Influence of foot strike pattern on co-contraction around the ankle and oxygen uptake during running at 19 km/h.

This study investigated the coactivation of plantar flexor and dorsiflexor muscles and oxygen uptake during running with forefoot and rearfoot strikes at 15 and 19 km/h. We included 16 male runners in this study. The participants ran each foot strike pattern for 5 min at 15 and 19 km/h on a treadmill. During the running, respiratory gas exchange data and surface electromyographic (EMG) activity of the medial gastrocnemius (MG), lateral gastrocnemius (LG), soleus, and tibialis anterior muscles of the right lower limb were continuously recorded. The indices of oxygen uptake, energy expenditure (EE), and muscle activation were calculated during the last 2 min in each condition. During the stance phase of running at 15 and 19 km/h, activation of the tibialis anterior and MG muscles was lower and higher, respectively, with forefoot strike than with rearfoot strike. The foot strike pattern did not influence the oxygen uptake. These results suggest that the foot strike pattern has no clear effect on the oxygen uptake when running at 15 and 19 km/h. However, forefoot strike leads to plantar flexion dominance during co-contraction of the tibialis anterior and MG muscles, which are an antagonist and agonist for plantar flexion, respectively, during the stance phase.

Brain network dynamics in patients with single- and multiple-domain amnestic mild cognitive impairment.

INTRODUCTION: Brain network dynamics have been extensively explored in patients with amnestic mild cognitive impairment (aMCI); however, differences in single- and multiple-domain aMCI (SD-aMCI and MD-aMCI) remain unclear. METHODS: Using multicenter datasets, coactivation patterns (CAPs) were constructed and compared among normal control (NC), SD-aMCI, MD-aMCI, and Alzheimer's disease (AD) patients based on individual high-order cognitive network (HOCN) and primary sensory network (PSN) parcellations. Correlations between spatiotemporal characteristics and neuropsychological scores were analyzed. RESULTS: Compared to NC, SD-aMCI showed temporal alterations in HOCN-dominant CAPs, while MD-aMCI showed alterations in PSN-dominant CAPs. In addition, transitions from SD-aMCI to AD may involve PSN, while MD-aMCI to AD involves both PSN and HOCN. Results were generally consistent across datasets from Chinese and White populations. DISCUSSION: The HOCN and PSN are distinctively involved in aMCI subtypes and in the transformation between aMCI subtypes and AD, highlighting the necessity of aMCI subtype classification in AD studies. HIGHLIGHTS: Individual functional network parcellations and coactivation pattern (CAP) analysis were performed to characterize spatiotemporal differences between single- and multiple-domain amnestic mild cognitive impairment (SD-aMCI and MD-aMCI), and between distinct aMCI subtypes and Alzheimer's disease (AD). The analysis of multicenter datasets converged on four pairs of recurrent CAPs, including primary sensory networks (PSN)-dominant CAPs, high-order cognitive networks (HOCN)-dominant CAPs, and PSN-HOCN-interacting CAPs. The HOCN and PSN are distinctively involved in aMCI subtypes and in the transformation between distinct aMCI subtypes and AD.

Reciprocal Inhibition and Coactivation of Ankle Muscles in Low- and High-Velocity Forward and Backward Perturbations.

Reciprocal inhibition and coactivation are strategies of the central nervous system used to perform various daily tasks. In automatic postural responses (APR), coactivation is widely investigated in the ankle joint muscles, however reciprocal inhibition, although clear in manipulative motor actions, has not been investigated in the context of APRs. The aim was to identify whether reciprocal inhibition can be observed as a strategy in the recruitment of gastrocnemius Medialis (GM), Soleus (So) and Tibialis Anterior (TA) muscles in low- and high-velocity forward and backward perturbations. We applied two balance perturbations with a low and a high velocity of displacement of the movable platform in forward and backward conditions and we evaluated the magnitude and latency time of TA, GM and So activation latency, measured by electromyography (EMG). In forward perturbations, coactivation of the three muscles was observed, with greater activation amplitude of the GM and lesser amplitude of the So and TA muscles. For backward, the pattern of response observed was activation of the TA muscle, a decrease in the EMG signal, which characterizes reciprocal inhibition of the GM muscle and maintenance of the basal state of the So muscle. This result indicates that backward perturbations are more challenging.

