EEG Effects Research Articles

EEG source space analysis of the supervised factor analytic approach for the classification of multi-directional arm movement

Objective. In electroencephalography (EEG)-based brain–computer interface (BCI) systems for motor control tasks the conventional practice is to decode motor intentions by using scalp EEG. However, scalp EEG only reveals certain limited information about the complex tasks of movement with a higher degree of freedom. Therefore, our objective is to investigate the effectiveness of source-space EEG in extracting relevant features that discriminate arm movement in multiple directions. Approach. We have proposed a novel feature extraction algorithm based on supervised factor analysis that models the data from source-space EEG. To this end, we computed the features from the source dipoles confined to Brodmann areas of interest (BA4a, BA4p and BA6). Further, we embedded class-wise labels of multi-direction (multi-class) source-space EEG to an unsupervised factor analysis to make it into a supervised learning method. Main Results. Our approach provided an average decoding accuracy of 71% for the classification of hand movement in four orthogonal directions, that is significantly higher (>10%) than the classification accuracy obtained using state-of-the-art spatial pattern features in sensor space. Also, the group analysis on the spectral characteristics of source-space EEG indicates that the slow cortical potentials from a set of cortical source dipoles reveal discriminative information regarding the movement parameter, direction. Significance. This study presents evidence that low-frequency components in the source space play an important role in movement kinematics, and thus it may lead to new strategies for BCI-based neurorehabilitation.

The Impact of Monaural Beat Stimulation on Anxiety and Cognition.

Application of auditory beat stimulation has been speculated to provide a promising new tool with which to alleviate symptoms of anxiety and to enhance cognition. In spite of reportedly similar EEG effects of binaural and monaural beats, data on behavioral effects of monaural beats are still lacking. Therefore, we examined the impact of monaural beat stimulation on anxiety, mood and memory performance. We aimed to target states related to anxiety levels and general well-being, in addition to long-term and working memory processes, using monaural beats within the range of main cortical rhythms. Theta (6 Hz), alpha (10 Hz) and gamma (40 Hz) beat frequencies, as well as a control stimulus were applied to healthy participants for 5 min. After each stimulation period, participants were asked to evaluate their current mood state and to perform cognitive tasks examining long-term and working memory processes, in addition to a vigilance task. Monaural beat stimulation was found to reduce state anxiety. When evaluating responses for the individual beat frequencies, positive effects on state anxiety were observed for all monaural beat conditions compared to control stimulation. Our results indicate a role for monaural beat stimulation in modulating state anxiety and are in line with previous studies reporting anxiety-reducing effects of auditory beat stimulation.

공익캠페인의 정서성, 자아관련성, 시각적 주의가 캠페인 태도에 미치는 영향: 디지털 뇌파(EEG) 기반 각성의 조절된 매개효과

본 연구는 조건과정모델링에 기초하여 공익광고캠페인의 정서성과 이슈에 대한 수용적 태도의 관계에서 시각적 주의와 지각된 자아관련성의 매개효과와 매개변인에 대한 EEG 각성의 조절효과를 알아보고자 했다. 이를 위해 SPSS 22.0의 Multiple Mediation 절차와 SPSS Macro(14번)를 이용하여 조절된 매개효과를 분석하였다. 본 연구결과는 첫째, 공익캠페인의 정서성은 지각된 자아관련성을 매개로 이슈에 대한 수용적 태도에 유의미한 영향을 보였다. 둘째, EEG 각성은 시각적 주의 및 지각된 자아관련성과 유의미한 상호작용효과를 나타냈다. 셋째, 정서성과 수용적 태도의 관계에서 지각된 자아관련성의 매개효과는 EEG 각성에 의해 조절되는 효과를 보였다. 본 연구결과는 공익캠페인의 부정소구보다는 긍정소구에서만 유효하였다. 이러한 결과를 바탕으로 공익광고캠페인의 정서소구를 활용하기 위해서는 공익캠페인에 대한 소비자의 지각된 자아관련성과 주의를 전략적으로 결합할 수 있음을 확인하였다. This study examined the conditional indirect effect of EEG (electroencephalogram) arousal on the relationship among affective valence, visual attention, perceived self-relevance, and attitudes toward campaign issues in the context of public service announcements (PSAs). Using SPSS macro (No. 14) of conditional process model, the findings in this current study indicated that the perceived self-relevance mediates the relationship between affective valence of PSA and attitudes toward issues and, in turn, is moderated by EEG arousal, indicating goodness-of-fit of the moderated mediation of psychophysiological arousal on PSAs. The results suggested that management of PSAs should be considered the strategic combination between affective valence and perceived self-relevance in advertising appeals.

