Brain Network Activity Research Articles

Microglia depletion facilitates the display of maternal behavior and alters activation of the maternal brain network in nulliparous female rats.

The peripartum period is accompanied by peripheral immune alterations to promote a successful pregnancy.We and others have also demonstrated significant neuroimmune changes that emerge during late pregnancy and persist postpartum, most prominently decreased microglia numbers within limbic brain regions. Here we hypothesized that microglial downregulation is important for the onset and display of maternal behavior. To test this, we recapitulated the peripartum neuroimmune profile by depleting microglia in non-mother (i.e., nulliparous) female rats who are typically not maternal but can be induced to behave maternally towards foster pups after repeated exposure, a process called maternal sensitization. BLZ945, a selective colony-stimulating factor 1 receptor (CSF1R) inhibitor, was administered systemically to nulliparous rats, which led to ~75% decrease in microglia number. BLZ- and vehicle-treated females then underwent maternal sensitization and tissue wasstained for ∆fosB to examine activation across maternally relevant brain regions. We found BLZ-treated females with microglial depletion met criteria for displaying maternal behavior significantly sooner than vehicle-treated females and displayed increased pup-directed behaviors. Microglia depletion also reduced threat appraisal behavior in an open field test. Notably, nulliparous females with microglial depletion had decreased numbers of ∆fosB+ cells in the medial amygdala and periaqueductal gray, and increased numbers in the prefrontal cortex and somatosensory cortex, compared to vehicle. Our results demonstrate that microglia regulate maternal behavior in adult females, possibly by shifting patterns of activity in the maternal brain network.

Effects of dorsolateral prefrontal cortex stimulation on network topological attributes in young individuals with high-level perceived stress: A randomized controlled trial

Individuals with high-level perceived stress are at higher risk of developing a psychiatric disorder. While repetitive transcranial magnetic stimulation (rTMS) is effective for improving emotional symptoms, there is little evidence of its effect on perceived stress. This randomized sham-controlled trial investigated the effect of rTMS on ameliorating high-level stress and explored the associated changes in brain network activity. Fifty participants with high-level perceived stress were randomly assigned to either the active or sham rTMS group and received 12 active/sham rTMS sessions over four weeks (three per week). Perceived stress score (PSS), Chinese affective scale (CAS) normal and now statuses, and functional network topology were measured. Our results showed greater improvements in PSS and CAS_Normal scores, and reduced path length in the default mode network after active rTMS. Functional activations of the angular gyrus, posterior insula, and prefrontal cortex were also modulated in the active group. There were significant associations between posterior insula efficiency and PSS scores, and between angular efficiency and CAS_Now scores in the active group. These cumulative findings suggest rTMS as a promising intervention for recovery from high-level perceived stress.

Altered regional brain activity and functional connectivity in resting-state brain networks associated with psychological erectile dysfunction.

Erectile dysfunction (ED), especially psychological ED (pED), is usually accompanied with psychological factors, which are related to abnormal activity in brain regions involved in sexual behavior. However, the mechanisms underlying functional changes in the brain of pED are still unclear. The present study aimed to explore the abnormalities of brain function, as well as their relationships with sexual behavior and emotion in pED patients. Resting state functional magnetic resonance imaging (rs-fMRI) data were collected from 31 pED patients to 31 healthy controls (HCs). The values of amplitude of fractional amplitude of low-frequency fluctuation (fALFF) and functional connectivity (FC) were calculated and compared between groups. In addition, the associations between abnormal brain regions and clinical features were evaluated by Pearson correlation analyses. Compared to HCs, pED patients demonstrated decreased fALFF values in the left medial superior frontal gyrus (had decreased FC values with the left dorsolateral superior frontal gyrus), the left lingual gyrus (had decreased FC values with the left parahippocamal gyrus and insula), the left putamen (had decreased FC values with the right caudate) and the right putamen (had decreased FC values with the left putamen and the right caudate). The fALFF values of the left medial superior frontal gyrus were negatively correlated with the fifth item scores of International Index of Erectile Function (IIEF-5). Negative relationships were found between fALFF values of the left putamen and the second item scores of Arizona Sexual Scale (ASEX). FC values between the right putamen and caudate were negatively related to the state scores of State-Trait Anxiety Inventory (STAI-S). Altered brain function were found in the medial superior frontal gyrus and caudate-putamen of pED patients, which were associated with sexual function and psychological condition. These findings provided new insights into the central pathological mechanisms of pED.

