Brain Topography最新文献

Hemodynamic responses in the dorsolateral prefrontal cortex (DLPFC) during gait initiation could influence anticipatory postural adjustments (APAs). However, how DLPFC during motor preparation modulates APA integration remains unknown. Seventeen right-handed participants completed two sessions of the rapid arm raising task and simultaneously received the real and sham repetitive transcranial magnetic stimulation (rTMS) over the left DLPFC during the motor preparation period before arm raising. The rTMS protocol involves 10 Hz stimulation at an intensity of 110% of the resting motor threshold. The activations of DLPFC, supplementary motor area (SMA), and primary motor cortex (M1) were recorded using the functional near-infrared spectroscopy (fNIRS) during the rapid arm raising task. The APAs were assessed by recording the latency and amplitude of the postural muscles using the surface electromyography. Compared with sham stimulation, the activation of DLPFC (t = -2.97, p = 0.033), SMA (t = -2.141, p = 0.048) and M1 (t = -2.787, p = 0.013) was significantly decreased during real rTMS. It was also observed that the latency was reduced (t = -2.209, p = 0.041) and the amplitude was decreased (t = -2.696, p = 0.010) during real rTMS in the superficial lumbar multifidus. The DLPFC activation was positively correlated with those of M1 (r = 0.569, p = 0.017) and SMA (r = 0.595, p = 0.012) in the real rTMS session. Finally, the oxygenated hemoglobin concentration in the DLPFC and M1 significantly correlated with the muscle amplitude (r = 0.646, p = 0.007 and r = 0.589, p = 0.013, respectively). The association between DLPFC and the APAs was totally mediated by M1. rTMS over the DLPFC during motor preparation could enhance the neural efficiency of the M1, and subsequently facilitate the integration of APAs with voluntary movement.

Electroencephalography (EEG) recordings are widely used in neuroscience to identify healthy individual brain rhythms and to detect alterations associated with various brain diseases. However, understanding the cellular origins of scalp EEG signals and their spatiotemporal changes during the resting state (RS) in humans remains challenging, as cellular-level recordings are typically restricted to animal models. The objective of this study was to simulate individual-specific spatiotemporal features of RS EEG and measure the degree of similarity between real and simulated EEG. Using a physiologically grounded whole-brain computational model (based on known neuronal subtypes and their structural and functional connectivity) that simulates interregional cortical circuitry activity, realistic individual EEG recordings during RS of three healthy subjects were created. The model included interconnected neural mass modules simulating activities of different neuronal subtypes, including pyramidal cells and four types of GABAergic interneurons. High-definition EEG and source localization were used to delineate the cortical extent of alpha and beta-gamma rhythms. To evaluate the realism of the simulated EEG, we developed a similarity index based on cross-correlation analysis in the frequency domain across various bipolar channels respecting standard longitudinal montage. Alpha oscillations were produced by strengthening the somatostatin-pyramidal loop in posterior regions, while beta-gamma oscillations were generated by increasing the excitability of parvalbumin-interneurons on pyramidal neurons in anterior regions. The generation of realistic individual RS EEG rhythms represents a significant advance for research fields requiring data augmentation, including brain-computer interfaces and artificial intelligence training.

This study investigates changes in resting-state networks (RSNs) associated with tobacco addiction (TA) and whether these changes reflect alterations in neurotransmitter systems. A total of 90 patients with TA and 46 healthy controls (HCs) matched for age, education, and body mass index undergo functional magnetic resonance imaging (fMRI) scans. Independent component analysis (ICA) is employed to extract RSNs based on a customized network template using the HCP ICA MATCHING toolbox. Additionally, a correlation study is conducted to examine the relationship between changes in functional connectivity (FC) within RSNs and positron emission tomography and single photon emission computed tomography-derived maps, aiming to identify specific neurotransmitter system changes underlying abnormal FC in TA. Compared to HCs, the TA group exhibits decreased FC values in the left precentral gyrus of the sensorimotor network B and in the right calcarine of the visual network B. Furthermore, changes in FC within the visual network B are associated with the 5-hydroxytryptamine system (1a) and opioid receptor system (Kappa) maps. Post-hoc power analysis confirms the adequacy of the sample size, with effect sizes (d) all greater than 0.9, supporting the robustness of the findings. Patients with TA show reduced intranetwork connectivity in the sensorimotor network B and visual network B, which may reflect underlying molecular changes. These findings improve understanding of the neurobiological aspects of TA.

