Connectivity Of Motor Cortex Research Articles

Motor versus Psychomotor? Deciphering the Neural Source of Psychomotor Retardation in Depression.

Major depressive disorder (MDD) is characterized by psychomotor retardation whose underlying neural source remains unclear. Psychomotor retardation may either be related to a motor source like the motor cortex or, alternatively, to a psychomotor source with neural changes outside motor regions, like input regions such as visual cortex. These two alternative hypotheses in main (n = 41) and replication (n = 18) MDD samples using 7 Tesla MRI are investigated. Analyzing both global and local connectivity in primary motor cortex (BA4), motor network and middle temporal visual cortex complex (MT+), the main findings in MDD are: 1) Reduced local and global synchronization and increased local-to-global output in motor regions, which do not correlate with psychomotor retardation, though. 2) Reduced local-to-local BA4 - MT+ functional connectivity (FC) which correlates with psychomotor retardation. 3) Reduced global synchronization and increased local-to-global output in MT+ which relate to psychomotor retardation. 4) Reduced variability in the psychophysical measures of MT+ based motion perception which relates to psychomotor retardation. Together, it is shown that visual cortex MT+ and its relation to motor cortex play a key role in mediating psychomotor retardation. This supports psychomotor over motor hypothesis about the neural source of psychomotor retardation in MDD.

Identifying biomarkers related to motor function in chronic stroke: A fNIRS and TMS study.

Upper limb motor impairment commonly occurs after stroke, impairing quality of life. Brain network reorganization likely differs between subgroups with differing impairment severity. This study explored differences in functional connectivity (FC) and corticospinal tract (CST) integrity between patients with mild/moderate versus severe hemiplegia poststroke to clarify the neural correlates underlying motor deficits. Sixty chronic stroke patients with upper limb motor impairment were categorized into mild/moderate and severe groups based on Fugl-Meyer scores. Resting-state FC was assessed using functional near-infrared spectroscopy (fNIRS) to compare connectivity patterns between groups across motor regions. CST integrity was evaluated by inducing motor evoked potentials (MEP) via transcranial magnetic stimulation. Compared to the mild/moderate group, the severe group exhibited heightened premotor cortex-primary motor cortex (PMC-M1) connectivity (t = 4.56, p < 0.01). Absence of MEP was also more frequent in the severe group (χ2 = 12.31, p = 0.01). Bayesian models effectively distinguished subgroups and identified the PMC-M1 connection as highly contributory (accuracy = 91.30%, area under the receiver operating characteristic curve [AUC] = 0.86). Distinct patterns of connectivity and corticospinal integrity exist between stroke subgroups with differing impairments. Strengthened connectivity potentially indicates recruitment of additional motor resources to compensate for damage. These findings elucidate the neural correlates underlying motor deficits poststroke and could guide personalized, network-based therapies targeting predictive biomarkers to improve rehabilitation outcomes.

Effects of acute aerobic exercise on resting state functional connectivity of motor cortex in college students

This study intends to inspect the effects of acute aerobic exercise (AE) on resting state functional connectivity (RSFC) in motor cortex of college students and the moderating effect of fitness level. Methods: 20 high fitness level college students and 20 ordinary college students were recruited in public. Subjects completed 25 min of moderate- and high-intensity acute aerobic exercise respectively by a bicycle ergometer, and the motor cortex’s blood oxygen signals in resting state were monitored by functional Near Infrared Spectroscopy (fNIRS, the Shimadzu portable Light NIRS, Japan) in pre- and post-test. Results: At the moderate intensity level, the total mean value of RSFC pre- and post-test was significantly different in the high fitness level group (pre-test 0.62 ± 0.18, post-test 0.51 ± 0.17, t(19) = 2.61, p = 0.02, d = 0.58), but no significant change was found in the low fitness level group. At the high-intensity level, there was no significant difference in the difference of total RSFC between pre- and post-test in the high and low fitness group. According to and change trend of 190 “edges”: at the moderate-intensity level, the number of difference edges in the high fitness group (d = 0.58, 23) were significantly higher than those in the low fitness group (d = 0.32, 15), while at high-intensity level, there was a reverse trend between the high fitness group (d = 0.25, 18) and the low fitness group (d = 0.39, 23). Conclusions: moderate-intensity AE can cause significant changes of RSFC in the motor cortex of college students with high fitness, while high fitness has a moderating effect on the relationship between exercise intensity and RSFC. RSFC of people with high fitness is more likely to be affected by AE and show a wider range of changes.

