Visuomotor Tracking Research Articles

Moment stability analysis of linear stochastic human controller model in visuomotor tracking task

We investigate the stability limits of linear stochastic human controller model. In our previous study, we had proposed a model by which the probability distributions of human visuomotor tracking data can be accurately reproduced. In this study, we conduct a stochastic analysis on our model by deriving a system of moment differential equations with respect to random state variables of this model. We evaluate the stability limits of our model by detecting zero-eigenvalue conditions of the Jacobian matrix of the moment differential equations. The resulting stability limits make it possible to characterize the human parameter values that were experimentally identified from the human participants in our previous study; this shows that during the visuomotor tracking experiments, the human participants generated huge fluctuations far from the stability limits while applying almost neutrally stable proportional gain.

The corticospinal responses of metronome-paced, but not self-paced strength training are similar to motor skill training.

The corticospinal responses to skill training may be different to strength training, depending on how the strength training is performed. It was hypothesised that the corticospinal responses would not be different following skill training and metronome-paced strength training (MPST), but would differ when compared with self-paced strength training (SPST). Corticospinal excitability, short-interval intra-cortical inhibition (SICI) and strength and tracking error were measured at baseline and 2 and 4 weeks. Participants (n = 44) were randomly allocated to visuomotor tracking, MPST, SPST or a control group. MPST increased strength by 7 and 18%, whilst SPST increased strength by 12 and 26% following 2 and 4 weeks of strength training. There were no changes in strength following skill training. Skill training reduced tracking error by 47 and 58% at 2 and 4 weeks. There were no changes in tracking error following SPST; however, tracking error reduced by 24% following 4 weeks of MPST. Corticospinal excitability increased by 40% following MPST and by 29% following skill training. There was no change in corticospinal excitability following 4 weeks of SPST. Importantly, the magnitude of change between skill training and MPST was not different. SICI decreased by 41 and 61% following 2 and 4 weeks of MPST, whilst SICI decreased by 41 and 33% following 2 and 4 weeks of skill training. Again, SPST had no effect on SICI at 2 and 4 weeks. There was no difference in the magnitude of SICI reduction between skill training and MPST. This study adds new knowledge regarding the corticospinal responses to skill and MPST, showing they are similar but different when compared with SPST.

Performance in complex motor tasks deteriorates in hyperthermic humans

ABSTRACTHeat stress, leading to elevations in whole-body temperature, has a marked impact on both physical performance and cognition in ecological settings. Lab experiments confirm this for physically demanding activities, whereas observations are inconsistent for tasks involving cognitive processing of information or decision-making prior to responding. We hypothesized that divergences could relate to task complexity and developed a protocol consisting of 1) simple motor task [TARGET_pinch], 2) complex motor task [Visuo-motor tracking], 3) simple math task [MATH_type], 4) combined motor-math task [MATH_pinch]. Furthermore, visuo-motor tracking performance was assessed both in a separate- and a multipart protocol (complex motor tasks alternating with the three other tasks). Following familiarization, each of the 10 male subjects completed separate and multipart protocols in randomized order in the heat (40°C) or control condition (20°C) with testing at baseline (seated rest) and similar seated position, following exercise-induced hyperthermia (core temperature ∼ 39.5°C in the heat and 38.2°C in control condition). All task scores were unaffected by control exercise or passive heat exposure, but visuo-motor tracking performance was reduced by 10.7 ± 6.5% following exercise-induced hyperthermia when integrated in the multipart protocol and 4.4 ± 5.7% when tested separately (both P < 0.05). TARGET_pinch precision declined by 2.6 ± 1.3% (P < 0.05), while no significant changes were observed for the math tasks. These results indicate that heat per se has little impact on simple motor or cognitive test performance, but complex motor performance is impaired by hyperthermia and especially so when multiple tasks are combined.

