EEG Activity In Patients Research Articles

Abnormal brain-heart electrophysiology in mild and severe orthostatic hypotension.

This study investigated the changes in cardiocerebral electrophysiology in patients with mild orthostatic hypotension (MOH) and severe orthostatic hypotension (SOH) and their relationship with the severity of orthostatic hypotension, psychiatric symptoms, and cognitive dysfunction. This study included 72 nonorthostatic hypotension (NOH), 17 with MOH, and 11 with SOH. Seated resting-state heart rate variability (HRV) and quantitative electroencephalogram parameters were synchronized and recorded. HRV measures in the time and frequency domains were analyzed, along with the peak frequency and power of the brain waves. Abnormal neuronal activity was found in FP1 in patients with MOH, whereas it was more widespread in FP1, FP2, and O2 in patients with SOH (P < 0.05). Cardiac and cerebral electrophysiological abnormalities were significantly associated with orthostatic hypotension severity, psychiatric symptoms, and cognitive dysfunction. Abnormal EEG activity in patients are mainly manifested in the prefrontal and occipital lobes, especially in patients with SOH. These results may help patients to better understand the mechanisms underlying orthostatic hypotension severity and psychiatric and cognitive impairment in orthostatic hypotension.

Reward-based decision-making in mesial temporal lobe epilepsy patients with unilateral hippocampal sclerosis pre- and post-surgery

BackgroundCorrect functioning of the reward processing system is critical for optimizing decision-making as well as preventing the development of addictions and/or neuropsychiatric symptoms such as depression, apathy, and anhedonia. Consequently, patients with mesial temporal lobe epilepsy due to unilateral hippocampal sclerosis (mTLE-UHS) represent an excellent opportunity to study the brain networks involved in this system. ObjectiveThe aim of the current study was to evaluate decision-making and the electrophysiological correlates of feedback processing in a sample of mTLE-UHS patients, compared to healthy controls. In addition, we assessed the impact of mesial temporal lobe surgical resection on these processes, as well as general, neuropsychological functioning. Method17 mTLE-UHS patients and 17 matched healthy controls completed: [1] a computerized version of the Game of Dice Task, [2] a Standard Iowa Gambling Task, and [3] a modified ERP version of a probabilistic gambling task coupled with multichannel electroencephalography. Neuropsychological scores were also obtained both pre- and post-surgery. ResultsBehavioral analyses showed a pattern of increased risk for the mTLE-UHS group in decision-making under ambiguity compared to the control group. A decrease in the amplitude of the Feedback Related Negativity (FRN), a weaker effect of valence on delta power, and a general reduction of delta and theta power in the mTLE-UHS group, as compared to the control group, were also found. The beta-gamma activity associated with the delivery of positive reward was similar in both groups. Behavioral performance and electrophysiological measures did not worsen post-surgery. ConclusionsPatients with mTLE-UHS showed impairments in decision-making under ambiguity, particularly when they had to make decisions based on the outcomes of their choices, but not in decision-making under risk. No group differences were observed in decision-making when feedbacks were random. These results might be explained by the abnormal feedback processing seen in the EEG activity of patients with mTLE-UHS, and by concomitant impairments in working memory, and memory. These impairments may be linked to the disruption of mesial temporal lobe networks. Finally, feedback processing and decision-making under ambiguity were already affected in mTLE-UHS patients pre-surgery and did not show evidence of clear worsening post-surgery.

Electroencephalographic Activity and Cognitive Function in Middle-Aged Patients with Obstructive Sleep Apnea Before and After Continuous Positive Airway Pressure Treatment.

