Increased Delta Activity Research Articles

Restoration of sleep-wake behavior following short photoperiod exposure in ventral subicular lesioned male Wistar rats: A 24-h sleep-wake electroencephalographical study.

The ventral subiculum regulates emotion, stress responses, and spatial and social cognition. In our previous studies, we have demonstrated anxiety- and depression-like symptoms, deficits in spatial and social cognition in ventral subicular lesioned (VSL) rats, and restoration of affective and cognitive behaviors following photoperiod manipulation (short photoperiod regime, SPR; 6:18 LD cycle). In the present study, we have studied the impact of VSL on sleep-wake behavioral patterns and the effect of SPR on sleep-wakefulness behavior. Adult male Wistar rats subjected to VSL demonstrated decreased wake duration and enhanced total sleep time due to increased non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). Power spectral analysis indicated increased delta activity during NREMS and decreased sigma band power during all vigilance states. Light is one of the strongest entrainers of the circadian rhythm, and its manipulation may have various physiological and functional consequences. We investigated the effect of 21-day exposure to SPR on sleep-wakefulness (S-W) behavior in VSL rats. We observed that SPR exposure restored S-W behavior in VSL rats, resulting in an increase in wake duration and a significant increase in theta power during wake and REMS. This study highlights the crucial role of the ventral subiculum in maintaining normal sleep-wakefulness patterns and highlights the effectiveness of photoperiod manipulation as a non-pharmacological treatment for reversing sleep disturbances reported in mood and neuropsychiatric disorders like Alzheimer's disease, bipolar disorder, and major depressive disorder, which also involve alterations in circadian rhythm.

Electrophysiology and hyperscanning applied to e-learning for organizational training

PurposeThe purpose of this study is to investigate the effects of the remote training process on distance learning with the application of neurometrics and investigate the features of the training that promote better synchronization between trainers and trainees in terms of cognitive and emotional processes favorable to learning, during a condition of remote professional training.Design/methodology/approachThe authors proposed a hyperscanning paradigm together with a conversational analysis to assess remote online training by collecting neurophysiological measures (frequency band analysis: delta, theta, alpha and beta) via multiple wearable electroencephalograms (EEGs) during a session of remote training.FindingsResults showed increased delta activity in the trainer when he was leading the session and when the participants were exchanging feedback. The delivery of feedback was also linked to increased theta activity compared with the normal activity of the trainees. Finally, synchronization of EEG between trainer and trainee groups was found for the beta band.Research limitations/implicationsThis study proposes to adopt a new multi-methodological approach that combines conversational analysis with the detection of remote neurometric parameters, in the field of educational neuroscience applied to organizational contexts.Practical implicationsFindings can help trainers in the development of their skills as trainers and in modeling remote training in organizations.Originality/valueFindings highlight the crucial role of particular phases of the e-learning process, such as the feedback phase and the interaction trainer group, and they pointed out the relevance of neurophysiological measures to test the e-learning process.

Common patterns of EEG reactivity in post-anoxic coma identified by quantitative analyses

ObjectiveDescription of typical kinds of EEG reactivity (EEG-R) in post-anoxic coma using a quantitative method. MethodsStudy of 101 out-of-hospital cardiac arrest patients, 71 with good outcome (cerebral performance category scale ≤ 2). EEG was recorded 12–24 hours after cardiac arrest and four noxious, one auditory, and one visual stimulation were applied for 30 seconds each. Individual reference intervals for the power in the delta, theta, alpha, and beta bands were calculated based on six 2-second resting epochs just prior to stimulations. EEG-R in consecutive 2-second epochs after stimulation was expressed in Z-scores. ResultsEEG-R occurred roughly equally frequent as an increase or as a decrease in EEG activity. Sternal rub and sound stimulation were most provocative with the most pronounced changes as an increase in delta activity 4.5–8.5 seconds after stimulation and a decrease in theta activity 0.5–4.5 seconds after stimulation. These parameters predicted good outcome with an AUC of 0.852 (95 % CI: 0.771–0.932). ConclusionsQuantitative EEG-R is a feasible method for identification of common types of reactivity, for evaluation of stimulation methods, and for prognostication. SignificanceThis method provides an objective measure of EEG-R revealing knowledge about the nature of EEG-R and its use as a diagnostic tool.