A multimodal approach to estimating vigilance using EEG and forehead EOG

Objective. Covert aspects of ongoing user mental states provide key context information for user-aware human computer interactions. In this paper, we focus on the problem of estimating the vigilance of users using EEG and EOG signals. Approach. The PERCLOS index as vigilance annotation is obtained from eye tracking glasses. To improve the feasibility and wearability of vigilance estimation devices for real-world applications, we adopt a novel electrode placement for forehead EOG and extract various eye movement features, which contain the principal information of traditional EOG. We explore the effects of EEG from different brain areas and combine EEG and forehead EOG to leverage their complementary characteristics for vigilance estimation. Considering that the vigilance of users is a dynamic changing process because the intrinsic mental states of users involve temporal evolution, we introduce continuous conditional neural field and continuous conditional random field models to capture dynamic temporal dependency. Main results. We propose a multimodal approach to estimating vigilance by combining EEG and forehead EOG and incorporating the temporal dependency of vigilance into model training. The experimental results demonstrate that modality fusion can improve the performance compared with a single modality, EOG and EEG contain complementary information for vigilance estimation, and the temporal dependency-based models can enhance the performance of vigilance estimation. From the experimental results, we observe that theta and alpha frequency activities are increased, while gamma frequency activities are decreased in drowsy states in contrast to awake states. Significance. The forehead setup allows for the simultaneous collection of EEG and EOG and achieves comparative performance using only four shared electrodes in comparison with the temporal and posterior sites.

Repeated transcranial direct current stimulation in prolonged disorders of consciousness: A double-blind cross-over study

ObjectiveTo evaluate effects of 5 sessions of transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex in patients with prolonged disorders of consciousness (DOC). MethodsSeven patients in vegetative state (VS) and 6 in minimally conscious state (MCS), at ≥3months after brain injury, were randomized into two groups: group 1 received one week of active tDCS and 1week of sham stimulation, separated by 1 resting week; group 2 received active and sham stimulation in reverse order. We performed clinical and EEG evaluations before and after the first stimulation session, two hours after the last weekly stimulation, twice during the resting week, and during a 3-month follow-up. ResultsWe observed small changes of patients' conditions after the first tDCS session and immediately after the 5 active stimulations. Substantial clinical and EEG changes were observed in 5/13 patients (3 in MCS and 2 in VS) starting after entire (active and sham) stimulation protocol and further progressing during the next months. No baseline features distinguished patients who improved from patients who did not improve. ConclusionsRepeated tDCS did not exert remarkable short-term clinical and EEG effects in patients with prolonged DOC. Further studies should ascertain whether tDCS might promote clinical recovery in the long-term period.

Acute effects and after-effects of acoustic coordinated reset neuromodulation in patients with chronic subjective tinnitus.