PurposeTo investigate the effect of continuous positive airway pressure (CPAP) on sleep electroencephalogram (EEG) activity in patients with obstructive sleep apnea (OSA) and to examine the correlation between quantitative EEG changes and cognitive function.Patients and MethodsA total of 69 men and 11 women were collected with an average age of 39.61 ± 7.67 years old from among middle-aged patients who had first visits with snoring as their main complaint. All of them completed sleep questionnaires, neurocognitive tests and night polysomnography (PSG). The patients in the OSA group also completed the second night of PSG monitoring under CPAP after pressure titration. A power spectrum analysis of EEG was used, and the correlation between the frequency powers of EEG and the scores of the Epworth Sleepiness Scale (ESS), Pittsburgh Sleep Quality Index (PSQI), Mini-Mental State Examination (MMSE), and the Montreal Cognitive Assessment (MoCA) were further analyzed.ResultsCompared with the control group, the delta/alpha power ratio (DAR) and the (delta + theta)/(alpha + beta) power ratio (the slowing ratio, TSR) of the OSA group before CPAP were higher (P < 0.05). The DAR and TSR of the OSA patients decreased significantly after CPAP. ESS scores were correlated with parameters such as respiratory-related microarousal index (RRMAI), apnea hypopnea index (AHI), and the average absolute power of delta, DAR and TSR (P < 0.05). The PSQI, MMSE and MoCA scores were not correlated with the average absolute power of each frequency band, DAR or TSR (P > 0.05).ConclusionPatients with OSA have greater slow frequency EEG activity during sleep than the control group. CPAP treatment reversed the slow frequency EEG activity in patients with OSA.

Disturbances in Aperiodic Neural Activity During Resting State in Patients With Schizophrenia

Abnormal oscillatory power measured in canonical frequency bands during resting EEG has been observed in schizophrenia, however, recent evidence suggests that aperiodic neural activity may be important to understanding functional brain abnormalities in the disorder. We characterized the frequency composition of aperiodic (i.e., non-oscillatory) EEG activity in patients with schizophrenia (SCZ) and healthy controls (CON) during rest, and determined whether shifts in aperiodic activity reflect aspects of psychiatric symptoms or cognition.

Neurophysiological Markers of Alzheimer's Disease: Quantitative EEG Approach.

Currently established and employed biomarkers of Alzheimer's disease (AD) predominantly mirror AD-associated molecular and structural brain changes. While they are necessary for identifying disease-specific neuropathology, they lack a clear and robust relationship with the clinical presentation of dementia; they can be altered in healthy individuals, while they often inadequately mirror the degree of cognitive and functional deficits in affected subjects. There is growing evidence that synaptic loss and dysfunction are early events during the trajectory of AD pathogenesis that best correlate with the clinical symptoms, suggesting measures of brain functional deficits as candidate early markers of AD. Resting-state electroencephalography (EEG) is a widely available and noninvasive diagnostic method that provides direct insight into brain synaptic activity in real time. Quantitative EEG (qEEG) analysis additionally provides information on physiologically meaningful frequency components, dynamic alterations and topography of EEG signal generators, i.e. neuronal signaling. Numerous studies have shown that qEEG measures can detect disruptions in activity, topographical distribution and synchronization of neuronal (synaptic) activity such as generalized EEG slowing, reduced global synchronization and anteriorization of neuronal generators of fast-frequency resting-state EEG activity in patients along the AD continuum. Moreover, qEEG measures appear to correlate well with surrogate markers of AD neuropathology and discriminate between different types of dementia, making them promising low-cost and noninvasive markers of AD. Future large-scale longitudinal clinical studies are needed to elucidate the diagnostic and prognostic potential of qEEG measures as early functional markers of AD on an individual subject level.

