Motor Mapping Research Articles

Optimizing Adjuvant Stereotactic Radiotherapy of Motor-Eloquent Brain Metastases: Sparing the nTMS-Defined Motor Cortex and the Hippocampus.

Brain metastases can effectively be treated with surgical resection and adjuvant stereotactic radiotherapy (SRT). Navigated transcranial magnetic stimulation (nTMS) has been used to non-invasively map the motor cortex prior to surgery of motor eloquent brain lesions. To date, few studies have reported the integration of such motor maps into radiotherapy planning. The hippocampus has been identified as an additional critical structure of radiation-induced deficits. The aim of this study is to assess the feasibility of selective dose reduction to both the nTMS-based motor cortex and the hippocampi in SRT of motor-eloquent brain metastases. Patients with motor-eloquent brain metastases undergoing surgical resection and adjuvant SRT between 07/2014 and 12/2018 were retrospectively analyzed. The radiotherapy treatment plans were retrieved from the treatment planning system (“original” plan). For each case, two intensity-modulated treatment plans were created: the “motor” plan aimed to reduce the dose to the motor cortex, the “motor & hipp” plan additionally reduce the dose to the hippocampus. The optimized plans were compared with the “original” plan regarding plan quality, planning target volume (PTV) coverage, and sparing of organs at risk (OAR). 69 plans were analyzed, all of which were clinically acceptable with no significant differences for PTV coverage. All OAR were protected according to standard protocols. Sparing of the nTMS motor map was feasible: mean dose 9.66 ± 5.97 Gy (original) to 6.32 ± 3.60 Gy (motor) and 6.49 ± 3.78 Gy (motor & hipp), p<0.001. In the “motor & hipp” plan, dose to the ipsilateral hippocampi could be significantly reduced (max 1.78 ± 1.44 Gy vs 2.49 ± 1.87 Gy in “original”, p = 0.003; mean 1.01 ± 0.92 Gy vs. 1.32 ± 1.07 Gy in “original”, p = 0.007). The study confirms the results from previous studies that inclusion of nTMS motor information into radiotherapy treatment planning is possible with a relatively straightforward workflow and can achieve reduced doses to the nTMS-defined motor area without compromising PTV coverage. Furthermore, we demonstrate the feasibility of selective dose reduction to the hippocampus at the same time. The clinical significance of these optimized plans yet remains to be determined. However, with no apparent disadvantages these optimized plans call for further and broader exploration.

Cortical Representations of Transversus Abdominis and Multifidus Muscles Were Discrete in Patients with Chronic Low Back Pain: Evidence Elicited by TMS.

Introduction The transversus abdominis (TVA) and multifidus (MF) muscles are the main segmental spinal stabilizers that are controlled by the primary motor cortex of the brain. However, relocations of the muscle representation in the motor cortex may occur after chronic lower back pain (cLBP); it still needs more evidence to be proven. The current study was aimed at applying transcranial magnetic stimulation (TMS) to investigate the changes of representation of TVA and MF muscles at the cortical network in individuals with cLBP. Methods Twenty-four patients with cLBP and 12 age-matched healthy individuals were recruited. Responses of TVA and MF to TMS during muscle contraction were monitored and mapped over the contralateral cortex using a standardized grid cap. Maps of the center of gravity (CoG), area, volume, and latency were analyzed, and the asymmetry index was also computed and compared. Results The locations of MF CoG in cLBP individuals were posterior and lateral to the CoG locations in healthy individuals. In the healthy group, the locations of TVA and MF CoG were closed to each other in both the left and right hemispheres. In the cLBP group, these two locations were next to each other in the right hemisphere but discrete in the left hemisphere. In the cLBP group, the cortical motor map of TVA and MF were mutually symmetric in five out of eleven (45.5%) subjects and leftward asymmetric in four out of ten (40.0%) subjects. Conclusions Neural representations of TVA and MF muscles were closely organized in both the right and left motor cortices in the healthy group but were discretely organized in the left motor cortex in the cLBP group. This provides strong support for the neural basis of pathokinesiology and clinical treatment of cLBP.

