Biology subjects

Lefevre, P.

Publications and source records attributed to Lefevre, P..

At least 19 recordsLinked to original sources

bioRxiv2026

Whole-fingertip 3D Skin Surface Deformation under Tangential Loading

AO_SCPLOWBSTRACTC_SCPLOWDuring tactile interaction, skin deformation drives the widespread activation of tactile afferents distributed across the fingertip. Yet the full spatial extent and evolution of these deformations remain largely unquantified. Using high-resolution 3D imaging, we reconstructed the complete volar surface of the fingertip under progressive tangential loadings typical of object manipulation. We show that much of the deformation occurs in the out-of-contact regions, accounting for approximately 70% of the total deformation energy. This deformation consistently initiates in the peripheral zones and smoothly propagates inward as partial slip develops. Tangential loading also induces pronounced directional asymmetries and local curvature changes, reflecting both surface and bulk tissue deformation. Furthermore, we observe localized strain patterns consistent with skin wrinkling across all participants, with individual variations in intensity and location driven by distinct frictional and biomechanical properties. This dataset provides a strong foundation for developing highly accurate biomechanical models and for linking fingertip mechanics to tactile neural encoding.

neuroscience↗

bioRxiv2026

Collagen Shapes Fingertip Surface Strains during Normal Loading

When making contact, fingertip mechanoreceptors respond to the skin deformation, and provide essential information for tactile perception and object manipulation. Since subsurface measurements remain challenging, strains close to the receptors are commonly estimated using numerical models. Here, we present a biomechanical finite element model simulating fingertip normal loading against a flat plate. Several model variants are designed to isolate the role of tissue heterogeneity and collagen-induced anisotropy. Their predictions are compared to experimental data of fingertip surface strains obtained with 3-D stereo imaging. By varying the stiffness contrast and fiber orientation, we demonstrate that incorporating collagen anisotropy is required to reproduce strain localization at the contact edge while maintaining realistic global shape changes. In particular, fibers aligned parallel to the skin surface induce local skin thickening and a pronounced radial expansion beneath the contact edge, affecting mechanoreceptors. This observation suggests a collagen-mediated contribution to the deep transmission of mechanical stimuli. These results highlight collagen architecture as a key determinant of fingertip mechanics and underscore its importance for accurate modeling of tactile interactions.

bioengineering↗

bioRxiv2026

TomoSegNet: Augmented membrane segmentation for cryo-electron tomography by simulating the cellular context

Membrane segmentation is an essential task in the workflow for processing cryo-electron tomography data. Recently, machine learning algorithms have successfully been adopted to perform membrane segmentation. However, the performance of these approaches is limited by the training dataset, as models are trained from manual annotations, thereby hindering the models generalization and preventing the recovery of membranes that have vanished due to distortions. Here, we address these limitations by generating training data with a simulator. To provide a representative and realistic dataset, we have extended the current state-of-the-art in simulators for cryo-electron tomography by incorporating a biophysical model for membranes. We demonstrate that our machine learning model, trained solely from synthetic data, and thanks to the physical knowledge learned from the simulator, outperforms the current state-of-the-art for membrane segmentation in a diverse set of experimental data. This performance is particularly noteworthy in terms of recovering membranes lost due to imaging distortions.

bioinformatics↗

bioRxiv2025

Interference between flexible and adaptive reaching control

Humans rapidly update the control of an ongoing movement following changes in contextual parameters. This involves adjusting the controller to exploit redundancy in the movement goal, such as when reaching for a narrow or wide target, and adapting to dynamic changes such as velocity-dependent force fields (FFs). Although flexible control and motor adaptation are computationally distinct, the fact that both unfold within the same movement suggests they may share common neural resources for task-specific adjustments. To test this hypothesis, we conducted a series of experiments combining changes in the target structure and a force field presented separately or in combination. Seventy-six human participants (both sexes) took part in this study, with each experiment involving different participants. They were asked to reach for a target that could change from a narrow square to a wide rectangle between or during trials. Step loads were used to assess whether participants exploited target redundancy. In a separate experiment, we added a force field in addition to target changes and step loads. Our results revealed a reduced ability to exploit target redundancy when sudden target changes occurred concurrently with FF adaptation. Furthermore, the magnitude of adaptation was reduced when step loads were added to the FF. Crucially, this interference emerged specifically when all perturbations impacted motor execution simultaneously. These results indicate that flexible control and motor adaptation interact in a non-trivial manner, suggesting possible overlap between their underlying neural mechanisms, and a clear identification of the timescale at which they are engaged - namely, during movement. Significant statementHumans rapidly adapt to changes in task demands, such as target structure changes or exposure to force fields (FFs). These two types of adjustments occur within a single movement, suggesting potential interactions between them. Our experiments revealed that the combination of FF exposure with online target shape changes selectively reduced participants ability to exploit target redundancy, while the combination of FF and step loads led to a reduced extent of motor adaptation. These findings confirm that motor adaptation occurs not only between trials but also during movement. The selective nature of the observed interference highlights an interplay between flexible control and motor adaptation, underscoring the importance of understanding the timing of these processes to better characterise their underlying neural circuits.

