Don't plan, just do it: Cognitive and sensorimotor contributions to manual dexterity.

Manual dexterity is referred to as the skill to perform fine motor movements and it has been assumed to be associated to the cognitive domain, as well as the sensorimotor one. In this work, we investigated with functional near-infrared spectroscopy the cortical activations elicited by the execution of the 9-HPT, i.e., a standard test evaluating manual dexterity in which nine pegs were taken, placed into and then removed from nine holes on a board as quickly as possible. For comparison, we proposed a new active control task mainly involving the sensorimotor domain, in which the pegs must be placed and removed using the same single hole (1-HPT). Behaviorally, we found two distinct groups based on the difference between the execution time of the 9-HPT and the 1-HPT (ΔHPT). Cortical areas belonging to the network controlling reaching and grasping movements were active in both groups; however, participants showing a large ΔHPT presented significantly higher activation in prefrontal cortical areas (right BA10 and BA11) during 9-HPT and 1-HPT performance with respect to the participants with a small ΔHPT, who showed a deactivation in BA10. Unexpectedly, we observed a significant linear relationship between ΔHPT and right BA10 activity. This suggested that participants performing the 9-HPT more slowly than the 1-HPT recruited prefrontal areas implicitly exploiting the cognitive skills of planning, perhaps in search of a motor strategy to solve the test activating attentional and cognitive control processes, but this resulted not efficient and instead increased the time to accomplish a manual dexterity task.

Primary motor cortex excitability as a marker of plasticity in a stimulation protocol combining action observation and kinesthetic illusion of movement.

Action observation combined with proprioceptive stimulation able to induce a kinesthetic illusion of movement (AO-KI) was shown to elicit a plastic increase in primary motor cortex (M1) excitability, with promising applications in rehabilitative interventions. Nevertheless, the known individual variability in response to combined stimulation protocols limits its application. The aim of this study was to examine whether a relationship exists between changes in M1 excitability during AO-KI and the long-lasting changes in M1 induced by AO-KI. Fifteen volunteers received a conditioning protocol consisting in watching a video showing a thumb-opposition movement and a simultaneous proprioceptive stimulation that evoked an illusory kinesthetic experience of their thumbs closing. M1 excitability was evaluated by means of single-pulse transcranial magnetic stimulation before, DURING the conditioning protocol, and up to 60 min AFTER it was administered. M1 excitability significantly increased during AO-KI with respect to a rest condition. Furthermore, AO-KI induced a long-lasting increase in M1 excitability up to 60 min after administration. Finally, a significant positive correlation appeared between M1 excitability changes during and after AO-KI; that is, participants who were more responsive during AO-KI showed greater motor cortical activity changes after it. These findings suggest that M1 response during AO-KI can be considered a neurophysiological marker of individual responsiveness to the combined stimulation since it was predictive of its efficacy in inducing long-lasting M1 increase excitability. This information would allow knowing in advance whether an individual will be a responder to AO-KI.

The Effect of Kinesio Taping on Spasticity: A Randomized, Controlled, Double-Blind Pilot Study in Para-Swimmers.

CONTEXT: Kinesio Taping (KT) produces several clinical effects, including pain relief, edema absorption, and improved muscle performance. When applied in the insertion to origin mode, it is claimed to inhibit excessive muscle contractions. OBJECTIVE: Investigate whether KT applied in the insertion to origin mode could reduce the exaggerated reflex contraction of spastic muscles. DESIGN: Randomized crossover trial, with a restricted block randomization. SETTING: Clinical laboratory and swimming pool. PATIENTS: Seven para-swimmers. INTERVENTION: KT, applied in inhibitory mode, to investigate its effect on knee extensor spasticity. MAIN OUTCOME MEASURES: Primary outcome is stretch reflex, as compared with clinical assessment of spasticity by Modified Ashworth Scale and self-perceived spasticity by numeric rating scale. Secondary outcomes were Medical Research Council for strength of knee extensor muscles and chronometric swimming performance in 100-m freestyle. RESULTS: KT significantly decreased the amplitude of stretch reflex (P < .001), whereas the placebo treatment produced no significant effects. Scores of Medical Research Council for strength and Modified Ashworth Scale did not change after KT, whereas numeric rating scale scores for spasticity significantly decreased (P = .001). The swimming performance was significantly improved after KT treatment as compared with baseline (P < .01). CONCLUSIONS: This exploratory study performed on para-athletes suggests that KT could reduce spasticity. This outcome has 3-fold implications for clinical, rehabilitation, and sport methods.