Relationships between attentional network functioning and spontaneous EEG activity in patients with coronary artery disease

Chinese mitten crab (Eriocheir sinensis) is an important aquaculture species in Crustacea. Functional analysis, although essential, has been hindered due to the lack of sufficient genomic or transcriptomic resources. In this study, transcriptome sequencing was conducted on 59 samples representing diverse developmental stages (fertilized eggs, zoea, megalopa, three sub-stages of larvae, juvenile crabs, and adult crabs) and different tissues (eyestalk, hepatopancreas, and muscle from juvenile crabs, and eyestalk, hepatopancreas, muscle, heart, stomach, gill, thoracic ganglia, intestine, ovary, and testis from adult crabs) of E. sinensis. A comprehensive reference transcriptome was assembled, including 19,023 protein-coding genes. Hierarchical clustering based on 128 differentially expressed cuticle-related genes revealed two distinct expression patterns during the early larval developmental stages, demonstrating the distinct roles of these genes in “crab-like” cuticle formation during metamorphosis and cuticle calcification after molting. Phylogenetic analysis of 1406 one-to-one orthologous gene families identified from seven arthropod species and Caenorhabditis elegans strongly supported the hypothesis that Malacostraca and Branchiopoda do not form a monophyletic group. Furthermore, Branchiopoda is more phylogenetically closely related to Hexapoda, and the clade of Hexapoda and Branchiopoda and the clade of Malacostraca belong to the Pancrustacea. This study offers a high-quality transcriptome resource for E. sinensis and demonstrates the evolutionary relationships of major arthropod groups. The differentially expressed genes identified in this study facilitate further investigation of the cuticle-related gene expression networks which are likely associated with “crab-like” cuticle formation during metamorphosis and cuticle calcification after molting.

P.3.d.055 - Effects of sertindole on EEG activity in patients with schizophrenia

P.3.d.055 - Effects of sertindole on EEG activity in patients with schizophrenia

Ictal source imaging and electroclinical correlation in self-limited epilepsy with centrotemporal spikes

PurposeTo elucidate the localization of ictal EEG activity, and correlate it to semiological features in self-limited epilepsy with centrotemporal spikes (formerly called “benign epilepsy with centrotemporal spikes”). MethodsWe have performed ictal electric source imaging, and we analysed electroclinical correlations in three patients with self-limited epilepsy with centrotemporal spikes. ResultsThe source of the evolving rhythmic ictal activity (9.7-13.5Hz) localized to the operculo-insular area. The rhythmic EEG activity was time-locked to the contralateral focal motor seizure manifestation: facial rhythmic myoclonic jerks, with the same frequency as the analysed ictal rhythm. In all three patients, the seizures had fluctuating course with pauses of clinical and electrographic seizure activity, ranging from 0.4 to 7s. ConclusionSource imaging of ictal EEG activity in patients with self-limited epilepsy with centrotemporal spikes showed activation of the operculo-insular area, time-locked to the contralateral focal myoclonic jerks. Fragmented seizure dynamics, with fluctuating course, previously described as a hallmark in patients with psychogenic non-epileptic seizures, can occur in rolandic seizures.

PS208. Preliminary Study on Asymmetry of Theta Quantitative EEG Activity in Patients with Depression and Anxiety Disorders

PS208. Preliminary Study on Asymmetry of Theta Quantitative EEG Activity in Patients with Depression and Anxiety Disorders

Oscillations Go the Distance: Low-Frequency Human Hippocampal Oscillations Code Spatial Distance in the Absence of Sensory Cues during Teleportation

Low-frequency (delta/theta band) hippocampal neural oscillations play prominent roles in computational models of spatial navigation, but their exact function remains unknown. Some theories propose they are primarily generated in response to sensorimotor processing, while others suggest a role in memory-related processing. We directly recorded hippocampal EEG activity in patients undergoing seizure monitoring while they explored a virtual environment containing teleporters. Critically, this manipulation allowed patients to experience movement through space in the absence of visual and self-motion cues. The prevalence and duration of low-frequency hippocampal oscillations were unchanged by this manipulation, indicating that sensorimotor processing was not required to elicit them during navigation. Furthermore, the frequency-wise pattern of oscillation prevalence during teleportation contained spatial information capable of classifying the distance teleported. These results demonstrate that movement-related sensory information is not required to drive spatially informative low-frequency hippocampal oscillations during navigation and suggest a specific function in memory-related spatial updating.

