Decrease In Theta Power Research Articles

The brain under pressure: Exploring neurophysiological responses to cognitive stress

Stress is an increasingly dominating part of our daily lives and higher performance requirements at work or to ourselves influence the physiological reaction of our body. Elevated stress levels can be reliably identified through electroencephalogram (EEG) and heart rate (HR) measurements. In this study, we examined how an arithmetic stress-inducing task impacted EEG and HR, establishing meaningful correlations between behavioral data and physiological recordings. Thirty-one healthy participants (15 females, 16 males, aged 20 to 37) willingly participated. Under time pressure, participants completed arithmetic calculations and filled out stress questionnaires before and after the task. Linear mixed effects (LME) allowed us to generate topographical association maps showing significant relations between EEG features (delta, theta, alpha, beta, and gamma power) and factors such as task difficulty, error rate, response time, stress scores, and HR. With task difficulty, we observed left centroparietal and parieto-occipital theta power decreases, and alpha power increases. Furthermore, frontal alpha, delta and theta activity increased with error rate and relative response time, while parieto-temporo-occipital alpha power decreased. Practice effects on EEG power included increases in temporal, parietal, and parieto-occipital theta and alpha activity. HR was positively associated with frontal delta, theta and alpha power whereas frontal gamma power decreases. Significant alpha laterality scores were observed for all factors except task difficulty and relative response time, showing overall increases in left parietal regions. Significant frontal alpha asymmetries emerged with increases in error rate, sex, run number, and HR and occipital alpha asymmetries were also found with run number and HR. Additionally we explored practice effects and noted sex-related differences in EEG features, HR, and questionnaire scores. Overall, our study enhances the understanding of EEG/ECG-based mental stress detection, crucial for early interventions, personalized treatment and objective stress assessment towards the development of a neuroadaptive system.

Darts fast-learning reduces theta power but is not affected by Hf-tRNS: A behavioral and electrophysiological investigation

Sports trainers have recently shown increasing interest in innovative methods, including transcranial electric stimulation, to enhance motor performance and boost the acquisition of new skills during training. However, studies on the effectiveness of these tools on fast visuomotor learning and brain activity are still limited. In this randomized single-blind, sham-controlled, between-subjects study, we investigated whether a single training session, either coupled or not with 2 mA online high-frequency transcranial random noise stimulation (hf-tRNS) over the bilateral primary motor cortex (M1), would affect dart-throwing performance (i.e., radial error, arm range of motion, and movement variability) in 37 healthy volunteers. In addition, potential neurophysiological correlates were monitored before and after the training through a 32-electrode portable electroencephalogram (EEG). Results revealed that a single training session improved radial error and arm range of motion during the dart-throwing task, but not movement variability. Furthermore, after the training, resting state-EEG data showed a decrease in theta power. Radial error, arm movement, and EEG were not further modulated by hf-tRNS. This indicates that a single training session, regardless of hf-tRNS administration, improves dart-throwing precision and movement accuracy. However, it does not improve movement variability, which might require multiple training sessions (expertise resulting in slow learning). Theta power decrease could describe a more efficient use of cognitive resources (i.e., attention and visuomotor skills) due to the fast dart-throwing learning. Further research could explore different sports by applying longer stimulation protocols and evaluating other EEG variables to enhance our understanding of the lasting impacts of multi-session hf-tRNS on the sensorimotor cortex within the framework of slow learning and training assistance.

Cholinergic and behavior-dependent beta and gamma waves are coupled between olfactory bulb and hippocampus.