Quantitative assessment of inter-individual variability in fMRI-based human brain atlas.

Inter-individual variability is an inherent and ineradicable feature of group-level brain atlases that undermines their reliability for clinical and other applications. To date, there have been no reports quantifying inter-individual variability in brain atlases. In the present study, we compared inter-individual variability in nine brain atlases by task-based functional magnetic resonance imaging (MRI) mapping of motor and temporal lobe language regions in both cerebral hemispheres. We analyzed complete motor and language task-based fMRI and T1 data for 893 young, healthy subjects in the Human Connectome Project database. Euclidean distances (EDs) between hotspots in specific brain regions were calculated from task-based fMRI and brain atlas data. General linear model parameters were used to investigate the influence of different brain atlases on signal extraction. Finally, the inter-individual variability of ED and extracted signals and interdependence of relevant indicators were statistically evaluated. We found that inter-individual variability of ED varied across the nine brain atlases (P<0.0001 for motor regions and P<0.0001 for language regions). There was no correlation between parcel number and inter-individual variability in left to right (LtoR; P=0.7959 for motor regions and P=0.2002 for language regions) and right to left (RtoL; P=0.7654 for motor regions and P=0.3544 for language regions) ED; however, LtoR (P≤0.0001) and RtoL (P≤0.0001) inter-individual variability differed according to brain region: the LtoR (P=0.0008) and RtoL (P=0.0004) inter-individual variability was greater for the right hand than for the left hand, the LtoR (P=0.0019) and RtoL (P=0.0179) inter-individual variability was greater for the right language than for the left language, but there was no such difference between the right foot and left foot (LtoR, P=0.2469 and RtoL, P=0.6140). Inter-individual variability in one motor region was positively correlated with mean values in the other three motor regions (left hand, P=0.0145; left foot, P=0.0103; right hand, P=0.1318; right foot, P=0.3785). Inter-individual variability in language region was positively correlated with mean values in the four motor regions (left language, P=0.0422; right language, P=0.0514). Signal extraction for LtoR (P<0.0001) and RtoL (P<0.0001) varied across the nine brain atlases, which also showed differences in inter-individual variability. These results underscore the importance of quantitatively assessing the inter-individual variability of a brain atlas prior to use, and demonstrate that mapping motor regions by task-based fMRI is an effective method for quantitatively assessing the inter-individual variability in a brain atlas.

Enhancing the efficiency of electric vehicle’s motor using electro-mechanical continuously variable transmission

Over the last decades, significant progress has been made on the technologies of battery electric vehicle (BEV) powertrain system. As a result, the driving mileage of the latest EVs has been improved tremendously, making the ownership of BEV more viable now. Nevertheless, even with the latest progress, the driving mileage of a BEV is still generally lower as compared to the vehicle with an advanced internal combustion engine. Thus, this paper investigates the potential of increasing the mileage of a BEV further by using electro-mechanical continuously variable transmission (EMCVT) in its powertrain system. The purpose of the EMCVT is to allow the electric motor used in the BEV powertrain system to operate in its most efficient condition for a wide range of vehicle’s speeds. This condition is defined using the efficiency mapping of a typical electric motor applied in the existing BEVs. Based on this mapping, the motor’s efficiency when used with EMCVT is compared with the efficiency of the same motor when used with a single speed transmission for various vehicle speeds. In this investigation, the efficiency of the EM CVT is considered at 75% to 95%, and the BEV with EMCVT is considered to be 80 kg heavier than the BEV using a single speed transmission. The comparison between the BEV with and without EMCVT shows that the application of EMCVT allows the motor to operate in its most efficient condition for a wider range of the vehicle’s velocity. However, the improved motor’s efficiency is compromised by the losses in the EMCVT, making it challenging to achieve lower power consumption during driving. Therefore, to achieve meaningful improvement in terms of power consumption, the efficiency of the EMCVT has to be higher than 85%.