neuroscience↗

bioRxiv2025

3-D Reconstruction of Fingertip Deformation during Contact Initiation

Dexterous manipulations rely on tactile feedback from the fingertips, which provides crucial information about contact events, object geometry, interaction forces, friction, and more. Accurately measuring skin deformations during tactile interactions can shed light on the mechanics behind such feedback. To address this, we developed a novel setup using 3-D digital image correlation (DIC) to both reconstruct the bulk deformation and local surface skin deformation of the fingertip under natural loading conditions. Here, we studied the local spatiotemporal evolution of the skin surface during contact initiation. We showed that, as soon as contact occurs, the skin surface deforms very rapidly and exhibits high compliance at low forces (<0.05 N). As loading and thus the contact area increases, a localized deformation front forms just ahead of the moving contact boundary. Consequently, substantial deformation extending beyond the contact interface was observed, with maximal amplitudes ranging from 5% to 10% at 5 N, close to the border of the contact. Furthermore, we found that friction influences the partial slip caused by these deformations during contact initiation, as previously suggested. Our setup provides a powerful tool to get new insights into the mechanics of touch and opens avenues for a deeper understanding of tactile afferent encoding.

neuroscience↗

bioRxiv2024

Main Sequence of Human Luminance-Evoked Pupil Dynamics

Pupil responses are commonly used to provide insight into visual perception, autonomic control, cognition, and various brain disorders. However, making inferences from pupil data can be complicated by nonlinearities in pupil dynamics and variability within and across individuals, which challenge the assumptions of linearity or group level homogeneity required for common analysis methods. In this study, we evaluated luminance evoked pupil dynamics in young healthy adults (N=10, 5:5 M:F, ages 19-25) by identifying nonlinearities, variability, and conserved relationships across individuals to improve the ability to make inferences from pupil data. We found a nonlinear relationship between final pupil diameter and luminance, linearized by considering the logarithm of luminance. Peak diameter change and peak velocity were nonlinear functions of log-luminance for constriction but not dilation responses. Across participants, curve fit parameters characterizing pupil responses as a function of luminance were highly variable, yet there was an across-participant linear correlation between overall pupil size and pupil gain (i.e. diameter change per unit log-luminance change). In terms of within-participant trial-by-trial variability, participants showed greater variability in final pupil size compared to constriction peak diameter change as a function of log-luminance. Despite the variability in stimulus-response metrics within and across participants, we found that all participants showed a highly stereotyped "main sequence" relationship between peak diameter change and peak velocity (independent of luminance). The main sequence relationship can be used to inform models of the neural control of pupil dynamics and as an empirical analysis tool to evaluate variability and abnormalities in pupil behaviour.

neuroscience↗

bioRxiv2024

Timing and Amplitude of Catch-up Saccades to Accelerating Targets

To track moving targets, humans move their eyes using both saccades and smooth pursuit. If pursuit eye movements fail to accurately track the moving target, catch-up saccades are initiated to rectify the tracking error. It is well known that retinal position and velocity errors determine saccade timing and amplitude, but the extent to which retinal acceleration error influences these aspects is not well quantified. To test this, 13 adult human participants performed an experiment where they pursued accelerating / decelerating targets. During ongoing pursuit, we introduced a randomly sized target step to evoke a catch-up saccade and analyzed its timing and amplitude. We observed that retinal acceleration error was a statistically significant predictor of saccade amplitude and timing. A multiple linear regression supported our hypothesis that retinal acceleration errors influence saccade amplitude in addition to the influence of retinal position and velocity errors. We also found that saccade latencies were shorter when retinal acceleration error increased the tracking error and vice versa. In summary, our findings support a model in which retinal acceleration error is used to compute a predicted position error [~]100ms into the future to trigger saccades and determine saccade amplitude. Significance statementWhen visually tracking object motion, humans combine smooth pursuit and saccadic eye movements to maintain the target image on the fovea. Retinal position and velocity errors are known to determine catch-up saccade amplitude and timing, however it is unknown if retinal acceleration error is also used to predict future target position. This study provides evidence of a small but statistically significant contribution of retinal acceleration error in determining saccade amplitude and timing.