Synchronization of EEG activity in patients with bipolar disorder

In paper we apply the method based on the Flicker-Noise Spectroscopy (FNS) to determine the differences in frequency-phase synchronization of the cortical electroencephalographic (EEG) activities in patients with bipolar disorder (BD). We found that for healthy subjects the frequency-phase synchronization of EEGs from long-range electrodes was significantly better for BD patients. In BD patients a high synchronization of EEGs was observed only for short-range electrodes. Thus, the FNS is a simple graphical method for qualitative analysis can be applied to identify the synchronization effects in EEG activity and, probably, may be used for the diagnosis of this syndrome.

Altered EEG resting-state effective connectivity in drug-naïve childhood absence epilepsy

ObjectiveWe investigated interictal EEG activity in patients with childhood absence seizures with the aim of detecting markers of network defects generating “idiopathic” hyperexcitability in this form of epilepsy. MethodsWe included 11 drug-naïve patients with childhood absence epilepsy (CAE), and 11 age matched controls (CTRL). We analyzed interictal EEG using partial directed coherence (PDC), a connectivity estimator in frequency domain based on autoregressive multivariate (MVAR) modeling giving the advantage of indicating the direction and strength of the interactions between multiple variables. ResultsOur results revealed the presence of an abnormal cortico-cortical network occurring in the interictal condition in CAE and involving a large span of frequencies, with prominence in the alpha band; the most evident finding was a highly significant increase of out-going connectivity involving frontal and central cortical areas in CAE patients compared to CTRL subjects. ConclusionsOur observation indicates that, in interictal conditions, a distorted network characterizes CAE, and a hyperconnected network is already detectable under resting conditions in the delta, theta and alpha bands. SignificanceThe increased interictal EEG connectivity demonstrated here provides support for a persistent abnormal relationship between the thalamus and a hyperexcitable cortex outside the ictal phase.

Reduced event-related low frequency EEG activity in patients with early onset schizophrenia and their unaffected siblings

Low-frequency oscillations in the electroencephalogram (EEG) have been found to be abnormal in patients with schizophrenia. It is unclear, however, whether these abnormalities are related to severity of illness or are a marker for risk. This study investigated total and evoked theta and delta activity in schizophrenia patients, unaffected siblings, and healthy controls (HCs). EEG data were recorded whilst 24 individuals with schizophrenia, 26 unaffected siblings of individuals with schizophrenia and 26 healthy control participants completed a Go/No-Go task. Event-related total activity and evoked theta and delta activity were calculated for correct hits (CH), failed inhibitions (FI) and correct inhibitions (CI) trials. Patients displayed significantly less total delta, evoked delta, total theta and evoked theta activity when compared with healthy controls. Unaffected siblings displayed abnormalities of evoked delta, but other measures were similar to those in control participants. The findings of this study add to evidence that abnormal low-frequency EEG oscillations contribute to impairments in information processing seen in schizophrenia. These findings also suggest abnormal evoked delta oscillations are associated with an increased familial risk of developing the disorder.