This study aimed to investigate the impaired cognitive flexibility and its underlying neural mechanisms in insomnia. By combining resting-state fMRI and the Cognitive Flexibility Inventory (CFI), we examined the associations between insomnia severity, spontaneous brain activity (the fractional amplitude of low-frequency fluctuations, fALFF) and functional connectivity (FC) with total cognitive flexibility scores. Behavioral results showed that insomnia severity significantly affected the control sub-dimension of cognitive flexibility. The fALFF analyses indicated that the right insula (Ins) was a key brain region significantly associated with cognitive flexibility. Further analysis based on the Ins revealed that FC between Ins and the bilateral superior temporal gyrus (STG), as well as Ins and the right precuneus, were significantly positively correlated with the total cognitive flexibility scores, with the right supplementary motor area (SMA) in the alternative sub-dimension, with the left lingual gyrus, right STG, right precuneus, and left paracentral lobule (PCL) in the control sub-dimension. The results suggest that the different sub-dimensions represent different neural pathways for cognitive flexibility, of which the PCL may be a brain region specific to insomnia patients. These findings reveal the impact of insomnia on the neural basis of cognitive flexibility and provides potential brain targets for future intervention and treatment.

Background: The primary distinction between narcolepsy type 1 (NT1) and narcolepsy type 2 (NT2) is the presence or absence of cataplexy, which is commonly determined through clinical interviews, though it can be prone to error due to vague patients descriptions.

Objective: This study aimed to investigate EEG microstate differences between NT1 and NT2 and their correlation with clinical assessments.

Methods: Polysomnography (PSG) and the Multiple Sleep Latency Test (MSLT) were performed on 14 NT1 and 13 NT2 patients from three hospitals, with data from the ISRUC-SLEEP dataset serving as the comparison group. After EEG preprocessing, we performed the spectral analysis in NT1 and NT2, followed by microstate analysis. Grand mean maps were used for backfitting to obtain microstate parameters. Then, Spearman correlation was performed between the microstate parameters and the ESS and MSLT parameters.

Results: We found that the relative delta power in N2 was lower in the NT1 group compared to the NT2 group. Four microstates were clustered in all groups, and no statistical differences were observed in the microstate parameters between NT1 and NT2 groups. In the NT1 group, microstate D during wakefulness showed a positive correlation with ESS, while in the NT2 group, microstate D during wakefulness showed a negative correlation with ESS.

Conclusions: There are spectral differences between the NT1 and NT2 groups, and the opposite correlation between microstate D and ESS during wakefulness in NT1 and NT2 suggest that the underlying mechanisms leading to excessive daytime sleepiness in the two groups may be different.

Transcranial magnetic stimulation (TMS)-evoked potentials (TEPs) represent an innovative measure for examining brain connectivity and developing biomarkers of psychiatric conditions. Minimizing TEP variability across studies and participants, which may stem from methodological choices, is therefore vital. By combining classic peak analysis and microstate investigation, we tested how TMS pulse waveform and current direction may affect cortico-cortical circuit engagement when targeting the primary motor cortex (M1). We aim to disentangle whether changing these parameters affects the degree of activation of the same neural circuitry or may lead to changes in the pathways through which the induced activation spreads. Thirty-two healthy participants underwent a TMS-EEG experiment in which the pulse waveform (monophasic, biphasic) and current direction (posterior-anterior, anterior-posterior, latero-medial) were manipulated. We assessed the latency and amplitude of M1-TEP components and employed microstate analyses to test differences in topographies. Results revealed that TMS parameters strongly influenced M1-TEP components' amplitude but had a weaker role over their latencies. Microstate analysis showed that the current direction in monophasic stimulations changed the pattern of evoked microstates at the early TEP latencies, as well as their duration and global field power. This study shows that the current direction of monophasic pulses may modulate cortical sources contributing to TEP signals, activating neural populations and cortico-cortical paths more selectively. Biphasic stimulation reduces the variability associated with current direction and may be better suited when TMS targeting is blind to anatomical information.

