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Fluctuating neuronal network states influence brain responses to transcranial magnetic stimulation (TMS). Our previous studies revealed that transient spontaneous bihemispheric brain states in the EEG, driven by oscillatory power, information flow and regional domination, modify cortical EEG responses to TMS. However, the impact of ongoing fluctuations of large-scale brain network states on TMS-EEG responses has not been explored. To determine the effects of large-scale brain network states on TMS-EEG responses. Resting-state EEG and structural MRI from 24 healthy subjects were recorded to infer large-scale brain states. TMS-EEG was acquired with TMS at state-related targets, identified by the spatial distribution of state activation power from resting-state EEG. TMS-induced oscillations were measured by event-related spectral perturbations (ERSPs), and classified with respect to the brain states preceding the TMS pulses. State-locked ERSPs with TMS at specific state-related targets and during state activation were compared with state-unlocked ERSPs. Intra-individual comparison of ERSPs by threshold free cluster enhancement (TFCE) revealed that posterior and visual state-locked TMS, respectively, increased beta and alpha responses to TMS of parietal and occipital cortex compared to state-unlocked TMS. Also, the peak frequencies of ERSPs were increased with state-locked TMS. In addition, inter-individual correlation analyses revealed that posterior and visual state-locked TMS-induced oscillation power (ERSP clusters identified by TFCE) positively correlated with state-dependent oscillation power preceding TMS. Spontaneous transient large-scale brain network states modify TMS-induced natural oscillations in specific brain regions. This significantly extends our knowledge on the critical importance of instantaneous state on explaining the brain's varying responsiveness to external perturbation. • Effects of large-scale brain network states on TMS-EEG responses were determined • Posterior state-locked TMS increased beta responses to TMS of parietal cortex • Visual state-locked TMS increased alpha responses to TMS of occipital cortex • State-locked TMS increased peak frequencies of event-related spectral perturbations • Large-scale brain network states modify TMS-induced natural oscillations [ABSTRACT FROM AUTHOR]

Auditory steady-state responses (ASSRs) are recurrent neural activities entrained to regular cyclic auditory stimulation. ASSRs are altered in individuals with schizophrenia, and may be related to hypofunction of the N-methyl- D -aspartate (NMDA) glutamate receptor. Noncompetitive NMDA receptor antagonists, including ketamine, have been used in ASSR studies of rodent models of schizophrenia. Although animal studies using non-human primates are required to complement rodent studies, the effects of ketamine on ASSRs are unknown in intact awake non-human primates. In this study, after administration of vehicle or ketamine, click trains at 20–83.3 Hz were presented to elicit ASSRs during recording of electroencephalograms in intact, awake macaque monkeys. The results indicated that ASSRs quantified by event-related spectral perturbation and inter-trial coherence were maximal at 83.3 Hz after vehicle administration, and that ketamine reduced ASSRs at 58.8 and 83.3 Hz, but not at 20 and 40 Hz. The present results demonstrated a reduction of ASSRs by the NMDA receptor antagonist at optimal frequencies with maximal responses in intact, awake macaques, comparable to ASSR reduction in patients with schizophrenia. These findings suggest that ASSR can be used as a neurophysiological biomarker of the disturbance of gamma-oscillatory neural circuits in this ketamine model of schizophrenia using intact, awake macaques. Thus, this model with ASSRs would be useful in the investigation of human brain pathophysiology as well as in preclinical translational research. • ASSRs are altered in schizophrenia, possibly due to NMDA receptor hypofunction. • ASSRs in response to click trains at 20–83.3 Hz were recorded in awake monkeys. • Ketamine, NMDA receptor antagonist, reduced ASSRs at 58.8 and 83.3 Hz. • Ketamine model mimics gamma-oscillatory deficits of schizophrenia in monkeys. • This model may be useful in preclinical translational research of schizophrenia. [ABSTRACT FROM AUTHOR]