Different sensitivity to anesthesia according to ECoG data in dopamine transporter knockout and heterozygous rats

Dopamine in the brain is involved in many important functions, including the regulation of wakefulness. There is also some evidence suggesting that the dopamine function is crucial in anesthetic function. The state of anesthesia is characterized by a change in the level of consciousness and a change in brain electrical activity.Due to impaired mechanisms of dopamine transportation back to the synaptic terminal, dopamine transporter (DAT) knockout and heterozygous rats have increased levels of the extracellular dopamine. In our work, we registered ECoG disturbances in knockout and heterozygous rats, as well as disturbances in tone and activity in acute experiments under the anesthesia Zoletil (tiletamine and zolazepam) from the somatosensory cortex using a NeuroNexus flat multielectrode array to study gamma activity. We also used four low-resistance electrodes to control the slow rhythm.Both low-resistance and high-resistance electrodes showed differences in the ECoG spectrum of heterozygotes and total knockouts from the wild type and from each other. Heterozygous rats for the DAT gene (HET) showed increased rapid beta and gamma activity and decreased slow delta activity, while complete knockouts (KO), on the contrary, showed increased delta activity and decreased beta and gamma activity. Thus, the ECoG spectrum of HET is shifted to the right, while that of KO is shifted to the left. Full knockouts also showed decreased spatial synchronization in the 30–100 Hz gamma range compared to the wild type (WT).It is assumed that sedation of HET and KO is shifted towards opposite directions compared to WT under the same anesthesia conditions.

An Exploratory EEG Analysis on the Effects of Virtual Reality in People with Neuropathic Pain Following Spinal Cord Injury.

Neuropathic pain in people with spinal cord injury is thought to be due to altered central neuronal activity. A novel therapeutic intervention using virtual reality (VR) head-mounted devices was investigated in this study for pain relief. Given the potential links to neuronal activity, the aim of the current study was to determine whether use of VR was associated with corresponding changes in electroencephalography (EEG) patterns linked to the presence of neuropathic pain. Using a within-subject, randomised cross-over pilot trial, we compared EEG activity for three conditions: no task eyes open state, 2D screen task and 3D VR task. We found an increase in delta activity in frontal regions for 3D VR with a decrease in theta activity. There was also a consistent decrease in relative alpha band (8–12 Hz) and an increase in low gamma (30–45 Hz) power during 2D screen and 3D VR corresponding, with reduced self-reported pain. Using the nonlinear and non-oscillatory method of extracting fractal dimensions, we found increases in brain complexity during 2D screen and 3D VR. We successfully classified the 3D VR condition from 2D screen and eyes opened no task conditions with an overall accuracy of 80.3%. The findings in this study have implications for using VR applications as a therapeutic intervention for neuropathic pain in people with spinal cord injury.

Distinct Slow-Wave Activity Patterns in Resting-State Electroencephalography and Their Relation to Language Functioning in Low-Grade Glioma and Meningioma Patients.