Muscle activation patterns and gait changes in unilateral knee osteoarthritis patients: a comparative study with healthy controls.

The objective of this study was to investigate the differences in muscle activation and kinematic parameters between patients with unilateral knee osteoarthritis (OA) and healthy individuals. Additionally, the study aimed to determine the correlation between muscle activation and kinematic parameters with knee OA symptoms. Participants with unilateral knee OA (n = 32) and healthy individuals (n = 32) completed the gait test. Electromyography (EMG) and motion capture were employed to collect muscle activation data and kinematic parameters. Spearman's correlation coefficient was used to analysis the correlation between BMI, symptomatic side EMG parameters, kinematic parameters, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. Furthermore, a multiple linear regression analysis of WOMAC pain was also conducted. The peak root mean square, integrated electromyography, and co-activation index (CCI) were increased bilaterally in the unilateral knee OA group compared to the healthy group. Furthermore, these values were higher on the symptomatic side than on the asymptomatic side. Compared with the healthy group, the knee OA group had lower gait speed, decreased stride length and cadence on bilateral sides, longer total stance time and double-stance time, and shorter single stance time and swing time. The maximum knee flexion angle of the swing phase on the symptomatic side of the knee OA group was smaller than that on the asymptomatic side and healthy group. Changes in EMG and gait parameters on the symptomatic side correlated with WOMAC scores. The main factors influencing WOMAC pain were the CCI values of the lateral femoral and biceps femoris muscles and gait speed. Muscle activation and kinematic parameters in the lower limbs of patients with unilateral knee OA were altered bilaterally during walking. These alterations on the symptomatic side were associated with knee OA-related pain. ChiCTR2200064958. Date of registration: 2022-10-24. Key Points • Unilateral symptomatic knee OA leads to bilateral alterations in muscle activation and gait parameters. • Symptomatic muscle activation and gait parameter changes in knee OA patients are associated with knee OA symptoms. • Correcting abnormal muscle activation conditions and gait training may reduce knee OA-related pain.

A coactivation strategy in anticipatory postural adjustments during voluntary unilateral arm movement while standing in individuals with bilateral spastic cerebral palsy.

Individuals with bilateral spastic cerebral palsy (BSCP) reportedly has problems with anticipatory postural adjustments (APAs) while standing. However, the use of coactivation strategy in APAs in individuals with BSCP has conflicting evidence. Hence, this study aimed to investigate postural muscle activities in BSCP during unilateral arm flexion task in which postural perturbations occur in the sagittal, frontal, and horizontal planes. We included 10 individuals with BSCP with level II on the Gross Motor Function Classification System (BSCP group) and 10 individuals without disability (control group). The participants stood on a force platform and rapidly flexed a shoulder from 0° to 90° at their own timing. Surface electromyograms were recorded from the rectus femoris, medial hamstring, tibialis anterior, and medial gastrocnemius. The control group showed a mixture of anticipatory activation and inhibition of postural muscles, whereas the BSCP group predominantly exhibited anticipatory activation with slight anticipatory inhibition. Compared with the control group, the BSCP group tended to activate the ipsilateral and contralateral postural muscles and the agonist-antagonist muscle pairs. The BSCP group had a larger disturbance in postural equilibrium, quantified by the peak displacement of center of pressure during the unilateral arm flexion, than those without disability. Individuals with BSCP may use coactivation strategy, mainly the anticipatory activation of postural muscle activity, during a task that requires a selective postural muscle activity to maintain stable posture.

Heteronymous feedback from quadriceps onto soleus in stroke survivors.