Test-retest reliability of intrahemispheric dorsal premotor and primary motor cortex dual-site TMS connectivity measures

ObjectiveInvestigating the optimal interstimulus interval (ISI) and the 24-hour test–retest reliability for intrahemispheric dorsal premotor cortex (PMd) – primary motor cortex (M1) connectivity using dual-site transcranial magnetic stimulation (dsTMS). MethodsIn 21 right-handed adults, left intrahemispheric PMd–M1 connectivity has been investigated with a stacked-coil dsTMS setup (conditioning stimulus: 75% of resting motor threshold; test stimulus: eliciting MEPs of 1–1.5 mV) at ISIs of 3, 5–8, and 10 ms. Additionally, M1–M1 short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) were investigated to assess comparability to standard paired-pulse setups. ResultsConditioning PMd led to significant inhibition of M1 output at ISIs of 3 and 5 ms, whereas 10 ms resulted in facilitation (all, p < 0.001), with a fair test–retest reliability for 3 (ICC: 0.47) and 6 ms (ICC: 0.44) ISIs. Replication of SICI (p < 0.001) and ICF (p = 0.017) was successful, with excellent test–retest reliability for SICI (ICC: 0.81). ConclusionThis dsTMS setup can probe the inhibitory and facilitatory PMd–M1 connections, as well as reliably replicate SICI and ICF paradigms. SignificanceThe stacked-coil dsTMS setup for investigating intrahemispheric PMd–M1 connectivity offers promising possibilities to better understand motor control.

Intrinsic functional connectivity of motor and heteromodal association cortex predicts individual differences in regulatory focus.

Regulatory focus theory (RFT) describes two cognitive-motivational systems for goal pursuit-the promotion and prevention systems-important for self-regulation and previously implicated in vulnerability to psychopathology. According to RFT, the promotion system is engaged in attaining ideal goals (e.g. hopes and dreams), whereas the prevention system is associated with accomplishing ought goals (e.g. duties and obligations). Prior task-based functional magnetic resonance imaging (fMRI) studies have mostly explored the mapping of these two systems onto the activity of a priori brain regions supporting motivation and executive control in both healthy and depressed adults. However, complex behavioral processes such as those guided by individual differences in regulatory focus are likely supported by widely distributed patterns of intrinsic functional connectivity. We used data-driven connectome-based predictive modeling to identify patterns of distributed whole-brain intrinsic network connectivity associated with individual differences in promotion and prevention system orientation in 1,307 young university volunteers. Our analyses produced a network model predictive of prevention but not promotion orientation, specifically the subjective experience of successful goal pursuit using prevention strategies. The predictive model of prevention success was highlighted by decreased intrinsic functional connectivity of both heteromodal association cortices in the parietal and limbic networks and the primary motor cortex. We discuss these findings in the context of strategic inaction, which drives individuals with a strong dispositional prevention orientation to inhibit their behavioral tendencies in order to shield the self from potential losses, thus maintaining the safety of the status quo but also leading to trade-offs in goal pursuit success.

Real-time cortical dynamics during motor inhibition

The inhibition of action is a fundamental executive mechanism of human behaviour that involve a complex neural network. In spite of the progresses made so far, many questions regarding the brain dynamics occurring during action inhibition are still unsolved. Here, we used a novel approach optimized to investigate real-time effective brain dynamics, which combines transcranial magnetic stimulation (TMS) with simultaneous electroencephalographic (EEG) recordings. 22 healthy volunteers performed a motor Go/NoGo task during TMS of the hand-hotspot of the primary motor cortex (M1) and whole-scalp EEG recordings. We reconstructed source-based real-time spatiotemporal dynamics of cortical activity and cortico-cortical connectivity throughout the task. Our results showed a task-dependent bi-directional change in theta/gamma supplementary motor cortex (SMA) and M1 connectivity that, when participants were instructed to inhibit their response, resulted in an increase of a specific TMS-evoked EEG potential (N100), likely due to a GABA-mediated inhibition. Interestingly, these changes were linearly related to reaction times, when participants were asked to produce a motor response. In addition, TMS perturbation revealed a task-dependent long-lasting modulation of SMA–M1 natural frequencies, i.e. alpha/beta activity. Some of these results are shared by animal models and shed new light on the physiological mechanisms of motor inhibition in humans.