Olfactory oscillations may enhance cognitive processing through coupling with beta (β, 15-30 Hz) and gamma (γ, 30-160 Hz) activity in the hippocampus (HPC). We hypothesize that coupling between olfactory bulb (OB) and HPC oscillations is increased by cholinergic activation in control rats and is reduced in kainic-acid-treated epileptic rats, a model of temporal lobe epilepsy. OB γ2 (63-100 Hz) power was higher during walking and immobility-awake (IMM) compared to sleep, while γ1 (30-57 Hz) power was higher during grooming than other behavioral states. Muscarinic cholinergic agonist pilocarpine (25 mg/kg ip) with peripheral muscarinic blockade increased OB power and OB-HPC coherence at β and γ1 frequency bands. A similar effect was found after physostigmine (0.5 mg/kg ip) but not scopolamine (10 mg/kg ip). Pilocarpine increased bicoherence and cross-frequency coherence (CFC) between OB slow waves (SW, 1-5 Hz) and hippocampal β, γ1 and γ2 waves, with stronger coherence at CA1 alveus and CA3c than CA1 stratum radiatum. Bicoherence further revealed a nonlinear interaction of β waves in OB with β waves at the CA1-alveus. Beta and γ1 waves in OB or HPC were segregated at one phase of the OB-SW, opposite to the phase of γ2 and γ3 (100-160 Hz) waves, suggesting independent temporal processing of β/γ1 versus γ2/γ3 waves. At CA1 radiatum, kainic-acid-treated epileptic rats compared to control rats showed decreased theta power, theta-β and theta-γ2 CFC during baseline walking, decreased CFC of HPC SW with γ2 and γ3 waves during baseline IMM, and decreased coupling of OB SW with β and γ2 waves at CA1 alveus after pilocarpine. It is concluded that β and γ waves in the OB and HPC are modulated by a slow respiratory rhythm, in a cholinergic and behavior-dependent manner, and OB-HPC functional connectivity at β and γ frequencies may enhance cognitive functions.

5-MeO-DMT induces sleep-like LFP spectral signatures in the hippocampus and prefrontal cortex of awake rats

5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a potent classical psychedelic known to induce changes in locomotion, behaviour, and sleep in rodents. However, there is limited knowledge regarding its acute neurophysiological effects. Local field potentials (LFPs) are commonly used as a proxy for neural activity, but previous studies investigating psychedelics have been hindered by confounding effects of behavioural changes and anaesthesia, which alter these signals. To address this gap, we investigated acute LFP changes in the hippocampus (HP) and medial prefrontal cortex (mPFC) of freely behaving rats, following 5-MeO-DMT administration. 5-MeO-DMT led to an increase of delta power and a decrease of theta power in the HP LFPs, which could not be accounted for by changes in locomotion. Furthermore, we observed a dose-dependent reduction in slow (20–50 Hz) and mid (50–100 Hz) gamma power, as well as in theta phase modulation, even after controlling for the effects of speed and theta power. State map analysis of the spectral profile of waking behaviour induced by 5-MeO-DMT revealed similarities to electrophysiological states observed during slow-wave sleep (SWS) and rapid-eye-movement (REM) sleep. Our findings suggest that the psychoactive effects of classical psychedelics are associated with the integration of waking behaviours with sleep-like spectral patterns in LFPs.

Compensatory brain activity pattern is not present in older adults during the n-back task performance-Findings based on EEG frequency analysis.

Cognitive ability is one of the most important enablers for successful aging. At the same time, cognitive decline is a well-documented phenomenon accompanying the aging process. Nevertheless, it is acknowledged that aging can also be related to positive processes that allow one to compensate for the decline. These processes include the compensatory brain activity of older adults primarily investigated using fMRI and PET. To strengthen the cognitive interpretation of compensatory brain activity in older adults, we searched for its indicators in brain activity measured by EEG. The study sample comprised 110 volunteers, including 50 older adults (60-75 years old) and 60 young adults (20-35 years old) who performed 1-back, 2-back, and 3-back tasks while recording the EEG signal. The study analyzed (1) the level of cognitive performance, including sensitivity index, the percentage of correct answers to the target, and the percentage of false alarm errors; (2) theta and alpha power for electrodes located in the frontal-midline (Fz, AF3, AF4, F3, F4, FC1, and FC2) and the centro-parietal (CP1, CP2, P3, P4, and Pz) areas. Cognitive performance was worse in older adults than in young adults, which manifested in a significantly lower sensitivity index and a significantly higher false alarm error rate at all levels of the n-back task difficulty. Simultaneously, performance worsened with increasing task difficulty regardless of age. Significantly lower theta power in the older participants was observed at all difficulty levels, even at the lowest one, where compensatory activity was expected. At the same time, at this difficulty level, cognitive performance was worse in older adults than in young adults, which could reduce the chances of observing compensatory brain activity. The significant decrease in theta power observed in both age groups with rising task difficulty can reflect a declining capacity for efficient cognitive functioning under increasing demands rather than adapting to this increase. Moreover, in young adults, alpha power decreased to some extent with increasing cognitive demand, reflecting adaptation to them, while in older adults, no analogous pattern was observed. In conclusion, based on the results of the current study, the presence of compensatory activity in older adults cannot be inferred.