Kinaesthetic illusion shapes the cortical plasticity evoked by action observation.

KEY POINTS: The combination of action observation (AO) and a peripheral nerve stimulation has been shown to induce plasticity in the primary motor cortex (M1). However, using peripheral nerve stimulation little is known about the specificity of the sensory inputs. The current study, using muscle tendon vibration to stimulate muscle spindles and transcranial magnetic stimulation to assess M1 excitability, investigated whether a proprioceptive stimulation leading to a kinaesthetic illusion of movement (KI) was able to evoke M1 plasticity when combined with AO. M1 excitability increased immediately and up to 60 min after AO-KI stimulation as a function of the vividness of the perceived illusion, and only when the movement directions of AO and KI were congruent. Tactile stimulation coupled with AO and KI alone were not sufficient to induce M1 plasticity. This methodology might be proposed to subjects during a period of immobilization to promote M1 activity without requiring any voluntary movement. ABSTRACT: Physical practice is crucial to evoke cortical plasticity, but motor cognition techniques, such as action observation (AO), have shown their potentiality in promoting it when associated with peripheral afferent inputs, without the need of performing a movement. Here we investigated whether the combination of AO and a proprioceptive stimulation, able to evoke a kinaesthetic illusion of movement (KI), induced plasticity in the primary motor cortex (M1). In the main experiment, the role of congruency between the observed action and the illusory movement was explored together with the importance of the specificity of the sensory input modality (proprioceptive vs. tactile stimulation) to induce plasticity in M1. Further, a control experiment was carried out to assess the role of the mere kinaesthetic illusion on M1 excitability. Results showed that the combination of AO and KI evoked plasticity in M1, with an increase of the excitability immediately and up to 60 min after the conditioning protocol (P always <0.05). Notably, a significant increase in M1 excitability occurred only when the directions of the observed and illusory movements were congruent. Further, a significant positive linear relationship was found between the amount of M1 excitability increase and the vividness of the perceived illusion (P = 0.03). Finally, the tactile stimulation coupled with AO was not sufficient to induce changes in M1 excitability as well as the KI alone. All these findings indicate the importance of combining different sensory input signals to induce plasticity in M1, and that proprioception is the most suitable sensory modality to allow it.

Boosting and consolidating the proprioceptive cortical aftereffect by combining tendon vibration and repetitive TMS over primary motor cortex.

Tendon vibration of a limb elicits illusory movements in the direction that the vibrated muscle would be stretched, followed by a transient perception of movement in the opposite direction, that was demonstrated to correspond to a "cortical" aftereffect (Goodwin et al. Science 175:1382-1384, 1972). Primary motor cortex (M1) excitability of the non-vibrated antagonist muscle of the vibrated muscle increased during vibration and decreased thereafter. The cortical aftereffect is of interest when considering the possibility to use tendon vibration in rehabilitation for restoring unbalance activity between antagonistic muscles but, due to its short-lasting duration, has not been explored so far. We investigated the possibility to consolidate the cortical aftereffect by combining tendon vibration with a concomitant high-frequency 5-Hz repetitive transcranial magnetic stimulation (rTMS) protocol. The distal tendon of the flexor carpi radialis muscle (FCR) was vibrated and concomitantly a 2-min 5-Hz rTMS protocol was administered on the left hemi-scalp hot spot of the vibrated FCR or its antagonist muscle (extensor carpi radialis (ECR)). We found that this protocol induced a pattern of unbalanced M1 excitability between vibrated muscle and its antagonist with increased excitability of the FCR and decreased excitability of ECR cortical areas, which persisted up to 30 min.

Dynamic Shaping of the Defensive Peripersonal Space through Predictive Motor Mechanisms: When the "Near" Becomes "Far".

