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The neurochemical underpinnings of sleep's contribution to the establishment and maintenance of memory traces are largely unexplored. Considering that intranasal insulin administration to the CNS improves memory functions in healthy and memory-impaired humans, we tested whether brain insulin signaling and sleep interact to enhance memory consolidation in healthy participants. We investigated the effect of intranasal insulin on sleep-associated neurophysiological and neuroendocrine parameters and memory consolidation in 16 men and 16 women (aged 18-30 years), who learned a declarative word-pair task and a procedural finger sequence tapping task in the evening before intranasal insulin (160 IU) or placebo administration and 8 h of nocturnal sleep. On the subsequent evening, they learned interfering word-pairs and a new finger sequence before retrieving the original memories. Insulin increased growth hormone concentrations in the first night-half and EEG delta power during the second 90 min of non-rapid-eye-movement sleep. Insulin treatment impaired the acquisition of new contents in both the declarative and procedural memory systems on the next day, whereas retrieval of original memories was unchanged. Results indicate that sleep-associated memory consolidation is not a primary mediator of insulin's acute memory-improving effect, but that the peptide acts on mechanisms that diminish the subsequent encoding of novel information. Thus, by inhibiting processes of active forgetting during sleep, central nervous insulin might reduce the interfering influence of encoding new information.

Virtual reality (VR) is an immersive technology capable of simulating alternate realities, however, it often leads to cybersickness, causing discomfort for users. We conducted an experiment using a group of 30 participants (aged 25 ± 2.1 years) to see the alpha and delta wave changes for three conditions: Blank, Video, and Video Pause, with electroencephalography (EEG) recordings. The experiments were repeated three times (Trial 1, Trial 2, and Trial 3). The results showed a significant increase in delta wave power for Video compared with the Blank ( p  < 0.05). Video Pause showed a significant decrease compared to Video. Alpha waves significantly decreased during the Video compared with Blank ( p  < 0.05). Alpha waves during Video Pause showed a significant increase compared to Video ( p  < 0.05). Our study showed consistent alterations in alpha and delta waves across various visual stimuli for inducing cybersickness, and we observed that the decrease in alpha waves may be significantly associated with cybersickness rather than visual stimuli. These findings have implications for advancing cybersickness research.

•Little is known regarding the effects of multi-task exercise on delta power.•Low-intensity multi-task exercise increased prefrontal cortex cortical activation.•This increase was positively correlated with the increase in delta power. Delta power in electroencephalography during sleep has been used as a more quantitative approach to determine sleep depth and quality. Despite the positive effects of both exercise and cognitive activity on delta power during sleep, limited information is available regarding the effects of multi-task exercise, which combines these two activities. Therefore, this study aimed to investigate the impact of multi-task exercise on delta power during sleep. Fifteen older female adults participated in both multi-task and single-task exercises at low and moderate-to-vigorous intensities for 30 min each. Sleep architecture was recorded using polysomnography to compare the amount of delta power during sleep. Additionally, cortical hemodynamic changes in the prefrontal cortex were monitored using functional near-infrared spectroscopy before and after each exercise session. Low-intensity multi-task exercise increased cortical activation in the right and left ventrolateral prefrontal cortex and frontopolar area, which positively correlated with the increase in delta power. This study provides the first experimental evidence that low-intensity multi-task exercise enhances cortical activation in the prefrontal cortex of older female adults, leading to an increase in delta power during sleep. It also suggests that low-intensity multi-task exercise may be a more useful intervention for improving sleep quality in older adults.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a promising technique that potentially influences cortical activity, mainly increasing electroencephalography (EEG) power spectrum activity in low-frequency oscillations, and demonstrates potential therapeutic benefits for various pathologic conditions, like depression and chronic pain. To learn further about taVNS brain mechanisms, the present study investigated how using a single taVNS session can affect brain oscillations in healthy subjects. 44 healthy participants were included in this randomized, double-blind, sham-controlled trial. Participants were divided into the active and sham taVNS groups. Resting-state EEG power was analyzed across the frontal, central, and parietal regions in both hemispheres. Our findings demonstrated that active taVNS modulates low-frequency oscillations in the frontal areas of healthy subjects. After the intervention, the average delta power at the frontal region increased in the active group compared to the sham group. These changes were also observed with an increase in delta asymmetry (towards the right hemisphere) in the active group compared to the sham group. In healthy subjects, active taVNS selectively induces changes in the resting-state frontal brain oscillations. Our results suggest that taVNS increases homeostatic low-frequency oscillatory activity mainly over the right frontal hemisphere. Active taVNS induces activation of the fronto-vagal network, which has a therapeutic potential to generate salutogenic and balanced brain activity.

