Hemispheric asymmetry in supplementary motor area connectivity during unilateral finger movements

Elevated Levels of Serum Biomarkers Associated with Damage to the CNS Neurons and Endothelial Cells Are Linked with Changes in Brain Connectivity in Breast Cancer Patients with Vestibulo-Atactic Syndrome

Vestibulo-atactic syndrome (VAS), which represents a combination of motor and vestibular disorders, can be manifested as a clinical complication of breast cancer treatment and has a significant impact on patients' quality of life. The identification of novel potential biomarkers that might help to predict the onset of VAS and its progression could improve the management of this group of patients. In the current study, the levels of intercellular cell adhesion molecule 1 (ICAM-1), platelet/endothelial cell adhesion molecule 1 (PECAM-1), NSE (neuron-specific enolase), and the antibodies recognizing NR-2 subunit of NMDA receptor (NR-2-ab) were measured in the blood serum of BC survivor patients with vestibulo-atactic syndrome (VAS) and associated with the brain connectome data obtained via functional magnetic resonance imaging (fMRI) studies. A total of 21 patients were registered in this open, single-center trial and compared to age-matched healthy female volunteers (control group) (n = 17). BC patients with VAS demonstrated higher serum levels of ICAM-1, PECAM-1, and NSE and a lower value of NR-2-ab, with values of 654.7 ± 184.8, 115.3 ± 37.03, 49.9 ± 103.9, and 0.5 ± 0.3 pg/mL, respectively, as compared to the healthy volunteers, with 230.2 ± 44.8, 62.8 ± 15.6, 15.5 ± 6.4, and 1.4 ± 0.7 pg/mL. According to the fMRI data (employing seed-to-voxel and ROI-to-ROI methods), in BC patients with VAS, significant changes were detected in the functional connectivity in the areas involved in the regulation of postural-tonic reflexes, the coordination of movements, and the regulation of balance. In conclusion, the detected elevated levels of serum biomarkers may reveal damage to the CNS neurons and endothelial cells that is, in turn, associated with the change in the brain connectivity in this group of patients.

Tactile perception of right middle fingertip suppresses excitability of motor cortex supplying right first dorsal interosseous muscle

The present study examined whether tactile perception of the fingertip modulates excitability of the motor cortex supplying the intrinsic hand muscle and whether this modulation is specific to the fingertip stimulated and the muscle and hand tested. Tactile stimulation was given to one of the five fingertips in the left or right hand, and transcranial magnetic stimulation eliciting motor evoked potential in the first dorsal interosseous muscle (FDI) or abductor digiti minimi was given 200 ms after the onset of tactile stimulation. The corticospinal excitability of the FDI at rest was suppressed by the tactile stimulation of the right middle fingertip, but such suppression was absent for the other fingers stimulated and for the other muscle or hand tested. The persistence and amplitude of the F-wave was not significantly influenced by tactile stimulation of the fingertip in the right hand. These findings indicate that tactile perception of the right middle fingertip suppresses excitability of the motor cortex supplying the right FDI at rest. The suppression of corticospinal excitability was absent during tonic contraction of the right FDI, indicating that the motor execution process interrupts the tactile perception-induced suppression of motor cortical excitability supplying the right FDI. These findings are in line with a view that the tactile perception of the right middle finger induces surround inhibition of the motor cortex supplying the prime mover of the finger neighboring the stimulated finger.

A Long Short-Term Memory Network for Sparse Spatiotemporal EEG Source Imaging

EEG inverse problem is underdetermined, which poses a long standing challenge in Neuroimaging. The combination of source-imaging and analysis of cortical directional networks enables us to noninvasively explore the underlying neural processes. However, existing EEG source imaging approaches mainly focus on performing the direct inverse operation for source estimation, which will be inevitably influenced by noise and the strategy used to find the inverse solution. Here, we develop a new source imaging technique, Deep Brain Neural Network (DeepBraiNNet), for robust sparse spatiotemporal EEG source estimation. In DeepBraiNNet, considering that Recurrent Neural Network (RNN) are usually "deep" in temporal dimension and thus suitable for time sequence modelling, the RNN with Long Short-Term Memory (LSTM) is utilized to approximate the inverse operation for the lead field matrix instead of performing the direct inverse operation, which avoids the possible effect of the direct inverse operation on the underdetermined lead field matrix prone to be influenced by noise. Simulations on various source patterns and noise conditions confirmed that the proposed approach could actually recover the spatiotemporal sources well, outperforming existing state of-the-art methods. DeepBraiNNet also estimated sparse MI related activation patterns when it was applied to a real Motor Imagery dataset, consistent with other findings based on EEG and fMRI. Based on the spatiotemporal sources estimated from DeepBraiNNet, we constructed MI related cortical neural networks, which clearly exhibited strong contralateral network patterns for the two MI tasks. Consequently, DeepBraiNNet may provide an alternative way different from the conventional approaches for spatiotemporal EEG source imaging.

Influence of the Inter-Trial Interval, Movement Observation, and Hand Dominance on the Previous Trial Effect

Previous studies have shown that current movement is influenced by the previous movement, which is known as the previous trial effect. In this study, we investigated the influence of the inter-trial interval, movement observation, and hand dominance on the previous trial effect of the non-target discrete movement. Right-handed healthy humans abducted the index finger in response to a start cue, and this task was repeated with constant inter-trial intervals. The absolute difference in the reaction time (RT) between the previous and current trials increased as the inter-trial interval increased. The absolute difference in RT reflects the reproducibility of the time taken for the motor execution between two consecutive trials. Thus, the finding supported the view that there is a carryover of movement information from one trial to the next, and that the underlying reproducibility of the RT between the two consecutive trials decays over time. This carryover of movement information is presumably conveyed by implicit short-term memory, which also decays within a short period of time. The correlation coefficient of the RT between the previous and current trials decreased with an increase in the inter-trial interval, indicating that the common responsiveness of two consecutive trials weakens over time. The absolute difference was smaller when the response was performed while observing finger movement, indicating that a carryover of the visual information to the next trial enhances the reproducibility of the motor execution process between consecutive trials. Hand dominance did not influence the absolute difference or correlation coefficient, indicating that the central process mediating previous trial effect of hand movement is not greatly lateralized.