IntroductionBrain tumours frequently cause language impairments and are also likely to co-occur with localised abnormal slow-wave brain activity. However, it is unclear whether this applies specifically to low-grade brain tumours. We investigate slow-wave activity in resting-state electroencephalography (EEG) in low-grade glioma and meningioma patients, and its relation to pre- and postoperative language functioning.MethodPatients with a glioma (N = 15) infiltrating the language-dominant hemisphere and patients with a meningioma (N = 10) with mass effect on this hemisphere underwent extensive language testing before and 1 year after surgery. EEG was registered preoperatively, postoperatively (glioma patients only), and once in healthy individuals. Slow-wave activity in delta- and theta- frequency bands was evaluated visually and quantitatively by spectral power at three levels over the scalp: the whole brain, the affected hemisphere, and the affected region.ResultsGlioma patients had increased delta activity (affected area) and increased theta activity (all levels) before and after surgery. In these patients, increased preoperative theta activity was related to the presence of language impairment, especially to poor word retrieval and grammatical performance. Preoperative slow-wave activity was also related to postoperative language outcomes. Meningioma patients showed no significant increase in EEG slow-wave activity compared to healthy individuals, but they presented with word retrieval, grammatical, and writing problems preoperatively, as well as with writing impairments postoperatively.DiscussionAlthough the brain-tumour pathology in low-grade gliomas and meningiomas has a different effect on resting-state brain activity, patients with low-grade gliomas and meningiomas both suffer from language impairments. Increased theta activity in glioma patients can be considered as a language-impairment marker, with prognostic value for language outcome after surgery.

Relationship between Cortical Thickness and EEG Alterations during Sleep in the Alzheimer's Disease.

Recent evidence showed that EEG activity alterations that occur during sleep are associated with structural, age-related, changes in healthy aging brains, and predict age-related decline in memory performance. Alzheimer’s disease (AD) patients show specific EEG alterations during sleep associated with cognitive decline, including reduced sleep spindles during NREM sleep and EEG slowing during REM sleep. We investigated the relationship between these EEG sleep alterations and brain structure changes in a study of 23 AD patients who underwent polysomnographic recording of their undisturbed sleep and 1.5T MRI scans. Cortical thickness measures were correlated with EEG power in the sigma band during NREM sleep and with delta- and beta-power during REM sleep. Thinning in the right precuneus correlated with all the EEG indexes considered in this study. Frontal–central NREM sigma power showed an inverse correlation with thinning of the left entorhinal cortex. Increased delta activity at the frontopolar and temporal regions was significantly associated with atrophy in some temporal, parietal, and frontal cortices, and with mean thickness of the right hemisphere. Our findings revealed an association between sleep EEG alterations and the changes to AD patients’ brain structures. Findings also highlight possible compensatory processes involving the sources of frontal–central sleep spindles.

Features of brain electrical activity in adult patients with POLG-related disorders

Introduction. Epilepsy is a common feature of mitochondrial disorders, including those associated with mutations in the POLG gene. Nevertheless, brain electrical activity features of POLG-related disorders in adult patients have not been adequately studied. Objective. To study the features and characteristics of the electroencephalography (EEG) pattern in adult patients with POLG-related disorders. Material and methods. Eight patients were examined: 7 with SANDO (Sensory Ataxic Neuropathy, Dysarthria, Ophthalmoparesis) syndrome, and 1 with MEMSA (Myoclonic Epilepsy Myopathy Sensory Ataxia) syndrome; median age was 32.5 years. All patients underwent routine EEG monitoring using a 19-channel electroencephalograph according to the generally accepted method. Results. Epileptic seizures were found in 3 patients, for 2 of them – as the first manifestation of the disease. In 6 patients, theta waves predominated in the occipital regions. Of those 6 patients, in 5 bilateral synchronous bursts of theta and delta wave groups were identified being more prominent in the frontocentral regions; 4 patients had transient non-lateralized delta activity in the occipital and parieto-occipital brain regions. In all patients, opening eyes led to the depression of rhythms and burst suppression. After photostimulation, in 2 cases bilateral synchronous bursts of delta and theta wave groups were recorded predominantly in frontal lobes. In 3 patients during hyperventilation an increase in delta activity in the occipital lobes and bilateral synchronous bursts of delta wave groups were observed. Epileptiform activity was recorded in 2 cases. Conclusion. In adult patients with POLG-related disorders, regardless of the clinical manifestation, typical EEG features include generalized background slowing, theta and delta bursts in occipital lobes with their suppression by opening eyes.