Detecting Corticospinal Tract Impairment in Tumor Patients With Fiber Density and Tensor-Based Metrics.

Tumors infiltrating the motor system lead to significant disability, often caused by corticospinal tract injury. The delineation of the healthy-pathological white matter (WM) interface area, for which diffusion magnetic resonance imaging (dMRI) has shown promising potential, may improve treatment outcome. However, up to 90% of white matter (WM) voxels include multiple fiber populations, which cannot be correctly described with traditional metrics such as fractional anisotropy (FA) or apparent diffusion coefficient (ADC). Here, we used a novel fixel-based along-tract analysis consisting of constrained spherical deconvolution (CSD)-based probabilistic tractography and fixel-based apparent fiber density (FD), capable of identifying fiber orientation specific microstructural metrics. We addressed this novel methodology’s capability to detect corticospinal tract impairment. We measured and compared tractogram-related FD and traditional microstructural metrics bihemispherically in 65 patients with WHO grade III and IV gliomas infiltrating the motor system. The cortical tractogram seeds were based on motor maps derived by transcranial magnetic stimulation. We extracted 100 equally distributed cross-sections along each streamline of corticospinal tract (CST) for along-tract statistical analysis. Cross-sections were then analyzed to detect differences between healthy and pathological hemispheres. All metrics showed significant differences between healthy and pathologic hemispheres over the entire tract and between peritumoral segments. Peritumoral values were lower for FA and FD, but higher for ADC within the entire cohort. FD was more specific to tumor-induced changes in CST than ADC or FA, whereas ADC and FA showed higher sensitivity. The bihemispheric along-tract analysis provides an approach to detect subject-specific structural changes in healthy and pathological WM. In the current clinical dataset, the more complex FD metrics did not outperform FA and ADC in terms of describing corticospinal tract impairment.

Impaired Glutamate Receptor Function Underlies Early Activity Loss of Ipsilesional Motor Cortex after Closed-Head Mild Traumatic Brain Injury.

Although mild traumatic brain injury (mTBI) accounts for the majority of TBI patients, the effects and cellular and molecular mechanisms of mTBI on cortical neural circuits are still not well understood. Given the transient and non-specific functional deficits after mTBI, it is important to understand whether mTBI causes functional deficits of the brain and the underlying mechanism, particularly during the early stage after injury. Here, we used in vivo optogenetic motor mapping to determine longitudinal changes in cortical motor map and in vitro calcium imaging to study how changes in cortical excitability and calcium signals may contribute to the motor deficits in a closed-head mTBI model. In channelrhodopsin 2 (ChR2)-expressing transgenic mice, we recorded electromyograms (EMGs) from bicep muscles induced by scanning blue laser on the motor cortex. There were significant decreases in the size and response amplitude of motor maps of the injured cortex at 2 h post-mTBI, but an increase in motor map size of the contralateral cortex in 12 h post-mTBI, both of which recovered to baseline level in 24 h. Calcium imaging of cortical slices prepared from green fluorescent calmodulin proteins-expressing transgenic mice showed a lower amplitude, but longer duration, of calcium transients of the injured cortex in 2 h post-mTBI. Blockade of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid or N-methyl-d-aspartate receptors resulted in smaller amplitude of calcium transients, suggesting impaired function of both receptor types. Imaging of calcium transients evoked by glutamate uncaging revealed reduced response amplitudes and longer duration in 2, 12, and 24 h after mTBI. Higher percentages of neurons of the injured cortex had a longer latency period after uncaging than that of the uninjured neurons. The results suggest that impaired glutamate neurotransmission contributes to functional deficits of the motor cortex in vivo, which supports enhancing glutamate neurotransmission as a potential therapeutic approach for the treatment of mTBI.