Background: Recent findings suggest increased excitatory heteronymous feedback from quadriceps onto soleus may contribute to abnormal coactivation of knee and ankle extensors after stroke. However, there is lack of consensus on whether persons post-stroke exhibit altered heteronymous reflexes and, when present, the origin of increased excitation (i.e. increased excitation alone and/or decreased inhibition). This study examined heteronymous excitation and inhibition from quadriceps onto soleus in paretic, nonparetic, and age-matched control limbs to determine whether increased excitation was due to excitatory and/or reduced inhibitory reflex circuits. A secondary purpose was to examine whether heteronymous reflex magnitudes were related to clinical measures of lower limb recovery, walking-speed, and dynamic balance. Methods: Heteronymous excitation and inhibition from quadriceps onto soleus were examined in fourteen persons post-stroke and fourteen age-matched unimpaired participants. Heteronymous feedback was elicited by femoral nerve and quadriceps muscle stimulation in separate trials while participants tonically activated soleus at 20% max. Fugl-Myer assessment of lower extremity, 10-meter walk test, and Mini-BESTest were assessed in stroke survivors. Results: Heteronymous excitation and inhibition onsets, durations, and magnitudes were not different between paretic, nonparetic or age-matched unimpaired limbs. Quadriceps stimulation elicited excitation that was half the magnitude of femoral nerve stimulation. Femoral nerve elicited paretic limb heteronymous excitation was positively correlated with walking speed but did not reach significance because only a subset of paretic limbs exhibited excitation (n = 8, Spearman r = 0.69, P = 0.058). Conclusions: Heteronymous feedback from quadriceps onto soleus assessed in a seated posture was not impaired in persons post-stroke. Despite being unable to identify whether reduced inhibition contributes to abnormal excitation reported in prior studies, our results indicate quadriceps stimulation may allow a better estimate of heteronymous inhibition in those that exhibit exaggerated excitation. Heteronymous excitation magnitude in the paretic limb was positively correlated with self-selected walking speed suggesting paretic limb excitation at the higher end of a normal range may facilitate walking ability after stroke. Future studies are needed to identify whether heteronymous feedback from Q onto SOL is altered after stroke in upright postures and during motor tasks as a necessary next step to identify mechanisms underlying motor impairment.

Alterations in neural circuit dynamics between the limbic network and prefrontal/default mode network in patients with generalized anxiety disorder.

BACKGROUND: Widespread functional alterations have been implicated in patients with generalized anxiety disorder (GAD). However, most studies have primarily focused on static brain network features in patients with GAD. The current research focused on exploring the dynamics within functional brain networks among individuals diagnosed with GAD. METHODS: Seventy-five participants were divided into patients with GAD and healthy controls (HCs), and resting-state functional magnetic resonance imaging data were collected. The severity of symptoms was measured using the Hamilton Anxiety Scale and the Patient Health Questionnaire. Co-activation pattern (CAP) analysis, centered on the bed nucleus of the stria terminalis, was applied to explore network dynamics. The capability of these dynamic characteristics to distinguish between patients with GAD and HCs was evaluated using a support vector machine. RESULTS: Patients with GAD exhibited disruptions in the limbic-prefrontal and limbic-default-mode network circuits. Particularly noteworthy was the marked reduction in dynamic indicators such as occurrence, EntriesFromBaseline, ExitsToBaseline, in-degree, out-degree, and resilience. Moreover, these decreased dynamic features effectively distinguished the GAD group from the HC in this study. CONCLUSIONS: The current findings revealed the underlying brain networks associated with compromised emotion regulation in individuals with GAD. The dynamic reduction in connectivity between the limbic-default mode network and limbic-prefrontal networks could potentially act as a biomarker and therapeutic target for GAD in the future.

EMG coherence of foot and ankle muscles increases with a postural challenge in men.

BACKGROUND: The functional role of intrinsic foot muscles in the control of standing balance is often overlooked in rehabilitation, partly because the interactions with ankle muscles are poorly understood. RESEARCH QUESTION: How does coactivation of Flexor Digitorum Brevis (FDB) and soleus (SOL) vary across standing tasks of increasing difficulty. METHODS: Postural sway (Centre of Pressure, CoP) and the electromyographic (EMG) activity of FDB, SOL, Medial Gastrocnemius (MG) and Tibialis Anterior (TA) were measured during bipedal standing, tandem stance, one-legged balance, and standing on toes. Coherence of the rectified EMG signals for SOL and FDB in two bandwidths (0-5 and 10-20 Hz) was calculated as a coactivation index. RESULTS AND SIGNIFICANCE: The CoP sway and the EMG activity of all muscles was greater (P<0.05) for the three difficult tasks. Significant coherence between the SOL and FDB EMG activity was found in both frequency regions: 0-5 and 10-20 Hz. The coherence integral increased with the difficulty of the postural task, especially in the 10-20 Hz band. The findings underscore the important role of FDB in the control of standing balance across tasks and its coactivation with SOL. Clinical recommendations to improve balance control need to consider the interaction between the plantar flexor and intrinsic-foot muscles.

From waste to strength: Tailor-made enzyme activation design transformation of denatured soy meal into high-performance all-biomass adhesive.