The Effect of Beat Frequency Vibration on Sleep Latency and Neural Complexity: A Pilot Study.

Insomnia affects millions of people worldwide, and non-pharmacological treatment options are limited. A bed excited with multiple vibration sources was used to explore beat frequency vibration (BFV) as a non-pharmacological treatment for insomnia. A repeated measures design pilot study of 14 participants with mild-moderate insomnia symptom severity (self-reported on the Insomnia Severity Index) was conducted to determine the effects of BFV, and traditional standing wave vibration (SWV) on sleep latency and sleep electrocortical activity. Participants were monitored using high-density electroencephalography (HD-EEG). Sleep latency was compared between treatment conditions. A trend of decreasing sleep latency due to BFV was found for unequivocal sleep latency (p ≤ 0.068). Neural complexity during wake, N1, and N2 stages were compared using Multi-Scale Sample Entropy (MSE), which demonstrated significantly lower MSE between wake and N2 stages (p ≤ 0.002). During N2 sleep, BFV showed lower MSE than the control session in the left frontoparietal region. As a measure of information integration, reduced entropy may indicate that BFV decreases conscious awareness during deeper stages of sleep. SWV caused reduced alpha activity and increased delta activity during wake. BFV caused increased delta activity during N2 sleep. These preliminary results suggest that BFV may help decrease sleep latency, reduce conscious awareness, and increase sleep drive expression during deeper stages of sleep. SWV may be beneficial for decreasing expression of arousal and increasing expression of sleep drive during wake, implying that beat frequency vibration may be beneficial to sleep.

Pediatric Multi-System Inflammatory Syndrome With Fatal Cerebral Edema in a Patient With COVID-19

INTRODUCTIONThere are increasing reports of a pediatric multi-system inflammatory syndrome associated with coronavirus disease 2019 (COVID-19) that presents with varying clinical features, but includes features of Kawasaki disease or toxic shock syndrome. Symptoms include fever, rash, abdominal pain, vomiting, and diarrhea. Many patients present without any respiratory symptoms and testing for SARS-CoV-2 is often negative.METHODSA retrospective chart review was performed.RESULTSA 7-year-old previously healthy male presented with 3 days of fevers up to 102.4F, headaches, abdominal pain, and intractable vomiting. Both parents had tested positive for SARS-CoV-2 four weeks prior. Nasopharyngeal swab tested positive for SARS-CoV-2 RNA. Echocardiogram was normal. CT venogram of his head was negative for any pathology. He developed severe neck pain and persistent headache during his hospitalization. Soon after receiving hydroxychloroquine, he developed a facial rash and altered mental status with episodes of aphasia, agitation, and pinpoint pupils. He then became unresponsive with left gaze deviation. A non-contrast head CT and CT angiography were negative. He was given levetiracetam and cefazolin and transferred to the pediatric intensive care unit. An electroencephalogram (EEG) showed no epileptiform activity. Over the following 7 hours, the EEG demonstrated left frontotemporal slowing, which progressed into a loss of fast activity over the right hemisphere with increased delta activity in the left hemisphere, then abruptly changed to generalized voltage attenuation.He rapidly lost brainstem reflexes, developing fixed and dilated pupils. Repeat CT scan revealed diffuse cerebral edema with loss of gray-white differentiation. Lab results then were consistent with severe inflammation. An intracranial pressure monitor revealed pressures greater than 76 mmHg. His exam soon became consistent with brain death. Pathologic evaluation showed diffuse cerebral edema with perivascular mononuclear infiltrates.CONCLUSIONThe cause of this pediatric multi-system inflammatory syndrome is unclear and the mechanism by which SARS-CoV-2 affects the nervous system is unknown. Pediatric patients with COVID-19 and neurologic symptoms should be closely monitored as they can rapidly decline due to fulminant cerebral edema.

