鼻腔内机械振荡刺激对健康人群静息态脑电图相对功率及有效连接的影响

鼻腔内机械振荡刺激(iMVS)是一种新型的无创神经刺激技术,可提升边缘系统内在功能活性从而改善自主神经平衡.通过分析iMVS对健康人群脑电图(EEG)相对功率以及EEG有效连接的影响,探索iMVS的神经生理机制.将22名健康成年被试随机均分为刺激组与对照组,并对11名刺激组被试两侧鼻腔各进行10 min的iMVS,11...     

Resting-state beta and gamma activity in Internet addiction

Internet addiction is the inability to control one's use of the Internet and is related to impulsivity. Although a few studies have examined neurophysiological activity as individuals with Internet addiction engage in cognitive processing, no information on spontaneous EEG activity in the eyes-closed resting-state is available. We investigated resting-state EEG activities in beta and gamma bands and examined their relationships with impulsivity among individuals with Internet addiction and healthy controls. Twenty-one drug-naïve patients with Internet addiction (age: 23.33 ± 3.50 years) and 20 age-, sex-, and IQ-matched healthy controls (age: 22.40 ± 2.33 years) were enrolled in this study. Severity of Internet addiction was identified by the total score on Young's Internet Addiction Test. Impulsivity was measured with the Barratt Impulsiveness Scale-11 and a stop-signal task. Resting-state EEG during eyes closed was recorded, and the absolute/relative power of beta and gamma bands was analyzed. The Internet addiction group showed high impulsivity and impaired inhibitory control. The generalized estimating equation showed that the Internet-addiction group showed lower absolute power on the beta band than did the control group (estimate = − 3.370, p < 0.01). On the other hand, the Internet-addiction group showed higher absolute power on the gamma band than did the control group (estimate = 0.434, p < 0.01). These EEG activities were significantly associated with the severity of Internet addiction as well as with the extent of impulsivity. The present study suggests that resting-state fast-wave brain activity is related to the impulsivity characterizing Internet addiction. These differences may be neurobiological markers for the pathophysiology of Internet addiction.     

Modulation of EEG Functional Connectivity Networks in Subjects Undergoing Repetitive Transcranial Magnetic Stimulation

Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique that utilizes magnetic fluxes to alter cortical activity. Continuous theta-burst repetitive TMS (cTBS) results in long-lasting decreases in indices of cortical excitability, and alterations in performance of behavioral tasks. We investigated the effects of cTBS on cortical function via functional connectivity and graph theoretical analysis of EEG data. Thirty-one channel resting-state EEG recordings were obtained before and after 40 s of cTBS stimulation to the left primary motor cortex. Functional connectivity between nodes was assessed in multiple frequency bands using lagged max-covariance, and subsequently thresholded to construct undirected graphs. After cTBS, we find widespread decreases in functional connectivity in the alpha band. There are also simultaneous increases in functional connectivity in the high-beta bands, especially amongst anterior and interhemispheric connections. The analysis of the undirected graphs reveals that interhemispheric and interregional connections are more likely to be modulated after cTBS than local connections. There is also a shift in the topology of network connectivity, with an increase in the clustering coefficient after cTBS in the beta bands, and a decrease in clustering and increase in path length in the alpha band, with the alpha-band connectivity primarily decreased near the site of stimulation. cTBS produces widespread alterations in cortical functional connectivity, with resulting shifts in cortical network topology.     

Endophenotypes in a Dynamically Connected Brain

We examined the longitudinal genetic architecture of three parameters of functional brain connectivity. One parameter described overall connectivity (synchronization likelihood, SL). The two others were derived from graph theory and described local (clustering coefficient, CC) and global (average path length, L) aspects of connectivity. We measured resting state EEG in 1,438 subjects from four age groups of about 16, 18, 25 and 50 years. Developmental curves for SL and L indicate that connectivity is more random at adolescence and old age, and more structured in middle-aged adulthood. Individual variation in SL and L were moderately to highly heritable at each age (SL: 40–82%; L: 29–63%). Genetic factors underlying these phenotypes overlapped. CC was also heritable (25–49%) but showed no systematic overlap with SL and L. SL, CC, and L in the alpha band showed high phenotypic and genetic stability from 16 to 25 years. Heritability for parameters in the beta band was lower, and less stable across ages, but genetic stability was high. We conclude that the connectivity parameters SL, CC, and L in the alpha band show the hallmarks of a good endophenotype for behavior and developmental disorders.     