Sleep deprivation alters task-related changes in functional connectivity of the frontal cortex: A near-infrared spectroscopy study

Sleep deprivation (SD) is known to be associated with decreased cognitive performance; however, the underlying mechanisms are poorly understood. As interactions between distinct brain regions depend on mental state, functional brain networks established by these connections typically show a reorganization during task. Hence, analysis of functional connectivity (FC) could reveal the task-related change in the examined frontal brain networks. Our objective was to assess the impact of SD on static FC in the prefrontal and motor cortices and find whether changes in FC correlate with changes in neuropsychological scores. Healthy young male individuals (n = 10, 27.6 ± 3.7 years of age) participated in the study. A battery of tests from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and 48 channel functional near-infrared spectroscopy (fNIRS) measurements were performed before and after 24 hr of SD. Network metrics were obtained by graph theoretical analysis using the fNIRS records in resting state and during finger-tapping sessions. During task, SD resulted in a significantly smaller decrease in the number and strength of functional connections (characterizing FC) in the frontal cortex. Changes in the global connection strengths correlated with decreased performance in the paired association learning test. These results indicate a global impact of SD on functional brain networks in the frontal lobes.

Sparsely Wiring Connectivity in the Upper Beta Band Characterizes the Brains of Top Swimming Athletes

Human brains are extremely energy costly in neural connections and activities. However, it is unknown what is the difference in the brain connectivity between top athletes with long-term professional trainings and age-matched controls. Here we ask whether long-term training can lower brain-wiring cost while have better performance. Since elite swimming requires athletes to move their arms and legs at different tempos in time with high coordination skills, we selected an eye-hand-foot complex reaction (CR) task to examine the relations between the task performance and the brain connections and activities, as well as to explore the energy cost-efficiency of top athletes. Twenty-one master-level professional swimmers and 23 age-matched non-professional swimmers as controls were recruited to perform the CR task with concurrent 8-channel EEG recordings. Reaction time and accuracy of the CR task were recorded. Topological network analysis of various frequency bands was performed using the phase lag index (PLI) technique to avoid volume conduction effects. The wiring number of connections and mean frequency were calculated to reflect the wiring and activity cost, respectively. Results showed that professional athletes demonstrated better eye-hand-foot coordination than controls when performing the CR task, indexing by faster reaction time and higher accuracy. Comparing to controls, athletes' brain demonstrated significantly less connections and weaker correlations in upper beta frequency band between the frontal and parietal regions, while demonstrated stronger connectivity in the low theta frequency band between sites of F3 and Cz/C4. Additionally, athletes showed highly stable and low eye-blinking rates across different reaction performance, while controls had high blinking frequency with high variance. Elite athletes' brain may be characterized with energy efficient sparsely wiring connections in support of superior motor performance and better cognitive performance in the eye-hand-foot complex reaction task.

An fMRI study of scientists with a Ph.D. in physics confronted with naive ideas in science

A central challenge in developing conceptual understanding in science is overcoming naive ideas that contradict the content of science curricula. Neuroimaging studies reveal that high school and university students activate frontal brain areas associated with inhibitory control to overcome naive ideas in science, probably because they persist despite scientific training. However, no neuroimaging study has yet explored how persistent naive ideas in science are. Here, we report brain activations of 25 scientists with a Ph.D. in physics assessing the scientific value of naive ideas in science. Results show that scientists are slower and have lower accuracy when judging the scientific value of naive ideas compared to matched control ideas. fMRI data reveals that a network of frontal brain regions is more activated when judging naive ideas. Results suggest that naive ideas are likely to persist, even after completing a Ph.D. Advanced experts may still rely on high order executive functions like inhibitory control to overcome naive ideas when the context requires it.

A Joint Analysis of Multi-Paradigm fMRI Data With Its Application to Cognitive Study

With the development of neuroimaging techniques, a growing amount of multi-modal brain imaging data are collected, facilitating comprehensive study of the brain. In this paper, we jointly analyzed functional magnetic resonance imaging (fMRI) collected under different paradigms in order to understand cognitive behaviors of an individual. To this end, we proposed a novel multi-view learning algorithm called structure-enforced collaborative regression (SCoRe) to extract co-expressed discriminative brain regions under the guidance of anatomical structure of the brain. An advantage of SCoRe over its predecessor collaborative regression (CoRe) lies in its incorporation of group structures in the brain imaging data, which makes the model biologically more meaningful. Results from real data analysis has confirmed that by incorporating prior knowledge of brain structure, SCoRe can deliver better prediction performance and is less sensitive to hyper-parameters than CoRe. After validation with simulation experiments, we applied SCoRe to fMRI data collected from the Philadelphia Neurodevelopmental Cohort and adopted the scores from the wide range achievement test (WRAT) to evaluate an individual's cognitive skills. We located 14 relevant brain regions that can efficiently predict WRAT scores and these brain regions were further confirmed by other independent studies.

Directed EEG neural network analysis by LAPPS (p≤1) Penalized sparse Granger approach

The conventional multivariate Granger Analysis (GA) of directed interactions has been widely applied in brain network construction based on EEG recordings as well as fMRI. Nevertheless, EEG is usually inevitably contaminated by strong noise, which may cause network distortion due to the L2-norm used in GAs for directed network recovery. The Lp (p ≤1) norm has been shown to be more robust to outliers as compared to LASSO and L2-GAs. Motivated to construct the sparse brain networks under strong noise condition, we hereby introduce a new approach for GA analysis, termed LAPPS (Least Absolute LP (0<p<1) Penalized Solution). LAPPS utilizes the L1-loss function for the residual error to alleviate the effect of outliers, and another Lp-penalty term (p=0.5) to obtain the sparse connections while suppressing the spurious linkages in the networks. The simulation results reveal that LAPPS obtained the best performance under various noise conditions. In a real EEG data test when subjects performed the left and right hand Motor Imagery (MI) for brain network estimation, LAPPS also obtained a sparse network pattern with the hub at the contralateral brain primary motor areas consistent with the physiological basis of MI.

The supplementary motor area modulates interhemispheric interactions during movement preparation

The execution of coordinated hand movements requires complex interactions between premotor and primary motor areas in the two hemispheres. The supplementary motor area (SMA) is involved in movement preparation and bimanual coordination. How the SMA controls bimanual coordination remains unclear, although there is evidence suggesting that the SMA could modulate interhemispheric interactions. With a delayed-response task, we investigated interhemispheric interactions underlying normal movement preparation and the role of the SMA in these interactions during the delay period of unimanual or bimanual hand movements. We used functional MRI and transcranial magnetic stimulation in 22 healthy volunteers (HVs), and then in two models of SMA dysfunction: (a) in the same group of HVs after transient disruption of the right SMA proper by continuous transcranial magnetic theta-burst stimulation; (b) in a group of 22 patients with congenital mirror movements (CMM), whose inability to produce asymmetric hand movements is associated with SMA dysfunction. In HVs, interhemispheric connectivity during the delay period was modulated according to whether or not hand coordination was required for the forthcoming movement. In HVs following SMA disruption and in CMM patients, interhemispheric connectivity was modified during the delay period and the interhemispheric inhibition was decreased. Using two models of SMA dysfunction, we showed that the SMA modulates interhemispheric interactions during movement preparation. This unveils a new role for the SMA and highlights its importance in coordinated movement preparation.