P.097 Effect of stimulation site on brain network activity and phonemic verbal fluency: an fMRI study.

Background: In Parkinson’s disease, deep brain stimulation (DBS) of the subthalamic nucleus (STN) or globus pallidus internus (GPi) produces comparable motor benefits. Although both increases the risk of cognition and verbal fluency (VF) decline, the risk is greater following STN-DBS. The consequences of stimulating these different sites on brain network activity is unknown. We use functional magnetic resonance imaging (fMRI) during in vivo stimulation to investigate differences between STN-DBS and GPi-DBS and correlate with change in VF. Methods: Left-sided, stimulation-cycling block-design fMRI was acquired at 3-Tesla in 51 STN-DBS and 15 GPi-DBS following routine clinical programming. Blood oxygen level-dependent (BOLD) response to stimulation was compared between groups. Phonemic VF was assessed pre- and postoperatively. Results: Voxel-wise t-test between STN-DBS and GPi-DBS BOLD response maps revealed areas of significant difference (p<0.001) in the left frontal operculum and the left caudate head. Stimulation BOLD response appears to show slight inverse correlation with postoperative VF decline. The trend is reversed at the left frontal operculum in STN-DBS compared to GPi-DBS. Conclusions: Decline in VF in PD-DBS seems associated with the stimulation BOLD response at the left frontal operculum and the left caudate head. The effect differs depending on stimulation site, suggesting differing effects on brain network activity.

Reduced Stress-Related Neural Network Activity Mediates the Effect of Alcohol on Cardiovascular Risk

BackgroundChronic stress associates with major adverse cardiovascular events (MACE) via increased stress-related neural network activity (SNA). Light/moderate alcohol consumption (ACl/m) has been linked to lower MACE risk, but the mechanisms are unclear. ObjectivesThe purpose of this study was to evaluate whether the association between ACl/m and MACE is mediated by decreased SNA. MethodsIndividuals enrolled in the Mass General Brigham Biobank who completed a health behavior survey were studied. A subset underwent 18F-fluorodeoxyglucose positron emission tomography, enabling assessment of SNA. Alcohol consumption was classified as none/minimal, light/moderate, or high (<1, 1-14, or >14 drinks/week, respectively). ResultsOf 53,064 participants (median age 60 years, 60% women), 23,920 had no/minimal alcohol consumption and 27,053 ACl/m. Over a median follow-up of 3.4 years, 1,914 experienced MACE. ACl/m (vs none/minimal) associated with lower MACE risk (HR: 0.786; 95% CI: 0.717-0.862; P < 0.0001) after adjusting for cardiovascular risk factors. In 713 participants with brain imaging, ACl/m (vs none/minimal) associated with decreased SNA (standardized beta −0.192; 95% CI: −0.338 to −0.046; P = 0.01). Lower SNA partially mediated the beneficial effect of ACl/m on MACE (log OR: −0.040; 95% CI: −0.097 to −0.003; P < 0.05). Further, ACl/m associated with larger decreases in MACE risk among individuals with (vs without) prior anxiety (HR: 0.60 [95% CI: 0.50-0.72] vs 0.78 [95% CI: 0.73-0.80]; P interaction = 0.003). ConclusionsACl/m associates with reduced MACE risk, in part, by lowering activity of a stress-related brain network known for its association with cardiovascular disease. Given alcohol’s potential health detriments, new interventions with similar effects on SNA are needed.