Attention is a core cognitive mechanism that allows the brain to allocate limited resources depending on current task demands. A number of frontal and posterior parietal cortical areas, referred to collectively as the fronto-parietal attentional control network, are engaged during attentional allocation in both humans and non-human primates. Numerous studies have examined this network in the human brain using various neuroimaging and scalp electrophysiological techniques. However, little is known about how these frontal and parietal areas interact dynamically to produce behavior on a fine temporal (sub-second) and spatial (sub-centimeter) scale. We addressed how human fronto-parietal regions control visuospatial attention on a fine spatiotemporal scale by recording electrocorticography (ECoG) signals measured directly from subdural electrode arrays that were implanted in patients undergoing intracranial monitoring for localization of epileptic foci. Subjects (n = 8) performed a spatial-cuing task, in which they allocated visuospatial attention to either the right or left visual field and detected the appearance of a target. We found increases in high gamma (HG) power (70-250 Hz) time-locked to trial onset that remained elevated throughout the attentional allocation period over frontal, parietal, and visual areas. These HG power increases were modulated by the phase of the ongoing delta/theta (2-5 Hz) oscillation during attentional allocation. Critically, we found that the strength of this delta/theta phase-HG amplitude coupling predicted reaction times to detected targets on a trial-by-trial basis. These results highlight the role of delta/theta phase-HG amplitude coupling as a mechanism for sub-second facilitation and coordination within human fronto-parietal cortex that is guided by momentary attentional demands.

Relationships between electroencephalographic (EEG) slow- and fast-wave frequency bands are considered to be of interest in the study of dispositional affective traits, emotion regulation, and attentional phenomena. However, to date, no previous studies had explored whether both state performance-based and self-reported attentional control (AC) measures potentially relate to different patterns of spontaneous EEG measures, in the absence of emotional stimuli. In the present study, individual differences in spontaneous EEG theta/beta ratio and delta–beta coupling at frontal and parietal sites were explored in a sample of 110 healthy volunteers as potential correlates of individual differences in performance-based attentional network functioning, as measured through the Attentional Network Test for Interactions (ANT-I) and self-reported AC. We found that stronger delta–beta coupling at parietal sites was associated with higher self-reported AC. However, no significant associations were found between executive control network functioning and the EEG ratio or coupling measures. Furthermore, a lower spontaneous fronto-parietal theta/beta ratio was found to be associated with better orienting network functioning. These results are discussed with a focus on the potential utility of spontaneous EEG measures in several cortical regions for capturing trait-like individual differences in temperament-related factors.

Several electrical neural oscillatory abnormalities have been associated with schizophrenia, although the underlying mechanisms of these oscillatory problems are unclear. Animal studies suggest that one of the key mechanisms of neural oscillations is through glutamatergic regulation; therefore, neural oscillations may provide a valuable animal–clinical interface on studying glutamatergic dysfunction in schizophrenia. To identify glutamatergic control of neural oscillation relevant to human subjects, we studied the effects of ketamine, an N -methyl- D -aspartate antagonist that can mimic some clinical aspects of schizophrenia, on auditory-evoked neural oscillations using a paired-click paradigm. This was a double-blind, placebo-controlled, crossover study of ketamine vs saline infusion on 10 healthy subjects. Clinically, infusion of ketamine in subanesthetic dose significantly increased thought disorder, withdrawal–retardation, and dissociative symptoms. Ketamine significantly augmented high-frequency oscillations (gamma band at 40–85 Hz, p =0.006) and reduced low-frequency oscillations (delta band at 1–5 Hz, p <0.001) compared with placebo. Importantly, the combined effect of increased gamma and reduced delta frequency oscillations was significantly associated with more withdrawal–retardation symptoms experienced during ketamine administration ( p =0.02). Ketamine also reduced gating of the theta-alpha (5–12 Hz) range oscillation, an effect that mimics previously described deficits in schizophrenia patients and their first-degree relatives. In conclusion, acute ketamine appeared to mimic some aspects of neural oscillatory deficits in schizophrenia, and showed an opposite effect on scalp-recorded gamma vs low-frequency oscillations. These electrical oscillatory indexes of subanesthetic ketamine can be potentially used to cross-examine glutamatergic pharmacological effects in translational animal and human studies.