EEG network connectivity changes in mild cognitive impairment — Preliminary results

Resting state EEGs were compared between patients with amnestic subtype of mild cognitive impairment (aMCI) and matched elderly controls at two times over a one year period. The study aimed at investigating the role of functional connectivity between and within different brain regions in relation to the progression of cognitive deficit in MCI. The EEG was recorded in two sessions during eyes closed and eyes open resting conditions. Functional brain connectivity was investigated based on the measurement of phase synchronization in different frequency bands. Delta and theta synchronization characteristics indicated decreased level of local and large-scale connectivity in the patients within the frontal, between the frontal and temporal, and frontal and parietal brain areas which was more pronounced 1 year later. As a consequence of opening the eyes connectivity in the alpha1 band within the parietal lobe decreased compared to the eyes closed condition but only in the control group. The lack of alpha1 band reactivity following eye opening could reliably differentiate patients from controls. Our preliminary results support the notion that the functional disconnection between distant brain areas is a characteristic feature of MCI, and may prove to be predictive in terms of the progression of this condition.     

Attenuated asymmetry of functional connectivity in schizophrenia: A high‐resolution EEG study

The interhemispheric asymmetries that originate from connectivity‐related structuring of the cortex are compromised in schizophrenia (SZ). Under the assumption that such abnormalities affect functional connectivity, we analyzed its correlate—EEG synchronization—in SZ patients and matched controls. We applied multivariate synchronization measures based on Laplacian EEG and tuned to various spatial scales. Compared to the controls who had rightward asymmetry at a local level (EEG power), rightward anterior and leftward posterior asymmetries at an intraregional level (1st and 2nd order S‐estimator), and rightward global asymmetry (hemispheric S‐estimator), SZ patients showed generally attenuated asymmetry, the effect being strongest for intraregional synchronization in the alpha and beta bands. The abnormalities of asymmetry increased with the duration of the disease and correlated with the negative symptoms. We discuss the tentative links between these findings and gross anatomical asymmetries, including the cerebral torque and gyrification pattern, in normal subjects and SZ patients.     

Abnormal ERD/ERS but Unaffected BOLD Response in Patients with Unverricht�CLundborg Disease During Index Extension: A Simultaneous EEG-fMRI Study

Electrophysiological studies indicate that Unverricht-Lundborg's disease (ULD), the most common form of progressive myoclonus epilepsy in Europe, is characterized by the involvement of multiple cortical regions in degenerative changes that lead to enhanced excitation and deficient inhibition. We searched for the haemodynamic correlates of these effects using functional MRI (fMRI) of self-paced index extensions, a well-accepted task highlighting significant differences. EEG and fMRI were simultaneously acquired in 11 ULD patients and 16 controls, performing the index extensions individually (event-related task) as well as repetitively (block task). ERD/ERS analysis was performed for the EEG data in the alpha and beta bands. fMRI time-series were analyzed using the traditional general linear model, as well as with an assumption-free approach, and by means of cross-region correlations representing functional connectivity. In line with the existing literature, ULD patients had enhanced desynchronization in the alpha band and reduced post-movement synchronization in the beta band. By contrast, fMRI did not reveal any difference between the two groups; there were no activation intensity, latency or extent effects, no significant engagement of additional regions, and no changes to functional connectivity. We conclude that, so long as the patients are executing a task which does not induce obvious action myoclonus, the hypothesized abnormalities in pyramidal neuron and interneuron dynamics are relatively subtle, embodied in processes which are not metabolically-demanding and take place at a time-scale invisible to fMRI.     