Negative symptoms represent pervasive symptoms in schizophrenia (SZ) and major depressive disorder (MDD). Empirical findings suggest that disrupted striatal function contributes significantly to negative symptoms. However, the changes in striatal functional connectivity in relation to these negative symptoms, in the transdiagnostic context, remain unclear. The present study aimed to capture the shared neural mechanisms underlying negative symptoms in SZ and MDD. Resting-state functional magnetic resonance imaging data were obtained from 60 patients with SZ and MDD (33 with SZ and 27 with MDD) exhibiting predominant negative symptoms, and 52 healthy controls (HC). Negative symptoms and hedonic capacity were assessed using the Scale for Assessment of Negative Symptoms (SANS) and the Temporal Experience of Pleasure Scale (TEPS), respectively. Signal extraction for time series from 12 subregions of the striatum was carried out to examine the group differences in resting-state functional connectivity (rsFC) between striatal subregions and the whole brain. We observed significantly decreased rsFC between the right dorsal rostral putamen (DRP) and the right pallidum, the bilateral rostral putamen and the contralateral putamen, as well as between the dorsal caudal putamen and the right middle frontal gyrus in both patients with SZ and MDD. The right DRP-right pallidum rsFC was positively correlated with the level of negative symptoms in SZ. However, patients with SZ showed increased rsFC between the dorsal striatum and the left precentral gyrus, the right middle temporal gyrus, and the right lingual gyrus compared with those with MDD. Our findings expand on the understanding that reduced putaminal rsFC contributes to negative symptoms in both SZ and MDD. Abnormal functional connectivity of the putamen may represent a partially common neural substrate for negative symptoms in SZ and MDD, supporting that the comparable clinical manifestations between the two disorders are underpinned by partly shared mechanisms, as proposed by the transdiagnostic Research Domain Criteria.

Virtual reality (VR) is an immersive technology capable of simulating alternate realities, however, it often leads to cybersickness, causing discomfort for users. We conducted an experiment using a group of 30 participants (aged 25 ± 2.1 years) to see the alpha and delta wave changes for three conditions: Blank, Video, and Video Pause, with electroencephalography (EEG) recordings. The experiments were repeated three times (Trial 1, Trial 2, and Trial 3). The results showed a significant increase in delta wave power for Video compared with the Blank (p < 0.05). Video Pause showed a significant decrease compared to Video. Alpha waves significantly decreased during the Video compared with Blank (p < 0.05). Alpha waves during Video Pause showed a significant increase compared to Video (p < 0.05). Our study showed consistent alterations in alpha and delta waves across various visual stimuli for inducing cybersickness, and we observed that the decrease in alpha waves may be significantly associated with cybersickness rather than visual stimuli. These findings have implications for advancing cybersickness research.

Electroencephalographic (EEG) oscillations occur across a wide range of spatial and spectral scales, and analysis of neural rhythmic variability have attracted recent attention as markers of development, intelligence, cognitive states and neural disorders. Nonnegative matrix factorization (NMF) has been successfully applied to multi-subject electroencephalography (EEG) spectral analysis. However, existing group NMF methods have not explicitly optimized the individual-level EEG components derived from group-level components. To preserve EEG characteristics at the individual level while establishing correspondence of patterns across participants, we present a novel framework for obtaining subject-specific EEG components, which we term group-information guided NMF (GIGNMF). In this framework, group information captured by standard NMF at the group level is utilized as guidance to compute individual subject-specific components through a multi-objective optimization strategy. Specifically, we propose a three-stage framework: first, group-level consensus EEG patterns are derived using standard group NMF tools; second, an optimal procedure is implemented to determine the number of components; and finally, the group-level EEG patterns serve as references in a new one-unit NMF employing a multi-objective optimization solver. We test the performance of the algorithm on both synthetic signals and real EEG recordings obtained from Alzheimer's disease data. Our results highlight the feasibility of using GIGNMF to identify EEG spatiotemporal patterns and present novel individual electrophysiological characteristics that enhance our understanding of cognitive function and contribute to clinical neuropathological diagnosis.

EEG is the most powerful tool for epilepsy discharge detection in brain. Visual evaluation is hard in long term monitoring EEG data as huge amount of data needs to be inspected. Considering the fast and efficient results from deep learning networks especially convolutional networks, and its capability for detection of complex epileptic wave forms, inspired us to evaluate YOLO network for spike detection solution.The most used versions of YOLO (V3, V4 and V7) were evaluated for various epileptic signals. The epileptic discharge wave-forms were first labeled to 9 different signal types, but classified to four group combinations based on their features. EEG data from 20 patients were used under guidance of expert epileptologist. The YOLO networks were all trained for four various class-grouping strategies. The most suitable network to recommend was found to be YOLO-V4, for all four classifying methods giving average sensitivity, specificity, and accuracy of 96.7, 94.3, and 92.8, respectively. YOLO networks have shown promising results in detection of epileptic signals, which by adding some extra measurements this can become a great assistant tool for epileptologists. In addition, besides YOLO's High speed and accuracy in detection of epileptic signals in EEG, it can classify these signals to different morphologies.