Sport expertise in perception–action coupling revealed in a visuomotor tracking task

We compared the visuomotor coordination of tennis players with different levels of expertise (Super-Experts, Experts and Non-Experts) in a visuomotor tracking (VMT) task. Participants were asked to track a moving target which could rebound on the sides of a 2D screen. Results indicated that the VMT task allowed the discrimination of expertise. Multiple regression analysis revealed that performance could be explained by the temporal adaptation of participants to rebounds and the number of movement adaptations. Compared to Non-Experts, the Experts had a shorter perturbation time with higher adaptation and regulation. This corresponds to a better perception–action coupling and the predominant use of a prospective control process. Results also indicate that perception–action coupling capacities are transferable to virtual tasks, and allow us to reveal processes of visuomotor coordination that differentiate experts and novices.

Action Monitoring Cortical Activity Coupled to Submovements.

Numerous studies have examined neural correlates of the human brain's action-monitoring system during experimentally segmented tasks. However, it remains unknown how such a system operates during continuous motor output when no experimental time marker is available (such as button presses or stimulus onset). We set out to investigate the electrophysiological correlates of action monitoring when hand position has to be repeatedly monitored and corrected. For this, we recorded high-density electroencephalography (EEG) during a visuomotor tracking task during which participants had to follow a target with the mouse cursor along a visible trajectory. By decomposing hand kinematics into naturally occurring periodic submovements, we found an event-related potential (ERP) time-locked to these submovements and localized in a sensorimotor cortical network comprising the supplementary motor area (SMA) and the precentral gyrus. Critically, the amplitude of the ERP correlated with the deviation of the cursor, 110 ms before the submovement. Control analyses showed that this correlation was truly due to the cursor deviation and not to differences in submovement kinematics or to the visual content of the task. The ERP closely resembled those found in response to mismatch events in typical cognitive neuroscience experiments. Our results demonstrate the existence of a cortical process in the SMA, evaluating hand position in synchrony with submovements. These findings suggest a functional role of submovements in a sensorimotor loop of periodic monitoring and correction and generalize previous results from the field of action monitoring to cases where action has to be repeatedly monitored.

Eye-hand coordination during visuomotor tracking under complex hand-cursor mapping

Eye-hand coordination during visuomotor tracking under complex hand-cursor mapping

P2-97. Different information processing in primary somatosensory area during force generation and relaxation

We investigated the modulation of somatosensory evoked potentials (SEPs) during force generation and force relaxation in a visuomotor tracking task. The target force line moved up continuously from 0% to 20% of maximal voluntary contraction (MVC) (the force generation phase: FG phase) and moved down from 20% to 0% of MVC (the force relaxation phase: FR phase) in 7 s at a constant velocity. Subjects tracked a target line with a line, which represented their own force generated by grip movement with the right hand as accurately as possible during concurrent electrical stimulation. SEPs following stimulation of the median nerve were obtained in each phase. Compared with the stationary condition, the N30 at Fz and P27 at C3’ showed a significant reduction in amplitude in the FG and FR phases. Furthermore, those were significantly smaller in amplitude in the FG than FR phase. Previous studies reported that the strength of muscle force affects the SEP gating. Although the average amount of force exertion was the same in the both phases, our results showed the different modulation of SEP amplitude. These results indicated that sensorimotor integration in the primary somatosensory area was dependent on the context of movement exertion.

Fine motor skills predict performance in the Jebsen Taylor Hand Function Test after stroke