Effect of Visual Feedback on Behavioral Control and Functional Activity During Bilateral Hand Movement.

Previous researches state vision as a vital source of information for movement control and more precisely for accurate hand movement. Further, fine bimanual motor activity may be associated with various oscillatory activities within distinct brain areas and inter-hemispheric interactions. However, neural coordination among the distinct brain areas responsible to enhance motor accuracy is still not adequate. In the current study, we investigated task-dependent modulation by simultaneously measuring high time resolution electroencephalogram (EEG), electromyogram (EMG) and force along with bi-manual and unimanual motor tasks. The errors were controlled using visual feedback. To complete the unimanual tasks, the participant was asked to grip the strain gauge using the index finger and thumb of the right hand thereby exerting force on the connected visual feedback system. Whereas the bi-manual task involved finger abduction of the left index finger in two contractions along with visual feedback system and at the same time the right hand gripped using definite force on two conditions that whether visual feedback existed or not for the right hand. Primarily, the existence of visual feedback for the right hand significantly decreased brain network global and local efficiency in theta and alpha bands when compared with the elimination of visual feedback using twenty participants. Brain network activity in theta and alpha bands coordinates to facilitate fine hand movement. The findings may provide new neurological insight on virtual reality auxiliary equipment and participants with neurological disorders that cause movement errors requiring accurate motor training. The current study investigates task-dependent modulation by simultaneously measuring high time resolution electroencephalogram, electromyogram and force along with bi-manual and unimanual motor tasks. The findings show that visual feedback for right hand decreases the force root mean square error of right hand. Visual feedback for right hand decreases local and global efficiency of brain network in theta and alpha bands.

Neuroscience of creativity or can the ungraspable be captured?

Creativity is a particularly complex entity that can be best conceptualized along dimensions of opposite polarities. It can simultaneously be considered as a phenomenon that comprises a multitude of processes but also be interpreted as a complex construct which indeed does not have a uniformly accepted definition despite extensive literature on creativity. Creativity researchers of various approaches offer alongside methodological diversity a vast array of paradigms and definitions, leading, on the other hand, to contradictions of results. Nevertheless, the concept of creativity is to be maintained in the sense that it encompasses the ability to produce innovatively original, valuable, adaptive solutions breaking with pre-existing categories and developing unconventional alternatives. Since creativity cannot definitely be subject of scientific investigations as an overarching entity and its essence has not been grasped so far, some of its components can be measured and defined such as specific cognitive processes (divergent and convergent thinking, remote associations, conceptual expansion, working memory), motivational factors, emotional/affective conditions or personality traits considered as predictors of creative performance (schizotypal, autistic spectrum traits). Even though definitional inconsistencies persist, gradually neurobiological approaches have become the main issue of creativity research. Recently, the analysis of brain network activity applying methods of electrophysiology and brain imaging seems to promote the understanding of the functional localization of creative performance. Certain brain regions were initially identified as correlates of creativity, such as lateral prefrontal cortex, inferior parietal lobe, insula, striatum. More recent studies emphasize the activation and effective functional connectivity of large brain networks (default mode network, frontoparietal executive control, and others) as well as highlight the importance of their brain and neurochemical substrate (gray matter volume, white matter integrity, dopamine), connecting with cognitive processes of opposite style (flexibility versus persistence). While this paradigm seems to converge toward the delineation of a coherent neurobiological model of creativity, obviously we would not infer the essence of such a complex phenomenon from a simplified sub-process. Orv Hetil. 2023; 164(18): 683-693.