The hand blink reflex is a subcortical defensive response, known to dramatically increase when the stimulated hand is statically positioned inside the defensive peripersonal space (DPPS) of the face. Here, we tested in a group of healthy human subjects the hand blink reflex in dynamic conditions, investigating whether the direction of the hand movements (up-to/down-from the face) could modulate it. We found that, on equal hand position, the response enhancement was present only when the hand approached to (and not receded from) the DPPS of the face. This means that, when the hand is close to the face but the subject is planning to move the hand down, the predictive motor system can anticipate the consequence of the movement: the "near" becomes "far." We found similar results both in passive movement condition, when only afferent (visual and proprioceptive) information can be used to estimate the final state of the system, and in motor imagery task, when only efferent (intentional) information is available to predict the consequences of the movement. All these findings provide evidence that the DPPS is dynamically shaped by predictive mechanisms run by the motor system and based on the integration of feedforward and sensory feedback signals.SIGNIFICANCE STATEMENT The defensive peripersonal space (DPPS) has a crucial role for survival, and its modulation is fundamental when we interact with the environment, as when we move our arms. Here, we focused on a defensive response, the hand blink reflex, known to increase when a static hand is stimulated inside the DPPS of the face. We tested the hand blink reflex in dynamic conditions (voluntary, passive, and imagined movements) and we found that, on equal hand position, the response enhancement was present only when the hand approached to (and not receded from) the DPPS of the face. This suggests that, through the integration of efferent and afferent signals, the safety boundary around the body is continuously shaped by the predictive motor system.

Adaptive vs. non-adaptive cognitive training by means of a personalized App: a randomized trial in people with multiple sclerosis.

BACKGROUND: Cognitive impairment is common in multiple sclerosis (MS), but the definition of the best cognitive rehabilitation tools and features is still an open issue among researchers. The aims of the present study were to evaluate the effectiveness of COGNI-TRAcK (a customized application software delivering personalized working memory-based exercises) on cognitively impaired people with MS and to investigate the effects of an adaptive vs. a non-adaptive cognitive training administered by means of COGNI-TRAcK. METHODS: Twenty eight patients (20 women, age 47.5 ± 9.3 years, Expanded Disability Status Scale score 3.8 ± 1.9) were randomized in two homogeneous groups, both performing a 8-week home-based cognitive rehabilitation treatment by means of COGNI-TRAcK. The study group (ADAPT-gr) underwent an adaptive training given by the automatic adjustment of tasks difficulty to the subjects' performance, whilst the control group (CONST-gr) was trained at constant difficulty levels. Before and after the treatment, patients' cognitive status was assessed using a gold standard neuropsychological evaluation. Moreover, the mostly affected cognitive domains in MS (i.e., attention, concentration and information processing speed) were also assessed 6 months after the end of the treatment. RESULTS: The analysis of variance showed a significant Group*Time interaction in six out of ten tests of the cognitive evaluation. Post-hoc analysis revealed a significant improvement between the performances before and after the intervention only in the ADAPT-gr in tests evaluating verbal memory acquisition (p <0.05) and delayed recall (p = 0.001), verbal fluency (p = 0.01), sustained attention, concentration and information processing speed (p < 0.01). This last effect was maintained also after 6 months (p < 0.05). CONCLUSIONS: We concluded that COGNI-TRAcK represents a suitable tool to administer a personalized training to cognitively impaired subjects and that an adaptive working load is a crucial feature determining the effectiveness of cognitive treatment, allowing transfer effects to several cognitive domains and long-term maintenance of results.

Functional connectivity in the resting-state motor networks influences the kinematic processes during motor sequence learning.

Neuroimaging studies support the involvement of the cerebello-cortical and striato-cortical motor loops in motor sequence learning. Here, we investigated whether the gain of motor sequence learning could depend on a-priori resting-state functional connectivity (rsFC) between motor areas and structures belonging to these circuits. Fourteen healthy subjects underwent a resting-state functional magnetic resonance imaging session. Afterward, they were asked to reproduce a verbally-learned sequence of finger opposition movements as fast and as accurately as possible. All subjects increased their movement rate with practice, by reducing the touch duration and/or intertapping interval. The rsFC analysis showed that, at rest, the left and right primary motor cortex (M1) and left and right supplementary motor area (SMA) were mainly connected with other motor areas. The covariate analysis taking into account the different kinematic parameters indicated that the subjects achieving greater movement rate increase were those showing stronger rsFC of the left M1 and SMA with the right lobule VIII of the cerebellum. Notably, the subjects with greater intertapping interval reduction showed stronger rsFC of the left M1 and SMA with the association nuclei of the thalamus. Conversely, the regression analysis with the right M1 and SMA seeds showed only a few significant clusters for the different covariates not located in the cerebellum and thalamus. No common clusters were found between the right M1 and SMA. All of these findings indicated important functional connections at rest of those neural circuits responsible for motor learning improvement, involving the motor areas related to the hemisphere directly controlling the finger movements, the thalamus and cerebellum.