Association Between EEG Power During Sleep and Attention Levels in Patients with Major Depressive Disorder.

Major depressive disorder (MDD) is associated with cognitive impairment through unclear mechanisms. We examined the relationship between sleep electroencephalogram (EEG) power and attention level in MDD. Forty-seven untreated patients with MDD and forty-seven age- and sex-matched controls were included. We examined relative EEG power during non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep by fast Fourier transform. The Attention Network Test (ANT) was performed to evaluate attention levels. Compared to controls, patients with MDD had lower theta power during NREM (P = 0.018) and REM (P = 0.002) sleep, while higher beta power (P = 0.050) during NREM sleep and delta power (P = 0.018) during REM sleep. Regarding attention level, patients with MDD had lower levels of accuracy (P = 0.021), longer mean reaction time (P < 0.001), poorer manifestations of the alerting effect (P = 0.038) and worse executive control (P = 0.048). Moreover, decreased theta power during NREM sleep was correlated with worsened accuracy (β = 0.329, P = 0.040), decreased theta power during REM sleep was correlated with worsened alerting effect (β = 0.355, P = 0.020), and increased delta power during REM sleep was correlated with longer mean reaction time (β = 0.325, P = 0.022) in patients with MDD. No association between ANT performance and other frequency bands was observed in patients with MDD. Our findings suggest that patients with MDD manifest impaired selective attention function that is associated with decreased theta power during NREM/REM sleep and increased delta power during REM sleep.

Exploring EEG resting state as a function of boredom proneness in pre-adolescents and adolescents.

Boredom is a prominent experience commonly reported in school settings and associated with poor academic achievement. Little is known, however, about the age-related trajectory of boredom. Here we examined self-reported ratings of boredom in a cross-sectional sample of 8 to 15-year olds (n = 185) as a function of resting state EEG. Results indicated that reports of boredom in school rose as a function of age. Resting state EEG showed a decrease in theta power with age perhaps reflective of increased control. While no effects were evident in beta and alpha bands, we did observe an interaction between boredom and age for frontal asymmetry such that for those higher in boredom, the asymmetry increased with age. Finally, for theta to beta ratios there were main effects of age (i.e., a decrease in theta/beta ratio with age) and boredom such that those higher in boredom had higher theta/beta ratios over frontal and central brain areas. The results are discussed in the context of prior work on school-related boredom and provide several important avenues for further research.

Comprehensive rehabilitation of preschool children with attention deficit hyperactivity disorder

Introduction. High incidence and great social significance of attention deficit hyperactivity disorder (ADHD) in preschool children determines the search and development of new options for their rehabilitation.Aim. To analyse the patient outcomes of the most up-to-date treatment and rehabilitation complex (biofeedback, sensory integration, psychological and speech, physiotherapeutic effects) and the possibility of its widespread practical application for the rehabilitation of preschool children with ADHD.Materials and methods. A total of 63 children (33 boys and 30 girls) aged 5–8 years were included in the prospective study. Patients were divided into two groups: Group I – 34 children aged 5 years – 5 years 11 months, 29 days with ADHD, and Group II – 29 children aged 6 years – 6 years 11 months, 29 days with ADHD. The follow-up period for each patient was 15 months. The children were examined by a neurologist, rehabilitation therapist, neuropsychologist, and speech pathologist with an assessment of active attention measures using the B. Bourdon scale for children of Group I and the Toulouse-Pieron scale (adapted by L.A. Yasyukova) for children of Group 2. Parents were surveyed and questioned using special questionnaires. Results. Before initiation of treatment, all children were diagnosed with active attention disorders of isolated (26.5 and 23.8%) and mixed (73.5 and 62.5%) nature in Groups I and II, respectively. After the rehabilitation activities complex was provided, a significant decrease in not only isolated, but also mixed attention disorders in children with ADHD was detected in both groups. Evaluation of electroencephalograms after the rehabilitation activities complex showed a decrease of theta power and an increase of low beta frequency power in 18.7% of children of Group I and in 16.2% of children of Group II, which indicated an improvement in neurodynamic functions and sufficient cognitive potential in that cohort of children.Conclusion. Early start and prolonged use of the proposed rehabilitation complex will enhance learning ability and prevent school and social maladjustment of children with ADHD.