Patterns of multiple brain network activation in dot perspective task

In this functional MRI (fMRI) study on 82 healthy adults using the dot perspective task, inconsistency of perspectives was associated with a significant increase of the mean reaction time and number of errors both in Self and Other conditions. Unlike the Arrow (non-mentalizing), the Avatar (mentalizing) paradigm was characterized by the recruitment of parts of the mentalizing and salience networks. These data provide experimental evidence supporting the fMRI distinction between mentalizing and non-mentalizing stimuli. A widespread activation of classical theory of mind (ToM) areas but also of salience network and decision making areas was observed in the Other compared to Self-conditions. Compared to Self-Consistent, Self-Inconsistent trials were related to increased activation in the lateral occipital cortex, right supramarginal and angular gyrus as well as inferior, superior and middle frontal gyri. Compared to the Other-Consistent, Other-Inconsistent trials yielded strong activation in the lateral occipital cortex, precuneus and superior parietal lobule, middle and superior precentral gyri and left frontal pole. These findings reveal that altercentric interference relies on areas involved in self-other distinction, self-updating and central executive functions. In contrast, egocentric interference needs the activation of the mirror neuron system and deductive reasoning, much less related to pure ToM abilities.

Early detection of silent brain function changes in multiple sclerosis using magnetoencephalography (MEG): Towards an imaging biomarker (P11-3.004)

<h3>Objective:</h3> The objective are to identify imaging biomarkers that differentiate MS patient from normal control subjects using MEG. <h3>Background:</h3> MEG is a noninvasive functional brain imaging technique that measures the magnetic brain waves arising from neuronal activity during rest or a cognitive task. MEG may help detect functional changes or abnormalities in MS patients early in the disease course. <h3>Design/Methods:</h3> In this single-center prospective pilot study, the resting state MEG data from 6 patients with MS were compared to 6 control subjects. MEG data were filtered into 4 different frequency bands: theta 4–7Hz, alpha 8–13HZ, beta 14–30Hz, and gamma 30–85 Hz. Network brain activity for each frequency band was mapped for connectivity strength across 27 regions in each hemisphere, resulting in 1431 pairings in the brain. A t-test was conducted to assess group differences in average coherence values for each pair of brain regions (N= 1,431). A P-value was produced for each region pair. The false discovery rate (FDR) was used to adjust for multiple testing. Only the most statistically significant connections between the control group and the patient group were further analyzed. These were based on a p-value of less than 0.05. <h3>Results:</h3> During the resting state, the MS patients had more hyperexcited/coherent connected activity in the frontal to occipital regions, while the control subjects had more coherent connections in the frontal to temporal, frontal to parietal as well as the parietal to the temporal areas. <h3>Conclusions:</h3> MEG could detect apparent differences in active networks during rest in patients with MS compared to controls. This will have future applications to improve or tailor treatments during the early neuronal dysfunction that could lead to functional and cognitive disabilities in patients with MS. The limitation of our study is the small sample size. The complete data analysis of 10 patients will be presented at AAN 2023. <b>Disclosure:</b> Mr. Hammami has nothing to disclose. Mr. Memon has nothing to disclose. Dr. Memon has nothing to disclose. Dr. Bowyer has nothing to disclose.

Early detection of mild cognitive impairment (MCI) using MEG (P11-6.005)

<h3>Objective:</h3> Use MEG to detect imaging bio markers for mild cognitive impairment <h3>Background:</h3> Alzheimer’s Disease (AD) is a type of dementia that effects 50 million people worldwide. This is a progressive disease that affects memory loss and cognitive dysfunction. Magnetoencephalography (MEG) is a noninvasive functional brain imaging technique that measures the magnetic brain waves arising from neuronal activity during rest or during a cognitive task. MEG may help detect AD in its early stages, when confusion first starts to happen. <h3>Design/Methods:</h3> Resting state MEG data from 20 patients with mild cognitive impairment were compared to 20 control subjects. MEG data were filtered into 4 different frequency bands: theta 4–7 Hz, alpha 8–13 HZ, beta 14–30 Hz, and gamma 30–85 Hz. Network brain activity for each frequency band was mapped for the strength of connectivity across 27 regions in each hemisphere, resulting in 1431 pairings in the brain. Only the most statistically significant connections between the control group and the patient group where further analyzed, these were based on a p-value of less than 0.05. <h3>Results:</h3> Patients with MCI had more hyperexcited/coherent activity in the default mode network compared to controls. The two most statistically significant pathways differences in the beta band frequency were found in the frontal to occipital and frontal to temporal connections. <h3>Conclusions:</h3> MEG was able to detect clear differences in active networks during rest in patients with MCI compared to controls. This will have future applications to improve or tailor treatments during the early diagnosis of dementia. Our next step will be to determine the identification of AD network differences from MCI. <b>Disclosure:</b> Mr. Hammami has nothing to disclose. Fernando Maestu has nothing to disclose. Dr. López has nothing to disclose. Dr. Bowyer has nothing to disclose.