The Dynamic Brain Networks of Motor Imagery: Time-Varying Causality Analysis of Scalp EEG

Motor imagery (MI) requires subjects to visualize the requested motor behaviors, which involves a large-scale network that spans multiple brain areas. The corresponding cortical activity reflected on the scalp is characterized by event-related desynchronization (ERD) and then by event-related synchronization (ERS). However, the network mechanisms that account for the dynamic information processing of MI during the ERD and ERS periods remain unknown. Here, we combined ERD/ERS analysis with the dynamic networks in different MI stages (i.e. motor preparation, ERD and ERS) to probe the dynamic processing of MI information. Our results show that specific dynamic network structures correspond to the ERD/ERS evolution patterns. Specifically, ERD mainly shows the contralateral networks, while ERS has the symmetric networks. Moreover, different dynamic network patterns are also revealed between the two types of MIs, in which the left-hand MIs exhibit a relatively less sustained contralateral network, which may be the network mechanism that accounts for the bilateral ERD/ERS observed for the left-hand MIs. Similar to the network topologies, the three MI stages also appear to be characterized by different network properties. The above findings all demonstrate that different MI stages that involve specific brain networks for dynamically processing the MI information.

Working Memory Deficits After Lesions Involving the Supplementary Motor Area

The Supplementary Motor Area (SMA)—located in the superior and medial aspects of the superior frontal gyrus—is a preferential site of certain brain tumors and arteriovenous malformations, which often provoke the so-called SMA syndrome. The bulk of the literature studying this syndrome has focused on two of its most apparent symptoms: contralateral motor and speech deficits. Surprisingly, little attention has been given to working memory (WM) even though neuroimaging studies have implicated the SMA in this cognitive process. Given its relevance for higher-order functions, our main goal was to examine whether WM is compromised in SMA lesions. We also asked whether WM deficits might be reducible to processing speed (PS) difficulties. Given the connectivity of the SMA with prefrontal regions related to executive control (EC), as a secondary goal we examined whether SMA lesions also hampered EC. To this end, we tested 12 patients with lesions involving the left (i.e., the dominant) SMA. We also tested 12 healthy controls matched with patients for socio-demographic variables. To ensure that the results of this study can be easily transferred and implemented in clinical practice, we used widely-known clinical neuropsychological tests: WM and PS were measured with their respective Wechsler Adult Intelligence Scale indexes, and EC was tested with phonemic and semantic verbal fluency tasks. Non-parametric statistical methods revealed that patients showed deficits in the executive component of WM: they were able to sustain information temporarily but not to mentally manipulate this information. Such WM deficits were not subject to patients' marginal PS impairment. Patients also showed reduced phonemic fluency, which disappeared after controlling for the influence of WM. This observation suggests that SMA damage does not seem to affect cognitive processes engaged by verbal fluency other than WM. In conclusion, WM impairment needs to be considered as part of the SMA syndrome. These findings represent the first evidence about the cognitive consequences (other than language) of damage to the SMA. Further research is needed to establish a more specific profile of WM impairment in SMA patients and determine the consequences of SMA damage for other cognitive functions.

Asymmetry and Structure of the Fronto-Parietal Networks Underlie Visuomotor Processing in Humans

Research in both humans and monkeys has shown that even simple hand movements require cortical control beyond primary sensorimotor areas. An extensive functional neuroimaging literature demonstrates the key role that cortical fronto-parietal regions play for movements such as reaching and reach-to-grasp. However, no study so far has examined the specific white matter connections linking the fronto-parietal regions, namely the 3 parallel pathways of the superior longitudinal fasciculus (SLF). The aim of the current study was to explore how selective fronto-parietal connections are for different kinds of hand movement in 30 right-handed subjects by correlating diffusion imaging tractography and kinematic data. We showed that a common network, consisting of bilateral SLF II and SLF III, was involved in both reaching and reach-to-grasp movements. Larger SLF II and SLF III in the right hemisphere were associated with faster speed of visuomotor processing, while the left SLF II and SLF III played a role in the initial movement trajectory control. Furthermore, the right SLF II was involved in the closing grip phase necessary for efficient grasping of the object. We demonstrated for the first time that individual differences in asymmetry and structure of the fronto-parietal networks were associated with visuomotor processing in humans.

Manual action verbs modulate the grip force of each hand in unimanual or symmetrical bimanual tasks

Manual action verbs modulate the right-hand grip force in right-handed subjects. However, to our knowledge, no studies demonstrate the ability to accomplish this modulation during bimanual tasks nor describe their effect on left-hand behavior in unimanual and bimanual tasks. Using load cells and word playlists, we evaluated the occurrence of grip force modulation by manual action verbs in unimanual and symmetrical bimanual tasks across the three auditory processing phases. We found a significant grip force increase for all conditions compared to baseline, indicating the occurrence of modulation. When compared to each other, the grip force variation from baseline for the three phases of both hands in the symmetrical bimanual task was not different from the right-hand in the unimanual task. The left-hand grip force showed a lower amplitude for auditory phases 1 and 2 when compared to the other conditions. The right-hand grip force modulation became significant from baseline at 220 ms after the word onset in the unimanual task. This moment occurred earlier for both hands in bimanual task (160 ms for the right-hand and 180 for the left-hand). It occurred later for the left-hand in unimanual task (320 ms). We discuss the hypothesis that Broca's area and Broca's homologue area likely control the left-hand modulation in a unilateral or a bilateral fashion. These results provide new evidence for understanding the linguistic function processing in both hemispheres.