The aim of this study was to look for differences in the power spectra and in EEG connectivity measures between patients in the vegetative state (VS/UWS) and patients in the minimally conscious state (MCS). The EEG of 31 patients was recorded and analyzed. Power spectra were obtained using modern multitaper methods. Three connectivity measures (coherence, the imaginary part of coherency and the phase lag index) were computed. Of the 31 patients, 21 were diagnosed as MCS and 10 as VS/UWS using the Coma Recovery Scale-Revised (CRS-R). EEG power spectra revealed differences between the two conditions. The VS/UWS patients showed increased delta power but decreased alpha power compared with the MCS patients. Connectivity measures were correlated with the CRS-R diagnosis; patients in the VS/UWS had significantly lower connectivity than MCS patients in the theta and alpha bands. Standard EEG recorded in clinical conditions could be used as a tool to help the clinician in the diagnosis of disorders of consciousness.

Rationale Adolescents and young adults with alcohol problems may also have sleep difficulties. However, whether these sleep problems are a result of a history of drinking or arise due to other comorbid disorders is difficult to disentangle in human studies. Additionally, the mechanisms underlying adolescent alcohol-induced sleep disturbances and potential targets for therapy also remain under-investigated. Recent clinical trials have demonstrated that the anticonvulsant and analgesic drug gabapentin may have therapeutic value in normalizing sleep quality in adult recovering alcoholics, yet its potential for the treatment of adolescent sleep disturbances has not been investigated. Objectives This study sought to evaluate the effects of a history of 5 weeks of chronic intermittent ethanol vapor exposure, administered during adolescence (AIE), on EEG sleep, in young adult rats ( n  = 29). The ability of two doses of gabapentin (30, 120 mg/kg) to modify sleep and slow wave activity were also investigated in these young adult rats exposed to alcohol vapor during adolescence. Results Adolescent vapor exposure in the rat was found to result in deficits in delta (1–4 Hz) and theta (4–8 Hz) power during slow wave sleep. Administration of gabapentin caused a “normalization” of the delta power deficits but did not affect theta power. Conclusions This report suggests that the potential mechanisms and therapeutic targets for sleep disturbance associated with adolescent alcohol exposure can be studied in preclinical models and that gabapentin may show partial efficacy in ameliorating these sleep deficits.

Background Atogepant is a novel oral calcitonin gene-related peptide (CGRP) receptor antagonist approved for the preventive treatment of migraine. While its peripheral mechanisms are well characterized, little is known about its potential effects on central functional brain networks. This study aims to investigate changes in resting-state functional connectivity (FC) using high-density EEG (HD-EEG) after one month of atogepant treatment in patients with migraine, and to assess the relationship between these changes and clinical response. Methods Twelve patients with high-frequency episodic migraine (HFEM; n  = 7) or chronic migraine (CM; n  = 5) underwent HD-EEG recordings at two time points: before starting Atogepant administration (T0) and after one month of treatment (T1). Fifteen healthy controls (HC) were also enrolled. Clinical evaluations included: monthly migraine days (MMD), monthly symptomatic drugs intake (MSI), modified Migraine Disability Assessment (mMIDAS), the headache impact test (HIT-6), the Migraine-Specific Quality of Life Questionnaire (MSQ), the 12-item Allodynia Symptom Checklist (ASC-12), and the Migraine Interictal Burden Scale (MIBS-4). EEG-based FC was analyzed in source space using the weighted Phase Lag Index (wPLI) across δ, θ, α, β, low-γ, and high-γ bands. To identify changes related to treatment, we applied Network-Based Statistics (NBS), while Spearman correlation was used to explore the relationship between clinical improvements and functional changes. Results Compared to HCs, HFEM + CM patients exhibited increased δ band functional connectivity (FC) in temporo-parietal, orbitofrontal, insular, and limbic regions. After one month of atogepant treatment, a significant reduction in this aberrant FC was observed, particularly in bilateral temporo-parietal, cingulate, insular, and prefrontal cortices. Baseline δ-band FC correlated with greater clinical disability (mMIDAS, MSQ), while treatment-induced FC changes (ΔmNC) were associated with improvements in mMIDAS, HIT-6, and ASC-12 scores, highlighting the clinical relevance of δ band network modulation. Conclusions This pilot study provides preliminary evidence that atogepant modulates δ band functional brain connectivity after one month of treatment in patients with episodic and chronic migraine. These changes in central brain networks are associated with clinical improvement and may serve as a neurophysiological marker of CGRP receptor antagonist efficacy. Larger-scale studies are needed to confirm and extend these findings.