Theta-tACS modulates cerebellar-related motor functions and cerebellar-cortical connectivity

ObjectiveTo evaluate the effects of cerebellar transcranial alternating current stimulation (tACS) delivered at cerebellar-resonant frequencies, i.e., theta (θ) and gamma (γ), on upper limb motor performance and cerebellum-primary motor cortex (M1) connectivity, as assessed by cerebellar-brain inhibition (CBI), in healthy subjects. MethodsParticipants underwent cerebellar-tACS while performing three cerebellar-dependent motor tasks: (i) rhythmic finger-tapping, (ii) arm reaching-to-grasp (‘grasping’) and (iii) arm reaching-to-point (‘pointing’) an object. Also, we evaluated possible changes in CBI during cerebellar-tACS. Resultsθ-tACS decreased movement regularity during the tapping task and increased the duration of the pointing task compared to sham- and γ-tACS. Additionally, θ-tACS increased the CBI effectiveness (greater inhibition). The effect of θ-tACS on movement rhythm correlated with CBI changes and less tapping regularity corresponded to greater CBI. ConclusionsCerebellar-tACS delivered at the θ frequency modulates cerebellar-related motor behavior and this effect is, at least in part, mediated by changes in the cerebellar inhibitory output onto M1. The effects of θ-tACS may be due to the modulation of cerebellar neurons that resonate to the θ rhythm. SignificanceThese findings contribute to a better understanding of the physiological mechanisms of motor control and provide new evidence on cerebellar non-invasive brain stimulation.

CONTRAST SENSITIVITY AND BRAIN NETWORK COMMUNITY STRUCTURE IN THE BRAIN NETWORKS AND MOBILITY STUDY

Abstract Contrast sensitivity (CS) is the ability to perceive differences in shades of light and dark, which is important for pattern recognition and depth perception. We have previously shown that impaired CS is associated with poor performance on the expanded short physical performance battery (eSPPB), and that performance on the eSPPB is associated with sensory motor cortex (SMC) connectivity at rest. We hypothesized that brain networks are important to the relationship of CS with eSPPB. Participants (n=192) were cognitively unimpaired older adults (mean age=76.5±4.7 years; 56.5% female, 9.4% black) with good visual acuity who completed CS testing. We applied graph theory to characterize the cross-sectional relationship of binocular CS to functional brain networks generated from fMRI both at rest and during a motor imagery (MI) task and determined the spatial patterns of SMC, visual (VIS) and default mode (DMN) network connectivity. Regression analyses were used to assess associations of CS with brain network connectivity without and with adjustment for sex and eSPPB. Lower CS (p=0.009) was significantly associated with degraded SMC connectivity at rest even in models adjusted for eSPPB and sex. Similarly, lower CS was significantly associated with degraded VIS and DMN connectivity during the MI task (all p&amp;lt; 0.005) when controlling for eSPPB and sex. These results indicate that low CS and poor eSPPB are both associated with connectivity in the SMC at rest and with VIS and DMN during MI in older adults. These findings may be important for understanding the relationship between age-related visual and mobility dysfunction.

Task-residual effective connectivity of motor network in transient ischemic attack

Transient ischemic attack (TIA) is a temporary episode of neurological dysfunction that results from focal brain ischemia. Although TIA symptoms are quickly resolved, patients with TIA have a high risk of stroke and persistent impairments in multiple domains of cognitive and motor functions. In this study, using spectral dynamic causal modeling, we investigate the changes in task-residual effective connectivity of patients with TIA during fist-closing movements. 28 healthy participants and 15 age-matched patients with TIA undergo functional magnetic resonance imaging at 7T. Here we show that during visually cued motor movement, patients with TIA have significantly higher effective connectivity toward the ipsilateral primary motor cortex and lower connectivity to the supplementary motor area than healthy controls. Our results imply that TIA patients have aberrant connections among motor regions, and these changes may reflect the decreased efficiency of primary motor function and disrupted control of voluntary movement in patients with TIA.

