Hand Movement Direction Research Articles

Impairment of Online Control of Hand and Eye Movements in a Monkey Model of Optic Ataxia

The parietal mechanisms for online control of hand trajectory were studied by combining single-cell recording and reversible inactivation of superior parietal area 5 (PE/PEc; SPL) of monkeys while these made reaches and saccades to visual targets, when the target position changed unexpectedly. Neural activity was modulated by hand position, speed, and movement direction, and by pre- and/or postsaccadic signals. After bilateral muscimol injection, an increase in the hand reaction- and movement-time toward both the first and second targets was observed. This caused an increase in the time necessary for the trajectory correction, and therefore an elongation of the hand-path toward the first target location. Furthermore, hand trajectories were different in shape than control ones. An elongation of the eye reaction time to both first and second targets was also observed, which could partially explain the deficit of planning and correction of hand movement. These results identify the superior parietal lobule as a crucial node in the online control of hand and eye movement and highlight the role of the eye impairment in the emergence of the reaching disorder so far regarded as the hallmark of optic ataxia.

Visuomotor Coordination and Motor Representation by Human Temporal Lobe Neurons

The division of cortical visual processing into distinct dorsal and ventral streams is a key concept in primate neuroscience [Goodale, M. A., & Milner, A. D. Separate visual pathways for perception and action. Trends in Neurosciences, 15, 20-25, 1992; Steele, G., Weller, R., & Cusick, C. Cortical connections of the caudal subdivision of the dorsolateral area (V4) in monkeys. Journal of Comparative Neurology, 306, 495-520, 1991]. The ventral stream is usually characterized as a "What" pathway, whereas the dorsal stream is implied in mediating spatial perception ("Where") and visually guided actions ("How"). A subpathway emerging from the dorsal stream and projecting to the medial-temporal lobe has been identified [Kravitz, D. J., Saleem, K. S., Baker, C. I., & Mishkin, M. A new neural framework for visuospatial processing. Nature Reviews Neuroscience, 12, 217-230, 2011; Cavada, C., & Goldman-Raiuc, P. S. Posterior parietal cortex in rhesus monkey: I. Parcellation of areas based on distinctive limbic and sensory cortico-cortical connections. Journal of Comparative Neurology, 287, 393-421, 1989]. The current article studies the coordination of visual information typically associated with the dorsal stream ("Where"), with planned movements, focusing on the temporal lobe. We recorded extracellular activity from 565 cells in the human medial-temporal and frontal lobes while 13 patients performed cued hand movements with visual feedback (visuomotor task), without feedback (motor task), or observed visual feedback without motor movement (visual-only task). We discovered two different neural populations in the human medial-temporal lobe. One consists of motor-like neurons representing hand position, speed or acceleration during the motor task but not during the visuomotor or visual tasks. The other is specific to the parahippocampal gyrus (an area known to process visual motion [Gur, M., & Snodderly, D. M. Direction selectivity in V1 of alert monkeys: Evidence for parallel pathways for motion processing. Journal of Physiology, 585, 383-400, 2007; Sato, N., & Nakamura, K. Visual response properties of neurons in the parahippocampal cortex of monkeys. Journal of Neurophysiology, 90, 876-886, 2003]) and encodes speed, acceleration, or direction of hand movements, but only during the visuomotor task: neither during visual-only nor during motor tasks. These findings suggest a functional basis for the anatomical subpathway between the dorsal stream and the medial-temporal lobe. Similar to the recent expansion of the motor control process into the sensory cortex [Matyas, F., Sreenivasan, V., Marbach, F., Wacongne, C., Barsy, B., Mateo, C., et al. Motor control by sensory cortex. Science, 330, 1240-1243, 2010], our findings render the human medial-temporal lobe an important junction in the process of planning and execution of motor acts whether internally or externally (visually) driven. Thus, the medial-temporal lobe might serve as an integration node between the two processing streams. Our findings thus shed new light on the brain mechanisms underlying visuomotor coordination which is a crucial capacity for everyday survival, whether it is identifying and picking up food, sliding a key into a lock, driving a vehicle, or escaping a predator.

Direction of Movement Is Encoded in the Human Primary Motor Cortex

The present study investigated how direction of hand movement, which is a well-described parameter in cerebral organization of motor control, is incorporated in the somatotopic representation of the manual effector system in the human primary motor cortex (M1). Using functional magnetic resonance imaging (fMRI) and a manual step-tracking task we found that activation patterns related to movement in different directions were spatially disjoint within the representation area of the hand on M1. Foci of activation related to specific movement directions were segregated within the M1 hand area; activation related to direction 0° (right) was located most laterally/superficially, whereas directions 180° (left) and 270° (down) elicited activation more medially within the hand area. Activation related to direction 90° was located between the other directions. Moreover, by investigating differences between activations related to movement along the horizontal (0°+180°) and vertical (90°+270°) axis, we found that activation related to the horizontal axis was located more anterolaterally/dorsally in M1 than for the vertical axis, supporting that activations related to individual movement directions are direction- and not muscle related. Our results of spatially segregated direction-related activations in M1 are in accordance with findings of recent fMRI studies on neural encoding of direction in human M1. Our results thus provide further evidence for a direct link between direction as an organizational principle in sensorimotor transformation and movement execution coded by effector representations in M1.