Preoperative Applications of Navigated Transcranial Magnetic Stimulation.

Preoperative mapping of cortical structures prior to neurosurgical intervention can provide a roadmap of the brain with which neurosurgeons can navigate critical cortical structures. In patients undergoing surgery for brain tumors, preoperative mapping allows for improved operative planning, patient risk stratification, and personalized preoperative patient counseling. Navigated transcranial magnetic stimulation (nTMS) is one modality that allows for highly accurate, image-guided, non-invasive stimulation of the brain, thus allowing for differentiation between eloquent and non-eloquent cortical regions. Motor mapping is the best validated application of nTMS, yielding reliable maps with an accuracy similar to intraoperative cortical mapping. Language mapping is also commonly performed, although nTMS language maps are not as highly concordant with direct intraoperative cortical stimulation maps as nTMS motor maps. Additionally, nTMS has been used to localize cortical regions involved in other functions such as facial recognition, calculation, higher-order motor processing, and visuospatial orientation. In this review, we evaluate the growing literature on the applications of nTMS in the preoperative setting. First, we analyze the evidence in support of the most common clinical applications. Then we identify usages that show promise but require further validation. We also discuss developing nTMS techniques that are still in the experimental stage, such as the use of nTMS to enhance postoperative recovery. Finally, we highlight practical considerations when utilizing nTMS and, importantly, its safety profile in neurosurgical patients. In so doing, we aim to provide a comprehensive review of the role of nTMS in the neurosurgical management of a patient with a brain tumor.

Intraoperative neurophysiological mapping: the effect of general anaesthetic impact on brain cortex affectability

Neuron irritation lies at the heart of intraoperative motor mapping and varies with the general anaesthetic type and dose. Basing on the analysis of 63 cases (male/female 25/38, aged 21–69) of brain tumors (glial tumors, metastasis, cavernous angiomas) the study explores the role of propofol and sevoflurane in the affectability of cortex neurons during the intraoperative neurophysiological mapping. The study has clearly demonstrated that the liminal current strength is notably higher when inhalation anaesthesia (sevoflurane) is used, than in the case of TIVA (propofol). The propofol activity in the doses causing brain activity depression results in a sharp increase in the excitability threshold. In contrast, sevoflurane causes a steady dose-related rise in the liminal current strength during the motor area galvanic stimulation due to the suppression of affectability and conduction in the nervous system.

Bone Wax as an Intra-Cavitary Fiducial for Intra-Operative Magnetic Resonance Imaging Guided Resections of Eloquent Cortex Glioma.

The extent of resection of eloquent cortex low-grade glioma is improved by intraoperative magnetic resonance imaging (IOMRI) which is faced with challenges such as difficulty in automated registration after the MRI and prolongation of operative time. We describe an easier and foolproof method of resection using bone wax as fiducial. A young male with right-frontal low-grade glioma anterior and superficial to the motor fibers was operated using IOMRI and awake craniotomy under neuromonitoring. Motor cortex mapping using phase reversal and continuous motor evoked potential (MEP) monitoring was used initially followed by continuous sub-cortical suction stimulation for deeper decompression until stimulation was seen. Bone wax in a triangular shape was placed at the suspicious margin and IOMRI was done. The tumor residue was seen anterior and deeper to the bone wax and removed subsequently. The use of bone wax as a fiducial can aid in IOMRI-guided resection of eloquent cortex glioma in awake patients.

