Brain Topography最新文献

The ability to maintain our body's balance and stability in space is crucial for performing daily activities. Effective postural control (PC) strategies rely on integrating visual, vestibular, and proprioceptive sensory inputs. While neuroimaging has revealed key areas involved in PC-including brainstem, cerebellum, and cortical networks-the rapid neural mechanisms underlying dynamic postural tasks remain less understood. Therefore, we used EEG microstate analysis within the BioVRSea experiment to explore the temporal brain dynamics that support PC. This complex paradigm simulates maintaining an upright posture on a moving platform, integrated with virtual reality (VR), to replicate the sensation of balancing on a boat. Data were acquired from 266 healthy subjects using a 64-channel EEG system. Using a modified k-means method, five EEG microstate maps were identified to best model the paradigm. Differences in each microstate maps feature (occurrence, duration, and coverage) between experimental phases were analyzed using a linear mixed model, revealing significant differences between microstates within the experiment phases. The temporal parameters of microstate C showed significantly higher levels in all experimental phases compared to other microstate maps, whereas microstate B displayed an opposite pattern, consistently showing lower levels. This study marks the first attempt to use microstate analysis during a dynamic task, demonstrating the decisive role of microstate C and, conversely, microstate B in differentiating the PC phases. These results demonstrate the utility of microstate technique in studying temporal brain dynamics during PC, with potential applications in the early detection of neurodegenerative diseases.

There is growing interest in the neural network of pragmatic language and its potential overlap with the Theory of Mind (ToM) network. However, no Spanish-adapted fMRI tasks were used for studying sarcasm, the subtype of pragmatic language most related to ToM. Furthermore, stimuli used in prior studies often impose high cognitive demands, confounding its sarcasm brain representation with the executive network. We investigate the neural correlates of sarcasm in Spanish using a novel experimental paradigm designed to minimize cognitive load and enhance ecological validity. Eighteen healthy, right-handed participants underwent a 3T fMRI session with a sarcasm comprehension task. Brain activations analysed with SPM12 were calculated for sarcasm vs. literal contrast. Sarcasm activated the left temporo-parietal junction, Medial Prefrontal Cortex (BA 10), Left Inferior Frontal Gyrus (BA 45), Left Medial and Superior Temporal Gyrus (BA 21 & 22), and Left Temporal Pole (BA 38). Sarcasm comprehension involves an extensive fronto-temporal-parietal network, with prominent activation of ToM-related areas. These findings suggest an overlap between sarcasm and ToM networks, emphasizing the role of the medial prefrontal cortex in pragmatic language, the left inferior frontal gyrus in semantic integration, and the role of a left-lateralized frontotemporal network for sarcasm processing.

Type 1 Diabetes Mellitus (T1DM) progression has a direct impact on brain microstructural integrity and typical functional organization from the early stages of neurodevelopment. Diffusion Tensor Imaging (DTI) is a neuroimaging method that has proven sensitive to changes in white matter microstructure. Using diffusion-weighted probabilistic tractography methods, we aim to evaluate the white matter integrity and anatomical relationships within the Default Mode Network (DMN) brain regions, which have been proven to be particularly affected by T1DM in a group of eighteen carefully selected clinically well-controlled young T1DM patients versus eighteen healthy matched controls according to sex, age, and education level. Results showed no relevant differences in the anatomical distribution of DMN between the groups. However, the transitivity graph metric was significantly lower in T1DM patients, who also showed weaker connectivity between the left ventral prefrontal cortex and the left medial temporal gyrus, representing the anatomical trajectory of the arcuate fasciculus. Considering that neural myelination is affected by language input and the critical role of language-related structures on brain development, the current findings denote early ill-driven brain modifications to better adapt to the increasing daily demands.

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.