Cerebello-Cortical Differences in Effective Connectivity of the Dominant and Non-dominant Hand during a Visuomotor Paradigm of Grip Force Control

Structural and functional differences are known to exist within the cortical sensorimotor networks with respect to the dominant vs. non-dominant hand. Similarly, the cerebellum, a key structure in the sensorimotor network with its cerebello-cortical connections, has been reported to respond differently when using the dominant vs. non-dominant hand. Several groups have already investigated causal interactions during diverse motor paradigms using effective connectivity but few have studied the larger visuomotor network, including key structures such as the parietal cortex and the cerebellum, with both hands. Moreover, the effect of force level on such interactions is still unclear. We therefore sought to determine the hemispheric asymmetries in the cerebello-cortical sensorimotor network in right-handers at two force levels (5% and 10% maximum voluntary contraction) for both hands. Cerebello-cortical modulations were investigated in 28 healthy, right-handed volunteers by determining the effective connectivity during a visuomotor task at two force levels under fMRI. A network was built consisting of the left and right primary motor (M1), ventral premotor (PMv) and posterior parietal cortices (PPC), in addition to the supplementary motor area (SMA), and the ipsilateral cerebellum (Cer) to the hand performing the motor task. Task performance (precision of isometric grip force tracking) did not differ between hands, nor did task-related activations in the sensorimotor areas apart from the contralateral primary motor cortex. However, during visuomotor control of the non-dominant hand, connectivity analysis revealed causal modulations between (i) the ipsilateral cerebellum and SMA, and (ii) the ipsilatearl cerebellum and contralateral PPC, which was not the case when using the dominant hand. These cerebello-cortical modulations for the non-dominant hand were more present at the higher of the two force levels. We conclude that precision force generation executed with the non-dominant hand, compared to the dominant hand, may require enhanced cerebello-cortical interaction to ensure equivalent left-right task performance.

Cortical Dynamic Causality Network for Auditory-Motor Tasks

Motor preparation and execution require the interactions of a large-scale brain network, while the study of the dynamic changes of their interactions could uncover the underlying neural mechanism of the corresponding information processing. This dynamic analysis requires high temporal resolution of the recorded signals. Electroencephalogram (EEG) with high temporal resolution has been widely used in related studies. However, studies based on scalp EEG always lead to distorted results, due to scalp volume conduction, compared with that of cortically recorded signals. In the current study, the dynamic networks of motor preparation and execution are investigated using Go/No-go tasks performed with the left/right hand. In the analysis, the EEG source localization and dynamic causal model are combined together to investigate the neural processes of motor preparation and execution. The results show that similar network patterns with nodes distributed in the bilateral occipital lobe, bilateral temporal lobe, bilateral dorsolateral prefrontal cortex, and contralateral supplementary motor area could be revealed for both the Go and No-go tasks. Statistical testing further indicates that stronger couplings with the supplementary motor area could be found in Go and right-hand response tasks compared with No-go and left-hand response tasks, respectively. The findings in the current study demonstrate that the information exchange within the motor related brain networks plays an important role for motor related functions, i.e., the different motor functions may have the different information exchange and processing network patterns.

Motor areas of the frontal cortex in patients with motor eloquent brain lesions

OBJECTIVE

Because of its huge clinical potential, the importance of premotor areas for motor function itself and plastic reshaping due to tumors or ischemic brain lesions has received increased attention. Thus, in this study the authors used navigated transcranial magnetic stimulation (nTMS) to investigate whether tumorous brain lesions induce a change in motor cortex localization in the human brain.

METHODS

Between 2010 and 2013, nTMS motor mapping was performed in a prospective cohort of 100 patients with brain tumors in or adjacent to the rolandic cortex. Spatial data analysis was performed by normalization of the individual motor maps and creation of overlays according to tumor location. Analysis of motor evoked potential (MEP) latencies was performed regarding mean overall latencies and potentially polysynaptic latencies, defined as latencies longer than 1 SD above the mean value. Hemispheric dominance, lesion location, and motor-function deficits were also considered.

RESULTS

Graphical analysis showed that motor areas were not restricted to the precentral gyrus. Instead, they spread widely in the anterior-posterior direction. An analysis of MEP latency showed that mean MEP latencies were shortest in the precentral gyrus and longest in the superior and middle frontal gyri. The percentage of latencies longer than 1 SD differed widely across gyri. The dominant hemisphere showed a greater number of longer latencies than the nondominant hemisphere (p < 0.0001). Moreover, tumor location–dependent changes in distribution of polysynaptic latencies were observed (p = 0.0002). Motor-function deficit did not show any statistically significant effect.

CONCLUSIONS

The distribution of primary and polysynaptic motor areas changes in patients with brain tumors and highly depends on tumor location. Thus, these data should be considered for resection planning.

A validation study of the use of near-infrared spectroscopy imaging in primary and secondary motor areas of the human brain

The electroencephalographically measured Bereitschafts (readiness)-potential in the supplementary motor area (SMA) serves as a signature of the preparation of motor activity. Using a multichannel, noninvasive near-infrared spectroscopy (NIRS) imager, we studied the vascular correlate of the readiness potential. Sixteen healthy subjects performed a self-paced or externally triggered motor task in a single or repetitive pattern, while NIRS simultaneously recorded the task-related responses of deoxygenated hemoglobin (HbR) in the primary motor area (M1) and the SMA. Right-hand movements in the repetitive sequence trial elicited a significantly greater HbR response in both the SMA and the left M1 compared to left-hand movements. During the single sequence condition, the HbR response in the SMA, but not in the M1, was significantly greater for self-paced than for externally cued movements. Nonetheless, an unequivocal temporal delay was not found between the SMA and M1. Near-infrared spectroscopy is a promising, noninvasive bedside tool for the neuromonitoring of epileptic seizures or cortical spreading depolarizations (CSDs) in patients with epilepsy, stroke, or brain trauma because these pathological events are associated with typical spatial and temporal changes in HbR. Propagation is a characteristic feature of these events which importantly supports their identification and characterization in invasive recordings. Unfortunately, the present noninvasive study failed to show a temporal delay during self-paced movements between the SMA and M1 as a vascular correlate of the readiness potential. Although this result does not exclude, in principle, the possibility that scalp-NIRS can detect a temporal delay between different regions during epileptic seizures or CSDs, it strongly suggests that further technological development of NIRS should focus on both improved spatial and temporal resolution. This article is part of a Special Issue entitled Status Epilepticus.