Given the severe protein denaturation and self-aggregation during the high-temperature desolubilization, denatured soy meal (DSM) is limited by its low reactivity, high viscosity, and poor water solubility. Preparing low-cost and high-performance adhesives with DSM as the key feedstock is still challenging. Herein, this study reveals a double-enzyme co-activation method targeting DSM with the glycosidic bonds in protein-carbohydrate complexes and partial amide bonds in protein, increasing the protein dispersion index from 10.2 % to 75.1 % improves the reactivity of DSM. The green crosslinker transglutaminase (TGase) constructs a robust adhesive isopeptide bond network with high water-resistant bonding strength comparable to chemical crosslinkers. The adhesive has demonstrated high dry/wet shear strength (2.56 and 0.93 MPa) for plywood. After molecular recombination by enzyme strategy, the adhesive had the proper viscosity, high reactivity, and strong water resistance. This research showcases a novel perspective on developing a DSM-based adhesive and blazes new avenues for changes in protein structural function and adhesive performance.

The switching and learning behavior of an octopus cell implemented on FPGA.

A dendrocentric backpropagation spike timing-dependent plasticity learning rule has been derived based on temporal logic for a single octopus neuron. It receives parallel spike trains and collectively adjusts its synaptic weights in the range [0, 1] during training. After the training phase, it spikes in reaction to event signaling input patterns in sensory streams. The learning and switching behavior of the octopus cell has been implemented in field-programmable gate array (FPGA) hardware. The application in an FPGA is described and the proof of concept for its application in hardware that was obtained by feeding it with spike cochleagrams is given; also, it is verified by performing a comparison with the pre-computed standard software simulation results.

A new methodological approach to characterize selective motor control in children with cerebral palsy.

Introduction: Despite being a primary impairment in individuals with cerebral palsy (CP), selective motor control (SMC) is not routinely measured. Personalized treatment approaches in CP will be unattainable without the ability to precisely characterize the types and degrees of impairments in motor control. The objective of this study is to report the development and feasibility of a new methodological approach measuring muscle activation patterns during single-joint tasks to characterize obligatory muscle co-activation patterns that may underly impaired SMC. Methods: Muscle activation patterns were recorded during sub-maximal voluntary isometric contraction (sub-MVIC) tasks at the hip, knee, and ankle with an interactive feedback game to standardize effort across participants. We calculated indices of co-activation, synergistic movement, mirror movement, and overflow (indices range 0-2, greater scores equal to greater impairment in SMC) for each isolated joint task in 15 children - 8 with typical development (TD) (mean age 4.7 ± 1.0 SD years) and 7 with CP (mean age 5.8 ± 0.7 SD years). Indices were compared with Mann-Whitney tests. The relationships between the indices and gross motor function (GMFM-66) were examined with Pearson's r. Results: Mean indices were higher in the CP vs. the TD group for each of the six tasks, with mean differences ranging from 0.05 (abduction and plantarflexion) to 0.44 (dorsiflexion). There was great inter-subject variability in the CP group such that significant group differences were detected for knee flexion mirroring (p = 0.029), dorsiflexion coactivation (p = 0.021), and dorsiflexion overflow (p = 0.014). Significant negative linear relations to gross motor function were found in all four indices for knee extension (r = -0.56 to -0.75), three of the indices for ankle dorsiflexion (r = -0.68 to -0.78) and in two of the indices for knee flexion (r = -0.66 to -0.67), and ankle plantarflexion (r = -0.53 to -0.60). Discussion: Indices of coactivation, mirror movement, synergy, and overflow during single-joint lower limb tasks may quantify the type and degree of impairment in SMC. Preliminary concurrent validity between several of the indices of SMC and gross motor function was observed. Our findings established the feasibility of a new methodological approach that quantifies muscle activation patterns using electromyography paired with biofeedback during single-joint movement.

No-load resistance training as a promising alternative to stop detraining period due to covid-19 lockdown in older adults - Case report.