Learning to stop looking at the task in hand

Many surgeons have difficulties transitioning from open to laparoscopic surgery. A common report is that surgeons (particularly novices) look at their hands when performing laparoscopic operations, rather than fixating on the screen (Law et al., 2004). Skilful movements require feedback information (typically visual) to make online corrections, but if there is a mismatch between the direction of hand motion and the ensuing action then the system needs to adapt. By adulthood, individuals have become proficient in visually guiding their hand to a target, but it seems that they are also adept at guiding their hand when visual feedback is absent or distorted (e.g. using a mouse to control the movement of a visual cursor on a computer screen). We hypothesised that if manual control is dominated by visual-feedback about hand-position then distorted visual-feedback would be most problematic when the hand is visible (‘visual capture’). We tested our hypothesis by studying the rate of adaptation to distorted visual-feedback in two separate groups (n = 44). One group (indirect) were prevented from seeing their hand and viewed the display on an external monitor. The other group (direct) viewed their hand and the visual display directly. The task involved carrying out a series of aiming movements using a handheld stylus on a tablet-laptop. Both groups completed baseline trials and then two distorted visual-feedback blocks (30° and 60° rotation, counterbalanced) before being tested at 45° the following day. We used movement duration as an index of learning. The results revealed group differences, with the indirect group adapting more readily to the distorted feedback. These results show that additional information about hand-position actually impairs adaptation to distorted visual feedback, which suggests that surgeons need to learn to fixate the screen rather than their hands during laparoscopic operations.

The Representation of Visual and Motor Aspects of Reaching Movements in the Human Motor Cortex

The human primary motor cortex (M1) is robustly activated during visually guided hand movements. M1 multivoxel patterns of functional MRI activation are more correlated during repeated hand movements to the same targets than to greatly differing ones, and therefore potentially contain information about movement direction. It is unclear, however, whether direction specificity is due to the motor command, as implicitly assumed, or to the visual aspects of the task, such as the target location and the direction of the cursor's trajectory. To disambiguate the visual and motor components, different visual-to-motor transformations were applied during an fMRI scan, in which participants made visually guided hand movements in various directions. The first run was the "baseline" (i.e., visual and motor mappings were matched); in the second run ("rotation"), the cursor movement was rotated by 45° with respect to the joystick movement. As expected, positive correlations were seen between the M1 multivoxel patterns evoked by the baseline run and by the rotation run, when the two movements were matched in their movement direction but the visual aspects differed. Importantly, similar correlations were observed when the visual elements were matched but the direction of hand movement differed. This indicates that M1 is sensitive to both motor and visual components of the task. However, repeated observation of the cursor movement without concurrent joystick control did not elicit significant activation in M1 or any correlated patterns of activation. Thus, visual aspects of movement are encoded in M1 only when they are coupled with motor consequences.

Compatibility Relationships With Simple Lever Tools

The study focuses on potential compatibility relationships when simple lever tools are used. Spatial compatibility between stimuli and responses determines performance. However, many tasks require the use of simple tools, such as levers that transform hand movements into tool movements. We explore with such a tool whether and how the correspondence or noncorrespondence between stimulus-side and hand movement (stimulus-response compatibility), between stimulus-side and tool-effect movement (stimulus-effect compatibility), and/or between hand movement and tool-effect movement (response-effect compatibility) affects performance. U-shaped and inverted-U-shaped levers were used as tools,allowing us to examine the contribution of each compatibility relationship to response times and errors without any confounds and omissions. Responding was delayed and error prone when the hand movement and the movement of the effect point of the tool did not correspond. Effects of stimulus-response compatibility and stimulus-effect compatibility were observed only when the hand movement direction remained untransformed in the tool-effect movement The results point out that the inversion or noninversion of tool-effect movements plays an underlying role when handling a tool. Potential applications of this research include the prediction and possibly manipulation of unwanted behavioral tendencies in laparoscopic surgery and other lever movements.