Predicting Inter-session Performance of SMR-Based Brain-Computer Interface Using the Spectral Entropy of Resting-State EEG

Currently most subjects can control the sensorimotor rhythm-based brain-computer interface (SMR-BCI) successfully after several training procedures. However, 15-30% of subjects cannot achieve SMR-BCI control even after long-term training, and they are termed as "BCI inefficiency". This study focuses on the investigation of reliable SMR-BCI performance predictor. 40 subjects participated in the first experimental session and 26 of them returned in the second session, each session consists of an eyes closed/open resting-state EEG recording run and four EEG recording runs with hand motor imagery. We found spectral entropy derived from eyes closed resting-state EEG of channel C3 has a high correlation with SMR-BCI performance (r = 0.65). Thus, we proposed to use it as a biomarker to predict individual SMR-BCI performance. Receiver operating characteristics analysis and leave-one-out cross-validation demonstrated that the spectral entropy predictor provide outstanding classification capability for high and low aptitude BCI users. To our knowledge, there has been no discussion about the reliability of inter-session prediction in previous studies. We further evaluated the inter-session prediction performance of the spectral entropy predictor, and the results showed that the average classification accuracy of inter-session prediction up to 89%. The proposed predictor is convenient to obtain because it derived from single channel resting-state EEG, it could be used to identify potential SMR-BCI inefficiency subjects from novel users. But there are still limitations because Kübler et al. have shown that some BCI users may need eight or more sessions before they develop classifiable SMR activity.

Hemispheric lateralization of topological organization in structural brain networks

The study on structural brain asymmetries in healthy individuals plays an important role in our understanding of the factors that modulate cognitive specialization in the brain. Here, we used fiber tractography to reconstruct the left and right hemispheric networks of a large cohort of 346 healthy participants (20-86 years) and performed a graph theoretical analysis to investigate this brain laterality from a network perspective. Findings revealed that the left hemisphere is significantly more "efficient" than the right hemisphere, whereas the right hemisphere showed higher values of "betweenness centrality" and "small-worldness." In particular, left-hemispheric networks displayed increased nodal efficiency in brain regions related to language and motor actions, whereas the right hemisphere showed an increase in nodal efficiency in brain regions involved in memory and visuospatial attention. In addition, we found that hemispheric networks decrease in efficiency with age. Finally, we observed significant gender differences in measures of global connectivity. By analyzing the structural hemispheric brain networks, we have provided new insights into understanding the neuroanatomical basis of lateralized brain functions.

Overactivation of the supplementary motor area in chronic stroke patients

Stroke induces a loss of neural function, but it triggers a complex amount of mechanisms to compensate the associated functional impairment. The present study aims to increase our understanding of the functional reshape of the motor system observed in chronic stroke patients during the preparation and the execution of movements. A cohort of 14 chronic stroke patients with a mild-to-moderate hemiparesis and 14 matched healthy controls were included in this study. Participants were asked to perform a bimanual reaction time task synchronizing alternated responses to the presentation of a visual cue. We used Laplacian-transformed EEG activity (LT-EEG) recorded at the locations Cz and C3/C4 to study the response-locked components associated with the motor system activity during the performance of this task. Behaviorally, patients showed larger variable errors than controls in synchronizing the frequency of execution of responses to the interstimulus interval, as well as slower responses compared with controls. LT-EEG analysis showed that whereas control participants increased their supplementary motor area (SMA) activity during the preparation of all responses, patients only showed an increment of activity over this area during their first response of the sequence. More interestingly, patients showed a clear increment of the LT-EEG activity associated with SMA shortly after motor responses as compared to the control participants. Finally, patients showed a hand-dependent inhibitory activity over motor areas ipsilateral to the response hand. Overall, our findings reveal drastic differences in the temporal dynamics of the LT-EEG components associated with the activity over motor and premotor cortices in chronic stroke patients compared with matched control participants during alternated hand responses.

Handedness and effective connectivity of the motor system

Handedness denotes the individual predisposition to consistently use the left or right hand for most types of skilled movements. A putative neurobiological mechanism for handedness consists in hemisphere-specific differences in network dynamics that govern unimanual movements. We, therefore, used functional magnetic resonance imaging and dynamic causal modeling to investigate effective connectivity between key motor areas during fist closures of the dominant or non-dominant hand performed by 18 right- and 18 left-handers. Handedness was assessed employing the Edinburgh-Handedness-Inventory (EHI). The network of interest consisted of key motor regions in both hemispheres including the primary motor cortex (M1), supplementary motor area (SMA), ventral premotor cortex (PMv), motor putamen (Put) and motor cerebellum (Cb). The connectivity analysis revealed that in right-handed subjects movements of the dominant hand were associated with significantly stronger coupling of contralateral (left, i.e., dominant) SMA with ipsilateral SMA, ipsilateral PMv, contralateral motor putamen and contralateral M1 compared to equivalent connections in left-handers. The degree of handedness as indexed by the individual EHI scores also correlated with coupling parameters of these connections. In contrast, we found no differences between right- and left-handers when testing for the effect of movement speed on effective connectivity. In conclusion, the data show that handedness is associated with differences in effective connectivity within the human motor network with a prominent role of SMA in right-handers. Left-handers featured less asymmetry in effective connectivity implying different hemispheric mechanisms underlying hand motor control compared to right-handers.

Differential contribution of bilateral supplementary motor area to the effective connectivity networks induced by task conditions using dynamic causal modeling

Functional imaging studies have indicated hemispheric asymmetry of activation in bilateral supplementary motor area (SMA) during unimanual motor tasks. However, the hemispherically special roles of bilateral SMAs on primary motor cortex (M1) in the effective connectivity networks (ECN) during lateralized tasks remain unclear. Aiming to study the differential contribution of bilateral SMAs during the motor execution and motor imagery tasks, and the hemispherically asymmetric patterns of ECN among regions involved, the present study used dynamic causal modeling to analyze the functional magnetic resonance imaging data of the unimanual motor execution/imagery tasks in 12 right-handed subjects. Our results demonstrated that distributions of network parameters underlying motor execution and motor imagery were significantly different. The variation was mainly induced by task condition modulations of intrinsic coupling. Particularly, regardless of the performing hand, the task input modulations of intrinsic coupling from the contralateral SMA to contralateral M1 were positive during motor execution, while varied to be negative during motor imagery. The results suggested that the inhibitive modulation suppressed the overt movement during motor imagery. In addition, the left SMA also helped accomplishing left hand tasks through task input modulation of left SMA→right SMA connection, implying that hemispheric recruitment occurred when performing nondominant hand tasks. The results specified differential and altered contributions of bilateral SMAs to the ECN during unimanual motor execution and motor imagery, and highlighted the contributions induced by the task input of motor execution/imagery.

Changes of inter-hemispheric functional connectivity between motor cortices after brachial plexuses injury: a resting-state fMRI study

OBJECT

The aim of this study is to explore the changes of inter-hemispheric functional connectivity in patients with unilateral brachial plexus injury.