Restrictions to control the COVID-19 pandemic have caused older adults to stop their usual activities, including physical exercises. The novel approach of isometric no-load resistance training (NLRT) can be an interesting alternative to conventional training to oppose the harmful effects of detraining. We described the design and preliminary evaluation of an eight-week, twice-weekly NLRT program for older adults returning to strength training programs after COVID-19 lockdown. An older woman (66 years, 61.9kg, 158.5cm) and an older man (66 years, 84.1kg, 166.5cm) who were engaged in conventional strength training programs before the first COVID-19 lockdown participated in this case study. We collected muscle thickness measures using a B-mode ultrasound imaging and maximum isometric torque using an isokinetic dynamometer. Our results revealed that NLRT seems to be a good alternative to increase muscle thickness of knee and elbow flexors and extensors muscles in older adults. However, NLRT effects were inconsistent for maximum torque.

Estimation of static and dynamic functional connectivity in resting-state fMRI using zero-frequency resonator.

Resting-state functional magnetic resonance imaging (rs-fMRI) is increasingly being used to infer the functional organization of the brain. Blood oxygen level-dependent (BOLD) features related to spontaneous neuronal activity, are yet to be clearly understood. Prior studies have hypothesized that rs-fMRI is spontaneous event-related and these events convey crucial information about the neuronal activity in estimating resting state functional connectivity (FC). Attempts have been made to extract these temporal events using a predetermined threshold. However, the thresholding methods in addition to being very sensitive to noise, may consider redundant events or exclude the low-valued inflection points. Here, we extract the event-related temporal onsets from the rs-fMRI time courses using a zero-frequency resonator (ZFR). The ZFR reflects the transient behavior of the BOLD events at its output. The conditional rate (CR) of the BOLD events occurring in a time course with respect to a seed time course is used to derive static FC. The temporal activity around the estimated events called high signal-to-noise ratio (SNR) segments are also obtained in the rs-fMRI time course and are then used to compute static and dynamic FCs during rest. Coactivation pattern (CAP) is the dynamic FC obtained using the high SNR segments driven by the ZFR. The static FC demonstrates that the ZFR-based CR distinguishes the coactivation and non-coactivation scores well in the distribution. CAP analysis demonstrated the stable and longer dwell time dominant resting state functional networks with high SNR segments driven by the ZFR. Static and dynamic FC analysis underpins that the ZFR-driven temporal onsets of BOLD events derive reliable and consistent FCs in the resting brain using a subset of the time points.

The influence of accelerated brain aging on coactivation pattern dynamics in Parkinson's disease.

Aging is widely acknowledged as the primary risk factor for brain degeneration, with Parkinson's disease (PD) tending to follow accelerated aging trajectories. We aim to investigate the impact of structural brain aging on the temporal dynamics of a large-scale functional network in PD. We enrolled 62 PD patients and 32 healthy controls (HCs). The level of brain aging was determined by calculating global and local brain age gap estimates (G-brainAGE and L-brainAGE) from structural images. The neural network activity of the whole brain was captured by identifying coactivation patterns (CAPs) from resting-state functional images. Intergroup differences were assessed using the general linear model. Subsequently, a spatial correlation analysis between the L-brainAGE difference map and CAPs was conducted to uncover the anatomical underpinnings of functional alterations. Compared to HCs (-3.73 years), G-brainAGE was significantly higher in PD patients (+1.93 years), who also exhibited widespread elevation in L-brainAGE. G-brainAGE was correlated with disease severity and duration. PD patients spent less time in CAPs involving activated default mode and the fronto-parietal network (DMN-FPN), as well as the sensorimotor and salience network (SMN-SN), and had a reduced transition frequency from other CAPs to the DMN-FPN and SMN-SN CAPs. Furthermore, the pattern of localized brain age acceleration showed spatial similarities with the SMN-SN CAP. Accelerated structural brain aging in PD adversely affects brain function, manifesting as dysregulated brain network dynamics. These findings provide insights into the neuropathological mechanisms underlying neurodegenerative diseases and imply the possibility of interventions for modifying PD progression by slowing the brain aging process.

Coactivation pattern analysis reveals altered whole-brain functional transient dynamics in autism spectrum disorder.