Chronic subjective tinnitus is an auditory phantom phenomenon characterized by abnormal neuronal synchrony in the central auditory system. As shown computationally, acoustic coordinated reset (CR) neuromodulation causes a long-lasting desynchronization of pathological synchrony by downregulating abnormal synaptic connectivity. In a previous proof of concept study acoustic CR neuromodulation, employing stimulation tone patterns tailored to the dominant tinnitus frequency, was compared to noisy CR-like stimulation, a CR version significantly detuned by sparing the tinnitus-related pitch range and including substantial random variability of the tone spacing on the frequency axis. Both stimulation protocols caused an acute relief as measured with visual analogue scale scores for tinnitus loudness (VAS-L) and annoyance (VAS-A) in the stimulation-ON condition (i.e. 15 min after stimulation onset), but only acoustic CR neuromodulation had sustained long-lasting therapeutic effects after 12 weeks of treatment as assessed with VAS-L, VAS-A scores and a tinnitus questionnaire (TQ) in the stimulation-OFF condition (i.e. with patients being off stimulation for at least 2.5 h). To understand the source of the long-lasting therapeutic effects, we here study whether acoustic CR neuromodulation has different electrophysiological effects on oscillatory brain activity as compared to noisy CR-like stimulation under stimulation-ON conditions and immediately after cessation of stimulation. To this end, we used a single-blind, single application, cross over design in 18 patients with chronic tonal subjective tinnitus and administered three different 16-minute stimulation protocols: acoustic CR neuromodulation, noisy CR-like stimulation and low frequency range (LFR) stimulation, a CR type stimulation with deliberately detuned pitch and repetition rate of stimulation tones, as control stimulation. We measured VAS-L and VAS-A scores together with spontaneous EEG activity pre-, during- and post-stimulation. Under stimulation-ON conditions acoustic CR neuromodulation and noisy CR-like stimulation had similar effects: a reduction of VAS-L and VAS-A scores together with a decrease of auditory delta power and an increase of auditory alpha and gamma power, without significant differences. In contrast, LFR stimulation had significantly weaker EEG effects and no significant clinical effects under stimulation-ON conditions. The distinguishing feature between acoustic CR neuromodulation and noisy CR-like stimulation were the electrophysiological after-effects.Acoustic CR neuromodulation caused the longest significant reduction of delta and gamma and increase of alpha power in the auditory cortex region. Noisy CR-like stimulation had weaker and LFR stimulation hardly any electrophysiological after-effects. This qualitative difference further supports the assertion that long-term effects of acoustic CR neuromodulation on tinnitus are mediated by a specific disruption of synchronous neural activity. Furthermore, our results indicate that acute electrophysiological after-effects might serve as a marker to further improve desynchronizing sound stimulation.

Repetitive transcranial magnetic stimulation modulates the impact of a negative mood induction.

High frequency repetitive Transcranial Magnetic Stimulation (rTMS) over the left dorsolateral prefrontal cortex (DLPFC) has been found to alleviate depressive symptoms. However, the mechanisms driving these effects are still poorly understood. In the current study, we tested the idea that this intervention protects against negative mood shifts following emotional provocation. We furthermore explored changes in EEG activity (frontal alpha asymmetry) and effects on attentional processing (emotional Stroop). To this end, 23 healthy individuals participated in two sessions separated by one week, whereby they once received 15 min of 10Hz rTMS stimulation (1500 pulses) at 110% of the individual motor threshold, and once sham stimulation. Then, negative mood was induced using sad movie clips. The results revealed a significantly stronger mood decline following rTMS compared to sham stimulation. No changes were observed in frontal alpha asymmetry and attentional processing. Our findings are at odds with the view that high frequency rTMS over the left DLPFC directly protects against the induction of negative mood, but rather suggest that it enhances the effects of emotional provocation. Possibly, in healthy young individuals, this stimulation protocol heightens susceptibility to mood induction procedures in general.

A Cross-Correlational Analysis between Electroencephalographic and End-Tidal Carbon Dioxide Signals: Methodological Issues in the Presence of Missing Data and Real Data Results.

Electroencephalographic (EEG) irreducible artifacts are common and the removal of corrupted segments from the analysis may be required. The present study aims at exploring the effects of different EEG Missing Data Segment (MDS) distributions on cross-correlation analysis, involving EEG and physiological signals. The reliability of cross-correlation analysis both at single subject and at group level as a function of missing data statistics was evaluated using dedicated simulations. Moreover, a Bayesian-based approach for combining the single subject results at group level by considering each subject’s reliability was introduced. Starting from the above considerations, the cross-correlation function between EEG Global Field Power (GFP) in delta band and end-tidal CO2 (PETCO2) during rest and voluntary breath-hold was evaluated in six healthy subjects. The analysis of simulated data results at single subject level revealed a worsening of precision and accuracy in the cross-correlation analysis in the presence of MDS. At the group level, a large improvement in the results’ reliability with respect to single subject analysis was observed. The proposed Bayesian approach showed a slight improvement with respect to simple average results. Real data results were discussed in light of the simulated data tests and of the current physiological findings.

Intracarotid Etomidate Decreases the Interhemispheric Synchronization in Electroencephalogram (EEG) During the Wada Test.