neuroscience↗

bioRxiv2023

Open-source instrumented object to study dexterous object manipulation

Humans use tactile feedback to perform skillful manipulation. When tactile sensory feedback is unavailable, for instance, if the fingers are anesthetized, dexterity is severely impaired. Imaging the deformation of the finger pad skin when in contact with a transparent plate provides information about the tactile feedback received by the central nervous system. Indeed, skin deformations are transduced into neural signals by the mechanoreceptors of the finger pad skin. Understanding how this feedback is used for active object manipulation would improve our understanding of human dexterity. In this paper, we present a new device for imaging the skin of the finger pad of one finger during manipulation performed with a precision grip. The devices weight (300 g) makes it easy to use during unconstrained dexterous manipulation. Using this device, we reproduced the experiment performed in Delhaye et al. 2021a. We extracted the strains aligned with the objects movement, i.e., the vertical strains in the ulnar and radial parts of the fingerpad, to see how correlated they were with the grip force (GF) adaptation. Interestingly, parts of our results differed from those in Delhaye et al. 2021a due to weight and inertia differences between the devices, with average GF across participants differing significantly. Our results highlight a large variability in the behavior of the skin across participants, with generally low correlations between strain and GF adjustments, suggesting that skin deformations are not the primary driver of GF adaptation in this manipulation scenario. Significance statementIn this paper, we introduce a new device weighing 300 g and capable of imaging the skin of the finger pad of one finger during manipulation performed with a precision grip. This object is also capable of recording the forces and accelerations applied to the object. We reproduced the experiment performed in Delhaye et al. 2021a using this device. We extracted the strains aligned with the objects movement to analyze how correlated these strains were with GF adaptation. The behavior of the skin across participants presented a large variability, and we observed low correlations between strain and GF adjustments in most participants. Our results suggest that skin deformations are not the primary driver of GF adaptation in this manipulation scenario.

neuroscience↗

bioRxiv2023

A haptic illusion created by gravity

Haptic force estimation is a critical aspect of human dexterity. To manipulate objects or interact with a haptic interface successfully, the normal and tangential components of the contact forces produced by our fingertips must be carefully coordinated. The tight coupling between tangential and normal contact forces observed during voluntary movements indicates that the nervous system can estimate these forces with high accuracy. Here, we examined the influence of gravity on manual force production in an isometric task. We trained participants to produce isometric tangential forces with the thumb and index finger on a dynamometer held in precision grip. They were tasked with reproducing these forces in a normal gravitational environment (1 g) and during parabolic maneuvers creating phases of micro- (0 g) and hypergravity (1.6 g). The isometric task results showed that arm weight biases estimation of the forces exerted by the fingertips. Reproduced tangential forces were consistently larger downward than upward in 1 g. This asymmetry was reduced under microgravity and increased under hypergravity. Critically, the normal forces did not reflect this asymmetry, demonstrating that tangential forces were misestimated and pointing to a haptic illusion created by gravity. This gravitational effect on haptic force estimation may have implications for the design of prostheses incorporating force feedback, haptic devices for teleoperations, or haptic supports aimed at improving sensorimotor performance in space.

neuroscience↗

bioRxiv2022

Continuous monitoring of cost-to-go for flexible reaching control and online decisions