ObjectiveTo determine factors characterizing the differences in fine motor performance between stroke patients and controls. To confirm the relevance of the factors by analyzing their predictive power with regard to the Jebsen Taylor Hand Function Test (JTHFT), a common clinical test of fine motor control. MethodsTwenty-two people with slight paresis in an early chronic phase following stroke and twenty-two healthy controls were examined. Performance on the JTHFT, Nine-Hole Peg Test and 2-point discrimination was evaluated. To analyze object manipulation skills, grip forces and temporal measures were examined during (1) lifting actions with variations of weight and surface (2) cyclic movements (3) predictive/reactive catching tasks. Three other aspects of force control included (4) visuomotor tracking (5) fast force changes and (6) grip strength. ResultsBased on 9 parameters which significantly distinguished fine motor performance in the two groups, we identified three principal components (factors): grip force scaling, motor coordination and speed of movement. The three factors are shown to predict JTHFT scores via linear regression (R2=0.687, p<0.001). ConclusionsWe revealed a factor structure behind fine motor impairments following stroke and showed that it explains JTHFT results to a large extend. SignificanceThis result can serve as a basis for improving diagnostics and enabling more targeted therapy.

The interacting effects of treadmill walking and different types of visuospatial cognitive task: Discriminating dual task and age effects

ObjectiveThe objective of this study is to examine the influence that visuospatial cognitive tasks have on gait function during DT treadmill walking, and as a function of age. Conversely, to examine the influence that walking has on executive functions involving visuospatial processing. MethodsTwenty-five young (26±6.1years) and 25 older adults (76±3.9) performed different types of computerized visuomotor (VM) tracking and visuospatial cognitive tasks (VCG) while standing and treadmill walking. Spatiotemporal gait variables, average values and co-efficient of variation (COV) were obtained from 40 consecutive steps during single- and dual-task walk trials. Performance-based measures of the VM and VCG task were obtained during standing and walking. ResultsVM dual-task walking had a significant effect on gait measures in the young age group (YG), but no DT effect was observed in the old age group (OG). Visuomotor tracking performance, however, was significantly reduced in the OG as compared to the YG when tested in both standing and walking. The opposite was true for VCG; a significant DT effect on gait performance was observed in the OG, but no DT effect was observed in the YG. Success rate of the VCG task decreased during walking, but only for OG. ConclusionControlling gait speed and objective evaluation of the visuospatial cognitive tasks helps to determine the level of engagement in the DT tasks. This is important in order to determine the strategies used during the DT test protocols, i.e. cross-domain interference.

DIFFERENCES BETWEEN MULTI-INFARCT DEMENTIA AND SMALL-VESSEL DISEASE DEMENTIA IN ATTENTION AND WORKING MEMORY DEFICITS

Attention and working memory deficit are significantly impaired in patients with small vessel disease dementia, but little is known about diferences in these cognitive domains between subtypes of vascular dementia. 60 patients were studied, 28 were randomised as multi infarct dementia (MID) and 32 in small vessel disease dementia (SVD), according to NINDS- AIREN (National Institute of Neurological Disorders and Stroke and Association Internationale pour la Recherché et l'Enseignement en Neurosciences) neuroradiological criteria. Patients with MMSE (Mini Mental State Examination) score 15–25 were included. Groups have been matched by sex, age and education. Patients with severe aphasia, depression, and hand weakness were excluded. Trail Making Test (TMT) A and B form was used to evaluate: processsing information speed, visuo- conceptual functions, visuo-motor tracking and attention. WMS- R(Wechsler Memory Scale – Revised) visual span subtest and digit-symbol coding subtest on the Wechsler Test of Intelligence was used to measure visual abilities and digit span for verbal capacities of attention and working memory. Processing information speed was significantly slower, and conceptual skills were more impaired in MID than in SVD group (p = 0,012), with coefficient of discrimination between reaction time 0,068 for TMTA and 0,022 for TMT B. There were no differences between groups in verbal and visual span WMS-R scores forward, but either verbal or visual backward scores and Digit Symbol Test score were significantly lower in MID (p=0,002). Coefficient of discrimination for verbal span backward was 0.122, for visual span backward was 0.109, for verbal span forward was 0,066 and for visual span forward was 0,064. The most predicatable scores were proposed for each group of vascular dementia patients (MID ˂2, SVD 3 and ˃3 for verbal span backward; MID ˂2, SVD 4 and ˃4 for visual span forward, MID ˂ 4, SVD 6 and ˃6 for visual span forward MID ˂3, SVD 4 and ˃4 for visual span forward; MID 0, SVD 1–6, and ˃6 for digit symbol coding). Attention and working memory deficit are more severe in MID than SVD.