Role of the lateral prefrontal cortex in speech monitoring

The role of lateral prefrontal cortex (LPFC) in speech monitoring has not been delineated. Recent work suggests that medial frontal cortex (MFC) is involved in overt speech monitoring initiated before auditory feedback. This mechanism is reflected in an event-related potential (ERP), the error negativity (Ne), peaking within 100 ms after vocal-onset. Critically, in healthy individuals the Ne is sensitive to the accuracy of the response; it is larger for error than correct trials. By contrast, patients with LPFC damage are impaired in non-verbal monitoring tasks showing no amplitude difference between the Ne measured in correct vs. error trials. Interactions between the LPFC and the MFC are assumed to play a necessary role for normal action monitoring. We investigated whether the LPFC was involved in speech monitoring to the same extent as in non-linguistic actions by comparing performance and EEG activity in patients with LPFC damage and in aged-matched controls performing linguistic (Picture Naming) and non-linguistic (Simon) tasks. Controls did not produce enough errors to allow the comparison of the Ne or other ERP in error vs. correct trials. PFC patients had worse performance than controls in both tasks, but their Ne was larger for error than correct trials only in Naming. This task-dependent pattern can be explained by LPFC-dependent working-memory requirements present in non-linguistic tasks used to study action monitoring but absent in picture naming. This suggests that LPFC may not be necessary for speech monitoring as assessed by simple picture naming. In addition, bilateral temporal cortex activity starting before and peaking around vocal-onset was observed in LPFC and control groups in both tasks but was larger for error than correct trials only in Naming, suggesting the temporal cortex is associated with on-line monitoring of speech specifically when access to lexical representations is necessary.

Nonlinear analysis of electroencephalogram at rest and during cognitive tasks in patients with schizophrenia

In spite of the large number of studies on schizophrenia, a full understanding of its core pathology still eludes us. The application of the nonlinear theory of electroencephalography (EEG) analysis provides an interesting tool to differentiate between physiologic conditions (e.g., resting state and mathematical task) and normal and pathologic brain activities. The aim of the present study was to investigate nonlinear EEG activity in patients with schizophrenia. We recorded 19-lead EEGs in patients with stable schizophrenia and healthy controls under 4 different conditions: eyes closed, eyes open, forward counting and backward counting. A nonlinear measure of complexity was calculated by means of correlation dimension (D2). We included 17 patients and 17 controls in our analysis. Comparing the 2 populations, we observed greater D2 values in the patient group. In controls, increased D2 values were observed during active states (eyes open and the 2 cognitive tasks) compared with baseline conditions. This increase of brain complexity, which can be interpreted as an increase of information processing and integration, was not preserved in the patient population. Patients with schizophrenia were taking antipsychotic medications, so the presence of medication effects cannot be excluded. Our results suggest that patients with schizophrenia present changes in brain activity compared with healthy controls, and this pathologic alteration can be successfully studied with nonlinear EEG analysis.

Cortical hyperexcitability in migraine and aversion to patterns

Patients with migraine are averse to certain visual stimuli, such as flicker and striped patterns that evoke paroxysmal EEG activity in patients with photosensitive epilepsy. Migraineurs demonstrate a hyper-responsiveness to such stimuli, and there is debate as to whether the aversion and hyper-responsiveness are due to a hyperexcitability of the cortex similar to that in patients with photosensitive epilepsy. In these patients grating patterns with certain spatial characteristics can be epileptogenic, depending critically on their movement. If the contours of the grating drift continually, the grating is not epileptogenic, but if the contours are static or if their direction is repeatedly and rapidly reversed so as to vibrate, the grating then becomes highly epileptogenic. We compared aversion to vibrating, drifting and static gratings in migraineurs and controls. The contrast of each grating was gradually increased, but only until the participant felt discomfort, so as to obtain a contrast threshold for aversion with minimal exposure. Migraineurs had lower thresholds than the control group, indicating greater aversion. For both groups the threshold was higher (aversion was lower) for static than for both types of moving gratings. The drifting gratings were more aversive than the vibrating gratings when both groups were combined. The findings suggest that the aversion shown by migraineurs is not attributable to a cortical hyperexcitability similar to that in photosensitive epilepsy.