Humans consider the parameters linked to movement goal during reaching to adjust their control strategy online. Indeed, rapid changes in target structure or disturbances interfering with their initial plan elicit rapid changes in behavior. Here, we hypothesize that these changes could result from the continuous use of a decision variable combining motor and cognitive components. We combine an optimal feedback controller with a real-time monitoring of the expected cost-to-go, which considers target- and movement-related costs, in a common theoretical framework. This model reproduces human behaviors in presence of changes in the target structure occurring during movement and of online decisions to flexibly change target following external perturbations. It also predicts that the time taken to decide to select a novel goal after a perturbation depends on the amplitude of the disturbance and on the rewards of the different options, which is a direct result of the continuous monitoring of the cost-to-go. We show that this result was present in our previously collected dataset. Together our developments point towards a continuous monitoring of the cost-to-go during reaching to update control online and make efficient decisions about movement goal. Author summaryThe way humans perform reaching movements is compatible with models considering that they result from the minimization of a task-related cost function. However, these models typically assume a cost function that does not change within movement, which is incompatible with experimental findings highlighting humans ability to adjust reaching control online and change target flexibly. We hypothesized that this later ability relied on the cost-to-go, which integrates task- and body-related information, being evaluated continuously during movement. We show that this model can optimally select and adjust control during movement in a way that reproduces human behavior in a set of tasks involving change in cost function and change in goal target. Our model predicted that decision-time to change target must be postponed when limb displacements and alternative rewards are smaller, which was borne out in our previous experimental dataset. To conclude, our model explains dynamic updates in reach control and suggests the cost-to-go as decision variable linking decision-making and motor control.

neuroscience↗

bioRxiv2022

Different control strategies drive interlimb differences in performance and adaptation during reaching movements in novel dynamics

Humans exhibit lateralization such that most individuals typically show a preference for using one arm over the other for a range of movement tasks. The computational aspects of movement control leading to these differences in skill are not yet understood. It has been hypothesized that the dominant and non-dominant arms differ in terms of the use of predictive or impedance control mechanisms. However, previous studies present confounding factors that prevented clear conclusions: either the performances were compared across two different groups, or in a design in which asymmetrical transfer between limbs could take place. To address these concerns, we studied a reach adaptation task during which healthy volunteers performed movements with their right and left arms in random order. We performed two experiments. Experiment 1 (18 participants) focused on adaptation to the presence of a perturbing force field and Experiment 2 (12 participants) focused on rapid adaptations in feedback responses. The randomization of the left and right arm led to simultaneous adaptation, allowing us to study lateralization in single individuals with symmetrical and minimal transfer between limbs. This design revealed that participants were able to adapt control of both arms, and that adaptation was greater in the dominant arm than in the non-dominant. We also observed that the non-dominant arm showed a different control strategy compatible with robust control when adapting to the force field perturbation. EMG data showed that these differences in control were not caused by differences in co-contraction across the arms. Thus, instead of assuming differences in predictive or reactive control schemes, our data show that in the context of optimal control, both arms can adapt, and that the non-dominant arm uses a more robust, model-free strategy likely to compensate for less accurate internal representations of movement dynamics. Significance statementWe studied a reach adaptation task during which volunteers performed the task with their right and left arm randomly. The randomization of the arms allowed us to study lateralization in single individuals with symmetrical and minimal transfer between limbs. We observed a slightly greater adaptation of the dominant arm in the force applied to counter the perturbation. Moreover, the non-dominant arm showed a more robust control strategy when adapting to the force field perturbation, which enabled similar deviations despite faster movements. These interlimb differences were not caused by differences in co-contraction across the two arms. Our results suggest that both arms can adapt to the presence of a force field but the non-dominant arm uses a more robust, model-free strategy.

neuroscience↗

bioRxiv2022

Biomechanics of Finger Pad Response under Torsion

Surface skin deformation of the finger pad during partial slippage at finger-object interfaces elicits tactile feedback. During object manipulation, torque is often present, which can cause partial slippage. Until now, studies of surface skin deformation have used stimuli sliding on rectilinear tangential trajectories. Here we studied surface skin dynamics under torsion. A custom robotic platform stimulated the finger pad with a flat transparent surface, controlling the normal forces and rotation speeds applied while monitoring the contact interface using optical imaging. We observed the characteristic pattern by which partial slips develop, starting at the periphery of the contact and propagating towards its centre, and the resulting surface strains. The 20-fold range of normal forces and angular velocities used highlights the effect of those parameters on the resulting torque and skin strains. While normal force increases the contact area, generated torque, strains, and twist angle required to reach full slip, angular velocity increases loss of contact at the periphery and strain rates (although not total strains). We also discuss the surprisingly large inter-individual variability in skin biomechanics, notably observed in the twist angle the stimulus needed to rotate before reaching full slip.