Manipulation of visual information affects control strategy during a visuomotor tracking task

Proper understanding of motor control requires insight into the extent and manner in which task performance and control strategy are influenced by various aspects of visual information. We therefore systematically manipulated the visual presentation (i.e., scaling factor and optical flow density) of a visuomotor tracking task without changing the task itself, and investigated the effect on performance, effort, motor control strategy (i.e., anticipatory or corrective steering) and underlying neuromechanical parameters (i.e., intrinsic muscle stiffness and damping, and proprioceptive and visual feedback). Twenty healthy participants controlled the left-right position of a virtual car (by means of wrist rotations in a haptic robot) to track a slightly curved virtual road (presented on a 60” LED screen), while small torque perturbations were applied to the wrist (1.25–20Hz multisine) for quantification of the neuromechanical parameters. This visuomotor tracking task was performed in conditions with low/medium/high scaling factor and low/high optical flow density. Task performance was high in all conditions (tracking accuracy 96.6%–100%); a higher scaling factor was associated with slightly better performance. As expected, participants did adapt their control strategy and the use of proprioceptive and visual feedback in response to changes in the visual presentation. These findings indicate that effects of visual representation on motor behavior should be taken into consideration in designing, interpreting and comparing experiments on motor control in health and disease. In future studies, these insights might be exploited to assess the sensory-motor adaptability in various clinical conditions.

Acute Exercise Improves Motor Memory Consolidation in Preadolescent Children.

Objective: The ability to acquire new motor skills is essential both during childhood and later in life. Recent studies have demonstrated that an acute bout of exercise can improve motor memory consolidation in adults. The objective of the present study was to investigate whether acute exercise protocols following motor skill practice in a school setting can also improve long-term retention of motor memory in preadolescent children.Methods: Seventy-seven pre-adolescent children (age 10.5 ± 0.75 (SD)) participated in the study. Prior to the main experiment age, BMI, fitness status and general physical activity level was assessed in all children and they were then randomly allocated to three groups. All children practiced a visuomotor tracking task followed by 20 min of rest (CON), high intensity intermittent floorball (FLB) or running (RUN) with comparable exercise intensity and duration for exercise groups. Delayed retention of motor memory was assessed 1 h, 24 h and 7 days after motor skill acquisition.Results: During skill acquisition, motor performance improved significantly to the immediate retention test with no differences between groups. One hour following skill acquisition, motor performance decreased significantly for RUN. Twenty-four hours following skill acquisition there was a tendency towards improved performance for FLB but no significant effects. Seven days after motor practice however, both FLB and RUN performed better when compared to their immediate retention test indicating significant offline gains. This effect was not observed for CON. In contrast, 7 days after motor practice, retention of motor memory was significantly better for FLB and RUN compared to CON. No differences were observed when comparing FLB and RUN.Conclusions: Acute intense intermittent exercise performed immediately after motor skill acquisition facilitates long-term motor memory in pre-adolescent children, presumably by promoting memory consolidation. The results also demonstrate that the effects can be accomplished in a school setting. The positive effect of both a team game (i.e., FLB) and running indicates that the observed memory improvements are determined to a larger extent by physiological factors rather than the types of movements performed during the exercise protocol.

Computerized Dual-Task Testing of Gait and Visuospatial Cognitive Functions; Test-Retest Reliability and Validity.