Introduction of a novel connection clip for the ultrasonic aspirator for subcortical continuous motor mapping

IntroductionA connection clip to the ultrasonic aspirator handpiece was introduced for simultaneous resection and mapping of corticospinal motor tract (CST) (Kombos et al., 2001).Research questionTo report retrospectively the use of this clip in cerebral surgery with CST mapping.Material and methodsEight women and four men were included (mean: 55.8 years, SD 17.3 years). The ultrasonic aspirator handpiece was stimulated every second (5 biphasic pulses, 0.4 ​ms per phase, max 14 ​mA). Motor evoked potentials (MEPs) (Taniguchi et al., 1993), with transcranial and direct cortical stimulation, were alternated with CST mapping. The distances between the stimulus locations to the CST (diffusion tensor imaging based fibre tractography) were determined postoperatively. Muscle strength was evaluated pre-operatively, at discharge and 3 months.ResultsMotor mapping thresholds ranged between 2 and 13 ​mA, in 12 consecutive patients (7 post-central, 5 insular). The distance of the stimulation site to the CST was fitted (y ​= ​0.63x+2.33, R2 ​= ​0.33; x, mA; y, mm), approximating the rule of thumb of 1 ​mA indicating 1 ​mm (R2 ​= ​0.22). One patient presented with a deterioration of motor function (wrist, M4+). No intraoperative seizures were observed.DiscussionThe concept that 1 ​mA corresponds to 1 ​mm from the CST, was roughly observed within this low current range. This rule must be applied, integrating the confidence limits, when getting close to the CST, in conjunction with MEPs.ConclusionThe standardization of this clip, for continuous stimulation of the ultrasonic aspirator with simultaneous tissue resection, made the guided surgical flow smoother, more refined and very natural.

Primary hand motor representation areas in healthy children, preadolescents, adolescents, and adults

The development of the organization of the motor representation areas in children and adolescents is not well-known. This cross-sectional study aimed to provide an understanding for the development of the functional motor areas of the upper extremity muscles by studying healthy right-handed children (6–9 years, n = 10), preadolescents (10–12 years, n = 13), adolescents (15–17 years, n = 12), and adults (22–34 years, n = 12). The optimal representation site and resting motor threshold (rMT) for the abductor pollicis brevis (APB) were assessed in both hemispheres using navigated transcranial magnetic stimulation (nTMS). Motor mapping was performed at 110% of the rMT while recording the EMG of six upper limb muscles in the hand and forearm. The association between the motor map and manual dexterity (box and block test, BBT) was examined. The mapping was well-tolerated and feasible in all but the youngest participant whose rMT exceeded the maximum stimulator output. The centers-of-gravity (CoG) for individual muscles were scattered to the greatest extent in the group of preadolescents and centered and became more focused with age. In preadolescents, the CoGs in the left hemisphere were located more laterally, and they shifted medially with age. The proportion of hand compared to arm representation increased with age (p = 0.001); in the right hemisphere, this was associated with greater fine motor ability. Similarly, there was less overlap between hand and forearm muscles representations in children compared to adults (p<0.001). There was a posterior-anterior shift in the APB hotspot coordinate with age, and the APB coordinate in the left hemisphere exhibited a lateral to medial shift with age from adolescence to adulthood (p = 0.006). Our results contribute to the elucidation of the developmental course in the organization of the motor cortex and its associations with fine motor skills. It was shown that nTMS motor mapping in relaxed muscles is feasible in developmental studies in children older than seven years of age.

Increased Anxiety-Like Behavior in the Acute Phase of a Preclinical Model of Periodontal Disease.