Neural effects of fatigue on cognition in relapsing multiple sclerosis detected by magnetoencephalography: Towards an imaging biomarker (P11-3.007)

<h3>Objective:</h3> Determining functional differences in MS patients during a task, compared to controls. <h3>Background:</h3> Fatigue affects 80% of patients with MS. Fatigue can also have adverse effects on cognitive abilities. MEG is a noninvasive functional brain imaging technique that measures the magnetic brain waves arising from neuronal activity during rest or during a cognitive task. MEG may help detect functional changes that happen in MS patients with fatigue and cognitive difficulties. <h3>Design/Methods:</h3> This study examined the effects of fatigue on cognition in patients with MS using the modified fatigue impact scale(MFIS) and symbol digits modalities test(SDMT) before and during MEG study respectively. MEG data from 6 patients with MS were compared to 3 control subjects. MEG data were filtered into 4 different frequency bands: theta, alpha, beta, and gamma. Network brain activity for each frequency band was mapped for the strength of connectivity across 27 regions in each hemisphere, resulting in 1431 pairings in the brain. The false discovery rate was used to adjust for multiple testing. Only the most statistically significant connections were based on a p-value of less than 0.05. <h3>Results:</h3> MS patients had most coherent beta and gamma connectivity in the fusiform and frontal regions respectively. The control subjects had more coherent connections in the frontal-parietal, frontal-temporal, and frontal-occipital regions. Individual MFIS scores in MS-patients were higher than the controls and correlated with lower SDMT scores in the MS patients. <h3>Conclusions:</h3> MEG was able to detect clear differences in active networks during SDMT tasks in patients with MS compared to controls. Slow processing speed has been associated with reduced frontal lobe activation in younger adults. Our study cohort supported the lack of coherent beta activity in the frontal lobe. The limitation of our study is a small sample size. The complete data analysis of 10 patients will be presented at AAN-2023. <b>Disclosure:</b> Dr. Memon has nothing to disclose. Mr. Hammami has nothing to disclose. Mr. Memon has nothing to disclose. Dr. Bowyer has nothing to disclose.

Changes in local and network brain activity after stereotactic thermocoagulation in patients with drug-resistant epilepsy.

Stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) aims to reduce seizure frequency by modifying epileptogenic networks through local thermocoagulative lesions. Although RF-TC is hypothesized to functionally modify brain networks, reports of changes in functional connectivity (FC) following the procedure are missing. We evaluated, by means of SEEG recordings, whether variation in brain activity after RF-TC is related to clinical outcome. Interictal SEEG recordings from 33 patients with drug-resistant epilepsy (DRE) were analyzed. Therapeutic response was defined as a >50% reduction in seizure frequency for at least 1 month following RF-TC. Local (power spectral density [PSD]) and FC changes were evaluated in 3-min segments recorded shortly before (baseline), shortly after, and 15 min after RF-TC. The PSD and FC strength values after thermocoagulation were compared with baseline as well as between the responder and nonresponder groups. In responders, we found a significant reduction in PSD after RF-TC in channels that were thermocoagulated for all frequency bands (p = .007 for broad, delta and theta, p <.001 for alpha and beta bands). However, we did not observe such PSD decrease in nonresponders. At the network level, nonresponders displayed a significant FC increase in all frequency bands except theta (broad, delta, beta band: p <.001; alpha band: p <.01), although responders showed a significant FC decrease in delta (p <.001) and alpha bands (p <.05). Nonresponders showed stronger FC changes with respect to responders exclusively in TC channels (broad, alpha, theta, beta: p >.05; delta: p = .001). Thermocoagulation induces both local and network-related (FC) changes in electrical brain activity of patients with DRE lasting for at least 15 min. This study demonstrates that the observed short-term modifications in brain network and local activity significantly differ between responders and nonresponders and opens new perspectives for studying the longer-lasting FC changes after RF-TC.