Cortico-cortical paired associative stimulation conditioning superficial ventral premotor cortex-primary motor cortex connectivity influences motor cortical activity during precision grip.

The ventral premotor cortex (PMv) and primary motor cortex (M1) represent critical nodes of a parietofrontal network involved in grasping actions, such as power and precision grip. Here, we investigated how the functional PMv-M1 connectivity drives the dissociation between these two actions. We applied a PMv-M1 cortico-cortical paired associative stimulation (cc-PAS) protocol, stimulating M1 in both postero-anterior (PA) and antero-posterior (AP) directions, in order to induce long-term changes in the activity of different neuronal populations within M1. We evaluated the motor-evoked potential (MEP) amplitude, MEP latency and cortical silent period, in both PA and AP, during the isometric execution of precision and power grip, before and after the PMv-M1 cc-PAS. The repeated activation of the PMv-M1 cortico-cortical network with PA orientation over M1 did not change MEP amplitude or cortical silent period duration during both actions. In contrast, the PMv-M1 cc-PAS stimulation of M1 with an AP direction led to a specific modulation of precision grip motor drive. In particular, MEPs tested with AP stimulation showed a selective increase of corticospinal excitability during precision grip. These findings suggest that the more superficial M1 neuronal populations recruited by the PMv input are involved preferentially in the execution of precision grip actions. KEY POINTS: Ventral premotor cortex (PMv)-primary motor cortex (M1) cortico-cortical paired associative stimulation (cc-PAS) with different coil orientation targets dissociable neural populations. PMv-M1 cc-PAS with M1 antero-posterior coil orientation specifically modulates corticospinal excitability during precision grip. Superficial M1 populations are involved preferentially in the execution of precision grip. A plasticity induction protocol targeting the specific PMv-M1subpopulation might have important translational value for the rehabilitation of hand function.

Characteristics of resting state functional connectivity of motor cortex of high fitness level college students: Experimental evidence from functional near infrared spectroscopy (fNIRS)

AbstractObjectiveThis study inspects difference of resting state functional connectivity (RSFC) of motor cortex between athletes and ordinary college students and the test‐retest reliability of RSFC.MethodsTwenty high fitness level college students (high fitness group) and 20 ordinary college students (control group) were recruited. The motor cortical blood oxygen signals in resting states were monitored by functional near infrared spectroscopy (fNIRS). RSFCs of brain signals were preprocessed and calculated by FC‐NIRS software. RSFC results of test‐retest reliability were evaluated by intra‐class correlation coefficient (ICC).ResultsTotal RSFC (HbO signal) was significantly different between high fitness group (0.62 ± 0.04) and low fitness group (0.81 ± 0.04) (p &lt; .05). Significant differences were found between the groups (HbO signal) in 50 edges among the 190 edges of motor cortex (14 edges after FDR corrected). At three hemoglobin concentrations, mean of group‐level ICC (C, 1) for total RSFC in two groups was 0.40 ± 0.10, whereas the mean of group‐level ICC (C, k) was 0.57 ± 0.11, depicting “fair” reliability. The mean of group‐level ICC (C, 1) of 190 “edges” was 0.88 ± 0.06, whereas mean of ICC (C, k) was 0.94 ± 0.03, exhibiting “excellent” reliability.ConclusionFitness level is the factor causing specific changes in RSFC strength of motor cortex that can be utilized as biomarker for evaluating the fitness level.

Cognitive and motor cortex activation during robot-assisted multi-sensory interactive motor rehabilitation training: An fNIRS based pilot study.