The common occurrence of age decline in mobility and cognition does cause a decrease in the level of physical activity and an increased falls risk. Consequently, dual -task (DT) assessment that simultaneously addresses both mobility skills and cognitive functions are important because, continued difficulties and fall injuries will have a sizable impact in this population. The first objective of the present study was to assess test-retest reliability of a computerized DT treadmill walking protocol and concurrent outcome measures of gait and visuospatial executive function in a group of healthy older adults. Secondly, discriminative validity was evaluated by examining the effect of DT conditions (single task vs. dual-task) on; (a) spatiotemporal gait measures (average and coefficient of variation) and (b) visuomotor and visuospatial executive performance measures. Twenty-five community-dwelling individuals median age 65 (range 61–67) were recruited from a Fitness Facility. Participants performed a computerized visuomotor tracking task and a visuospatial executive game task in standing and while treadmill walking. Testing was conducted on two occasions, 1 week apart. Moderate to high test-retest reliability (ICC values of 0.65–0.88) were observed for spatiotemporal gait variables. No significant differences between the group means were observed between test periods in any gait variable. Moderate test-retest reliability (ICC values of 0.6–0.65) was observed for measures of visuomotor and visuospatial executive performance during treadmill walking. Significant DT effects were observed for both spatiotemporal gait variables and visuospatial executive performance measures. This study demonstrates the reliability and reproducibility of the computer-based assessment tool for dual task treadmill walking. The high to moderate ICC values and the lack of systematic errors in the measures indicate that this tool has the ability to repeatedly record reliable data from community-dwelling older adults. The present computerized dual-task protocols broaden the types of standardized visuomotor and visuospatial executive activities for use with DT treadmill walking that has previously been reported.

P317 Transcranial direct current stimulation combined with visuo-motor training as treatment for chronic stroke patients

Recent studies exploring the combined effect of motor learning and transcranial direct current stimulation (tDCS) have shown conflicting results. The optimization of the employed training paradigms can be one way to maximize treatment effects. Methods A newly developed visuo-motor force tracking task is directed to the improvement of fine force control in the hand. During the task, a target force is presented on a computer screen and controlled by patients by pressing a power grip force manipulandum with the affected hand. In the present pilot study we investigated motor effects of four-week training with the visuo-motor force tracking task combined with tDCS in 11 chronic stroke patients with different levels of paresis. Anodal (0.5 mA; 5 patients) or sham (6 patients) tDCS was applied on the primary motor cortex (M1) of the lesioned side for 20 min twice a day simultaneously with training.Upper Extremity Fugl-Meyer assessment (FMA; the primary outcome measure) was done before, after and on two months follow-up. Parameters of performance – ramp error, hold error, release duration and mean hold force – were calculated. Results Total UE FMA score was significantly increased immediately after the treatment, but had declined at two months follow-up. The most prominent improvement occurred in the shoulderelbow sub-score of the FMA; in this segment (but not in the total UE FMA score) a significantly greater improvement in the Active compared to the Sham group was observed (Fig. 1 Figure options Download full-size image Download high-quality image (338 K) Download as PowerPoint slide ). A clinically significant improvement (FMA > 5) was revealed in four patients out of five in the Active group and in two out of six – in the Sham group. Hold error decreased significantly in all patients; ramp error – in the Active group. Mean Hold Force during the first treatment session predicted the change in total UE FMA score after treatment (Fig. 2 Figure options Download full-size image Download high-quality image (213 K) Download as PowerPoint slide ). Conclusions The results show that this treatment protocol can result in clinically significant improvement of motor function in chronic stroke patients, including patients with severe paresis. Individual clinical characteristics of the patients could explain heterogeneity of results and lack of difference in the total UE FMA score. Performance during the initial session might inform about clinical outcomes and guide tDCS protocol optimization in future combined treatments.

Interactive effects of visuomotor perturbation and an afternoon nap on performance and the flow experience.