The Wada test is a diagnostic method to anesthetize 1 cerebral hemisphere and assess the language and memory functions of awake contralateral hemisphere before temporal lobectomy in patients with epilepsy. The effects of an ipsilateral injection of etomidate on the functional properties of contralateral hemisphere are not known. Our aim was to characterize the electroencephalographic (EEG) effects after intracarotid injection of etomidate and to determine the changes in synchronization between the ipsilateral and contralateral hemispheres. We retrospectively analyzed EEG data from 15 patients who underwent Wada test with etomidate. Continuous EEG data from 4 electrodes (2 anterior [F3, F4] and 2 posterior [P3, P4]) were analyzed. After artifact rejection, we measured the amplitudes of delta (1 to 4 Hz) and alpha (7 to 13 Hz) waves and the changes in the interhemispheric synchronization before, during, and after etomidate injection. Ipsilateral injection of etomidate causes EEG changes in both hemispheres with increased amplitude of delta waves anteriorly and the alpha waves posteriorly. However this effect of etomidate is not uniform. Although there was a decrease in the interhemispheric synchronization of delta waves, there was no change in the synchronization of the alpha waves. Our study showed that the EEG effects of intracarotid ipsilateral injection of etomidate is not uniform in both hemispheres. Decrease in the interhemispheric synchronization of delta waves might serve as an indicator of ipsilateral effect of etomidate on the brain. Additional studies are needed to confirm our findings.

Diagnostic accuracy of somatosensory evoked potential and electroencephalography during carotid endarterectomy

Background and Purpose: Perioperative stroke risk following carotid endarterectomy (CEA) is reported to be approximately 2–3%. The diagnostic accuracies of intraoperative EEG and SSEP monitoring during CEA have been studied separately. However, to date, the effectiveness of simultaneous EEG and SSEP monitoring during CEA has only been evaluated in small study populations. This study examined the diagnostic accuracy of combined EEG and SSEP monitoring in a large (N = 1165) patient population.Methods: This study included 1165 patients who underwent CEA from 2000 to 2012 at the University of Pittsburgh Medical Center. The sensitivities, specificities, and diagnostic odds ratio of EEG and SSEP monitoring methods were examined separately and together. Receiver operating characteristic curves were plotted to assess sensitivity and specificity of single and combined Intraoperative monitoring (IONM) methods.Results: Maximum sensitivity was obtained with multimodality monitoring with an IONM change in either EEG or SSEP of 50.00 (95% CI, 30.66–69.34). The specificity of simultaneous EEG and SSEP changes was 93.95 (95% CI, 92.28–95.35%). Maximum area under ROC curve obtained for IONM change in either EEG or SSEP was 0.660 (95% CI, 0.547–0.773, p-value 0.004).Conclusion: The diagnostic accuracy of multimodality IONM during CEA is higher than an approach using single modality IONM. Simultaneous EEG and SSEP monitoring improves the likelihood of detecting periprocedural strokes after CEA. Neuro protective therapies to prevent periprocedural strokes can be based on changes in SSEP and EEG during CEA.

Long-Term (Six Years) Clinical Outcome Discrimination of Patients in the Vegetative State Could be Achieved Based on the Operational Architectonics EEG Analysis: A Pilot Feasibility Study.

Electroencephalogram (EEG) recordings are increasingly used to evaluate patients with disorders of consciousness (DOC) or assess their prognosis outcome in the short-term perspective. However, there is a lack of information concerning the effectiveness of EEG in classifying long-term (many years) outcome in chronic DOC patients. Here we tested whether EEG operational architectonics parameters (geared towards consciousness phenomenon detection rather than neurophysiological processes) could be useful for distinguishing a very long-term (6 years) clinical outcome of DOC patients whose EEGs were registered within 3 months post-injury. The obtained results suggest that EEG recorded at third month after sustaining brain damage, may contain useful information on the long-term outcome of patients in vegetative state: it could discriminate patients who remain in a persistent vegetative state from patients who reach a minimally conscious state or even recover a full consciousness in a long-term perspective (6 years) post-injury. These findings, if confirmed in further studies, may be pivotal for long-term planning of clinical care, rehabilitative programs, medical-legal decisions concerning the patients, and policy makers.