This study aimed to evaluate the effects of multiple virtual reality (VR) interaction modalities based on force-haptic feedback combined with visual or auditory feedback in different ways on cerebral cortical activation by functional near-infrared spectroscopy (fNIRS). Methods: A modular multi-sensory VR interaction system based on a planar upper-limb rehabilitation robot was developed. Twenty healthy participants completed active elbow flexion and extension training in four VR interaction patterns, including haptic (H), haptic + auditory (HA), haptic + visual (HV), and haptic + visual + auditory (HVA). Cortical activation changes in the sensorimotor cortex (SMC), premotor cortex (PMC), and prefrontal cortex (PFC) were measured. Four interaction patterns all had significant activation effects on the motor and cognitive regions of the cerebral cortex (p < 0.05). Among them, in the HVA interaction mode, the cortical activation of each ROI was the strongest, followed by HV, HA, and H. The connectivity between channels of SMC and bilateral PFC, as well as the connectivity between channels in PMC, was the strongest under HVA and HV conditions. Besides, the two-way ANOVA of visual and auditory feedback showed that it was difficult for auditory feedback to have a strong impact on activation without visual feedback. In addition, under the condition of visual feedback, the effect of fusion auditory feedback on the activation degree was significantly higher than that of no auditory feedback. The interaction mode of visual, auditory, and haptic multi-sensory integration is conducive to stronger cortical activation and cognitive control. Besides, there is an interaction effect between visual and auditory feedback, thus improving the cortical activation level. This research enriches the research on activation and connectivity of cognitive and motor cortex in the process of modular multi-sensory interaction training of rehabilitation robots. These conclusions provide a theoretical basis for the optimal design of the interaction mode of the rehabilitation robot and the possible scheme of clinical VR rehabilitation.

Mapping alterations in the local synchrony of the cerebral cortex in schizophrenia.

Observations from different fields of research coincide in indicating that a defective gamma-aminobutyric acid (GABA) interneuron system may be among the primary factors accounting for the varied clinical expression of schizophrenia. GABA interneuron deficiency is locally expressed in the form of neural activity desynchronization. We mapped the functional anatomy of local synchrony in the cerebral cortex in schizophrenia using functional connectivity MRI. Data from 86 patients with schizophrenia and 137 control subjects were obtained from publicly available repositories. Resting-state functional connectivity maps based on Iso-Distant Average Correlation measures across three distances were estimated detailing the local functional structure of the cerebral cortex. Patients with schizophrenia showed weaker local functional connectivity (i.e., lower MRI signal synchrony) in (i) prefrontal lobe areas, (ii) somatosensory, auditory, visual, and motor cortices, (iii) paralimbic system at the anterior insula and anterior cingulate cortex, and (iv) hippocampus. The distribution of the defect in cortical area synchrony largely coincided with the synchronization effect of the GABA agonist alprazolam previously observed using identical functional connectivity measures. There was also a notable resemblance between the anatomy of our findings and cortical areas showing higher density of parvalbumin (prefrontal lobe and sensory cortices) and somatostatin (anterior insula and anterior cingulate cortex) GABA interneurons in humans. Our results thus provide detail of the functional anatomy of synchrony changes in the cerebral cortex in schizophrenia and suggest which elements of the interneuron system are affected. Such information could ultimately be relevant in the search for specific treatments.

Effects of a maximal cycling all-out anaerobic test on visual performance

ABSTRACT Clinical relevance All-out exercise may not impair all central nervous system processes, such as those related to visual-motor abilities, and may actually prove stimulatory to such tasks allowing athletes and sports conditioning specialists to develop strategies to take advantage of/mitigate the effects of such exercise on athletic performance. Background Despite research indicating that visual-motor abilities play a critical role in athletic performance, research has primarily focused on the effect of all-out exercise on processes along the motor pathway, such as resultant force production or simple cognitive tasks. Such research has neglected to investigate the effect of all-out exercise on visual tasks. When investigations on visual tasks are forthcoming, they focus on prolonged aerobic exercise, which is not the primary metabolic pathway for all, or even the majority of sports. Methods Sixty untrained males (experimental group; N = 30, control group; N = 30) completed a standardised six-item baseline sports vision test battery and one week later, the experimental participants returned to undertake a 30-second Wingate anaerobic test (30-WAnT) immediately followed by the same test battery. Results Significant (P < 0.05) improvements were found in accommodation facility, saccadic eye movement, speed of recognition, peripheral awareness and hand-eye coordination (P < 0.001 for all), but not visual memory (P = 0.242) following the 30-WAnT. Conclusions Although the mechanisms underlying these improvements in visual task performance have not yet been studied, this study suggests that simple anaerobic all-out exercise does not cause central- or brain-based fatigue impairing the oculomotor system but may rather provide “excitability” of the underlying motor cortex, motoneurons and/or corticofugal connections utilised in visual task response. It appears that the sweeping improvements in visual task performance elucidate the need for an intense anaerobic warm-up when training visual skills and when visual skills form an integral part of athletic performance.