Frequency-specific modulation of oscillatory activity in the rat auditory cortex by vagus nerve stimulation

BackgroundWe previously found that vagus nerve stimulation (VNS) strengthened stimulus-evoked activity in the superficial layer of the sensory cortex but not in the deep layer, suggesting that VNS altered the balance between the feedforward (FF) and feedback (FB) pathways. Band-specific oscillatory activities in the cortex could serve as an index of the FF-FB balance, but whether VNS affects cortical oscillations along sensory pathways through neuromodulators remains unclear. HypothesisVNS modulates the FF-FB balance through the cholinergic and noradrenergic systems, which modulate stimulus gain in the cortex. MethodsWe investigated the effects of VNS using electrocorticography in the auditory cortex of 34 Wistar rats under general anesthesia while presenting click stimuli. In the time-frequency analyses, the putative modulation of the FF and FB pathways was estimated using high- and low-frequency power. We assessed, using analysis of variance, how VNS modulates auditory-evoked activities and how the modulation changes with cholinergic and noradrenergic antagonists. ResultsVNS increased auditory cortical evoked potentials, consistent with results of our previous work. Furthermore, VNS increased auditory-evoked gamma and beta powers and decreased theta power. Local administration of cholinergic antagonists in the auditory cortex selectively disrupted the VNS-induced increase in gamma and beta power, while noradrenergic antagonists disrupted the decrease in theta power. ConclusionsVNS might strengthen the FF pathway through the cholinergic system and attenuate the FB pathway through the noradrenergic system in the auditory cortex. Cortical gain modulation through the VNS-induced neuromodulatory system provides new mechanistic insights into the effect of VNS on auditory processing.

The effect of choice on memory: The role of theta oscillations.

People value the opportunity to exercise control over the environment or make their own choices. Recent studies have revealed that simply having the opportunity to make choices can facilitate memory performance, suggesting an interaction between reward (due to choice making) and memory systems. However, little is known about the electrophysiological basis of choice-related memory. In the current study, we used scalp electroencephalography combined with a choice encoding task to examine the role of theta oscillations (which have been widely connected to reward and memory processing) in choice-related memory formation. The encoding task had two conditions. In the choice condition, participants were asked to choose between two occluded memoranda by themselves, whereas in the fixed condition, the decision was made by the computer. Behavioral results showed the choice effect, with better performance in the choice condition than the fixed condition on the recognition test given after a 24-h delay. Increases in theta power during an early latency of encoding period predicted successful memory formation in the choice condition, but not in the fixed condition. Furthermore, decreases in theta power during a late latency predicted successful memory formation in both the fixed and the choice conditions. Finally, we observed increased theta power in the choice condition compared to the fixed condition during an early latency of encoding period and decreased theta power in the choice condition compared to the fixed condition during a late latency. Our results suggest that theta oscillations play a significant role in choice-related memory formation.