Changes of EEG spectra and coherence following performance in a cognitive task in Alzheimer's disease.

Electroencephalographic measures combined with cognitive tasks are widely used for the assessment of cognitive and pathophysiological changes in Alzheimer's disease (AD). Instead of the analysis of EEG data obtained during the performance of the task, in this study data recorded in the immediate after-task period were analyzed. It was expected that this period would correspond to the electrophysiological consequences of the cognitive effort. Data of 14 patients with AD (MMS score: 16-24) were compared to that of 10 healthy control subjects. Reverse counting of a fix duration was used as a cognitive task. Changes of relative frequency spectra, and those of inter-and intrahemispheric coherence were analyzed. Relative theta power was significantly higher in AD patients compared to the controls both before and after the task. The performance of the task resulted in an increase of the relative alpha2 band in the AD group, whereas it slightly decreased in the control group. The most prominent coherence differences between AD and controls were found in the alpha1 band, especially for long-range coherence values. Coherence in this frequency band increased in the control group following the task, not seen in the AD group. We conclude that EEG parameters calculated from epochs following the completion of a cognitive task clearly differentiates patients with AD from normal controls. The electrophysiological changes found in AD may correspond to the decrease of functional connectivity of cortical areas and to the malfunctioning of the networks engaged in the cognitive task investigated.     

基于脑电的意识障碍重复经颅磁刺激调控评估

近年来,研究表明重复经颅磁刺激(rTMS)可以有效调控颅脑损伤后意识障碍患者的意识状态,但是最小意识状态患者和植物状态患者在调控中的临床反应存在显著差异。通过脑电活动和脑功能网络,评估rTMS对意识障碍患者的调控,探索rTMS对意识障碍患者脑调控的潜在机理。共纳入24名意识障碍患者参加rTMS的真假调控实验。在调控前后记录分析64导联脑电信号的相对功率谱能量,相位锁值以及功能网络特征用研究,以评估脑功能活动的变化。结果发现,rTMS可以显著调控最小意识状态患者的Gamma活动:谱能量和功能连接显著增强,这种增强主要发生在前额-中央区以及前额-顶叶部位。基于图论的功能网络分析表明,rTMS可显著降低最小意识状态患者的功能网络平均路径(1.32±0.31 vs 1.08±0.22),提高网络集聚系数(0.95±0.15 vs 1.12±0.21)和小世界特性(0.76±0.24 vs 1.06±0.32)。研究结果表明,rTMS并不能明显调控植物状态患者的脑电Gamma活动。由于Gamma活动在人类意识和认知活动中至关重要,该研究能为rTMS对意识障碍患者的临床康复应用提供潜在的评估方法和理论。     

Cognitive decline in Parkinson's disease is associated with slowing of resting-state brain activity: a longitudinal study

The pathophysiological mechanisms of Parkinson's disease (PD)-related dementia (PDD) are still poorly understood. Previous studies using electroencephalography (EEG) and magnetoencephalography (MEG) have demonstrated widespread slowing of oscillatory brain activity as a neurophysiological characteristic of PD-related dementia. Here, we use MEG to longitudinally study early changes in oscillatory brain activity in initially nondemented PD patients that may be associated with cognitive decline. Using a longitudinal design, resting-state MEG recordings were performed twice at an approximate 4-year interval in 14 healthy controls and 49 PD patients. Changes in peak frequency and in relative spectral power for 10 brain regions were analyzed in relation to clinical measures of cognitive and motor function. In contrast to healthy controls, PD patients showed a slowing of the dominant peak frequency. Furthermore, analysis per frequency band revealed an increase in theta power over time, along with decreases in alpha1 and alpha2 power. In PD patients, decreasing cognitive performance was associated with increases in delta and theta power, as well as decreases in alpha1, alpha2, and gamma power, whereas increasing motor impairment was associated with a theta power increase only. The present longitudinal study revealed widespread progressive slowing of oscillatory brain activity in initially nondemented PD patients, independent of aging effects. The slowing of oscillatory brain activity strongly correlated with cognitive decline and therefore holds promise as an early marker for the development of dementia in PD.     