Engaging distributed cortical and cerebellar networks through motor execution, observation, and imagery.

When we interact with the environment around us, we are sometimes active participants, making directed physical motor movements and other times only mentally engaging with our environment, taking in sensory information and internally planning our next move without directed physical movement. Traditionally, cortical motor regions and key subcortical structures such as the cerebellum have been tightly linked to motor initiation, coordination, and directed motor behavior. However, recent neuroimaging studies have noted the activation of the cerebellum and wider cortical networks specifically during various forms of motor processing, including the observations of actions and mental rehearsal of movements through motor imagery. This phenomenon of cognitive engagement of traditional motor networks raises the question of how these brain regions are involved in the initiation of movement without physical motor output. Here, we will review evidence for distributed brain network activation during motor execution, observation, and imagery in human neuroimaging studies as well as the potential for cerebellar involvement specifically in motor-related cognition. Converging evidence suggests that a common global brain network is involved in both movement execution and motor observation or imagery, with specific task-dependent shifts in these global activation patterns. We will further discuss underlying cross-species anatomical support for these cognitive motor-related functions as well as the role of cerebrocerebellar communication during action observation and motor imagery.

Neural oscillations during acupuncture imagery partially parallel that of real needling.

Tasks involving mental practice, relying on the cognitive rehearsal of physical motors or other activities, have been reported to have similar patterns of brain activity to overt execution. In this study, we introduced a novel imagination task called, acupuncture imagery and aimed to investigate the neural oscillations during acupuncture imagery. Healthy volunteers were guided to watch a video of real needling in the left and right KI3 (Taixi point). The subjects were then asked to perform tasks to keep their thoughts in three 1-min states alternately: resting state, needling imagery left KI3, and needling imagery right KI3. Another group experienced real needling in the right KI3. A 31-channel-electroencephalography was synchronously recorded for each subject. Microstate analyses were performed to depict the brain dynamics during these tasks. Compared to the resting state, both acupuncture needling imagination and real needling in KI3 could introduce significant changes in neural dynamic oscillations. Moreover, the parameters involving microstate A of needling imagery in the right KI3 showed similar changes as real needling in the right KI3. These results confirm that needling imagination and real needling have similar brain activation patterns. Needling imagery may change brain network activity and play a role in neural regulation. Further studies are needed to explore the effects of acupuncture imagery and the potential application of acupuncture imagery in disease recovery.

Zuranolone, a Positive Allosteric Modulator of the GABAA Receptor: Hypothesized Mechanism of Action in Major Depressive Disorder