Functional neurotoxicity evaluation of noribogaine using video-EEG in cynomolgus monkeys

IntroductionContinuous video-electroencephalographic (EEG) monitoring remains the gold standard for seizure liability assessments in preclinical drug safety assessments. EEG monitored by telemetry was used to assess the behavioral and EEG effects of noribogaine hydrochloride (noribogaine) in cynomolgus monkeys. Noribogaine is an iboga alkaloid being studied for the treatment of opioid dependence. MethodsSix cynomolgus monkeys (3 per gender) were instrumented with EEG telemetry transmitters. Noribogaine was administered to each monkey at both doses (i.e., 160 and 320mg/kg, PO) with an interval between dosing of at least 6days, and the resulting behavioral and EEG effects were evaluated. IV pentylenetetrazol (PTZ), served as a positive control for induced seizures. ResultsThe administration of noribogaine at either of the doses evaluated was not associated with EEG evidence of seizure or with EEG signals known to be premonitory signs of increased seizure risk (e.g., sharp waves, unusual synchrony, shifts to high-frequency patterns). Noribogaine was associated with a mild reduction in activity levels, increased scratching, licking and chewing, and some degree of poor coordination and related clinical signs. A single monkey exhibited brief myoclonic movements that increased in frequency at the high dose, but which did not appear to generalize, cluster or to be linked with EEG abnormalities. Noribogaine was also associated with emesis and partial anorexia. In contrast, PTZ was associated with substantial pre-ictal EEG patterns including large amplitude, repetitive sharp waves leading to generalized seizures and to typical post-ictal EEG frequency attenuation. InterpretationEEG patterns were within normal limits following administration of noribogaine at doses up to 320mg/kg with concurrent clinical signs that correlated with plasma exposures and resolved by the end of the monitoring period. PTZ was invariably associated with EEG paroxysmal activity leading to ictal EEG. In the current study, a noribogaine dose of 320mg/kg was considered to be the EEG no observed adverse effect level (NOAEL) in conscious freely moving cynomolgus monkeys.

Spurious correlations in simultaneous EEG-fMRI driven by in-scanner movement

Simultaneous EEG-fMRI provides an increasingly attractive research tool to investigate cognitive processes with high temporal and spatial resolution. However, artifacts in EEG data introduced by the MR scanner still remain a major obstacle. This study, employing commonly used artifact correction steps, shows that head motion, one overlooked major source of artifacts in EEG-fMRI data, can cause plausible EEG effects and EEG–BOLD correlations. Specifically, low-frequency EEG (<20Hz) is strongly correlated with in-scanner movement. Accordingly, minor head motion (<0.2mm) induces spurious effects in a twofold manner: Small differences in task-correlated motion elicit spurious low-frequency effects, and, as motion concurrently influences fMRI data, EEG–BOLD correlations closely match motion-fMRI correlations. We demonstrate these effects in a memory encoding experiment showing that obtained theta power (~3–7Hz) effects and channel-level theta–BOLD correlations reflect motion in the scanner. These findings highlight an important caveat that needs to be addressed by future EEG-fMRI studies.

Decoding motor responses from the EEG during altered states of consciousness induced by propofol

Objective. Patients undergoing general anesthesia may awaken and become aware of the surgical procedure. Due to neuromuscular blocking agents, patients could be conscious yet unable to move. Using brain–computer interface (BCI) technology, it may be possible to detect movement attempts from the EEG. However, it is unknown how an anesthetic influences the brain response to motor tasks. Approach. We tested the offline classification performance of a movement-based BCI in 12 healthy subjects at two effect-site concentrations of propofol. For each subject a second classifier was trained on the subject’s data obtained before sedation, then tested on the data obtained during sedation (‘transfer classification’). Main results. At concentration 0.5 μg ml−1, despite an overall propofol EEG effect, the mean single trial classification accuracy was 85% (95% CI 81%–89%), and 83% (79%–88%) for the transfer classification. At 1.0 μg ml−1, the accuracies were 81% (76%–86%), and 72% (66%–79%), respectively. At the highest propofol concentration for four subjects, unlike the remaining subjects, the movement-related brain response had been largely diminished, and the transfer classification accuracy was not significantly above chance. These subjects showed a slower and more erratic task response, indicating an altered state of consciousness distinct from that of the other subjects. Significance. The results show the potential of using a BCI to detect intra-operative awareness and justify further development of this paradigm. At the same time, the relationship between motor responses and consciousness and its clinical relevance for intraoperative awareness requires further investigation.