Topographic Quantitative EEG in Elderly Subjects with Major Depression

Some previous quantitative EEG research indicates that depressed subjects show increased alpha and beta compared to controls. In this report, absolute and relative amplitude measures of topographic EEG were used to compare elderly subjects with major depression to sex and age matched control subjects. Elderly depressed subjects showed significantly higher absolute alpha amplitude than controls, but regional differences did not specifically distinguish them. Relative alpha amplitudes, and absolute and relative measures of beta, delta, and theta did not reliably distinguish depressed and control subjects. The results are discussed in the context of previous EEG research in depression and the elderly. Methodological features and the implications of these findings for state and trait dependent conceptualizations of depression are considered.     

Prefrontal brain asymmetry and aggression in imprisoned violent offenders

Anterior brain asymmetry, assessed through the alpha and beta band in resting-state electroencephalogram (EEG) is associated with approach-related behavioral dispositions, particularly with aggression in the general population. To date, the association between frontal asymmetry and aggression has not been examined in highly aggressive groups. We examined the topographic characteristics of alpha and beta activity, the relation of both asymmetry metrics to trait aggression, and whether alpha asymmetry was extreme in anterior regions according to clinical standards in a group of imprisoned violent offenders. As expected, these individuals were characterized by stronger right than left-hemispheric alpha activity, which was putatively extreme in anterior regions in one third of the cases. We also report that in line with observations made in the general population, aggression was associated with stronger right-frontal alpha activity in these violent individuals. This suggests that frontal alpha asymmetry, as a correlate of trait aggression, might be utilizable as an outcome measure in studies which assess the effects of anti-aggressiveness training in violent offenders.     

Functional dysconnectivity of the dorsolateral prefrontal cortex in first-episode schizophrenia using resting-state fMRI

The known regional abnormality of the dorsolateral prefrontal cortex (DLPFC) and its role in various neural circuits in schizophrenia has given prominence to its importance in studies on the dysconnection associated with schizophrenia. Abnormal functional connectivities of the DLPFC have been found during various goal-directed tasks; however, the occurrence of the abnormality during rest in patients with schizophrenia has rarely been reported. In the present study, we selected bilateral Brodmann's area 46 as region of interest and analyzed the differences in the DLPFC functional connectivity pattern between 17 patients with first-episode schizophrenia (FES) and 17 matched controls using resting-state fMRI. We found that the bilateral DLPFC showed reduced functional connectivities to the parietal lobe, posterior cingulate cortex, thalamus and striatum in FES patients. We also found enhanced functional connectivity between the left DLPFC and the left mid-posterior temporal lobe and the paralimbic regions in FES patients. Our results suggest that functional dysconnectivity associated with the DLPFC exists in schizophrenia during rest. This may be partially related to disturbance in the intrinsic brain activity.     

Electrophysiological Signatures of Intrinsic Functional Connectivity Related to rTMS Treatment for Mal de Debarquement Syndrome

To determine intrinsic functional connectivity (IFC) related to symptom changes induced by rTMS in mal de debarquement syndrome (MdDS), a motion perceptual disorder induced by entrainment to oscillating motion. Twenty right-handed women (mean age: 52.9?±?12.6 years; mean duration illness: 35.2?±?24.2 months) with MdDS received five sessions of rTMS (1 Hz right DLPFC, 10 Hz left DLPFC) over consecutive days. High-density (128-channel) resting-state EEG were recorded prior to and following treatment sessions and analyzed using a group-level independent component (IC) analysis. IFC between 19 ICs was quantified by inter-IC phase coherence (ICPC) in six frequency bands (delta, theta, low alpha, high alpha, beta, gamma). Correlational analyses between IFCs and symptoms were performed. Symptom improvement after rTMS was significantly correlated with (1) an increase in low alpha band (8–10 Hz) IFC but a decrease of IFC in all other bands, and (2) high baseline IFC in the high alpha (11–13 Hz) and beta bands (14–30 Hz). Most treatment related IFC changes occurred between frontal and parietal regions with a linear association between the degree of symptom improvement and the number of coherent IFC changes. Frequency band and region specific IFC changes correlate with and can predict symptom changes induced by rTMS over DLPFC in MdDS. MdDS symptom response correlates with high baseline IFC in most frequency bands. Treatment induced increase in long-range low alpha IFC and decreases in IFC in other bands as well as the proportion of coherent IFC changes correlate with symptom reduction.     