Large-scale all-optical dissection of motor cortex connectivity shows a segregated organization of mouse forelimb representations

Large-scale all-optical dissection of motor cortex connectivity shows a segregated organization of mouse forelimb representations

Large-scale all-optical dissection of motor cortex connectivity shows a segregated organization of mouse forelimb representations.

In rodent motor cortex, the rostral forelimb area (RFA) and the caudal forelimb area (CFA) are major actors in orchestrating the control of complex forelimb movements. However, their intrinsic connectivity and reciprocal functional organization are still unclear, limiting our understanding of how the brain coordinates and executes voluntary movements. Here, we causally probe cortical connectivity and activation patterns triggered by transcranial optogenetic stimulation of ethologically relevant complex movements exploiting a large-scale all-optical method in awake mice. Results show specific activation features for each movement class, providing evidence for a segregated functional organization of CFA and RFA. Importantly, we identify a second discrete lateral grasping representation area, namely the lateral forelimb area (LFA), with unique connectivity and activation patterns. Therefore, we propose the LFA as a distinct forelimb representation in the mouse somatotopic motor map.

Exploring the Role of Specialist Physiotherapy in Awake Craniotomy Surgery for the Neuro-Oncology Patient

Abstract AIMS To describe the methods used to assess and monitor motor function during awake craniotomy surgery for tumour resection. METHOD A service review was carried out over 10 months. Patients with highly motor eloquent lesions – invasion of primary motor cortex or fronto-parietal connections involved in motor cognition – were included. Clinical notes were reviewed and summarised using descriptive analysis. Dexterity and grip strength were measured using 9-hole peg test and handheld dynameter pre/intra and post-operatively. Patient occupation/interests were reported to guide bespoke assessments to trial intra-operatively. RESULTS From April 2021 to January 2022, 13 patients (mean age 39.7 years, 4 female:10 male, 9 low grade:5 high grade gliomas) were included. Mean score 9-hole peg test 22.2sec pre-operatively, 30.6sec post-operatively; handheld dynameter 26.7kg pre-operatively, 18.4kg post-operatively. At discharge 5 of 7 impaired patients demonstrated motor improvement. For motor coordination, motor tasks used frequently included repetitive finger tapping, open/closed hand. Bespoke tasks included texting/writing, playing instruments, and computer games. Movement was closely monitored and verbal feedback given to the neurosurgeons throughout. With video analysis movement comparisons were made. CONCLUSION The role of physiotherapy in awake surgery is evolving to provide movement analysis for complex motor tasks such as upper limb sequencing and dexterity. A combination of standard and bespoke assessments have been trialled and their feasibility within surgery tested. A post-operative deterioration of motor function (power and cognition) is expected after surgery for highly eloquent motor gliomas. However, intraoperative motor assessment for motor cognition allows function preservation and potentiates its recovery.

Abnormal dynamic brain activity and functional connectivity of primary motor cortex in blepharospasm.

Accumulating evidence indicates that dynamic amplitude of low-frequency fluctuations (dALFF) or dynamic functional connectivity (dFC) can provide complementary information, distinct from static amplitude of low-frequency fluctuations (sALFF) or static functional connectivity (sFC), in detecting brain functional abnormalities in brain diseases. We aimed to examine whether dALFF and dFC can offer valuable information for the detection of functional brain abnormalities in patients with blepharospasm. We collected resting-state functional magnetic resonance imaging data from 46 patients each of blepharospasm, hemifacial spasm (HFS), and healthy controls (HCs). We examined intergroup differences in sALFF and dALFF to investigate abnormal regional brain activity in patients with blepharospasm. Based on the dALFF results, we conducted seed-based sFC and dFC analyses to identify static and dynamic connectivity changes in brain networks centered on areas showing abnormal temporal variability of local brain activity in patients with blepharospasm. Compared with HCs, patients with blepharospasm displayed different brain functional change patterns characterized by increased sALFF in the left primary motor cortex (PMC) but increased dALFF variance in the right PMC. However, differences were not found between patients with HFS and HCs. Additionally, patients with blepharospasm exhibited decreased dFC strength, but no change in sFC, between right PMC and ipsilateral cerebellum compared with HCs; these findings were replicated when patients with blepharospasm were compared to those with HFS. Our findings highlight that dALFF and dFC are complementary to sALFF and sFC and can provide valuable information for detecting brain functional abnormalities in blepharospasm. Blepharospasm may be a network disorder involving the cortico-ponto-cerebello-thalamo-cortical circuit.