Impact of preoperative cognitive impairment on changes in electrical activity of the brain in patients undergoing combined carotid endarterectomy and coronary artery bypass grafting

HighlightsThe presence of preoperative mild cognitive impairment (MCI) in patients undergoing combined carotid endarterectomy and coronary artery bypass grafting is associated with an increased theta activity at the frontal and parieto-occipital regions of both hemispheres after surgery. AbstractAim. To study the impact of preoperative cognitive impairment on changes in electrical activity of the brain in patients undergoing combined carotid endarterectomy and coronary artery bypass grafting.Methods. Sixty-three patients undergoing combined carotid endarterectomy (CAE) and coronary artery bypass grafting (CABG) were included in the study. The patients were divided into three groups, depending on the preoperative cognitive functions: without cognitive impairment (n = 17), with MCI (n = 29), and with severe cognitive impairment (n = 17). High-resolution electroencephalography (EEG) (62 channels, bandpass filtered between 0.1–50.0 Hz, sampling rate of 1000 Hz) was performed 3–5 days before and 7–10 days after surgery.Results. Patients with severe cognitive impairment at baseline presented with higher theta activity at the frontal region of the left hemisphere compared to patients without cognitive impairment and patients with MCI (p = 0.048). At the same time, patients with MCI showed the most pronounced theta activity increase after surgery compared to preoperative levels at the frontal and parieto-occipital cortical regions of both the left and right hemispheres (p≤0.05). Postoperative changes of theta activity in patients with severe cognitive impairment were minimal and statistically insignificant.Conclusion. Patients without severe preoperative cognitive impairment presented with higher grade brain dysfunction in the form of increased theta activity at the frontal and parieto-occipital regions after combined CAE and CABG. A smaller decrease in theta power after surgery in patients with severe preoperative cognitive impairment, on the one hand, can indicate compensation after cerebral ischemia and resistance to hypoperfusion during on-pump cardiac surgery, and on the other, can be a manifestation of the ceiling effect and insufficiency of brain functional reserves.

Quantitative Electroencephalographic Analysis in Women with Migraine during the Luteal Phase

Migraine is a common, headache disorder characterized by recurrent episodes of headache often associated with nausea, vomiting, photophobia, and phonophobia. Prior to puberty, boys and girls are equally affected. Female preponderance emerges after puberty. Migraine pathophysiology is not fully understood, and although the hormonal effect of estrogen is significant, it is not clear how hormonal phases affect brain excitability and EEG patterns in women with migraine. The objective of this research was to study the effect of migraine on the resting-state EEG activity of women during the luteal phase. This work compares electroencephalographic (EEG) absolute power in different frequency bands and scalp areas between young women who suffer from migraine and had a migraine attack within 24 h prior to EEG recording (experimental) and ten age-matched young healthy women (controls), all with normal menstrual cycles. For women with migraine, we found a significant decrease/increase in alpha power in the occipitoparietal/frontocentral area, significant decrease in beta power for all areas, significant decrease in delta power in the temporal area, and significant decrease in theta power in the frontocentral and occipitoparietal area. We concluded that women with migraine have a distinct electroencephalographic pattern during the luteal phase in comparison with control women. A possible explanation might be an intermittent rhythmic activity linked to pain.

Nx4 ameliorated peripheral and central stress-induced changes at resting state - A post hoc analysis of a randomized controlled trial

Psychosocial stress provokes restlessness and perpetuates anxiety states, which may subsequently lead to major psychiatric disorders. Momentary adaptive responses to psychosocial stress can be reflected by electrophysiological (electroencephalogram: EEG) and physiological (heart rate variability: HRV) signals. A recent double-blind, placebo-controlled, crossover trial (NEURIM, NCT02602275) investigated the stress-reducing effects of Neurexan (Nx4) on neurophysiological and physiological changes in response to acute psychosocial stressors. This post hoc analysis aims to explore the stress-reducing effect of Nx4 on peripheral physiological (HRV) and central electrophysiological (EEG) levels at resting state. Thirty-nine healthy male participants received a single dose of Nx4 before exposure to a psychosocial stress paradigm. EEG and photoplethysmogram (PPG) data were acquired before and after psychosocial stress exposure induced by the ScanSTRESS task. Stress responsivity under placebo and Nx4 were assessed by HRV parameters and EEG frequency power. Psychosocial stress induction led to changes (i) in various parameters of heart rate variability, including increased LF/HF ratio, increased Baevsky’s Stress Index, and reduced RMSSD. As well as (ii) to changes in EEG frequency power with increased alpha and decreased theta power, both indicating successful stress induction. Nx4 reduced the stress-induced changes on both peripheral physiological and central electrophysiological levels. In the current study, we showed that the Nx4 reduced the acute peripheral physiological and central electrophysiological stress responses to psychosocial challenges. We suggest Nx4 may be a significant means to buffer the bodily responses of daily life stress exposure.