Recent studies on autism spectrum disorder (ASD) have identified recurring states dominated by similar coactivation pattern (CAP) and revealed associations between dysfunction in seed-based large-scale brain networks and clinical symptoms. However, the presence of abnormalities in moment-to-moment whole-brain dynamics in ASD remains uncertain. In this study, we employed seed-free CAP analysis to identify transient brain activity configurations and investigate dynamic abnormalities in ASD. We utilized a substantial multisite resting-state fMRI dataset consisting of 354 individuals with ASD and 446 healthy controls (HCs, from HC groups and 2). CAP were generated from a subgroup of all HC subjects (HC group 1) through temporal K-means clustering, identifying four CAPs. These four CAPs exhibited either the activation or inhibition of the default mode network (DMN) and were grouped into two pairs with opposing spatial CAPs. CAPs for HC group 2 and ASD were identified by their spatial similarity to those for HC group 1. Compared with individuals in HC group 2, those with ASD spent more time in CAPs involving the ventral attention network but less time in CAPs related to executive control and the dorsal attention network. Support vector machine analysis demonstrated that the aberrant dynamic characteristics of CAPs achieved an accuracy of 74.87% in multisite classification. In addition, we used whole-brain dynamics to predict symptom severity in ASD. Our findings revealed whole-brain dynamic functional abnormalities in ASD from a single transient perspective, emphasizing the importance of the DMN in abnormal dynamic functional activity in ASD and suggesting that temporally dynamic techniques offer novel insights into time-varying neural processes.

Neuromuscular and trunk control mediate factors associated with injury in fatigued runners.

This study aimed to determine how fatigue affects factors associated with injury, neuromuscular activity, and control in recreational runners. Previously identified injury risk factors were defined as peak vertical instantaneous loading rates (pVILR) for tibial stress fracture (TSF) and peak hip adduction (pHADD) for patellofemoral pain syndrome and iliotibial band syndrome. Kinematics, kinetics, and electromyography data were collected from 11 recreational runners throughout a fatiguing run. Three trials were collected in the first and final minutes of the run. Coactivation was quantified about the knee and ankle for the entire stance phase and anticipatory, weight acceptance (WA), and propulsion sub-phases of stance. Trunk control was quantified by the peak mediolateral lean, peak forward lean, and flexion range of motion (ROM). There were significant increases in pHADD and pVILR when fatigued. Significant decreases in coactivation around the knee were found over the entire stance phase, in the anticipatory phase, and WA phase. Coactivation decreased about the ankle during WA. Lateral trunk lean significantly increased when fatigued, but no significant changes were found in flexion ROM or lean. Mediation analyses showed changes in ankle coactivation during WA, and lateral trunk lean are significant influences on pVILR, a measure associated with TSF. Fatigue-induced adaptations of decreasing ankle coactivation during WA and increased lateral trunk lean may increase the likelihood of TSF. In this study, a fatiguing run influenced changes in control in recreational runners. Further investigation of causal fatigue-induced injuries is necessary to better understand the effects of coactivation and trunk control.

The co-activation patterns of multiple brain regions in Juvenile Myoclonic Epilepsy.

Juvenile myoclonic epilepsy (JME) as an idiopathic generalized epilepsy has been studied by many advanced neuroimaging techniques to elucidate its neuroanatomical basis and pathophysiological mechanisms. In this paper, we used co-activation patterns (CAPs) to explore the differences of dynamic brain activity changes in resting state between JME patients and healthy controls. 27 cases JME patients and 27 cases healthy of fMRI data were collected. The structural image data of the subjects were analyzed by voxel-based morphological analysis, and the regions with gray matter volume atrophy and high voxel were selected as the regions of interest. Further, the mean disease duration was used as boundary to divide the patients' data into the below-average time and the above-average time groups, which were defined as patient disease duration groups. And these data were used to construct CAPs and to compare changes in brain dynamics. It was found that the number of patterns occurrences and the possibility of switching between patterns were smaller than those in the healthy control, which indicated patients with damage to brain regions. For the patient time control group, the number of patterns occurrences and the possibility of switching between patterns were similar, while there was linear regression between the three values and disease duration. Collectively, this study provides important evidence for revealing the key brain regions of JME by studying the transformation between CAPs. Future studies could investigate the effects of receiving treatment on patient dynamic brain activity.

Co-activation patterns during viewing of different video game genres.