Periodontal disease (PD) is an infectious-inflammatory oral disease that is highly prevalent among adolescence and adulthood and can lead to chronic orofacial pain and be associated with anxiety, stress and depression. This study aimed to identify anxiety-like behaviors in the ligature-induced murine preclinical model of PD in different phases of the disease (i.e., acute vs. chronic). Also, we investigated orofacial mechanical allodynia thresholds and superficial cortical plasticity along the orofacial motor cortex in both disease phases. To this aim, 25 male Wistar rats were randomly allocated in acute (14 days) or chronic (28 days) ligature-induced-PD groups and further divided into active-PD or sham-PD. Anxiety-like behavior was evaluated using the elevated plus maze, mechanical allodynia assessed using the von Frey filaments test and superficial motor cortex mapping was performed with electrical transdural stimulation. We observed increased anxiety-like behavior in active-PD animals in the acute phase, characterized by decreased number of entries into the open arm extremities [t(1,7) = 2.42, p = 0.04], and reduced time spent in the open arms [t(1,7) = 3.56, p = 0.01] and in the open arm extremities [t(1,7) = 2.75, p = 0.03]. There was also a reduction in the mechanical allodynia threshold in all active-PD animals [Acute: t(1,7) = 8.81, p < 0.001; Chronic: t(1,6) = 60.0, p < 0.001], that was positively correlated with anxiety-like behaviors in the acute group. No differences were observed in motor cortex mapping. Thus, our findings show the presence of anxiety-like behaviors in the acute phase of PD making this a suitable model to study the impact of anxiety in treatment response and treatment efficacy.

Navigated TMS in the ICU: Introducing Motor Mapping to the Critical Care Setting.

Navigated transcranial magnetic stimulation (nTMS) is a modality for noninvasive cortical mapping. Specifically, nTMS motor mapping is an objective measure of motor function, offering quantitative diagnostic information regardless of subject cooperation or consciousness. Thus far, it has mostly been restricted to the outpatient setting. This study evaluates the feasibility of nTMS motor mapping in the intensive care unit (ICU) setting and solves the challenges encountered in this special environment. We compared neuronavigation based on computed tomography (CT) and magnetic resonance imaging (MRI). We performed motor mappings in neurocritical patients under varying conditions (e.g., sedation or hemicraniectomy). Furthermore, we identified ways of minimizing electromyography (EMG) noise in the interference-rich ICU environment. Motor mapping was performed in 21 patients (six females, median age: 69 years). In 18 patients, motor evoked potentials (MEPs) were obtained. In three patients, MEPs could not be evoked. No adverse reactions occurred. We found CT to offer a comparable neuronavigation to MRI (CT maximum e-field 52 ± 14 V/m vs. MRI maximum e-field 52 ± 11 V/m; p = 0.6574). We detailed EMG noise reduction methods and found that propofol sedation of up to 80 mcg/kg/h did not inhibit MEPs. Yet, nTMS equipment interfered with exposed pulse oximetry. nTMS motor mapping application and use was illustrated in three clinical cases. In conclusion, we present an approach for the safe and reliable use of nTMS motor mapping in the ICU setting and outline possible benefits. Our findings support further studies regarding the clinical value of nTMS in critical care settings.

Spinal motor mapping by epidural stimulation of lumbosacral posterior roots in humans.

SummaryEpidural electrical stimulation of the spinal cord is an emergent strategy for the neurological recovery of lower-extremity motor function. Motoneuron pools are thought to be recruited by stimulation of posterior roots. Here, we linked electromyographic data of epidurally evoked lower-extremity responses of 34 individuals with upper motoneuron disorders to a population model of the spinal cord constructed using anatomical parameters of thousands of individuals. We identified a relationship between segmental stimulation sites and activated spinal cord segments, which made spinal motor mapping from epidural space possible despite the complex anatomical interface imposed by the posterior roots. Our statistical approach provided evidence for low-threshold sites of posterior roots and effects of monopolar and bipolar stimulation previously predicted by computer modeling and allowed us to test the impact of different upper motoneuron disorders on the evoked responses. Finally, we revealed a statistical association between intraoperative and postoperative mapping of the spinal cord.

Rapid and Accumulated Modulation of Action-Effects on Action.