Clinical Pattern of Epilepsy and their Electroencephalogram Findings

Background: Electroencephalogram (EEG) is a primary diagnostic tool for epilepsy in Nepal. There is virtually rare literature and published data on clinical pattern of epilepsy and their EEG finding in Nepal. Therefore, I attempted to study the clinical pattern of epilepsy and their EEG findings along with the effectiveness of EEG as a primary diagnostic tool for epilepsy and about its other better options. Methods: A descriptive retrospective study was conducted in tertiary care hospital, Chitwan, Nepal. Demographic profile, provisional diagnosis and EEG findings of epileptic patients between February 2011 to March 2014 were included and descriptive analysis was performed. Results: The incidence of epilepsy was higher in males than in females (57.2% vs. 42.8%). The majority of patients (54.7%) referred for EEG lie in the age group of 11-30 years. More than half (61.12%) of the seizures remained unclassified. Among the classified seizure, the incidence of generalized seizure is higher than partial seizure (75.85% vs 23.21%). Similarly, majority (55.8%) of the initial EEG recordings of the patients with provisional diagnosis of epilepsy were found to be normal and more than one third EEG records (38.1%) were unclassified Conclusion: Routine twenty-minute EEGs are easy to perform and are well tolerated by patients; however, in more than half of the patients with provisional diagnosis of epilepsy, the initial EEG does not show epileptiform activity and the paroxysmal events due to its low sensitivity. Despite of EEG being the primary diagnostic tool for epilepsy in Nepal, diagnosis should not completely rely on its reading for critically ill patients and for patients with recurrent seizure. Twenty-four hour EEG recording or Video-EEG monitoring (VEEG) or serial EEG (up to four recordings) may be more useful for diagnosis and treatment of epilepsy.

Stochastic Pharmacokinetic-Pharmacodynamic Analysis of the Effect of Transdermal Buprenorphine on Electroencephalogram and Analgesia.

The analgesic effect of opioids is often based on subjective one dimensional measurements. Electroencephalography (EEG) offers a possibility to objectively quantify the brain's activity before and after the administration of opioids. The aim of this study was to investigate the pharmacokinetic-pharmacodynamic (PKPD) properties of the buprenorphine transdermal patch on resting EEG and pain tolerance. Twenty-two healthy male subjects (mean age 23.1 ± 3.8 years) were studied. They received a 144-hour buprenorphine (20 μg/h) or placebo transdermal patch in this experimental, randomized, crossover, double-blind study. Skin heat pain tolerance was measured on the arm before the recordings of resting EEG. From the EEG, the ratio of slow and fast oscillations was calculated for further analysis. A population PKPD model with a stochastic differential equation for drug absorption from the patch was used to analyze the PK and PD data simultaneously by use of the statistical analysis package NONMEM. Buprenorphine increased EEG ratio (P = 0.0006) and skin pain tolerance (P = 0.0008) compared with placebo. The stochastic model adequately characterized the concentration-time and effect-time courses for both the skin heat stimulation and the resting EEG outcomes with variations in the drug's absorption rate during the 144-hour treatment period. As measured by the potency parameter, the EEG effect was 10 ± 3 (median ± SE) times more sensitive to buprenorphine than the skin pain test. Using a stochastic PKPD analysis, the effect of a 144-hour buprenorphine patch application on resting EEG and skin pain tolerance was quantified successfully. Both end points were affected by buprenorphine, although the resting EEG was more sensitive to buprenorphine. The stochastic PKPD analysis allowed the computation of a time-dependent variability in drug absorption from patch to blood. The data suggest that the resting EEG is an attractive and objective alternative for assessing opioid effect.

Effect of invasive EEG monitoring on cognitive outcome after left temporal lobe epilepsy surgery.

The objective of this cohort study was to compare neuropsychological outcomes following left temporal lobe resection (TLR) in patients with epilepsy who had or had not undergone prior invasive monitoring. Data were obtained from an institutional review board-approved, neuropsychology registry for patients who underwent epilepsy surgery at Cleveland Clinic between 1997 and 2013. A total of 176 patients (45 with and 131 without invasive EEG) met inclusion criteria. Primary outcome measures were verbal memory and language scores. Other cognitive outcomes were also examined. Outcomes were assessed using difference in scores from before to after surgery and by presence/absence of clinically meaningful decline using reliable change indices (RCIs). Effect of invasive EEG on cognitive outcomes was estimated using weighting and propensity score adjustment to account for differences in baseline characteristics. Linear and logistic regression models compared surgical groups on all cognitive outcomes. Patients with invasive monitoring showed greater declines in confrontation naming; however, when RCIs were used to assess clinically meaningful change, there was no significant treatment effect on naming performance. No difference in verbal memory was observed, regardless of how the outcome was measured. In secondary outcomes, patients with invasive monitoring showed greater declines in working memory, which were no longer apparent using RCIs to define change. There were no outcome differences on other cognitive measures. Results suggest that invasive EEG monitoring conducted prior to left TLR is not associated with greater cognitive morbidity than left TLR alone. This information is important when counseling patients regarding cognitive risks associated with this elective surgery.