Past research has revealed cognitive improvements resulting from engagement with both traditional action video games and newer action-like video games, such as action real-time strategy games (ARSG). However, the cortical dynamics elicited by different video gaming genres remain unclear. This study explored the temporal dynamics of cortical networks in response to different gaming genres. Functional magnetic resonance imaging (fMRI) data were obtained during eye-closed resting and passive viewing of gameplay videos of three genres: life simulation games (LSG), first-person shooter games (FPS), and ARSG. Data analysis used a seed-free Co-Activation Pattern (CAP) based on Regions of Interest (ROIs). When comparing the viewing of action-like video games (FPS and ARSG) to LSG viewing, significant dynamic distinctions were observed in both primary and higher-order networks. Within action-like video games, compared to FPS viewing, ARSG viewing elicited a more pronounced increase in the Fraction of Time and Counts of attentional control-related CAPs, along with an increased Transition Probability from sensorimotor-related CAPs to attentional control-related CAPs. Compared to ARSG viewing, FPS viewing elicited a significant increase in the Fraction of Time of sensorimotor-related CAPs, when gaming experience was considered as a covariate. Thus, different video gaming genres, including distinct action-like video gaming genres, elicited unique dynamic patterns in whole-brain CAPs, potentially influencing the development of various cognitive processes.

Altered resting-state functional connectivity and dynamic network properties in cognitive impairment: an independent component and dominant-coactivation pattern analyses study.

Introduction: Cognitive impairment (CI) due to Alzheimer's disease (AD) encompasses a decline in cognitive abilities and can significantly impact an individual's quality of life. Early detection and intervention are crucial in managing CI, both in the preclinical and prodromal stages of AD prior to dementia. Methods: In this preliminary study, we investigated differences in resting-state functional connectivity and dynamic network properties between 23 individual with CI due to AD based on clinical assessment and 15 healthy controls (HC) using Independent Component Analysis (ICA) and Dominant-Coactivation Pattern (d-CAP) analysis. The cognitive status of the two groups was also compared, and correlations between cognitive scores and d-CAP switching probability were examined. Results: Results showed comparable numbers of d-CAPs in the Default Mode Network (DMN), Executive Control Network (ECN), and Frontoparietal Network (FPN) between HC and CI groups. However, the Visual Network (VN) exhibited fewer d-CAPs in the CI group, suggesting altered dynamic properties of this network for the CI group. Additionally, ICA revealed significant connectivity differences for all networks. Spatial maps and effect size analyses indicated increased coactivation and more synchronized activity within the DMN in HC compared to CI. Furthermore, reduced switching probabilities were observed for the CI group in DMN, VN, and FPN networks, indicating less dynamic and flexible functional interactions. Discussion: The findings highlight altered connectivity patterns within the DMN, VN, ECN, and FPN, suggesting the involvement of multiple functional networks in CI. Understanding these brain processes may contribute to developing targeted diagnostic and therapeutic strategies for CI due to AD.

Early altered directionality of resting brain network state transitions in the TgF344-AD rat model of Alzheimer's disease.

Introduction: Alzheimer's disease (AD) is a progressive neurodegenerative disease resulting in memory loss and cognitive decline. Synaptic dysfunction is an early hallmark of the disease whose effects on whole-brain functional architecture can be identified using resting-state functional MRI (rsfMRI). Insights into mechanisms of early, whole-brain network alterations can help our understanding of the functional impact of AD's pathophysiology. Methods: Here, we obtained rsfMRI data in the TgF344-AD rat model at the pre- and early-plaque stages. This model recapitulates the major pathological and behavioral hallmarks of AD. We used co-activation pattern (CAP) analysis to investigate if and how the dynamic organization of intrinsic brain functional networks states, undetectable by earlier methods, is altered at these early stages. Results: We identified and characterized six intrinsic brain states as CAPs, their spatial and temporal features, and the transitions between the different states. At the pre-plaque stage, the TgF344-AD rats showed reduced co-activation of hub regions in the CAPs corresponding to the default mode-like and lateral cortical network. Default mode-like network activity segregated into two distinct brain states, with one state characterized by high co-activation of the basal forebrain. This basal forebrain co-activation was reduced in TgF344-AD animals mainly at the pre-plaque stage. Brain state transition probabilities were altered at the pre-plaque stage between states involving the default mode-like network, lateral cortical network, and basal forebrain regions. Additionally, while the directionality preference in the network-state transitions observed in the wild-type animals at the pre-plaque stage had diminished at the early-plaque stage, TgF344-AD animals continued to show directionality preference at both stages. Discussion: Our study enhances the understanding of intrinsic brain state dynamics and how they are impacted at the early stages of AD, providing a nuanced characterization of the early, functional impact of the disease's neurodegenerative process.