Aberrant neural correlates of multisensory processing of audiovisual social cues related to social anxiety: An electrophysiological study.

Social anxiety disorder (SAD) is characterized by abnormal fear to social cues. Although unisensory processing to social stimuli associated with social anxiety (SA) has been well described, how multisensory processing relates to SA is still open to clarification. Using electroencephalography (EEG) measurement, we investigated the neural correlates of multisensory processing and related temporal dynamics in social anxiety disorder (SAD). Twenty-five SAD participants and 23 healthy control (HC) participants were presented with angry and neutral faces, voices and their combinations with congruent emotions and they completed an emotional categorization task. We found that face-voice combinations facilitated auditory processing in multiple stages indicated by the acceleration of auditory N1 latency, attenuation of auditory N1 and P250 amplitudes, and decrease of theta power. In addition, bimodal inputs elicited cross-modal integrative activity which is indicated by the enhancement of visual P1, N170, and P3/LPP amplitudes and superadditive response of P1 and P3/LPP. More importantly, excessively greater integrative activity (at P3/LPP amplitude) was found in SAD participants, and this abnormal integrative activity in both early and late temporal stages was related to the larger interpretation bias of miscategorizing neutral face-voice combinations as angry. The study revealed that neural correlates of multisensory processing was aberrant in SAD and it was related to the interpretation bias to multimodal social cues in multiple processing stages. Our findings suggest that deficit in multisensory processing might be an important factor in the psychopathology of SA.

Inhibitory and excitatory responses in the dorso-medial prefrontal cortex during threat processing.

To evaluate cortical excitability during instructed threat processing. Single and paired transcranial magnetic stimulation (TMS) pulses were applied to the right dorsomedial prefrontal cortex (dmPFC) during high-density electroencephalography (EEG) recording in young healthy participants (n = 17) performing an instructed threat paradigm in which one of two conditioned stimuli (CS+ but not CS-) was paired with an electric shock (unconditioned stimulus [US]). We assessed TMS-induced EEG responses with spectral power (both at electrode and source level) and information flow (effective connectivity) using Time-resolved Partial Directed Coherence (TPDC). Support vector regression (SVR) was used to predict behavioral fear ratings for CS+ based on TMS impact on excitability. During intracortical facilitation (ICF), frontal lobe theta power was enhanced for CS+ compared to single pulse TMS for the time window 0-0.5 s after TMS pulse onset (t(16) = 3.9, p < 0.05). At source level, ICF led to an increase and short intracortical inhibition (SICI) to a decrease of theta power in the bilateral dmPFC, relative to single pulse TMS during 0-0.5 s. Compared to single pulse TMS, ICF increased information flows, whereas SICI reduced the information flows in theta band between dmPFC, amygdala, and hippocampus (all at p < 0.05). The magnitude of information flows between dmPFC to amygdala and dmPFC to hippocampus during ICF (0-0.5 s), predicted individual behavioral fear ratings (CS+; coefficient above 0.75). Distinct excitatory and inhibitory mechanisms take place in the dmPFC. These findings may facilitate future research attempting to investigate inhibitory/facilitatory mechanisms alterations in psychiatric disorders and their behavioral correlates.

Muscarinic and N-methyl-D-aspartate receptor blockade reveal differences in hippocampal local field potentials in mice with low cholinergic tone.