METHODS

Nine patients with five roots of unilateral brachial plexus avulsion injury and 11 healthy controls were recruited in this study. Resting-state functional connectivity magnetic resonance image was used to study the differences of inter-hemispheric functional connectivity between patients and healthy controls. Four areas were defined as regions of interest (ROI): the two primary motor areas (M1 areas) and two supplementary motor areas (SMAs) in the two hemispheres activated when the healthy controls performed unilateral hand grasping movement of the two hands, respectively. Functional connectivity maps were generated by correlating the regional time course of each ROI with that of every voxel in the whole brain. Then, functional connectivity was calculated by correlating the functional magnetic resonance image signal time courses of every two ROIs.

RESULTS

Resting-state inter-hemispheric functional connectivity of the primary motor areas was reduced following brachial plexus avulsion injury. The correlation coefficients of the SMAs showed no difference between the brachial plexus patients and healthy volunteers.

CONCLUSIONS

Our results indicate that brachial plexus injury decreases resting-state inter-hemispheric functional connectivity of the two primary motor areas. These results provide new insight into functional reorganization of the cerebral cortex after brachial plexus injury.

Unilateral hemispherectomy at adulthood asymmetrically affects motor performance of male Swiss mice

Evidence exists indicating that cerebral lateralization is a fundamental feature of all vertebrates. In humans, a series of studies demonstrated that the left hemisphere plays a major role in controlling movement. No such asymmetries have been identified in rodents, in spite of the fact that these animals have been frequently used in studies assessing motor behavior. In this regard, here, we used unilateral hemispherectomy to study the relative importance of each hemisphere in controlling movement. Adult Swiss mice were submitted to right unilateral hemispherectomy (RH), left unilateral hemispherectomy (LH) or sham surgery. Fifteen days after surgery, motor performance was assessed in the accelerating rotarod test and in the foot-fault test (in which performance depends on skilled limb use) and in the elevated body swing test (in which performance depends on trunk movements). The surgical removal of the right hemisphere caused a more pronounced impairment in performance than the removal of the left hemisphere both in the rotarod and in the foot-fault tests. In the rotarod, the RH group presented smaller latencies to fall than both LH and sham groups. In the foot-fault test, while both the sham and the LH groups showed no differences between left and right hind limbs, the RH group showed significantly worse performance with the left hind limb than with the right one. The elevated body swing test revealed a similar impairment in the two hemispherectomized groups. Our data suggest a major role of the right hemisphere in controlling skilled limb movements in mice.

Intrasurgical mapping of complex motor function in the superior frontal gyrus

A lesion to the superior frontal gyrus (SFG) has been associated with long-lasting deficits in complex motor functions. The aim of this study was to analyze the functional role of the SFG by means of electrical cortical stimulation. Direct intraoperative electrical stimulation was used in a group of 21 subjects with lesions within or close to the SFG while they performed three motor tasks that require high skills or bimanual synergy. The results were compared to functional magnetic resonance imaging (fMRI). Ninety-four of the 98 (94.9%) labels identified were located on the convexity surface of the SFG and only four (4.1%) labels were located on the middle surface of the SFG. Areas of blockage of the three tasks were identified in six of the 12 (50%) hemispheres with lesions that had infiltrated the SFG, compared to all 10 of the 10 hemispheres (100%) with lesions that spared the SFG. The difference between these two proportions was statistically significant (P=0.015). fMRI activation was mainly located on the medial aspect of the SFG. We show that the convexity surface of the SFG has an important role in bilateral control of complex movements and in bimanual coordination. The infiltration of the posterior part of the SFG by a lesion disturbs some of the complex hand motor functions, which may be assumed by the contralesional homologous area. Finally, the current study emphasizes the discrepancies between fMRI and intraoperative electrical stimulation maps in complex hand motor function.

Brain hemispheric structural efficiency and interconnectivity rightward asymmetry in human and nonhuman primates

Evidence for interregional structural asymmetries has been previously reported for brain anatomic regions supporting well-described functional lateralization. Here, we aimed to investigate whether the two brain hemispheres demonstrate dissimilar general structural attributes implying different principles on information flow management. Common left hemisphere/right hemisphere structural network properties are estimated and compared for right-handed healthy human subjects and a nonhuman primate, by means of 3 different diffusion-weighted magnetic resonance imaging fiber tractography algorithms and a graph theory framework. In both the human and the nonhuman primate, the data support the conclusion that, in terms of the graph framework, the right hemisphere is significantly more efficient and interconnected than the left hemisphere, whereas the left hemisphere presents more central or indispensable regions for the whole-brain structural network than the right hemisphere. From our point of view, in terms of functional principles, this pattern could be related with the fact that the left hemisphere has a leading role for highly demanding specific process, such as language and motor actions, which may require dedicated specialized networks, whereas the right hemisphere has a leading role for more general process, such as integration tasks, which may require a more general level of interconnection.

Loss of laterality in chronic cocaine users: an fMRI investigation of sensorimotor control

Movement disturbances are often overlooked consequences of chronic cocaine abuse. The purpose of this study was to systematically investigate sensorimotor performance in chronic cocaine users and characterize changes in brain activity among movement-related regions of interest (ROIs) in these users. Functional magnetic resonance imaging data were collected from 14 chronic cocaine users and 15 age- and gender-matched controls. All participants performed a sequential finger-tapping task with their dominant, right hand interleaved with blocks of rest. For each participant, percent signal change from rest was calculated for seven movement-related ROIs in both the left and right hemisphere. Cocaine users had significantly longer reaction times and higher error rates than controls. Whereas the controls used a left-sided network of motor-related brain areas to perform the task, cocaine users activated a less lateralized pattern of brain activity. Users had significantly more activity in the ipsilateral (right) motor and premotor cortical areas, anterior cingulate cortex and the putamen than controls. These data demonstrate that, in addition to the cognitive and affective consequences of chronic cocaine abuse, there are also pronounced alterations in sensorimotor control in these individuals, which are associated with functional alterations throughout movement-related neural networks.

Changes in regional activity are accompanied with changes in inter-regional connectivity during 4 weeks motor learning

Structural equation modeling (SEM) and fMRI were used to test whether changes in the regional activity are accompanied by changes in the inter-regional connectivity as motor practice progresses. Ten healthy subjects were trained to perform finger movement task daily for 4 weeks. Three sessions of fMRI images were acquired within 4 weeks. The changes in inter-regional connectivity were evaluated by measuring the effective connectivity between the primary motor area (M1), supplementary motor area (SMA), dorsal premotor cortex (PMd), basal ganglia (BG), cerebellum (CB), and posterior ventrolateral prefrontal cortex (pVLPFC). The regional activities in M1 and SMA increased from pre-training to week 2 and decreased from week 2 to week 4. The inter-regional connectivity generally increased in strength (with SEM path coefficients becoming more positive or negative) as practice progressed. The increases in the strength of the inter-regional connectivity may reflect long-term reorganization of the skilled motor network. We suggest that the performance gain was achieved by dynamically tuning the inter-regional connectivity in the motor network.