Response inhibition alterations in migraine: evidence from event-related potentials and evoked oscillations

BackgroundMigraine is characterized by a hypersensitivity to environmental stimulation which climaxes during headache attacks but persists during attack-free period. Despite ongoing debates about the nature of the mechanisms giving rise to this abnormality, the presence of deficient inhibitory cortical processes has been proposed to be one possible mechanism underlying its pathogenesis. Empirical evidence supporting this claim is mainly based on previous accounts showing functional cortical disexcitability in the sensory domain. Considering that a general inhibitory control process can play an important role across early to later stage of information processing, this may indicate the important role other dimensions of inhibitory control can play in migraine disability. The present study examined the pathophysiological features of inhibitory control that takes place during suppression of prepotent responses in migraineurs.MethodsTwenty-two patients with migraine without aura (mean age = 30.86 ± 5.69 years; 19 females) during the interictal period and 25 healthy controls (mean age = 30.24 ± 3.52 years; 18 females) were recruited. We used a stop signal task in combination with event-related potentials (ERPs) to examine participants’ neural activity supporting response inhibition.ResultsBehaviorally, migraineurs exhibited prolonged stop signal reaction times relative to healthy controls. At the neural level, the amplitude of the stop-N2 over fronto-central, central and centro-parietal scalp regions, a component of the ERPs related to conflict monitoring during early, non-motoric stages of inhibition, was significantly increased in migraineurs. Meanwhile, the amplitude of the stop-P3 over central and centro-parietal scalp regions, a component of the ERPs reflecting late-stage inhibition of the motor system and cognitive evaluation of motor inhibition, was also significantly increased in migraineurs. Ultimately, our time-frequency analysis further revealed increased delta activity in migraineurs.ConclusionsConsistent with the theory that alterations in cognitive cortical processes are a key signature of migraine, our findings revealed an abnormal state of suppressing prepotent responses in migraineurs, which can be attributed to cortical disexcitability of the pre-frontal executive network and centro-parietal sensorimotor network. These novel findings extend to show the existence of dysfunctional inhibition control that occurs during suppression of prepotent responses in migraneurs.

Levetiracetam effect on behavioral and electrophysiological parameters in rat model of global brain ischemia

Post-stroke paroxysmal activity is a neurophysiological indicator of epileptogenesis and increase of seizure susceptibility, so treatments with neuroprotective activity and anti-paroxysmal activity can be more beneficial during post-ischemic period. The goal of this study was evaluation of levetiracetam (100 mg/kg, 7 days of administration) effect on behavior and brain bioelectric activity changes in the post-ischemic period. Global ischemia model was carried out with bilateral ligation of carotid arteries in rats. Neurological deficit and electrophysiological changes of brain structures (striatum, cortex, hypothalamus, hippocampus) were analyzed during 28 days. Paroxysmal activity was not observed on the 1st day after ischemia and had early (2nd day) and late (28th day) onsets. Spectral analysis showed that rats, that died by the 10th day, had delta wave increase and theta decrease on the 1st day and delta activity reduction on the 2-7th days. LEV did not affect survival rate, however, it contributed to neurological disorder regression towards lighter forms on the 1st day after ischemia. It suppressed paroxysmal activity with an early onset and affected delta and theta waves on the 1st day in all structures except hippocampus. On the 7th and 28th days LEV increased delta activity due to 1–3 Hz frequency. Thus, LEV eliminates early onset post-ischemic paroxysmal activity and contributes to normalization of delta waves activity on the 1st day after ischemia, that positively affects neurological status of animals in post-ischemic period. It allows one to make a conclusion about possible LEV application in the post-ischemic period.

Sex differences in brain oscillatory activity during sleep and wakefulness in obstructive sleep apnea.