The present study was designed (1) to clarify the relationship between the flow experience and improvements in visuomotor skills, (2) to examine the effects of rotating the axis of a computer mouse on visuomotor skills, and (3) to investigate the effects of sleep for improving visuomotor skills. Participants (N = 18) responded to Perturbation and nap (PER+Nap), No-perturbation and nap (NoPER+Nap) and Perturbation and rest (PER+Rest) conditions. In the PER+Nap condition, participants conducted a visuomotor tracking task using a computer mouse, which was accompanied by perturbation caused by rotating the axis of their mouse. After the task, they took a 90 min nap. In NoPER+Nap condition, they conducted the same visuomotor task without any perturbation and took a nap. In the PER+Rest condition, participants conducted the task with the perturbation and took a 90 min break spent reading magazines instead of taking a nap. Results indicated (1) the flow experience did not occur when participants’ skills and the degree of the visuomotor challenge were matching, (2) improvements of visuomotor skills occurred regardless of the perturbation, (3) improvements of visuomotor skills occurred unrelated to the flow experience, or to mood states, and (4) improvements of visuomotor performance occurred regardless of sleep. These findings suggest that improvements of visuomotor skills occur regardless of mood status and occur independently of perturbations by axis rotation. The study also suggests that the acquisition of skills is related to merely the time elapsed since learning, rather than to sleep.

Abstract 11: Targeted Training of a Motor-parietal Circuit Improves Its Behavioral Output

Introduction: Emerging brain mapping methods measure function of individual brain circuits and have the potential to predict a patient’s gains and needs in the context of stroke rehabilitation. We recently described a motor-parietal circuit underlying visuomotor tracking and defined an EEG coherence measure (reflecting connectivity) that predicts visuomotor learning. Here we test the hypothesis that this EEG metric predicts visuomotor learning after stroke. Methods: After baseline dense-array resting EEG, patients with chronic hemiparetic stroke were provided with a home-based gaming system. During 9 half-hour training sessions, patients played games in which the stroke-affected arm tracked objects moving on the tabletop. Games were implemented using augmented reality, which we have found has advantages for motor training and in which virtual objects are projected into the real world and modified during game play. Results: Subjects (n=12) had affected arm Box&amp;Blocks score of 15±12 and were 35±26 mo post-stroke. Visuomotor tracking improved significantly: on a standardized visuomotor test using the gaming system, scores increased from 60.5±11.5% to 74.0±3.2% (p=0.003). Gains were specific, as other behaviors were unchanged. Individual gains in visuomotor tracking score were predicted by the EEG connectivity metric from our prior study, coherence between leads overlying ipsilesional primary motor cortex (M1i) and ipsilesional lateral parietal region in the high beta (20-30 Hz) range, with higher connectivity predicting greater visuomotor tracking gains (r=0.61, p=0.037). This too was specific, as connectivity between M1i and other brain areas did not predict gains. Secondary analysis found that baseline visuomotor tracking scores correlated with several EEG connectivity measures, all inversely and all between M1i and contralesional regions. Conclusions: We found that (1) training that targets a specific brain circuit improves behavioral output of that circuit, and (2) an EEG measure of brain connectivity within that circuit predicts these behavioral gains--both with specificity. This approach may be useful for many neural circuits and their respective rehabilitation-related behaviors.

Elasticity improves handgrip performance and user experience during visuomotor control.

Passive rehabilitation devices, providing motivation and feedback, potentially offer an automated and low-cost therapy method, and can be used as simple human–machine interfaces. Here, we ask whether there is any advantage for a hand-training device to be elastic, as opposed to rigid, in terms of performance and preference. To address this question, we have developed a highly sensitive and portable digital handgrip, promoting independent and repetitive rehabilitation of grasp function based around a novel elastic force and position sensing structure. A usability study was performed on 66 healthy subjects to assess the effect of elastic versus rigid handgrip control during various visuomotor tracking tasks. The results indicate that, for tasks relying either on feedforward or on feedback control, novice users perform significantly better with the elastic handgrip, compared with the rigid equivalent (11% relative improvement, 9–14% mean range; p < 0.01). Furthermore, there was a threefold increase in the number of subjects who preferred elastic compared with rigid handgrip interaction. Our results suggest that device compliance is an important design consideration for grip training devices.