Relation between resting EEG to cognitive performance and clinical symptoms in adults with attention-deficit/hyperactivity disorder

Attention-deficit/hyperactivity disorder (ADHD) in children is characterized by elevated levels of slow wave activity and reduced fast wave activity in resting-state electroencephalogram (EEG). In adults with ADHD, resting-state EEG findings are scarce and inconsistent. The present study examined whether the disparate findings are due EEG recording conditions (i.e., eyes-open vs. eyes-closed). A second goal of the current study was to assess relations between EEG spectral indices to performance measures obtained using a stop-signal task, and to behavioral ADHD symptoms. The present study included 24 adults with ADHD and 24 control adults. The EEG results showed a greater reduction in alpha power from eyes-closed to eyes-open (i.e., alpha attenuation) in ADHD compared to controls. In addition, theta/beta ratio was negatively correlated to the speed of responding to choice stimuli. These findings were interpreted vis-à-vis a biophysical model assuming that the hypo-arousal in ADHD is due to an overdrive of the nucleus coeruleus resulting in inhibitory activity of the thalamic reticular nucleus.     

Brain connectivity in positive and negative syndrome schizophrenia

If, as is widely believed, schizophrenia is characterized by abnormalities of brain functional connectivity, then it seems reasonable to expect that different subtypes of schizophrenia could be discriminated in the same way. However, evidence for differences in functional connectivity between the subtypes of schizophrenia is largely lacking and, where it exists, it could be accounted for by clinical differences between the patients (e.g. medication) or by the limitations of the measures used. In this study, we measured EEG functional connectivity in unmedicated male patients diagnosed with either positive or negative syndrome schizophrenia and compared them with age and sex matched healthy controls. Using new methodology (Medkour et al., 2009) based on partial coherence, brain connectivity plots were constructed for positive and negative syndrome patients and controls. Reliable differences in the pattern of functional connectivity were found with both syndromes showing not only an absence of some of the connections that were seen in controls but also the presence of connections that the controls did not show. Comparing connectivity graphs using the Hamming distance, the negative-syndrome patients were found to be more distant from the controls than were the positive syndrome patients. Bootstrap distributions of these distances were created which showed a significant difference in the mean distances that was consistent with the observation that negative-syndrome diagnosis is associated with a more severe form of schizophrenia. We conclude that schizophrenia is characterized by widespread changes in functional connectivity with negative syndrome patients showing a more extreme pattern of abnormality than positive syndrome patients.     

Impairments in cognition and resting-state connectivity of the hippocampus in elderly subjects with type 2 diabetes

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of Alzheimer's disease, which involves hippocampus-mediated cognitive impairment. The present study investigated whether the resting-state functional connectivity of the hippocampus would be changed in patients with T2DM. A region of interest-based resting-state functional magnetic resonance imaging (fMRI) approach was applied to explore functional connectivity differences between 21 elderly patients with T2DM and 19 well-matched healthy controls, with all participants assessed by multi-dimensional neuropsychological tests. We found that T2DM patients performed significantly worse in the Auditory Verbal Learning Test (AVLT) (especially for Delayed Recall and Recognition) and Clock Drawing Test (CDT) when compared with the control group, and cognitive function was negatively related to BMI and HbA_1c. Importantly, the hippocampus showed reduced functional connectivity bilaterally to widespread regions, including fusiform gyrus, frontal gyrus, temporal gyrus, anterior cingulate gyrus, medial frontal gyrus, posterior cingulate gyrus, precuneus and inferior parietal lobule in T2DM patients compared to healthy controls. T2DM is associated with an impaired pattern of default network function, and the specific disconnection pattern identified may be involved in the neuropathophysiology of this disease.     