AbstractMajor depressive disorder (MDD) is a heterogeneous condition characterized by depressed mood and/or loss of interest/pleasure in activities, among other symptoms. Most currently available treatments for depression were developed on the hypothesis that depressive symptoms arise from a depletion of monoamines within the central nervous system (CNS). However, clinical understanding has advanced to identify brain network dysregulation as the primary driver of depression, with monoamines playing a lesser role. Prolonged inability to regulate brain networks may lead to the core symptoms and clinical presentation of MDD. Depression has been linked to impaired neuronal activity in brain networks (e.g., central executive network [CEN], default mode network [DMN], and salience network [SN]). It is hypothesized that improvement in depressive symptoms may result from restoring balance in brain networks governing mood.γ-aminobutyric acid (GABA) is critical for maintaining and restoring excitatory-inhibitory balance in the brain and regulating brain networks. Approximately one-third of neurons in the CNS are GABAergic, regulating network activity throughout the brain, including regions involved in mood, sleep, and cognition. GABA activates GABAA receptors (GABAAR), inhibiting neuronal activity through phasic (via synaptic GABAAR) and tonic (via extrasynaptic GABAAR) currents. Tonic GABA currents may play a particularly important role in regulating network activity, since they produce a large net inhibitory effect and are also involved in controlling the excitability of inhibitory interneurons, the key regulators of rhythmic brain network activity.Zuranolone is an investigational oral GABAAR positive allosteric modulator and neuroactive steroid. In clinical trials, treatment with zuranolone has shown significant improvement over placebo in depressive symptoms in adults with MDD or postpartum depression, with a generally well-tolerated and consistent safety profile.The hypothesized mechanism of zuranolone differs from monoamine-based antidepressants and from benzodiazepines. Unlike benzodiazepines, which bind to the α/γ subunit interface in synaptic GABAAR and enhance phasic inhibitory currents, zuranolone binds to the α/β subunit interface present in nearly all GABAAR, leading to enhanced phasic (synaptic) and tonic (extrasynaptic) inhibitory currents. Furthermore, in vitro evidence suggests that whereas benzodiazepines are associated with GABAAR downregulation, zuranolone upregulates the surface expression of GABAAR.In conclusion, by upregulating GABAAR expression and increasing phasic and tonic inhibitory GABAergic signaling, zuranolone may rapidly restore and maintain excitatory-inhibitory balance in brain networks, thus allowing the brain to potentially respond appropriately to internal and external stimuli.FundingSage Therapeutics, Inc., and Biogen Inc.

Нейрофизиологический метод исследования изменения активности сети пассивной работы головного мозга

Curiosity about the activity of neural networks in the human brain results from the search for definition of human self-consciousness as an identifier of human personality. Today, the RS-fMRI technology occupies a leading position among methods used to study this problem. The widespread use of the technology is limited by certain drawbacks. Starting from 2010, there is a growing interest in the possibility of using neurophysiological methods for the diagnosis of the brain's default mode network (DMN) state based on the analysis of EEG microstates. The study was aimed to demonstrate the possibility of recording the activity of brain networks both at rest and under exposure to the stimulus evoking a known response. A total of 42 people underwent assessment in the relaxed wakefulness state with the eyes closed that involved extraction of certain EEG microstate sequences and the EEG inverse problem solution. The data obtained were tested for adequacy via comparison with the results obtained by the preset stimulation of auditory and language function. The conclusion was made about the possibility of assesing the brain's DMN’s activity by combining the analysis of EEG microstates with the EEG inverse problem solution. The proposed technology can be used in both scientific research and clinical practice in the form of new techniques and systems allowing one to determine alterations in neuropsychological processes.

Disturbance of functional brain networks and cognitive decline in Parkinson's disease: Severe cerebral small vessel disease aggravates this relationship

IntroductionSeveral studies have identified a relationship between functional brain network disturbance and cognitive decline in people with Parkinson's disease (PwP); however, few studies have explored whether cerebral small vessel disease (CSVD) burden modifies this relationship. This study aimed to investigate the potential moderating effect of CSVD on the relationship between functional brain network disturbance and cognitive decline in PwP. MethodsWe prospectively recruited 61 PwP from Beijing Tiantan Hospital between October 2021 to September 2022. The Montreal Cognitive Assessment (MoCA) score was used to assess cognition. CSVD imaging markers were evaluated following the STandards for ReportIng Vascular changes on nEuroimaging instructions, and the CSVD burden score was calculated. The functional connectivity indicator was obtained and calculated using quantitative electroencephalography examination. The moderating effect of CSVD burden on the relationship between functional brain network disturbance and cognitive decline was examined using hierarchical linear regression. ResultsForty-six of 61 (75.4%) PwP had cognitive impairment. Higher global weighted phase lag index (wPLI) values in beta1 bands were significantly associated with lower adjusted MoCA scores. CSVD burden aggravated the effect of the global wPLI in beta1 bands on adjusted MoCA scores. This effect was reinforced by the high level of CSVD burden. ConclusionsHigher wPLI indicates a possible pathological activation of functional brain networks that are associated with cognitive decline in PwP, and the high level of CSVD burden aggravates this relationship.