EEG reactivity to pain in comatose patients: Importance of the stimulus type.

Electroencephalogram (EEG) background reactivity is a potentially interesting outcome predictor in comatose patients, especially after cardiac arrest, but recent studies report only fair interrater reliability. Furthermore, there are no definite guidelines for its testing. We therefore investigated the EEG effect of standardized noxious stimuli in comatose patients not reactive to auditory stimuli. In this prospective study we applied a protocol using three different painful stimuli (bilateral nipple pinching, pinprick at the nose base, finger-nail compression on each side), grouped in three distinct clusters with an alternated sequence, during EEG recordings in comatose patients. We only analyzed recordings showing any reactivity to pain. Fisher and χ2 tests were used as needed to assess contingency tables. Of 42 studies, 12 did not show any background reactivity, 2 presented SIRPIDs, and 2 had massive artefacts; we thus analyzed 26 EEGs recorded in 17 patients (4 women, 24%). Nipple pinching more frequently induced a change in EEG background activity (p<0.001), with a sensitivity of 97.4% for reactivity. Neither the order of the stimuli in the cluster (p=0.723), nor the cluster order (p=0.901) influenced the results. In this pilot study, bilateral, synchronous nipple pinching seems to be the most efficient method to test nociceptive EEG reactivity in comatose patients. This approach may enhance interrater reliability, but deserves confirmation in larger cohorts.

Pharmacological evaluation of a novel phosphodiesterase 10A inhibitor in models of antipsychotic activity and cognition

In this study, we report the pharmacological effects of a novel PDE10A inhibitor, SEP-39. SEP-39 is a potent (1.0nM) inhibitor of human PDE10A in vitro, with good selectivity (>16000-fold) against other PDEs. In an in vivo occupancy study, the RO50 value was determined to be 0.7mg/kg (p.o.), corresponding to plasma and brain exposures of 28ng/mL and 43ng/g, respectively. Using microdialysis, we show that 3mg/kg (p.o.) SEP-39 significantly increased rat striatal cGMP concentrations. Furthermore, SEP-39 inhibits PCP-induced hyperlocomotion at doses of 1 and 3mg/kg (p.o.) corresponding to 59–86% occupancy. At similar doses in a catalepsy study, the time on the bar was increased but the maximal effect was less than that seen with haloperidol. In an EEG study, 3 and 10mg/kg (p.o.) SEP-39 suppressed REM intensity and increased the latency to REM sleep. We also demonstrate the procognitive effects of SEP-39 in the rat novel object recognition assay. These effects appear to require less PDE10A inhibition than the reversal of PCP-induced hyperlocomotion or EEG effects, as improvements in recognition index were seen at doses of 0.3mg/kg and above. Our data demonstrate that SEP-39 is a potent, orally active PDE10A inhibitor with therapeutic potential in a number of psychiatric indications.

The Acute electrocortical and Blood Pressue Effects of Chocolate

Objective: The present study investigated the effects of consuming chocolate on electroencephalograph (EEG) frequencies and localization and on blood pressure. Method: Across six conditions, 122 participants consumed either higher (60%) cacao chocolate, low (0%) cacao chocolate, higher cacao chocolate +L-theanine, high sugar water, low sugar water, or water. EEGs, blood pressure, and mood were measured before and after a 60-minute digestion period. Results: Analyses indicated a decrease in frontal, parietal, and temporal theta and an increase in occipital beta EEG following the consumption of a 60% cacao confection compared with control conditions. Diastolic blood pressure increased with the consumption of higher cacao chocolate when compared to water alone and to higher cacao chocolate + L-theanine. Diastolic and systolic blood pressure decreased following consumption of higher cacao + L-theanine chocolate, averaging 4-8 mmHg. No condition-specific mood changes or gender differences were found. Conclusions: This study suggests an acute stimulating effect of cacao on the human brain and vasoconstrictive effects on peripheral vasculature, the latter of which appear to be offset by an L-theanine additive. Significance: This is the first known study to investigate acute EEG effects of consuming chocolate and suggests a potential attention-enhancing effect.