neuroscience↗

bioRxiv2022

Continuous tracking of task parameters tunes reaching control online

A hallmark of human reaching movements is that they are appropriately tuned to the task goal and to the environmental context. This was demonstrated by the way humans flexibly respond to mechanical and visual perturbations that happen during movement. Furthermore, it was previously showed that the properties of goal-directed control can change within a movement, following abrupt changes in the goal structure. Such online adjustment was characterized by a modulation of feedback gains following switches in target shape. However, it remains unknown whether the underlying mechanism merely switches between prespecified policies, or whether it results from continuous and potentially dynamic adjustments. Here, we address this question by investigating participants feedback control strategies in presence of various changes in target width during reaching. More specifically, we studied whether the feedback responses to mechanical perturbations were sensitive to the rate of change in target width, which would be inconsistent with the hypothesis of a single, discrete switch. Based on movement kinematics and surface EMG data, we observed a modulation of feedback response clearly dependent on dynamical changes in target width. Together, our results demonstrate a continuous and online transformation of task-related parameters into suitable control policies. Significance statementHumans can adjust their control policy online in response to changes in the goal structure. However, it was unknown whether this adjustment resulted from a switch between two policies, or from dynamic and continuous adjustments. To address this question, we investigated whether online adjustments were tuned to dynamic changes in goal target which varied at different rates. Our results demonstrated that online adjustments were tuned to the rate of change in target width, suggesting that human reaching control policies are derived based on continuous monitoring of task-related parameters supporting online and dynamic adjustments.

neuroscience↗

bioRxiv2022

Separability of Human Motor Memories during Reaching Adaptation with Force Cues

Judging by the breadth of our motor repertoire during daily activities, it is clear that acquiring multiple motor skills is a hallmark of the human motor system. However, for reaching movements the different planning conditions under which this is possible in laboratory settings have remained a challenging question. Considering the sensitivity of limb afferent feedback relative to externally applied forces, we hypothesised that independent cues delivered by means of background loads could support simultaneous formation of different motor memories of various velocity-dependent force fields. We demonstrate in a series of experiments that indeed healthy adults can form internal priors about opposite force fields, independently of the direction of the background force cue. However, when the cue and force field were only related by their magnitude, a separation was still observed but the associated mechanism was subject to interference. Finally, we highlight that this paradigm allows dissociating trial-by-trial acquisition of internal representations from within-trial feedback adaptation, as these two adaptation mechanisms are associated with different time scales that can be measured reliably. Significance StatementThe conditions under which humans can adapt to different contexts in parallel remain the subject of active debates. Mounting evidence highlights that contextual factors linked to movement planning are necessary to form different motor memories. Here we show that background forces indicative of the direction of a force field could play the role of contextual factors, and enable dual adaptation to different force fields. However, we uncovered that when the cue and the force field were in the same direction but of different magnitudes, the motor memories were still distinct but subject to interference. We further show that different timescales of adaptation observed can be explained by offline and online mechanisms in a model of reaching adaptation and control.

neuroscience↗

bioRxiv2021

Reward-dependent selection of feedback gains impacts rapid motor decisions

Target reward influences motor planning strategies through modulation of movement vigor. Considering current theories of sensorimotor control suggesting that movement planning consists in selecting a goal-directed control strategy, we sought to investigate the influence of reward on feedback control. Here we explored this question in three human reaching experiments. First, we altered the explicit reward associated with the goal target and found an overall increase in feedback gains for higher target rewards, highlighted by larger velocities, feedback responses to external loads, and background muscle activity. Then, we investigated whether the differences in target rewards across multiple goals impacted rapid motor decisions during movement. We observed idiosyncratic switching strategies dependent on both target rewards and, surprisingly, the feedback gains at perturbation onset: the more vigorous movements were less likely to switch to a new goal following perturbations. To gain further insight into a causal influence of the feedback gains on rapid motor decisions, we demonstrated that biasing the baseline activity and reflex gains by means of a background load evoked a larger proportion of target switches in the direction opposite to the background load associated with lower muscle activity. Together, our results demonstrate an impact of target reward on feedback control and highlight the competition between movement vigor and flexibility. Significance statementHumans can modulate their movement vigor based on the expected reward. However, a potential influence of reward on feedback control has not been documented. Here we investigated reaching control strategies in different contexts associated with explicit rewards for one or multiple goals, while exposed to external perturbations. We report two strategies: reward could either increase feedback gains, or promote flexible switches between goals. The engagement of peripheral circuits in the modulation of feedback gains was confirmed by the application of a background load that biased feedback vigor directionally, evoking differences in switching behavior in the opposite direction. We conclude that feedback vigor and flexible changes in goal are two competing mechanisms to be selected when interacting with a dynamic environment.