Reduced functional connectivity in early-stage drug-naive Parkinson's disease: a resting-state fMRI study

Although cardinal motor symptoms in Parkinson's disease (PD) are attributed to dysfunction of corticostriatal loops, early clinical nonmotor features are more likely to be associated with other pathologic mechanisms. We enrolled 52 early-stage drug-naive PD patients and 52 age- and sex-matched healthy controls and used resting-state functional connectivity magnetic resonance imaging to evaluate alteration of the functional brain network in PD, focusing in particular on the functional connectivity of the striatum subregions. Relative to healthy controls, the PD patient group showed reduced functional connectivity in mesolimbic-striatal and corticostriatal loops. Although the deceased functional connectivity within cortical sensorimotor areas was only evident in the most affected putamen subregion, reduced functional connectivity with mesolimbic regions was prevalent throughout the striatum. No increased functional connectivity was found in this cohort. By studying a cohort of early-stage drug-naive PD patients, we ruled out the potential confounding effect of prolonged antiparkinson medication use on the functional integration of neural networks. We demonstrate decreased functional integration across neural networks involving striatum, mesolimbic cortex, and sensorimotor regions in these patients and postulate that the prevalent disconnection in mesolimbic-striatal loops is associated with some early clinical nonmotor features in PD. This study offers additional insight into the early functional integration of neural networks in PD.     

Analysis of EEG activity in response to binaural beats with different frequencies

When two coherent sounds with nearly similar frequencies are presented to each ear respectively with stereo headphones, the brain integrates the two signals and produces a sensation of a third sound called binaural beat (BB). Although earlier studies showed that BB could influence behavior and cognition, common agreement on the mechanism of BB has not been reached yet. In this work, we employed Relative Power (RP), Phase Locking Value (PLV) and Cross-Mutual Information (CMI) to track EEG changes during BB stimulations. EEG signals were acquired from 13 healthy subjects. Five-minute BBs with four different frequencies were tested: delta band (1 Hz), theta band (5 Hz), alpha band (10 Hz) and beta band (20 Hz). We observed RP increase in theta and alpha bands and decrease in beta band during delta and alpha BB stimulations. RP decreased in beta band during theta BB, while RP decreased in theta band during beta BB. However, no clear brainwave entrainment effect was identified. Connectivity changes were detected following the variation of RP during BB stimulations. Our observation supports the hypothesis that BBs could affect functional brain connectivity, suggesting that the mechanism of BB–brain interaction is worth further study.     

基于平滑最小方差无失真响应的一致性同步算法研究

脑电信号一致性反映双通道信号在一定频率范围上波动形式的一致程度,反映相应位点大脑之间的联络性。将基于最小方差无失真响应的一致性算法与核滤波相结合,提出平滑最小方差无失真响应一致性算法(SMVDR);仿真实验表明,SMVDR在窄带信号和宽带信号中均有较好的准确性和抗噪性能。利用新算法SMVDR,对31例糖尿病患者(遗忘型轻度认知障碍aMCI组18人,认知功能正常对照组13 人)的脑电信号在大脑不同区域、不同频带(δ,θ,α,β)进行一致性分析,统计分析发现:aMCI组在左右颞间δ频段的一致性下降而β频段一致性增加,前额枕区的θ频段的一致性增加,右颞枕区和前额右颞区域的α频段一致性下降。一致性值与MOCA得分的相关性分析发现,在特征通道下δ和α频段的一致性与MOCA得分存在显著的正相关,θ和β频段一致性与MOCA分数呈负相关。SMVDR算法可以更好地计算双通道脑电信号之间的一致程度,对于理解老年期轻度认知障碍的患病机制并进行早期诊断与干预具有重要的意义。