Epidemiological studies consistently show a male predominance in obstructive sleep apnea (OSA). Hormonal differences, breathing control, upper airway anatomy and fat distribution have been proposed as causes of gender differences in OSA. Clinical manifestations are accentuated in men, although white matter structural integrity is affected in women.To the best of our knowledge, no previous studies have explored gender differences in the electrical brain activity features of OSA. Polysomnography was performed on43 patientswith untreated OSA (21 women, 22 men),and power spectral density (1-50Hz) was compared between groups across sleep and wakefulnessat two levels of OSA severity. Severe versus moderate OSA showed decreased power for fast frequencies (25-29Hz) during wakefulness. OSA men displayed decreased power of a large frequency range (sigma, beta and gamma) during sleep compared with women. Comparisons of men with severe versus moderate OSA presented significantly decreased sigma power during non-rapid eye movement (NREM) sleep, but significantly increased delta activity during REM sleep. Meanwhile, women with severe versus moderate OSA showed no significant power differences in any condition. These findings indicated a different evolution of brain oscillations between OSA men and women with significant impairment of brain activity related to cognitive processes. Our study emphasizes the importance of understanding the differential effects of sleep disorders on men and women in order to develop more precise diagnostic criteria according to gender, including quantitative electroencephalogram (EEG) analysis tools.

EEG correlates of induced anxiety in obsessive-compulsive patients: comparison of autobiographical and general anxiety scenarios.

BackgroundThe underlying symptomatology of obsessive–compulsive disorder (OCD) can be viewed as an impairment in both cognitive and behavioral inhibition, regarding difficult inhibition of obsessions and behavioral compulsions. Converging results from neuroimaging and electroencephalographic (EEG) studies have identified changes in activities throughout the medial frontal and orbital cortex and subcortical structures supporting the cortico-striato-thalamo-cortical circuit model of OCD. This study aimed to elucidate the electrophysiological changes induced by autobiographical and general anxiety scenarios in patients with OCD.MethodsResting-state eyes-closed EEG data were recorded in 19 OCD patients and 15 healthy controls. Cortical EEG sources were estimated by standardized low-resolution electromagnetic tomography (sLORETA). The changes in the emotional state were induced by two different scenarios: the autobiographical script related to patient’s OCD symptoms and the script triggering general anxiety.ResultsDuring the resting state, we proved increased delta activity in the frontal, limbic and temporal lobe and the sub-lobar area in OCD patients. In a comparison of neural activities during general anxiety in OCD patients and the control group, we proved an increase in delta (parietal, temporal, occipital, frontal and limbic lobes, and sub-lobal area), theta (temporal, parietal and occipital lobes) and alpha-1 activities (parietal lobe). Finally, we explored the neural activity of OCD patients during exposure to the autobiographic scenario. We proved an increase in beta-3 activity (left frontal lobe).ConclusionOur study proved differences in neural activation in OCD patients and healthy controls during imagination of general anxiety. Exposure to the autobiographic OCD scenario leads to activation of left frontal brain areas. The results show the possibility of using specific scenarios in OCD therapy.

Confusional arousals during non-rapid eye movement sleep: evidence from intracerebral recordings.

Confusional arousals (CA) are characterized by the association of behavioral awakening with persistent slow-wave electroencephalographic (EEG) activity during non-rapid eye movement (NREM) sleep-suggesting that sensorimotor areas are "awake" while non-sensorimotor areas are still "asleep." In the present work, we aimed to study the precise temporo-spatial dynamics of EEG changes in cortical areas during CA using intracerebral recordings. Nineteen episodes of CA were selected in five drug-resistant epileptic patients suffering incidentally from arousal disorders. Spectral power of EEG signal recorded in 30 non-lesioned, non-epileptogenic cortical areas and thalamus was compared between CA and baseline slow-wave sleep. Clear sequential modifications in EEG activity were observed in almost all studied areas. In the last few seconds before behavior onset, an increase in delta activity occurred predominantly in frontal regions. Behavioral arousal was associated with an increase of signal power in the whole studied frequency band in the frontal lobes, cingulate cortex, insular cortex, and precuneus. Afterwards, a diffuse cessation of very low frequencies (<1 Hz) occurred. Simultaneously, a hypersynchronous delta activity (HSDA) (1-1.5 Hz) arose in a broad network involving medial and lateral frontoparietal cortices, whereas higher frequency activities increased in sensorimotor, orbitofrontal, and temporal lateral cortices. This HSDA was predominantly observed in the inferior frontal gyrus. During CA, the level of activity changed in almost all the studied areas. The embedding of a broad frontoparietal network, especially the inferior frontal gyrus, in an HSDA might explain the participants' altered state of consciousness.