Cingulum bundle alterations underlie subjective fatigue in multiple sclerosis.

OBJECTIVE: To evaluate the neural basis of subjective fatigue in subjects with multiple sclerosis (MS) using a connectionist framework. METHODS: Seventy seven subjects with relapsing-remitting MS were recruited in the study and underwent subjective fatigue evaluations and a diffusion MRI scan. Firstly, local white matter Fractional Anisotropy values were correlated with subjective fatigue scores using a voxel-wise approach. The long-range loss of connectivity due to structural damage in the white matter voxels thus associated with subjective fatigue was then assessed using the Network Modification (NeMo) package. RESULTS: A voxel-wise regression analysis with fatigue scores revealed a significant association between structural damage and fatigue levels in two discrete white matter clusters, both included in the left cingulate bundle. The connectivity analysis revealed that damage in these clusters was associated with loss of structural connectivity in the anterior and medial cingulate cortices, dorsolateral prefrontal areas and in the left caudate. DISCUSSION: Our data point to the cingulum bundle and its projections as the key network involved in subjective fatigue perception in MS. More generally, these results suggest the potential of the connectionist framework to generate coherent models of the neural basis of complex symptomatology in MS.

Innovative quantitative testing of hand function in Charcot-Marie-Tooth neuropathy.

To describe a new test to quantitatively evaluate hand function in patients affected by Charcot-Marie-Tooth neuropathy (CMT). The sensor-engineered glove test (SEGT) was applied to CMT patients (N: 26) and compared with a cohort of healthy controls (HC, N: 26). CMT patients were further divided into subjects with clinically normal (group 1) or impaired hand (group 2) function. The SEGT parameters evaluated were touch duration, inter-tapping interval, and movement rate parameters of two different sequences: finger tapping (FT) and index-medium-ring-little (IMRL) performed at self-paced mode (SPM) and maximum velocity (MV). Hand function and strength were assessed by the 9-hole peg test (9HPT) and dynamometry. Disability of patients was measured by the CMT neuropathy score. CMT patients had significantly worst performances at SEGT than controls regarding the rate of execution of both FT (at MV) and IMRL sequences (at SPM and MV). The rate parameter at MV in IMRL sequence showed a significant trend of decreasing in its average between HC (n: 26, rate = 3.08 ± 0.52 Hz), group 1 (n: 9, rate = 2.64 ± 0.66 Hz) and group 2 (n: 17, rate = 2.19 ± 0.45 Hz) (p for trend <0.001). No correlations were found with either 9HPT, dynamometry, electrophysiology, and the CMT neuropathy score. The SEGT test is sensitive to show hand dysfunction in CMT patients, with and without clinically impaired hands.

Training the motor cortex by observing the actions of others during immobilization.

Limb immobilization and nonuse are well-known causes of corticomotor depression. While physical training can drive the recovery from nonuse-dependent corticomotor effects, it remains unclear if it is possible to gain access to motor cortex in alternative ways, such as through motor imagery (MI) or action observation (AO). Transcranial magnetic stimulation was used to study the excitability of the hand left motor cortex in normal subjects immediately before and after 10 h of right arm immobilization. During immobilization, subjects were requested either to imagine to act with their constrained limb or to observe hand actions performed by other individuals. A third group of control subjects watched a nature documentary presented on a computer screen. Hand corticomotor maps and recruitment curves reliably showed that AO, but not MI, prevented the corticomotor depression induced by immobilization. Our results demonstrate the existence of a visuomotor mechanism in humans that links AO and execution which is able to effect cortical plasticity in a beneficial way. This facilitation was not related to the action simulation, because it was not induced by explicit MI.