Auditory feedback to a keypress is used in many devices to facilitate the motor output. The timing of auditory feedback is known to have an impact on the motor output, yet it is not known if a keypress action can be modulated on-line by an auditory feedback or how quick an auditory feedback can influence an ongoing keypress. Furthermore, it is not clear if the prediction of auditory feedback already changes the early phase of a keypress action independent of sensory feedback, which would suggest that such prediction changes the motor plan. In the current study, participants pressed a touch-sensitive device with auditory feedback in a self-paced manner. The auditory feedback was given either after a short (60 msec) or long (160 msec) delay, and the delay was either predictable or not. Our results showed that the keypress peak force was modulated by the amount of auditory feedback delay even when the delay was unpredictable, thus demonstrating an on-line modulation effect. The latency of the on-line modulation was suggested to be as low as 70 msec, indicating a very fast sensory to motor mapping circuit in the brain. When the auditory feedback delay was predictable, a change in the very early phase of keypress motor output was found, suggesting that the prediction of sensory feedback is crucial to motor control. Therefore, even a simple keypress action contains rich motor dynamics, which depend on expected as well as on-line perceived sensory feedback.

Intraoperative Lumbar Muscle Motor Evoked Potential Monitoring With Transcortical Stimulation

Stimulating electrodes for lower extremity motor-evoked potential (LE-MEP) monitoring with transcortical stimulation are usually placed on the medial side of motor cortex convexity, which is not lower extremity but lumbar motor area. Lumbar MEP may be elicited with lower stimulation intensity than LE-MEP through this location, and it is useful to monitor lower extremity motor function intraoperatively. Intraoperative lumbar and LE-MEP monitoring with transcortical stimulation during surgery of 12 patients with lesions involving the motor cortex from January 2012 to February 2019 at Shinshu University Hospital were reviewed retrospectively. Stimulations were delivered by a train of 5 pulses of anodal constant current stimulation. Stimulating electrode position was determined by motor cortex mapping. Recording needle electrodes were placed on bilateral lumbar muscles and contralateral leg muscles. The threshold-level stimulation method was used for MEP monitoring. The thresholds, monitoring result, and postoperative motor function of lumbar and lower extremities were compared. The mean baseline thresholds were 19.9 ± 8.9 mA for lumbar MEP and 26.5 ± 11.5 mA for LE-MEP (P= 0.02). Patterns of intraoperative monitoring changes were the same between lumbar and LE-MEP monitoring. Lumbar MEP was stimulated with lower stimulation intensity than the LE-MEP with the same intraoperative pattern of waveform changes in 12 patients. Lumbar MEP monitoring may be useful for preserving the corticospinal tract of lower extremities intraoperatively.

Corticospinal properties are associated with sensorimotor performance in action video game players

Notwithstanding the apparent demands regarding fine motor skills that are required to perform in action video games, the motor nervous system of players has not been studied systematically. In the present study, we hypothesized to find differences in sensorimotor performance and corticospinal characteristics between action video game players (Players) and Controls.We tested sensorimotor performance in video games tasks and used transcranial magnetic stimulation (TMS) to measure motor map, input-output (IO) and short intra-cortical inhibition (SICI) curves in the first dorsal interosseous (FDI) muscle of Players (n = 18) and Control (n = 18).Players scored higher in performance tests and had stronger SICI and higher motor evoked potential (MEP) amplitudes. Multiple linear regressions showed that Players and Control differed with respect to their relation between reaction time and corticospinal excitability. However, we did not find different motor map topography or different IO curves for Players when compared to Controls.Action video game players showed an increased efficiency of motor cortical inhibitory and excitatory neural networks. Players also showed a different relation of MEPs with reaction time.The present study demonstrates the potential of action video game players as an ideal population to study the mechanisms underlying visuomotor performance and sensorimotor learning.

White matter damage and altered connectivity between primary motor cortices in chronic obstructive pulmonary disease.

White matter damage and altered connectivity between primary motor cortices in chronic obstructive pulmonary disease.

Short-Interval Intracortical Facilitation Improves Efficacy in nTMS Motor Mapping of Lower Extremity Muscle Representations in Patients with Supra-Tentorial Brain Tumors.