• An evaluation framework is proposed based on quantitative metrics to \ort the choice of the preferable EEG pre-processing strategy. • The effect of different pre-processing approaches is explored and quantified on an illustrative application. • The most critical steps result to be the segmentation of the data and the re-reference method, while the Independent Component Analysis algorithm has a small effect on the cleaning procedure. Electroencephalography (EEG) to study brain functions has become fundamental in many research settings across very different protocols. Indeed, a plethora of processing methods have been developed, for both data preparation (pre-processing) and analysis. While an effect of the pre-processing on the signal is admitted and accepted, there is an increasing effort to better understand to which extent such an influence may affect the analysis results, and which may be the best practices for the correct data pre-processing. Pre-processing procedures include different steps, and each of them may induce modifications affecting the study results. Thus, we analyze the effect of different methodologies at each step and propose quantitative parameters for the choice of the preferable strategy. We illustrate how method selection may affect the quality of EEG signal in an Action Observation and Motor Imagery protocol, using quantitative indices. We analyzed the effect of different strategies for early-stage data preparation; two independent component analysis (ICA) algorithms (SOBI and Extended Infomax) used for artifact removal; and four re-reference approaches (Common averaged reference-CAR, robust-CAR, reference electrode standardization technique – REST, and reference electrode standardization and interpolation technique – RESIT). The effects of the different pipelines were also evaluated through the computation of event-related spectral perturbation (ERSP) of the sensorimotor rhythm. Results showed that signal segmentation significantly affects the cleaning procedure, while comparable results are obtained across ICA approaches. Finally, similar topographical representations were obtained after the application of CAR, REST, and RESIT re-referencing approaches, where rCAR showed the most different ERSP topographical pattern. [ABSTRACT FROM AUTHOR]

• Attention dysfunction in idiopathic REM sleep behavior disorder (iRBD) patients was studied by event-related EEG analysis. • Normal cortical activity reflecting 'inhibition of return' (IOR) was absent in iRBD patients. • The absence of IOR in iRBD may imply dysfunctions in visuoperceptual processing and motor control. Idiopathic REM sleep behavior disorder (iRBD) patients are susceptible to cognitive deficits, especially attention dysfunction. The objective of this study is to elucidate the neural mechanism of the dysfunction in attention known as 'inhibition of return' (IOR) in iRBD patients based on an analysis of oscillatory cortical activity during a selective attention task. Event-related potentials (ERPs) were recorded from iRBD patients and normal control subjects while performing a Posner task. The differences in N1 ERP and theta- and beta-bands event-related spectral perturbations (ERSPs) between valid and invalid stimuli were compared between groups. The N1 amplitude was significantly higher for the invalid stimuli in controls, while the valid-invalid difference was not significant in iRBD patients. The valid-invalid differences in ERSPs were prominent in controls at ∼100–400 ms for the theta-band and ∼200–400 ms for the beta-band, and the valid-invalid differences in ERSPs were not significant in the iRBD patients. The results demonstrated that valid-invalid differences in neural activity were absent in iRBD patients, and these neural findings were in accord with the behavioral results. Our findings imply impairment in sensory-perceptual processing mediated by attentional control and response inhibition in early-stage iRBD before clinical neurodegeneration. [ABSTRACT FROM AUTHOR]

Highlights • Time–frequency analyses were used to identify dynamic electroencephalographic markers of donepezil's effect in healthy young adults. • Inter-trial coherence and event-related spectral perturbation analyses can detect subtle changes related to donepezil's effects. • Electroencephalography may be a valuable tool for predicting the efficacy of drug candidates prior to Phase II/III clinical trials in Alzheimer's disease. Abstract Objective To identify possible electroencephalographic (EEG) markers of donepezil's effect on cortical activity in young, healthy adult volunteers at the group level. Methods Thirty subjects were administered a daily dose of either 5 mg donepezil or placebo for 15 days in a double-blind, randomized, cross-over trial. The electroencephalogram during an auditory oddball paradigm was recorded from 58 scalp electrodes. Current source density (CSD) transformations were applied to EEG epochs. The event-related potential (ERP), inter-trial coherence (ITC: the phase consistency of the EEG spectrum) and event-related spectral perturbation (ERSP: the EEG power spectrum relative to the baseline) were calculated for the target (oddball) stimuli. Results The donepezil and placebo conditions differed in terms of the changes in delta/theta/alpha/beta ITC and ERSP in various regions of the scalp (especially the frontal electrodes) but not in terms of latency and amplitude of the P300-ERP component. Conclusion Our results suggest that ITC and ERSP analyses can provide EEG markers of donepezil's effects in young, healthy, adult volunteers at a group level. Significance Novel EEG markers could be useful to assess the therapeutic potential of drug candidates in Alzheimer's disease in healthy volunteers prior to the initiation of Phase II/III clinical studies in patients. [ABSTRACT FROM AUTHOR]

