow modulation as a function of the amount of information being stored in WM in PSZ. In the present study, both alpha suppression and posterior parietal BOLD activity increased as the number of items stored in WM increased. The magnitude of alpha suppression modulation was correlated with the magnitude of BOLD signal modulation in PSZ, but not in HCS. This finding suggests that the same illness-related biological processes constrain both alpha suppression and BOLD signal modulation as a function of WM storage in PSZ. The complementary strengths of these two techniques may thus combine to advance the identification of the processes underlying WM deficits in PSZ.

BackgroundAlthough people with schizophrenia (PSZ) frequently exhibit reduced working memory capacity relative to healthy comparison subjects (HCS), the mechanisms that underlie this impairment are not yet known. The present study aimed to assess one putative mechanism: impaired suppression of alpha and beta frequency bands during the delay period of a visual working memory task.MethodsThe electroencephalogram (EEG) was recorded from 30 PSZ and 31 HCS while they completed a change detection task in which they were required to remember a briefly presented array of colored squares over an 1800-ms delay interval.ResultsOverall, we found that PSZ had significantly reduced alpha and beta-band suppression during the delay interval compared to HCS, and that these significant differences emerged early (100-200 ms after the onset of the memory array). Furthermore, the magnitude of suppression was significantly associated with task performance across both groups. Finally, the magnitude of suppression in alpha and beta frequency bands was significantly associated with a range of cognitive measures among HCS, but not PSZ.ConclusionsThese results implicate impaired alpha/beta suppression during the consolidation period of working memory tasks as a promising neural mechanism that constrains capacity in PSZ.

The cognitive impairments associated with schizophrenia have long been known to involve deficits in working memory (WM) capacity. To date, however, the causes of WM capacity deficits remain unknown. The present study examined selective attention impairments as a putative contributor to observed capacity deficits in this population. To test this hypothesis, we used an experimental paradigm that assesses the role of selective attention in WM encoding and has been shown to involve the prefrontal cortex and the basal ganglia. In experiment 1, participants were required to remember the locations of 3 or 5 target items (red circles). In another condition, 3-target items were accompanied by 2 distractor items (yellow circles), which participants were instructed to ignore. People with schizophrenia (PSZ) exhibited significant impairment in memory for the locations of target items, consistent with reduced WM capacity, but PSZ and healthy control subjects did not differ in their ability to filter the distractors. This pattern was replicated in experiment 2 for distractors that were more salient. Taken together, these results demonstrate that reduced WM capacity in PSZ is not attributable to a failure of filtering irrelevant distractors.

Background Research suggests that effort-cost decision-making (ECDM), the estimation of work required to obtain reward, may be a relevant framework for understanding motivational impairment in psychotic and mood pathology. Specifically, research has suggested that people with psychotic and mood pathology experience effort as more costly than controls, and thus pursue effortful goals less frequently. This study examined ECDM across psychotic and mood pathology. Hypothesis We hypothesized that patient groups would show reduced willingness to expend effort compared to controls. Study Design People with schizophrenia (N  = 33), schizoaffective disorder (N  = 28), bipolar disorder (N  = 39), major depressive disorder (N  = 40), and controls (N  = 70) completed a physical ECDM task. Participants decided between completing a low-effort or high-effort option for small or larger rewards, respectively. Reward magnitude, reward probability, and effort magnitude varied trial-by-trial. Data were analyzed using standard and hierarchical logistic regression analyses to assess the subject-specific contribution of various factors to choice. Negative symptoms were measured with a clinician-rated interview. Study Results There was a significant effect of group, driven by reduced choice of high-effort options in schizophrenia. Hierarchical logistic regression revealed that reduced choice of high-effort options in schizophrenia was driven by weaker contributions of probability information. Use of reward information was inversely associated with motivational impairment in schizophrenia. Surprisingly, individuals with major depressive disorder and bipolar disorder did not differ from controls. Conclusions Our results provide support for ECDM deficits in schizophrenia. Additionally, differences between groups in ECDM suggest a seemingly similar behavioral phenotype, reduced motivation, could arise from disparate mechanisms. [ABSTRACT FROM AUTHOR]

Background and Hypothesis Hallucinations may be driven by an excessive influence of prior expectations on current experience. Initial work has supported that contention and implicated the anterior insula in the weighting of prior beliefs. Study Design Here we induce hallucinated tones by associating tones with the presentation of a visual cue. We find that people with schizophrenia who hear voices are more prone to the effect and using computational modeling we show they overweight their prior beliefs. In the same participants, we also measured glutamate levels in anterior insula, anterior cingulate, dorsolateral prefrontal, and auditory cortices, using magnetic resonance spectroscopy. Study Results We found a negative relationship between prior-overweighting and glutamate levels in the insula that was not present for any of the other voxels or parameters. Conclusions Through computational psychiatry, we bridge a pathophysiological theory of psychosis (glutamate hypofunction) with a cognitive model of hallucinations (prior-overweighting) with implications for the development of new treatments for hallucinations. [ABSTRACT FROM AUTHOR]

Microbiome profiling using the 16S rRNA gene was used to examine the composition and diversity of bacteria residing in thin, whitish, iridescent microbial biofilms 1470 m below the surface in the Sanford Underground Research Facility (SURF), a former gold mine in South Dakota, USA. The biofilms superficially resemble "cave silver" biofilms described from limestone caves. The communities are dominated by bacteria, although significant Thuamarchaeota are also present. The most abundant bacterial groups were Actinobacteria (mainly Pseudonocardiaceae), Acidobacteria, Proteobacteria, Chloroflexi, and Planctomycetes. The composition of the biofilms varied considerably from sample to sample. Like cave silver biofilms in Europe and other locations, Proteobacteria and Actinobacteria are abundant, but nearly all operational taxonomic units (OTUs) (at 97% similarity) are different. Apart from one Pseudonocardia species, most abundant OTUs observed here were not isolated by a previous culture-based study at SURF. This indicates that culture-based techniques do not accurately represent the diversity of bacterial taxa in SURF "cave silver." [ABSTRACT FROM AUTHOR]