Spontaneous changes in brain network centrality in patients with pathological myopia: A voxel-wise degree centrality analysis.

Myopia has become a worldwide problem that endangers public health and adds a serious socioeconomic burden. Current research has focused on the pathogenesis and manifestations of pathological myopia (PM). However, few studies have been conducted on the spontaneous activity of the patient's brain. To study the potential brain network activity in patients with PM by the degree centrality (DC) method. This experiment included 15 PM patients and 15 healthy controls (HCs). Every participant experienced a resting-state functional magnetic resonance imaging (rs-fMRI) scan. Receiver operating characteristic (ROC) curve analysis was used to distinguish between PM patients and HCs. Correlation analysis was used to explore the relationships between mean DC values and clinical performance in different brain regions. It showed that patients with PM had lower DC values in the right fusiform gyrus (FR) and right cingulate (CAR). The ROC curve was used to indicate the accuracy of the correlation. It showed that in PM group, left best corrected visual acuity (BCVA-L) and right best corrected visual acuity (BCVA-R) were negatively correlated with the DC value of FR. The occurrence of PM is mainly related to the abnormal activity of the fusiform and cingulum. DC value might be used as a biological marker of abnormal brain activity in PM patients.

Volume-transmitted GABA waves pace epileptiform rhythms in the hippocampal network

Mechanisms that entrain and pace rhythmic epileptiform discharges remain debated. Traditionally, the quest to understand them has focused on interneuronal networks driven by synaptic GABAergic connections. However, synchronized interneuronal discharges could also trigger the transient elevations of extracellular GABA across the tissue volume, thus raising tonic conductance (Gtonic) of synaptic and extrasynaptic GABA receptors in multiple cells. Here, we monitor extracellular GABA in hippocampal slices using patch-clamp GABA "sniffer" and a novel optical GABA sensor, showing that periodic epileptiform discharges are preceded by transient, region-wide waves of extracellular GABA. Neural network simulations that incorporate volume-transmitted GABA signals point to a cycle of GABA-driven network inhibition and disinhibition underpinning this relationship. We test and validate this hypothesis using simultaneous patch-clamp recordings from multiple neurons and selective optogenetic stimulation of fast-spiking interneurons. Critically, reducing GABA uptake in order to decelerate extracellular GABA fluctuations-without affecting synaptic GABAergic transmission or resting GABA levels-slows down rhythmic activity. Our findings thus unveil a key role of extrasynaptic, volume-transmitted GABA in pacing regenerative rhythmic activity in brain networks.

Reconfiguration of brain network dynamics underlying spatial deficits in subjective cognitive decline

Brain dynamics and the associations with spatial navigation in individuals with subjective cognitive decline (SCD) remain unknown. In this study, a hidden Markov model (HMM) was inferred from resting-state functional magnetic resonance imaging data in a cohort of 80 SCD and 77 normal control (NC) participants. By HMM, 12 states with distinct brain activity were identified. The SCD group showed increased fractional occupancy in the states with less activated ventral default mode, posterior salience, and visuospatial networks, while decreased fractional occupancy in the state with general network activation. The SCD group also showed decreased probabilities of transition into and out of the state with general network activation, suggesting an inability to dynamically upregulate and downregulate brain network activity. Significant correlations between brain dynamics and spatial navigation were observed. The combined features of spatial navigation and brain dynamics showed an area under the curve of 0.854 in distinguishing between SCD and NC. The findings may provide exploratory evidence of the reconfiguration of brain network dynamics underlying spatial deficits in SCD.