Shaping motor cortex plasticity through proprioception.

Short-term upper limb disuse induces a hemispheric unbalance between the primary motor cortices (M1s). However, it is still unclear whether these changes are mainly attributable to the absence of voluntary movements or to the reduction of proprioceptive information. The goal of this work was to investigate the role of proprioception in modulating hemispheric balance during a short-term right arm immobilization. We evaluated the 2 M1s excitability and the interhemispheric inhibition (IHI) between M1s in 3 groups of healthy subjects. Two groups received during the immobilization a proprioceptive (P-VIB, 80 Hz) and tactile (T-VIB, 30 Hz) vibration to the right hand, respectively. Another group did not receive any conditioning sensory inputs (No-VIB). We found that in the No-VIB and in the T-VIB groups immobilization induced a decrease of left M1 excitability and IHI from left to right hemisphere and an increase of right M1 excitability and IHI from right to left hemisphere. Differently, only a partial decrease in left M1 excitability, no change in right M1 excitability and in IHI was observed in the P-VIB group. Our findings demonstrate that the maintenance of dynamic proprioceptive inputs in an immobilized arm through muscle vibration can prevent the hemispheric unbalance induced by short-term limb disuse.

Upper limb motor rehabilitation impacts white matter microstructure in multiple sclerosis.

Upper limb impairments can occur in patients with multiple sclerosis, affecting daily living activities; however there is at present no definite agreement on the best rehabilitation treatment strategy to pursue. Moreover, motor training has been shown to induce changes in white matter architecture in healthy subjects. This study aimed at evaluating the motor behavioral and white matter microstructural changes following a 2-month upper limb motor rehabilitation treatment based on task-oriented exercises in patients with multiple sclerosis. Thirty patients (18 females and 12 males; age=43.3 ± 8.7 years) in a stable phase of the disease presenting with mild or moderate upper limb sensorimotor deficits were randomized into two groups of 15 patients each. Both groups underwent twenty 1-hour treatment sessions, three times a week. The "treatment group" received an active motor rehabilitation treatment, based on voluntary exercises including task-oriented exercises, while the "control group" underwent passive mobilization of the shoulder, elbow, wrist and fingers. Before and after the rehabilitation protocols, motor performance was evaluated in all patients with standard tests. Additionally, finger motor performance accuracy was assessed by an engineered glove. In the same sessions, every patient underwent diffusion tensor imaging to obtain parametric maps of fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity. The mean value of each parameter was separately calculated within regions of interest including the fiber bundles connecting brain areas involved in voluntary movement control: the corpus callosum, the corticospinal tracts and the superior longitudinal fasciculi. The two rehabilitation protocols induced similar effects on unimanual motor performance, but the bimanual coordination task revealed that the residual coordination abilities were maintained in the treated patients while they significantly worsened in the control group (p=0.002). Further, in the treatment group white matter integrity in the corpus callosum and corticospinal tracts was preserved while a microstructural integrity worsening was found in the control group (fractional anisotropy of the corpus callosum and corticospinal tracts: p=0.033 and p=0.022; radial diffusivity of the corpus callosum and corticospinal tracts: p=0.004 and p=0.008). Conversely, a significant increase of radial diffusivity was observed in the superior longitudinal fasciculi in both groups (p=0.02), indicating lack of treatment effects on this structure, showing damage progression likely due to a demyelination process. All these findings indicate the importance of administering, when possible, a rehabilitation treatment consisting of voluntary movements. We also demonstrated that the beneficial effects of a rehabilitation treatment are task-dependent and selective in their target; this becomes crucial towards the implementation of tailored rehabilitative approaches.

Temporal expectation in focal hand dystonia.