Role of the parietal cortex in predicting incoming actions

Animal and human studies have shown that the parietal and the ventral premotor cortices constitute the neural substrate of the so-called mirror system. The word "mirror" originally referred to the discovery of neurons in non-human primates whose visual response echoes their motor response. This account proposes that action understanding and imitation depend on a mechanism which activates directly our own motor system as we observe the actions of other agents (Rizzolatti and Sinigaglia, 2010). Single unit recording experiments have also demonstrated that parietal neurons have predictive activity and discharge well ahead of a planned movement. Interestingly, patients with parietal damage can show impairments in their ability to imitate or understand an observed action, but they have also difficulties in monitoring early phases of their own movement planning, be it simple reaching movements or more complex object-directed actions. The fact that both deficits may co-occur after a parietal lesion raises the question whether this reflects the impairment of a common mechanism. To address this question we examined EEG activity in patients with selective lesions in the inferior parietal lobe (N=6) who were requested to watch passively a video showing an actor grasping a colored object. The object's color cued the subject that the actor was about to move. We recorded the Readiness Potential (RP), a marker of motor preparation which also arises when preparing to observe an action (Kilner et al., 2004). Parietal patients' performance was compared to that of neurologically normal subjects (n=9) and patients with a ventral premotor cortex lesion (N=4). We show that neurologically normal subjects and premotor patients exhibit a significant RP prior to the observed action, whereas no such RP is observed in parietal patients. Our results indicate that parietal cortex injury alters the ability to monitor the early planning phases not only of one's own actions but those of other agents as well. We speculate that parietal activity during action observation does not only or essentially reflect a mirroring process, as recently proposed by mirror neurons' account, but involve instead an anticipatory process which arises through prior learning and predictive mechanisms.

Symptoms of epilepsy and organic brain dysfunctions in patients with acute, brief depression combined with other fluctuating psychiatric symptoms: a controlled study from an acute psychiatric department

BackgroundIn psychiatric acute departments some patients present with brief depressive periods accompanied with fluctuating arrays of other psychiatric symptoms like psychosis, panic or mania. For the purpose of the present study we call this condition Acute Unstable Depressive Syndrome (AUDS).The aims of the present study were to compare clinical signs of organic brain dysfunctions and epilepsy in patients with AUDS and Major Depressive Episode (MDE).MethodsOut of 1038 consecutive patients admitted to a psychiatric acute ward, 16 patients with AUDS and 16 age- and gender-matched MDE patients were included in the study. Using standardized instruments and methods we recorded clinical data, EEG and MRI.ResultsA history of epileptic seizures and pathologic EEG activity was more common in the AUDS group than in the MDE group (seizures, n = 6 vs. 0, p = 0.018; pathologic EEG activity, n = 8 vs. 1, p = 0.015). Five patients in the AUDS group were diagnosed as having epilepsy, whereas none of those with MDE had epilepsy (p = 0.043). There were no differences between the groups regarding pathological findings in neurological bedside examination and cerebral MRI investigation.ConclusionCompared to patients admitted with mood symptoms fulfilling DSM 4 criteria of a major depressive disorder, short-lasting atypical depressive symptoms seem to be associated with a high frequency of epileptic and pathologic EEG activity in patients admitted to psychiatric acute departments.Trial registrationNCT00201474

Enhanced low and high frequency resting EEG activity in patients with chronic severe obsessive-compulsive and psychotic disorders

Enhanced low and high frequency resting EEG activity in patients with chronic severe obsessive-compulsive and psychotic disorders

Are oscillatory brain responses generally reduced in schizophrenia during long sustained attentional processing?

Deficits in sustained attention and vigilance were assessed for oscillatory delta, theta, alpha, and gamma EEG activity during an auditory continuous performance task in patients with schizophrenia and healthy controls by quantifying peak-to-peak amplitudes of averaged and single-trial data. Averaged data indicated significantly reduced amplitudes in schizophrenia patients in all analyzed frequency bands, mainly at anterior locations. Single-trial analysis suggested that the amplitude reductions observed in the averaged delta, theta, and alpha response in patients originated from increased inter-trial phase variability. Gamma activity maximum amplitudes were reduced at the single-trial level. The findings imply that EEG activity in patients with schizophrenia can be characterized by multiple deficits in oscillatory networks, which indicates a disturbance in the temporal integration and interaction of all frequency components and their inter-trial variability.