Kernel Granger causality mapping effective connectivity on FMRI data

Although it is accepted that linear Granger causality can reveal effective connectivity in functional magnetic resonance imaging (fMRI), the issue of detecting nonlinear connectivity has hitherto not been considered. In this paper, we address kernel Granger causality (KGC) to describe effective connectivity in simulation studies and real fMRI data of a motor imagery task. Based on the theory of reproducing kernel Hilbert spaces, KGC performs linear Granger causality in the feature space of suitable kernel functions, assuming an arbitrary degree of nonlinearity. Our results demonstrate that KGC captures effective couplings not revealed by the linear case. In addition, effective connectivity networks between the supplementary motor area (SMA) as the seed and other brain areas are obtained from KGC.

Training improves multitasking performance by increasing the speed of information processing in human prefrontal cortex

Our ability to multitask is severely limited: task performance deteriorates when we attempt to undertake two or more tasks simultaneously. Remarkably, extensive training can greatly reduce such multitasking costs. While it is not known how training alters the brain to solve the multitasking problem, it likely involves the prefrontal cortex given this brain region's purported role in limiting multitasking performance. Here, we show that the reduction of multitasking interference with training is not achieved by diverting the flow of information processing away from the prefrontal cortex or by segregating prefrontal cells into independent task-specific neuronal ensembles, but rather by increasing the speed of information processing in this brain region, thereby allowing multiple tasks to be processed in rapid succession. These results not only reveal how training leads to efficient multitasking, they also provide a mechanistic account of multitasking limitations, namely the poor speed of information processing in human prefrontal cortex.

Ipsilateral coordination at preferred rate: effects of age, body side and task complexity

Functional imaging studies have shown that elderly individuals activate widespread additional brain networks, compared to young subjects, when performing motor tasks. However, the parameters that effect this unique neural activation, including the spatial distribution of this activation across hemispheres, are still largely unknown. Here, we examined the effect of task complexity and body side on activation differences between older and younger adults while performing cyclical flexion-extension movements of the ipsilateral hand and foot. In particular, easy (isodirectional) and more difficult (non-isodirectional) coordination patterns were performed with either the left or right body side at a self-selected, comfortable rate. Even in the absence of imposed pacing the older group activated a larger brain network, suggestive of increased attentional deployment for monitoring the spatial relationships between the simultaneously moving segments and enhanced sensory processing and integration. Evidence of age-dependent underactivation was also found in contralateral M1, SMA and bilateral putamen, possibly reflecting a functional decline of the basal ganglia-mesial cortex pathway in the older group. An ANOVA model revealed significant main effects of task complexity and body side. However the interaction of these factors with age did not reach significance. Consequently, we conclude that under self-paced conditions, task complexity and body side did not have a modulatory effect on age-related brain activation.

Functional connectivity estimation in fMRI data: influence of preprocessing and time course selection

A number of techniques have been used to provide functional connectivity estimates for a given fMRI data set. In this study we compared two methods: a 'rest-like' method where the functional connectivity was estimated for the whitened residuals after regressing out the task-induced effects, and a within-condition method where the functional connectivity was estimated separately for each experimental condition. In both cases four pre-processing strategies were used: 1) time courses extracted from standard pre-processed data (standard); 2) adjusted time courses extracted using the volume of interest routines in SPM2 from standard pre-processed data (spm); 3) time courses extracted from ICA denoised data (standard denoised); and 4) adjusted time courses extracted from ICA denoised data (spm denoised). The temporal correlation between time series extracted from two cortical regions were statistically compared with the temporal correlation between a time series extracted from a cortical region and a time series extracted form a region placed in CSF. Since the later correlation is due to physiological noise and other artifacts, we used this comparison to investigate whether rest-like and task modulated connectivity could be estimated from the same data set. The pre-processing strategy had a significant effect on the connectivity estimates with the standard time courses providing larger connectivity values than the spm time courses for both estimation methods. The CSF comparison indicated that for our data set only rest-like connectivity could be estimated. The rest-like connectivity values were similar with connectivity estimated from resting state data.

Network activation during bimanual movements in humans

The coordination of movement between the upper limbs is a function highly distributed across the animal kingdom. How the central nervous system generates such bilateral, synchronous movements, and how this differs from the generation of unilateral movements, remain uncertain. Electrophysiologic and functional imaging studies support that the activity of many brain regions during bimanual and unimanual movement is quite similar. Thus, the same brain regions (and indeed the same neurons) respond similarly during unimanual and bimanual movements as measured by electrophysiological responses. How then are different motor behaviors generated? To address this question, we studied unimanual and bimanual movements using fMRI and constructed networks of activation using Structural Equation Modeling (SEM). Our results suggest that (1) the dominant hemisphere appears to initiate activity responsible for bimanual movement; (2) activation during bimanual movement does not reflect the sum of right and left unimanual activation; (3) production of unimanual movement involves a network that is distinct from, and not a mirror of, the network for contralateral unimanual movement; and (4) using SEM, it is possible to obtain robust group networks representative of a population and to identify individual networks which can be used to detect subtle differences both between subjects as well as within a single subject over time. In summary, these results highlight a differential role for the dominant and non-dominant hemispheres during bimanual movements, further elaborating the concept of handedness and dominance. This knowledge increases our understanding of cortical motor physiology in health and after neurological damage.

Empirical comparison of sources of variation for FMRI connectivity analysis

BACKGROUND

In neuroimaging, connectivity refers to the correlations between signals in different brain regions. Although fMRI measures of connectivity have been widely explored, the methods used have varied. This complicates the interpretation of existing literature in cases when different techniques have been used with fMRI data to measure the single concept of "connectivity." Additionally the optimum choice of method for future analyses is often unclear.

METHODOLOGY/PRINCIPAL FINDINGS

In this study, measures of functional and effective connectivity in the motor system were calculated based on three sources of variation: inter-subject variation in task activation level; within-subject variation in task-related responses; and within-subject residual variation after removal of task effects. Two task conditions were compared. The methods yielded different inter-regional correlation coefficients. However, all three approaches produced similar results, qualitatively and sometimes quantitatively, for condition differences in connectivity.