Psychophysiological characteristics in the ChNPP accident clean-up workers, exclusion zone evacuees and anti-terrorist operation servicemen

Evaluation of interdependencies between psychometric parameters and spontaneous cerebral electric activity in the ChNPP accident clean up workers, evacuees from exclusion zone, and anti terrorist operation service men. Psychometric and neurophysiological parameters were reviewed in the study subjects retro spectively and in comparison. Study population included the ChNPP accident clean up workers (ACUW), evacuees from the 30 kilometer exclusion zone, specifically in a sample from a cohort of the NRCRM Clinical Epidemiological Register (n=316), and anti terrorist operation servicemen (n=81) undergoing rehabilitation in the NRCRM Radiation psychoneurology department. A control group of persons (n=84) was also involved in the study. Diagnostic method ology for the characteristic personality features, namely the personality test of character accentuation by G. Shmishek and K. Leonhard, and Eysenck Personality Inventory (by H. J. Eysenck) were applied. Computer EEGs were registered and analyzed on the 16 channel electroencephalograph DX 4000 (Kharkiv, Ukraine). In the aftermath of the emergency period, a personality deformation occurs in the clean up workers and survivors of the ChNPP accident, which is characterized by aggravation of such personality traits as jam (fixedness), emotiveness, pedantry, anxiety, cyclothymia, excitability and disthymia, with diminished hyperthymia and ostenta tion (demonstrability). Increased incidence of fixedness, pedantry, cyclothymia, affectability and disthymia with decreased hyperthymia were revealed in the group of ATO participants. Cerebral bioelectrical activity in the ChNPP ACUW was characterized by an increased delta activity power with decreased beta and theta activity power and dom inant frequency in comparison with all groups of survivors and control group. The ATO group was different from groups of survivors and control group with a lower power of delta, theta and beta activity, and a higher dominant frequency. Introversion featured a negative correlation with delta and theta activity index along with positive cor relation with alpha activity index. The absolute spectral power of beta, alpha and theta bands positively correlated with introversion. Increase in neuroticism featured a decrease in theta activity index and an increase in beta activ ity index along with decreased theta and delta band absolute spectral power. There is a deformation of personality in the group of ChNPP ACUW, evacuees from the 30 kilometer zone and ATO servicemen. Deformation of personality correlates with abnormal cerebral bioelectrical activity.

Corticostriatal Field Potentials Are Modulated at Delta and Theta Frequencies during Interval-Timing Task in Rodents.

Organizing movements in time is a critical and highly conserved feature of mammalian behavior. Temporal control of action requires corticostriatal networks. We investigate these networks in rodents using a two-interval timing task while recording LFPs in medial frontal cortex (MFC) or dorsomedial striatum. Consistent with prior work, we found cue-triggered delta (1–4 Hz) and theta activity (4–8 Hz) primarily in rodent MFC. We observed delta activity across temporal intervals in MFC and dorsomedial striatum. Rewarded responses were associated with increased delta activity in MFC. Activity in theta bands in MFC and delta bands in the striatum was linked with the timing of responses. These data suggest both delta and theta activity in frontostriatal networks are modulated during interval timing and that activity in these bands may be involved in the temporal control of action.