Prehabilitation and rehabilitation using data-driven, parcel-guided transcranial magnetic stimulation treatment for brain tumor surgery

Improved knowledge of the neuroplastic potential of the brain connectome has facilitated the advancement of neuromodulatory treatments for brain tumor patients especially in the perioperative period. More recently, the idea of inducing neuroplastic changes before surgery as “prehabilitation” has been suggested in low-grade gliomas with favorable data. However, it is uncertain the degree to which this treatment with transcranial magnetic stimulation (TMS) would benefit patients with high-grade gliomas, especially with additional rehabilitation after surgery and targets defined by personalized connectomic data. The current report details a case of a patient with recurrent glioblastoma in the right motor area 2 years after previous total resection. Given the desire for a more aggressive recurrent surgery in a highly functional area, the authors decided to proceed with “prehabilitation” by stimulating the surrounding motor cortices around the lesion to turn down the motor cortex connectivity before the recurrent surgery and then completing “rehabilitation” after the surgery. Structural-functional connectomic analyses were completed using Infinitome software based on an individualized patient brain atlas using machine-learning based parcellations. Repetitive TMS was employed, specifically using continuous and intermittent theta burst stimulation protocols. Prehabilitation consisted of using continuous theta burst stimulation at the estimated surgical entry point parcel and intermittent theta burst stimulation at adjacent parcellations for a total of 10 days with 5 sessions per day per target leading up until the surgery. A gross-total resection was obtained, but the patient woke up with left-sided hemiparesis. Resting-state functional magnetic resonance imaging derived connectivity demonstrated a case of a primarily pure cingulate-motor resection causing hemiplegia with an intact corticospinal tract and supplementary motor area. Functional connectivity outliers in cingulate-motor parcels were identified and compared with connectivity matrices from a healthy control atlas. Anomalies, parcels defined as functioning significantly outside a normal range, were chosen as rehabilitation TMS targets to be similarly treated for a total of 10 days with 5 sessions per day per target approximately two weeks after surgery. By using continuous theta burst stimulation on hyperconnected parcels and intermittent theta burst stimulation on hypoconnected parcels, the patient demonstrated significant motor improvement with only 4+/5 strength in the left arm 1 month after surgery. This report demonstrates for the first time the feasibility of using TMS treatment for glioblastoma surgery near “eloquent” cortices as a means of prehabilitation before surgery and rehabilitation after surgery. This parcel-guided approach for TMS treatment based on the cortical site of entry and individualized connectivity analyses allowed for maximal tumor resection and minimal long-term neurologic deficits.

A Novel Method to Assess Motor Cortex Connectivity and Event Related Desynchronization Based on Mass Models.

Knowledge of motor cortex connectivity is of great value in cognitive neuroscience, in order to provide a better understanding of motor organization and its alterations in pathological conditions. Traditional methods provide connectivity estimations which may vary depending on the task. This work aims to propose a new method for motor connectivity assessment based on the hypothesis of a task-independent connectivity network, assuming nonlinear behavior. The model considers six cortical regions of interest (ROIs) involved in hand movement. The dynamics of each region is simulated using a neural mass model, which reproduces the oscillatory activity through the interaction among four neural populations. Parameters of the model have been assigned to simulate both power spectral densities and coherences of a patient with left-hemisphere stroke during resting condition, movement of the affected, and movement of the unaffected hand. The presented model can simulate the three conditions using a single set of connectivity parameters, assuming that only inputs to the ROIs change from one condition to the other. The proposed procedure represents an innovative method to assess a brain circuit, which does not rely on a task-dependent connectivity network and allows brain rhythms and desynchronization to be assessed on a quantitative basis.