Patients with writer's cramp present sensory and representational abnormalities relevant to motor control, such as impairment in the temporal discrimination between tactile stimuli and in pure motor imagery tasks, like the mental rotation of corporeal and inanimate objects. However, only limited information is available on the ability of patients with dystonia to process the time-dependent features (e.g. speed) of movement in real time. The processing of time-dependent features of movement has a crucial role in predicting whether the outcome of a complex motor sequence, such as handwriting or playing a musical passage, will be consistent with its ultimate goal, or results instead in an execution error. In this study, we sought to evaluate the implicit ability to perceive the temporal outcome of different movements in a group of patients with writer's cramp. Fourteen patients affected by writer's cramp in the right hand and 17 age- and gender-matched healthy subjects were recruited for the study. Subjects were asked to perform a temporal expectation task by predicting the end of visually perceived human body motion (handwriting, i.e. the action performed by the human body segment specifically affected by writer's cramp) or inanimate object motion (a moving circle reaching a spatial target). Videos representing movements were shown in full before experimental trials; the actual tasks consisted of watching the same videos, but interrupted after a variable interval ('pre-dark') from its onset by a dark interval of variable duration. During the 'dark' interval, subjects were asked to indicate when the movement represented in the video reached its end by clicking on the space bar of the keyboard. We also included a visual working memory task. Performance on the timing task was analysed measuring the absolute value of timing error, the coefficient of variability and the percentage of anticipation responses. Patients with writer's cramp exhibited greater absolute timing error compared with control subjects in the human body motion task (whereas no difference was observed in the inanimate object motion task). No effect of group was documented on the visual working memory tasks. Absolute timing error on the human body motion task did not significantly correlate with symptom severity, disease duration or writing speed. Our findings suggest an alteration of the writing movement representation at a central level and are consistent with the view that dystonia is not a purely motor disorder, but it also involves non-motor (sensory, cognitive) aspects related to movement processing and planning.

Sonication technique improves microbiological diagnosis in patients treated with antibiotics before surgery for prosthetic joint infections.

Microbiological diagnosis is crucial for the appropriate management of implant-associated orthopedic infections (IAOIs). Sonication of biomaterials for microbiological diagnosis has not yet been introduced in routine clinical practice. Aim of this study was to describe the advantages and feasibility of this procedure in the clinical setting. We prospectively studied 56 consecutive patients undergoing revision because of IAOI and compared the sensitivity of sonication of explanted orthopedic implants with standard cultures. Patients were divided into two groups: those with foreign body infection (FBI, 15 patients) and those with prosthetic joint infection (PJI, 41 patients). Clinical, radiological and microbiological features were recorded. In the PJI group the sensitivity of sonication in detecting bacterial growth was higher than conventional culture (77% vs 34.1% respectively, p<0.002), while no difference was observed in the FBI group (85.7% vs 86% respectively, p>0.05). Coagulase-negative Staphylococci accounted for 90% of the bacteria detected by sonication. Moreover, we found that in the PJI group the sensitivity of sonication was not affected by the timing of antibiotic interruption before surgery. Sonication remains an important tool to improve microbiological diagnosis in PJIs, especially in patients who received previous antimicrobial treatment.

Italian version of University of California at Los Angeles (UCLA) Activity Score: cross-cultural adaptation.

Over the last 10 years, patient-oriented evaluations using questionnaires have become an important aspect of clinical outcome studies. Any questionnaire must be translated and culturally adapted in order to be used with different language groups, and the translated version must then be evaluated for reliability, validity and responsiveness which are fundamental attributes of any measurement tool. The aim of this study is the validation, translation and cross-cultural adaptation of the Italian version of UCLA activity Score, following the Guillemin criteria. The results show that our Italian version of the UCLA score has the following: reproducibility expressed as ICC=0.994, an internal consistency calculated as Spearman-Brown coefficient=0.754 and finally the construct validity has demonstrated a significant Pearson's correlation coefficient with other validated hip questionnaires.

Basal ganglia are active during motor performance recovery after a demanding motor task.

Motor performance recovery after a demanding finger motor task does not follow the excitability dynamics of primary motor cortex (M1), which remains depressed also when performance is restored. Thus, other neural circuits are supposed to cope with central fatigue, re-establishing adequate motor performance levels. A hint that the basal ganglia (BG) can be involved in this process is provided by studies showing an association of central fatigue with the BG. To investigate this possibility, we conducted an fMRI study with simultaneous motor performance recording in 20 healthy volunteers at different stages of a demanding finger motor task: baseline, central fatigue induced by 5-min sequence repetition, performance recovery after a short rest period. When motor performance was recovered, we observed a significant activation with respect to baseline in subcortical structures belonging to different BG circuits (putamen and globus pallidus), involving the limbic system functionally interacting with the BG (amygdala). Then, to assess whether the BG activation was exclusively related to the fatigue and recovery processes or to increasing automatism in motor performance, a control fMRI experiment based on a shorter motor task duration was carried out on 14 healthy subjects. In this case, the task repetition did not induce decreased performance, and no significant effect on the BOLD signal change was found in BG regions of interest with respect to baseline. All these findings suggest that motor and non-motor BG circuits run parallel and converge in a common motor path to successfully compensate motor performance deterioration in a central fatigue condition.