Stimuli that have been frequently used to induce self-relevant processing are highly familiar to individuals (e.g., self-name [SN] and self-face). One’s surname is an important form of collective self-concept; it represents the line of ancestry, and is psychologically salient. According to this concept, a stranger with the same surname may also elicit salient self-relevant processing, despite unfamiliarity; however, this has not yet been directly investigated. The present study adopted a three-stimulus oddball paradigm and multimodal electroencephalography to study the potential self-relevant processing of such stimuli. Behavioral results indicated that same-surname unfamiliar (SSU) names were rated more self-relevant than different-surname unfamiliar (DSU) names, although they were rated equally unfamiliar to subjects. Analysis of EEG data showed similar P2 enhancement in response to SN and SSU when compared to DSU. In contrast, the self-relevant effect on P3 amplitudes and theta synchronization decreased linearly from SN, SSU, to DSU conditions. Thus, both the behavioral and electrophysiological data indicate that unfamiliar names with the same surname can evoke reliable self-relevant processing. [ABSTRACT FROM AUTHOR]

Objective We investigated neuronal correlates of faces versus non-faces processing in a cortically blind patient (TN) and a group of healthy age-matched controls in order to test electrophysiological correlates of the processing of pertinent stimuli in this patient. Methods An EEG paradigm was used, in which intact and scrambled faces were displayed on a screen. First, time-frequency transforms were conducted on the patients’ data alone. These oscillations were then compared to the frontal activity of six control participants. Results Post stimulus oscillatory modulations (synchronisation in theta and alpha frequency bands) of both intact and scrambled faces at frontal scalp sites were observed in TN. These modulations were different for correct and incorrect responses. A more important increase in the theta band for incorrect responses was observed. The oscillatory rhythms highlighted in blindsight and in frontal regions differ from the ones observed in control participants. Conclusion Despite the destruction of the visual cortex, oscillatory rhythms are not cancelled out but are shifted to anterior regions, revealing the activity of an alternate pathway for residual visual function. Significance The results provide evidence for a top-down cognitive control process in blindsight. [ABSTRACT FROM AUTHOR]

Highlights: [•] Whether conceptual and emotional incongruities can be differentiated was examined. [•] Both emotional and conceptual incongruities related to N400 effect. [•] Conceptual incongruity induced theta power increase. [•] Emotional incongruity induced gamma power increase. [ABSTRACT FROM AUTHOR]

Abstract: Recent studies have demonstrated that mentally rotating the hands involves participants engaging in motor imagery processing. However, far less is known about the possible neurophysiological basis of such processing. To contribute to a better understanding of hand mental rotation processing, event-related spectral perturbation (ERSP) methods were applied to electroencephalography (EEG) data collected from participants mentally rotating their hands. Time–frequency analyses revealed that alpha-band power suppression was larger over central-parietal regions. This is in accordance with motor imagery findings suggesting that the motor regions may be involved in processing or detection of kinaesthetic information. Furthermore, the presence of a significant negative correlation between reaction times (RTs) and alpha-band power suppression over central regions is illustrated. These findings are consistent with the neural efficiency hypothesis, which proposes the non-use of many brain regions irrelevant for the task performance as well as the more focused use of specific task-related regions in individuals with better performance. These results indicate that ERSP provides some independent insights into the mental rotation process and further confirms that parietal and motor cortices are involved in mental rotation. [Copyright &y& Elsevier]

Abstract: The brain–computer interface P300 speller is aimed to help those patients unable to activate muscles to spell words by utilizing their brain activity. However, a problem associated with the use of this brain–computer interface paradigm is the generation mechanics of P300 related to responses to visual stimuli. Herein, we investigated the event-related potential (ERP) response for the P300-based brain–computer interface speller. A signal preprocessing method integrated coherent average, principal component analysis (PCA) and independent component analysis (ICA) to reduce the dimensions and noise in the raw data. The time–frequency analysis was based on wavelet and two characteristic parameters of event-related spectral perturbation (ERSP) and inter-trial coherence (ITC) were computed to indicate the evoked response (time-locked) and phase reset (phase-locked) activity, respectively. Results demonstrated that the proposed method was valid for the time-locked and phase-locked feature extraction and both the evoked response and phase reset contributed to the genesis of the P300 signal. These electrophysiological responses characteristics of ERPs would be used for BCI P300 speller design and its signal processing strategies. [ABSTRACT FROM AUTHOR]

Abstract: It is now well established that human brain is endowed with an auditory-motor system which may depend on individual''s motor experience. Here we designed an electroencephalography (EEG) experiment for investigating this dependency. A sound with not-so-obvious meaning was presented to subjects firstly. Then a visual exposure process was carried out to establish an association between the sound and action. By analyzing event-related spectral perturbation (ERSP) in the mu rhythm, we expected to find response differences in the motor cortex between the pre- and post-exposure periods. Results of 14 subjects indicated that the activation of motor cortex was stronger in the post-exposure phase. Our study suggests that the auditory-motor association can be established rapidly by a simple exposure process. [Copyright &y& Elsevier]