Quantitative EEG-reactivity to different stimulation methods in comatose patients

Objective This study investigates quantitative EEG-reactivity (EEG-R) as a tool for comparison of the efficiency of different clinical stimulation methods. Methods Standardized pain (right and left arm, one leg and sternal massage), auditory and visual stimulation in 30-second epochs were performed during EEG-monitoring of 31 comatose neurosurgical patients. The logarithm to the ratio between the power in a stimulation epoch and the power in the 30-second epoch of rest immediately before was used as a measure of EEG-R in the delta, theta, alpha and beta frequency bands. Results As muscle artifacts contributed to the power in the beta band, this was not used for further analyses. All four pain stimulation methods showed an increase in alpha activity compared to the auditory and visual stimulation methods. There were no differences between the four pain stimulation methods, except for increased delta activity during sternal massage compared to stimulation of the left hand. Conclusions It is possible to use quantitative EEG-R in the assessment of different stimulation methods. Pain stimulation provoked more EEG-R than auditory or visual stimulation. Key message Quantitative EEG-R was used to show that pain stimulation might be more effective than auditory and visual stimulation in comatose patients.

Electroencephalography during general anaesthesia differs between term-born and premature-born children

ObjectivesPremature birth is associated with a wide range of complications in later life, including structural and functional neurological abnormalities and altered pain sensitivity. We investigated whether during anaesthesia premature-born children display different patterns of background EEG activity and exhibit increased responses to nociceptive stimuli. MethodsWe examined background EEG and time-locked responses to clinical cannulation in 45 children (mean age (±SD) at study: 4.9(±3.0)years) under sevoflurane monoanaesthesia maintained at a steady-state end-tidal concentration of 2.5%. 15 were born prematurely (mean gestational age at birth: 29.2±3.9weeks) and 30 were age-matched term-born children. ResultsBackground levels of alpha and beta power were significantly lower in the premature-born children compared to term-born controls (p=0.048). Clinical cannulation evoked a significant increase in delta activity (p=0.032), which was not significantly different between the two groups (p=0.44). ConclusionsThe results indicate that whilst under anaesthesia premature-born children display different patterns of background brain activity compared to term-born children. SignificanceAs electrophysiological techniques are increasingly used by anaesthetists to gauge anaesthetic depth, differences in background levels of electrophysiological brain activity between premature and term-born children may be relevant when considering titration of anaesthetic dose.

V4. Focal slow wave in patients after epilepsy surgery with and without seizure recurrence

Background Recurrence of seizure after epilepsy surgery occurs in approx. 40% of operated patients ( Rosenow and Luders, 2001 ). Due to skull defects, the resection volume and scarification, reevaluation for potential epilepsy surgery is challenging. Conductivity differences caused by such alterations has an almost negligible effect on magnetoencephalography (MEG). MEG may thus provide valuable localizing information in this patient group. In addition to epileptic spikes, focal slow wave activity in the delta and theta frequency range have been utilized for epileptic focus localizations in patients without previous surgery only ( Kaltenhauser et al., 2007 ). In the presented study, we use an automatic procedure to investigate focal delta in patients with and without recurrent seizures after surgery to differentiate delta related to epilepsy from delta caused by surgery. Patients and methods We investigated 15 patients with recurrent seizures and 10 seizure free patients after surgery, as well as 15 healthy controls. MEG was recorded for 10 min in supine positions using a WHS3600 magnetometer system (4D Neuroimaging, San Diego, USA) with 248 channels. Distribution of delta activity (1–4 Hz) in source space was calculated (DICS) using the Fieldtrip ( Oostenveld et al., 2011 ) Matlab toolbox (The Mathworks, Natick, CA, USA). Source activity was morphed onto a common coordinate system (MNI). Delta activity in patients was then related to healthy controls by calculating location specific z-values. Results Both patient groups showed significantly increased delta activity compared to healthy controls (p 3) in all patients. Conclusions In patients with recurrent seizures after epilepsy surgery, focal delta may be utilized for epileptic focus localization and complement MEG spike analysis. Furthermore, the significant difference between patients with and without recurrent seizures indicates a potential role of focal delta activity in the relapse of epilepsy.