Imagined actions in multiple sclerosis patients: evidence of decline in motor cognitive prediction.

Motor imagery is a mental process during which subjects internally simulate a movement without any motor output. Mental and actual movement durations are similar in healthy adults (isochrony) while temporal discrepancies (anisochrony) could be an expression of neurological deficits on action representation. It is unclear whether patients with multiple sclerosis (PwMS) preserve the capacity to simulate their own movements. This study investigates the ability of PwMS to predict their own actions by comparing temporal features of dominant and non-dominant actual and mental actions. Fourteen PwMS and nineteen healthy subjects (HS) were asked to execute and to imagine pointing arm movements among four pairs of targets of different sizes. Task duration was calculated for both actual and mental movements by an optoelectronic device. Results showed temporal consistency and target-by-target size modulation in actual movements through the four cycles for both groups with significantly longer actual and mental movement durations in PwMS with respect to HS. An index of performance (IP) was used to examine actual/mental isochrony properties in the two groups. Statistical analysis on IP showed in PwMS significantly longer actual movement durations with respect to mental movement durations (anisochrony), more relevant for the non-dominant than dominant arm. Mental prediction of motor actions is not well preserved in MS where motor and cognitive functional changes are present. Differences in performing imagined task with dominant and non-dominant arm could be related to increased cognitive effort required for performing non-dominant movements.

Time-of-day influences resting-state functional cortical connectivity.

Time-of-day is rarely considered during experimental protocols investigating motor behavior and neural activity. The goal of this work was to investigate differences in functional cortical connectivity at rest linked to the time of the day using functional Near-Infrared Spectroscopy (fNIRS). Since resting-state brain is shown to be a succession of cognitive, emotional, perceptual, and motor processes that can be both conscious and nonconscious, we studied self-generated thought with the goal to help in understanding brain dynamics. We used the New-York Cognition Questionnaire (NYC-Q) for retrospective introspection to explore a possible relationship between the ongoing experience and the brain at resting-state to gather information about the overall ongoing experience of subjects. We found differences in resting-state functional connectivity in the inter-hemispheric parietal cortices, which was significantly greater in the morning than in the afternoon, whilst the intra-hemispheric fronto-parietal functional connectivity was significantly greater in the afternoon than in the morning. When we administered the NYC-Q we found that the score of the question 27 ("during RS acquisition my thoughts were like a television program or film") was significantly greater in the afternoon with respect to the morning. High scores in question 27 point to a form of thought based on imagery. It is conceivable to think that the unique relationship found between NYC-Q question 27 and the fronto-parietal functional connectivity might be related to a mental imagery process during resting-state in the afternoon.

Sensorimotor expertise influences perceptual weight judgments during observation of a sport-specific gesture.

This study aimed to investigate the role of sensorimotor expertise in evaluating relative weight of a lifted object during the observation of a sport-specific gesture, namely the deadlift. Fifty-six participants, assigned to three groups according to their experience in weight lifting, powerlifters, CrossFit® practitioners and naïve participants (controls), performed a perceptual weight judgments task. Participants observed videos showing a powerlifter executing a deadlift at the 80%, 90% and 100% of 1 repetition maximum (1RM) and answered a question about the weight of the lifted object. Participants' response accuracy and variability were evaluated. Findings showed that powerlifters were more accurate than controls. No differences appeared between powerlifter and CrossFit® practitioners, and between CrossFit® practitioners and controls. Response variability was similar in the three groups. These findings suggest that a fine sensorimotor expertise specific for the observed gesture is crucial to detect the weight of the object displayed in the observed movement, since it might allow detecting small changes in the observed movement kinematics, which we speculate are at the basis of the object weight recognition.