We hypothesize that hippocampal local field potentials in acetylcholine (ACh)-deficient mutant mice, compared to wild-type (WT) mice, will show lower sensitivity to muscarinic cholinergic antagonist scopolamine (5mg/kg i.p.) but higher sensitivity to NMDA receptor antagonist 3-(2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP, 10mg/kg i.p.). Recordings were made during walk and awake-immobility (IMM) in WT mice, and in mice with forebrain knockout (KO) of the vesicular acetylcholine transporter (VAChT) gene, or heterozygous knockdown of VAChT gene (KD). Scopolamine or CPP did not significantly alter walk theta frequency, which was higher in KD than WT/KO mice. Scopolamine decreased theta power peak rise during walk in WT/KD mice but not in KO mice, while CPP suppressed theta peak rise more in WT/KO mice than KD mice. During IMM, scopolamine decreased gamma1 (γ1, 30-58 Hz) power more in KD/WT mice than KO mice, while delta (1-4Hz) power and delta-gamma cross-frequency coherence (CFC) were increased in all mouse groups during IMM or walk. During walk, scopolamine increased delta and beta (13-30 Hz) power and decreased gamma2 (γ2, 62-100 Hz) power and theta-γ2 CFC more in WT/KD than KO mice. Theta-γ2, but not theta-γ1, CFC increased with theta-peak-frequency in WT/KD mice, and was suppressed by scopolamine at high theta (8-10Hz) frequency; theta-γ2 CFC in KO mice was not significantly altered by scopolamine. CPP decreased beta and gamma power more in KD/KO mice compared to WT mice, while delta power and delta-gamma CFC were increased in all mouse groups. ACh deficiency exacerbates the attenuation of beta and gamma power by CPP. We conclude that both muscarinic and NMDA transmission contribute toward hippocampal theta, beta, and gamma power, and a decrease in gamma power or theta-gamma CFC may be associated with loss of arousal and cognitive functions.

Electroencephalography Theta/Beta Ratio Decreases in Patients with Severe Obstructive Sleep Apnea.

PurposeAccumulating evidence suggests that theta/beta ratio (TBR), an electroencephalographic (EEG) frequency band parameter, might serve as an objective marker of executive cognitive control in healthy adults. Obstructive sleep apnea (OSA) has a detrimental impact on patients’ behavior and cognitive performance while whether TBR is different in OSA population has not been reported. This study aimed to explore the difference in relative EEG spectral power and TBR during sleep between patients with severe OSA and non-OSA groups.Patients and Methods142 participants with in-laboratory nocturnal PSG recording were included, among which 100 participants suffered severe OSA (apnea hypopnea index, AHI > 30 events/hour; OSA group) and 42 participants had no OSA (AHI ≤ 5 events/h; control group). The fast Fourier transformation was used to compute the EEG power spectrum for total sleep duration within contiguous 30-second epochs of sleep. The demographic and polysomnographic characteristics, relative EEG spectral power and TBR of the two groups were compared.ResultsIt was found that the beta band power during NREM sleep and total sleep was significantly higher in the OSA group than controls (p < 0.001, p = 0.012, respectively), and the theta band power during NREM sleep and total sleep was significantly lower in the OSA group than controls (p = 0.019, p = 0.014, respectively). TBR during NREM sleep, REM sleep and total sleep was significantly lower in the OSA group compared to the control group (p < 0.001 for NREM sleep and total sleep, p = 0.015 for REM sleep). TBR was negatively correlated with AHI during NREM sleep (r=−0.324, p < 0.001) and total sleep (r=−0. 312, p < 0.001).ConclusionTBR was significantly decreased in severe OSA patients compared to the controls, which was attributed to both increased beta power and decreased theta power. TBR may be a stable EEG-biomarker of OSA patients, which may accurately and reliably identify phenotype of patients.

Enhanced Interplay of Neuronal Coherence and Coupling in the Dying Human Brain.