CONCLUSIONS/SIGNIFICANCE

While these results are specific to the motor regions studied, they do suggest that within-subject and across-subject results may be usefully compared. Also, the presence of task-specific correlations in residual time series supports arguments that residuals may not substitute for resting-state data, but rather may reflect the same underlying variations present during steady-state performance.

Assessing functional connectivity in the human brain by fMRI

Functional magnetic resonance imaging (fMRI) is widely used to detect and delineate regions of the brain that change their level of activation in response to specific stimuli and tasks. Simple activation maps depict only the average level of engagement of different regions within distributed systems. FMRI potentially can reveal additional information about the degree to which components of large-scale neural systems are functionally coupled together to achieve specific tasks. In order to better understand how brain regions contribute to functionally connected circuits, it is necessary to record activation maps either as a function of different conditions, at different times or in different subjects. Data obtained under different conditions may then be analyzed by a variety of techniques to infer correlations and couplings between nodes in networks. Several multivariate statistical methods have been adapted and applied to analyze variations within such data. An approach of particular interest that is suited to studies of connectivity within single subjects makes use of acquisitions of runs of MRI images obtained while the brain is in a so-called steady state, either at rest (i.e., without any specific stimulus or task) or in a condition of continuous activation. Interregional correlations between fluctuations of MRI signal potentially reveal functional connectivity. Recent studies have established that interregional correlations between different components of circuits in each of the visual, language, motor and working memory systems can be detected in the resting state. Correlations at baseline are changed during the performance of a continuous task. In this review, various methods available for assessing connectivity are described and evaluated.

Lateralization of brain activity during lower limb joints movement. An fMRI study

Studies of unilateral finger movement in right-handed subjects have shown asymmetrical patterns of activation in primary motor cortex and subcortical regions. In order to investigate the existence of an analogous pattern during lower limb joints movements, functional magnetic resonance imaging (fMRI) was used. Eighteen healthy, right leg dominant volunteers participated in a motor block design study, performing unilateral right and left repetitive knee, ankle and toes flexion/extension movements. Aiming to relate lower limb joints activation to the well-described patterns of finger movement, serial finger-to-thumb opposition was also assessed. All movements were auditory paced at 72 beats/min (1.2 Hz). Brain activation during movement of the nondominant joints was more bilateral than during the same movement performed with the dominant joints. Finger movement had a stronger lateralized pattern of activation in comparison with lower limb joints, implying a different functional specialization. Differences were also evident between the joints of the lower limb. Ankle and toes movements elicited the same extend of MR signal change in the majority of the examined brain regions, whereas knee joint movement was associated with a different pattern. Finally, lateralization index in primary sensorimotor cortex and basal ganglia was significantly affected by the main effect of dominance, whereas the lateralization index in cerebellum was significantly affected by the joint main effect, demonstrating a lateralization index increase from proximal to distal joints.

Partial correlation for functional brain interactivity investigation in functional MRI

Examination of functional interactions through effective connectivity requires the determination of three distinct levels of information: (1) the regions involved in the process and forming the spatial support of the network, (2) the presence or absence of interactions between each pair of regions, and (3) the directionality of the existing interactions. While many methods exist to select regions (Step 1), very little is available to complete Step 2. The two main methods developed so far, structural equation modeling (SEM) and dynamical causal modeling (DCM), usually require precise prior information to be used, while such information is sometimes lacking. Assuming that Step 1 was successfully completed, we here propose a data-driven method to deal with Step 2 and extract functional interactions from fMRI datasets through partial correlations. Partial correlation is more closely related to effective connectivity than marginal correlation and provides a convenient graphical representation for functional interactions. As an instance of brain interactivity investigation, we consider how simple hand movements are processed by the bihemispheric cortical motor network. In the proposed framework, Bayesian analysis makes it possible to estimate and test the partial statistical dependencies between regions without any prior model on the underlying functional interactions. We demonstrate the interest of this approach on real data.

Altered functional connectivity related to white matter changes inside the working memory network at the very early stage of MS

Functional magnetic resonance imaging (fMRI) using paced auditory serial addition test (PASAT) as paradigm was used to study the functional connectivity in 18 patients at the very early stage of multiple sclerosis (MS) compared with 18 controls, to determine the existence of circuitry disturbance inside the working memory network and its relationship with white matter abnormalities assessed by conventional MRI and magnetization transfer ratio (MTR) imaging. The left BA 45/46 was selected as the seed region to compute correlation maps with other brain regions. After obtaining the correlation map for each subject, between-group comparisons were performed using random effect procedure. Compared with controls, patients did not show any greater functional connectivity between left BA 45/46 and other regions during PASAT. In contrast, decrease in functional connectivity was observed in patients between left BA 45/46 and left BA 9, right BA 3, and the anterior cingulate cortex (BA 24). In patients, no correlations were found between altered functional connectivity and clinical data. However, functional connectivity observed between left BA 45/46 and BA 24 in patients was correlated with the MTR of normal appearing white matter, and with brain T(2) lesion load. Altered functional connectivity is present inside the working memory network of patients at the very early stage of MS and is related to the extent of diffuse white matter changes.

Medidas eletrencefalográficas durante a aprendizagem de tarefa motora sob efeito do bromazepam

Neuromoduladores alteram constantemente as relações neurais pré-existentes no sistema nervoso. O bromazepam é utilizado com freqüência na prática clínica para diminuir padrões de ansiedade. Poucos são os experimentos correlacionando este ansiolítico às tarefas motoras. Neste contexto, o presente experimento visa analisar as alterações motoras e eletrocorticais decorrentes da administração de diferentes doses de bromazepam mediante a prática motora, e relacionar o efeito da droga a performance motora mão-dominante versus não dominante. Sujeitos saudáveis (39), de ambos os sexos, entre 20 a 30 anos compuseram a amostra. Os grupos controle (placebo) e experimental (bromazepam de 3mg e 6mg) foram treinados na tarefa de datilografia num modelo duplo-cego randomizado. Resultados do teste Stroop (atenção) não demonstraram diferenças no escore bruto e no tempo de execução do mesmo. Em contrapartida, nos resultados comportamentais foram observados um efeito principal entre blocos nas variáveis tempo de execução e erros cometidos durante a pratica motora. Os dados eletrofisiológicos evidenciaram interações significantes para: lateralidade/condição/momento; lateralidade/condição; lateralidade/momento; condição/momento; condição/setor.