Simple SummaryPresurgical motor mapping of cortical muscle representations by single-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used to localize and enclose motor function in patients harboring motor-eloquent lesions. This study investigates paired-pulse nTMS (pp-nTMS) with biphasic pulses for motor mapping of lower extremity (lE) muscle representations, showing that significantly lower stimulation intensities are needed while reliable motor maps can be achieved even in the most demanding patient cases in whom conventionally used sp-nTMS fails. Thus, novel pp-nTMS with biphasic pulses may have potential to considerably facilitate improvements of currently used nTMS-based mapping procedures in the preoperative workup of neurooncological patients.Navigated transcranial magnetic stimulation (nTMS) is increasingly used for mapping of motor function prior to surgery in patients harboring motor-eloquent brain lesions. To date, single-pulse nTMS (sp-nTMS) has been predominantly used for this purpose, but novel paired-pulse nTMS (pp-nTMS) with biphasic pulse application has been made available recently. The purpose of this study was to systematically evaluate pp-nTMS with biphasic pulses in comparison to conventionally used sp-nTMS for preoperative motor mapping of lower extremity (lE) muscle representations. Thirty-nine patients (mean age: 56.3 ± 13.5 years, 69.2% males) harboring motor-eloquent brain lesions of different entity underwent motor mapping of lE muscle representations in lesion-affected hemispheres and nTMS-based tractography of the corticospinal tract (CST) using data from sp-nTMS and pp-nTMS with biphasic pulses, respectively. Compared to sp-nTMS, pp-nTMS enabled motor mapping with lower stimulation intensities (61.8 ± 13.8% versus 50.7 ± 11.6% of maximum stimulator output, p < 0.0001), and it provided reliable motor maps even in the most demanding cases where sp-nTMS failed (pp-nTMS was able to provide a motor map in five patients in whom sp-nTMS did not provide any motor-positive points, and pp-nTMS was the only modality to provide a motor map in one patient who also did not show motor-positive points during intraoperative stimulation). Fiber volumes of the tracked CST were slightly higher when motor maps of pp-nTMS were used, and CST tracking using pp-nTMS data was also possible in the five patients in whom sp-nTMS failed. In conclusion, application of pp-nTMS with biphasic pulses enables preoperative motor mapping of lE muscle representations even in the most challenging patients in whom the motor system is at high risk due to lesion location or resection.

Paired-pulse navigated TMS is more effective than single-pulse navigated TMS for mapping upper extremity muscles in brain tumor patients

ObjectiveSingle-pulse navigated transcranial magnetic stimulation (sp-nTMS) is used for presurgical motor mapping in patients with motor-eloquent lesions. However, recently introduced paired-pulse nTMS (pp-nTMS) with biphasic pulses could improve motor mapping. MethodsThirty-four patients (mean age: 56.0 ± 12.7 years, 53.0% high-grade glioma) with motor-eloquent lesions underwent motor mapping of upper extremity representations and nTMS-based tractography of the corticospinal tract (CST) by both sp-nTMS and pp-nTMS with biphasic pulses for the tumor-affected hemisphere before resection. ResultsIn three patients (8.8%), conventional sp-nTMS did not provide motor-positive points, in contrast to pp-nTMS that was capable of generating motor maps in all patients. Good concordance between pp-nTMS and sp-nTMS in the spatial location of motor hotspots and center of gravity (CoG) as well as for CST tracking was observed, with pp-nTMS leading to similar motor map volumes (585.0 ± 667.8 vs. 586.8 ± 204.2 mm3, p = 0.9889) with considerably lower resting motor thresholds (35.0 ± 8.8 vs. 32.8 ± 7.6% of stimulator output, p = 0.0004). ConclusionsPp-nTMS with biphasic pulses may provide motor maps even in highly demanding cases with tumor-affected motor structures or edema, using lower stimulation intensity compared to sp-nTMS. SignificancePp-nTMS with biphasic pulses could replace standardly used sp-nTMS for motor mapping and may be safer due to lower stimulation intensity.