Long-term progressive motor skill training enhances corticospinal excitability for the ipsilateral hemisphere and motor performance of the untrained hand.

It is well established that unilateral motor practice can lead to increased performance in the opposite non-trained hand. Here, we test the hypothesis that progressively increasing task difficulty during long-term skill training with the dominant right hand increase performance and corticomotor excitability of the left non-trained hand. Subjects practiced a visuomotor tracking task engaging right digit V for 6weeks with either progressively increasing task difficulty (PT) or no progression (NPT). Corticospinal excitability (CSE) was evaluated from the resting motor threshold (rMT) and recruitment curve parameters following application of transcranial magnetic stimulation (TMS) to the ipsilateral primary motor cortex (iM1) hotspot of the left abductor digiti minimi muscle (ADM). PT led to significant improvements in left-hand motor performance immediately after 6weeks of training (63±18%, P<0.001) and 8days later (76±14%, P<0.001). In addition, PT led to better task performance compared to NPT (19±15%, P=0.024 and 27±15%, P=0.016). Following the initial training session, CSE increased across all subjects. After 6weeks of training and 8days later, only PT was accompanied by increased CSE demonstrated by a left and upwards shift in the recruitment curves, e.g. indicated by increased MEPmax (P=0.012). Eight days after training similar effects were observed, but 14months later motor performance and CSE were similar between groups. We suggest that progressively adjusting demands for timing and accuracy to individual proficiency promotes motor skill learning and drives the iM1-CSE resulting in enhanced performance of the non-trained hand. The results underline the importance of increasing task difficulty progressively and individually in skill learning and rehabilitation training.

Sensori-Motor Learning with Movement Sonification: Perspectives from Recent Interdisciplinary Studies.

This article reports on an interdisciplinary research project on movement sonification for sensori-motor learning. First, we describe different research fields which have contributed to movement sonification, from music technology including gesture-controlled sound synthesis, sonic interaction design, to research on sensori-motor learning with auditory-feedback. In particular, we propose to distinguish between sound-oriented tasks and movement-oriented tasks in experiments involving interactive sound feedback. We describe several research questions and recently published results on movement control, learning and perception. In particular, we studied the effect of the auditory feedback on movements considering several cases: from experiments on pointing and visuo-motor tracking to more complex tasks where interactive sound feedback can guide movements, or cases of sensory substitution where the auditory feedback can inform on object shapes. We also developed specific methodologies and technologies for designing the sonic feedback and movement sonification. We conclude with a discussion on key future research challenges in sensori-motor learning with movement sonification. We also point out toward promising applications such as rehabilitation, sport training or product design.

Dynamic motor tracking is sensitive to subacute mTBI.

Effective screening for mild traumatic brain injury (mTBI) is critical to accurate diagnosis, intervention, and improving outcomes. However, detecting mTBI using conventional clinical techniques is difficult, time intensive, and subject to observer bias. We examine the use of a simple visuomotor tracking task as a screening tool for mTBI. Thirty participants, 16 with clinically diagnosed mTBI (mean time since injury: 36.4±20.9days (95% confidence interval); median=20days) were asked to squeeze a hand dynamometer and vary their grip force to match a visual, variable target force for 3min. We found that controls outperformed individuals with mTBI; participants with mTBI moved with increased variability, as quantified by the standard deviation of the tracking error. We modeled participants' feedback response-how participants changed their grip force in response to errors in position and velocity-and used model parameters to classify mTBI with a sensitivity of 87% and a specificity of 93%, higher than several standard clinical scales. Our findings suggest that visuomotor tracking could be an effective supplement to conventional assessment tools to screen for mTBI and track mTBI symptoms during recovery.