The neurophysiological footprint of brain activity after cardiac arrest and during near-death experience (NDE) is not well understood. Although a hypoactive state of brain activity has been assumed, experimental animal studies have shown increased activity after cardiac arrest, particularly in the gamma-band, resulting from hypercapnia prior to and cessation of cerebral blood flow after cardiac arrest. No study has yet investigated this matter in humans. Here, we present continuous electroencephalography (EEG) recording from a dying human brain, obtained from an 87-year-old patient undergoing cardiac arrest after traumatic subdural hematoma. An increase of absolute power in gamma activity in the narrow and broad bands and a decrease in theta power is seen after suppression of bilateral hemispheric responses. After cardiac arrest, delta, beta, alpha and gamma power were decreased but a higher percentage of relative gamma power was observed when compared to the interictal interval. Cross-frequency coupling revealed modulation of left-hemispheric gamma activity by alpha and theta rhythms across all windows, even after cessation of cerebral blood flow. The strongest coupling is observed for narrow- and broad-band gamma activity by the alpha waves during left-sided suppression and after cardiac arrest. Albeit the influence of neuronal injury and swelling, our data provide the first evidence from the dying human brain in a non-experimental, real-life acute care clinical setting and advocate that the human brain may possess the capability to generate coordinated activity during the near-death period.

Improved cognitive function in patients with major depressive disorder after treatment with vortioxetine: A EEG study.

IntroductionVortioxetine has a positive effect on cognitive function in patients with major depressive disorder (MDD). This study aimed to examine the changes in cognitive function and EEG (spectral power and mismatch negativity (MMN)) in patients with MDD pre‐ and postvortioxetine treatment.MethodsThirty patients with MDD were included in the study. They were given vortioxetine (10‐20mg po per day) for eight weeks. Depression and anxiety severities, social function (Korean version of the social adjustment scale (K‐SAS)), and cognitive function (digit‐symbol substitution Test (DSST), Korean version of the attentional control questionnaire (K‐ACQ), and Korean version of the perceived deficits questionnaire for depression (K‐PDQD)) were evaluated. Spectral power of EEG and MMN was also measured pre‐ and postvortioxetine treatment.ResultsDepression and anxiety severity, social function, and cognitive functioning significantly improved after vortioxetine treatment. Also, there was a significant decrease in the right central delta band and an increase in the right central beta 2 band following vortioxetine treatment. The changes in EEG spectral power were not related to changes in cognitive functions. Baseline MMN significantly predicted changes in DSST score after controlling for the baseline clinical variables.ConclusionVortioxetine treatment improved cognitive function and induced changes in EEG (decreased theta power and increased beta power) in patients with MDD. Our results suggest that greater negative MMN amplitude is associated with greater potential for cognitive improvement following vortioxetine treatment.

Decrease of event related theta power is more profound in patients with Parkinson's disease dementia in comparison to Alzheimer's disease dementia

AbstractBackgroundAlzheimer's disease dementia (ADD) and Parkinson's disease dementia (PDD) are the most common types of dementia. ADD and PDD have different pathophysiology and clinical profile. It is important to understand mechanisms underlying pathophysiology, clinical symptoms, and the electrophysiological differences between these two types of dementia. Event‐related theta responses during cognitive paradimgs are one of the essential biomarkers that could succfesully show cognitive decline in dementia patients (Yener et al.,2007;Güntekin et al.,2020). The aim of the present study was to investigate the Event‐related theta responses during the visual cognitive task in patients with PDD and ADD in order to find the differentiation between these two types of dementia.MethodEEG recordings of 15 patients with ADD, 15 patients with PDD, and matched 15 healthy elderly controls (HC) were performed during the visual oddball paradigm. Event‐related phase‐locking and power analysis were performed for theta frequency band (4‐7 Hz). Repeated measures of ANOVA was used for statistical analysis (p&lt;0.05).ResultThere were significant differences among groups for both event‐related theta phase‐locking (p=0.004) and theta power (p&lt;0.0001). ADD (p&lt;0.005) and PDD (p&lt;0.005) groups had reduced theta phase‐locking in comparison to the HC group (Figure 1). Especially, this reduction was more pronounced in the PDD group. In addition, the PDD group had decreased theta power as compared to the HC (p&lt;0.0001) and ADD (p&lt;0.005) group (Figure 1). Figure 1 shows the grand average of event‐related theta power (upper part) and phase‐locking (lower part) and in HC, ADD and PDD groups.ConclusionThe present study showed decreased event‐related theta responses during the visual oddball paradigm in patients with dementia. Especially, PDD patients had the worst event‐related theta responses. These findings could be interpreted as the visual cognitive processes are more impaired in PDD patients compared to ADD patients.