neuroscience↗

bioRxiv2021

Measuring fingerpad deformation during active object manipulation

AO_SCPLOWBSTRACTC_SCPLOWDuring active object manipulation, the finger-object interactions give rise to complex fingertip skin deformations. These deformations are in turn encoded by the local tactile afferents and provide rich and behaviorally relevant information to the central nervous system. Most of the work studying the mechanical response of the finger to dynamic loading has been performed under a passive setup, thereby precisely controlling the kinematics or the dynamics of the loading. However, to identify aspects of the deformations that are relevant to online control during object manipulation, it is desirable to measure the skin response in an active setup. To that end, we developed a device that allows us to monitor finger forces, skin deformations, and kinematics during fine manipulation. We describe the device in detail and test it to precisely describe how the fingertip skin in contact with the object deforms during a simple vertical oscillation task. We show that the level of grip force directly influences the fingerpad skin strains and that the strain rates are substantial during active manipulation (norm up to 100%/s). The developed setup will enable us to causally relate sensory information, i.e. skin deformation, to online control, i.e. grip force adjustment, in future studies.

neuroscience↗

bioRxiv2021

Fast grip force adaptation to friction relies on localized fingerpad strains

AO_SCPLOWBSTRACTC_SCPLOWHumans can quickly adjust their grip force to a change in friction at the object-skin interface during dexterous manipulation in a precision grip. To perform this adjustment, they rely on the feedback of the mechanoreceptive afferents innervating the fingertip skin. Because these tactile afferents encode information related to skin deformation, the nature of the feedback signaling a change in friction must somehow originate from a difference in the way the skin deforms when manipulating objects of different frictions. To better characterize the origin of the underlying sensory events, we asked human participants to perform a grip-lifting task with a manipulandum equipped with an optical imaging system. This system enabled to monitor fingertip skin strains through transparent plates of glass that had different levels of friction. We observed that, following an unexpected change in friction, participants adapted their grip force within 370ms after contact with the surface. By comparing the deformation patterns when unexpectedly switching from a high to a low friction condition, we found a significant increase in skin deformation inside the contact area arising over 100ms before the motor response, during the loading phase, suggesting that local and partial deformation patterns prior to lift-off are used in the nervous system to adjust the grip force as a function of the frictional condition.

neuroscience↗

bioRxiv2021

Savings in human force field learning supported by feedback adaptation

Savings have been described as the ability of healthy humans to relearn a previously acquired motor skill faster than the first time, which in the context of motor adaptation suggests that the learning rate in the brain could be adjusted when a perturbation is recognized. Alternatively, it has been argued that apparent savings were the consequence of a distinct process that instead of reflecting a change in the learning rate, revealed an explicit re-aiming strategy. Based on recent evidence that feedback adaptation may be central to both planning and control, we hypothesized that this component could genuinely accelerate relearning in human adaptation to force fields during reaching. Consistent with our hypothesis, we observed that upon re-exposure to a previously learned force field, the very first movement performed by healthy volunteers in the relearning context was better adapted to the external disturbance, and this occurred without any anticipation or cognitive strategy because the relearning session was started unexpectedly. We conclude that feedback adaptation is a medium by which the nervous system can genuinely accelerate learning across movements. Significance StatementSavings describe the ability of healthy humans to faster relearn a previously acquired motor skill. It is debated whether savings result from implicit changes in the learning rate or an explicit strategy. Given recent evidence that feedback control plays a key role in movement adaptation, we hypothesized that this component also contributed to savings in the context of force field adaptation. We confirm that relearning was faster and demonstrate that the very first relearning movement was better adapted to the external disturbance, i.e., the online corrections in the first re-exposure trial carried imprints of feedback adaptation from the previous sessions in the absence of any explicit strategy. We conclude that this non-explicit feedback component can genuinely accelerate motor learning.

neuroscience↗