Clustering Linear Discriminant Analysis for MEG-Based Brain Computer Interfaces

In this paper, we propose a clustering linear discriminant analysis algorithm (CLDA) to accurately decode hand movement directions from a small number of training trials for magnetoencephalography-based brain computer interfaces (BCIs). CLDA first applies a spectral clustering algorithm to automatically partition the BCI features into several groups where the within-group correlation is maximized and the between-group correlation is minimized. As such, the covariance matrix of all features can be approximated as a block diagonal matrix, thereby facilitating us to accurately extract the correlation information required by movement decoding from a small set of training data. The efficiency of the proposed CLDA algorithm is theoretically studied and an error bound is derived. Our experiment on movement decoding of five human subjects demonstrates that CLDA achieves superior decoding accuracy over other traditional approaches. The average accuracy of CLDA is 87% for single-trial movement decoding of four directions (i.e., up, down, left, and right).

601 非接触動作識別技術のヒューマンマシンインターフェイスへの応用

In this paper, we present an effective non-contact technique for the measurement of human hand motion for application to a human-machine interface. We propose a new method for detecting the motion of a subject's hand with respect to a given measurement electrode; this method involves the measurement of the current generated due to the difference in the capacitance between a subject's hand and the measurement electrode. An occurrence model for the electrostatic induction current generated due to a change in the electric capacitance between the electrode and human body has been proposed. This model effectively explains the behavior of the electrostatic induction current flowing through the measurement electrode. This method can be used to detect the direction and velocity of the subject's hand movement under perfect non-contact conditions.

Acceptability of sign manipulations

This study contains the results of an experiment in which signers were asked to judge the acceptability of a set of sign manipulations. Signs were recorded with variations in different categories, in the temporal and spatial dimension. Participants varied much in tolerance, i.e. in the percentage of movies they judged to be acceptable, but their rankings of the acceptability of sign manipulations correlated well. On the level of dimensionality, we found that temporal manipulations were highly acceptable while spatial (and spatiotemporal) manipulations were often judged unacceptable. Further division of the manipulations into categories, such as changes in hand orientation or movement direction, showed much variability and little regularity. The roles of phonology and iconicity in acceptability judgments were studied. Part of the variability in the acceptability of sign manipulations could be explained on the basis of the type of phonological error caused by each manipulation, and by considering a sign’s iconicity and classifying whether manipulations are compatible or incompatible with that iconicity. Finally, human judgments were compared to acceptability ratings by three automatic sign recognizers for three of the signs. With some exceptions, the rankings of the acceptability of sign manipulations as calculated by these sign recognizers did not correlate well with the rankings by humans.

Tuning Curves for Movement Direction in the Human Visuomotor System

Neurons in macaque primary motor cortex (M1) are broadly tuned to arm movement direction. Recent evidence suggests that human M1 contains directionally tuned neurons, but it is unclear which other areas are part of the network coding movement direction and what characterizes the responses of neuronal populations in those areas. Such information would be highly relevant for the implementation of brain-computer interfaces (BCIs) in paralyzed patients. We used functional magnetic resonance imaging adaptation to identify which areas of the human brain show directional selectivity and the degree to which these areas are affected by the type of motor act (to press vs to grasp). After adapting participants to one particular hand movement direction, we measured the release from adaptation during occasional test trials, parametrically varying the angular difference between adaptation and test direction. We identified multiple areas broadly tuned to movement direction, including M1, dorsal premotor cortex, intraparietal sulcus, and the parietal reach region. Within these areas, we observed a gradient of directional selectivity, with highest directional selectivity in the right parietal reach region, for both right- and left-hand movements. Moreover, directional selectivity was modulated by the type of motor act to varying degrees, with the largest effect in M1 and the smallest modulation in the parietal reach region. These data provide an important extension of our knowledge about directional tuning in the human brain. Furthermore, our results suggest that the parietal reach region might be an ideal candidate for the implementation of BCI in paralyzed patients.

Coordinative constraints in bimanual tool use

This study investigates coordinative constraints when participants execute discrete bimanual tool use actions. Participants moved two levers to targets that were either presented near the proximal parts of the levers or near the distal tips of the levers. In the first case, the tool transformation (i.e. the relationship between hand movement direction and target direction) was compatible, whereas in the second case, it was incompatible. We hypothesized that an egocentric constraint (i.e. a preference for moving the hands and tools in a mirror-symmetrical fashion) would be dominant when targets are presented near the proximal parts of the levers because in this situation, movements can be coded in terms of body-related coordinates. Furthermore, an allocentric constraint (i.e. a preference to move the hands in the same (parallel) direction in extrinsic space) was expected to be dominant when one of the targets or both are presented near the distal parts of the levers because in this condition, movements have to be coded in an external reference frame. The results show that when both targets are presented near the proximal parts of the levers, participants are faster and produce less errors with mirror-symmetrical when compared to parallel movements. Furthermore, the RT mirror-symmetry advantage is eliminated, when both targets are presented near the distal parts of the levers, and it is reversed, when the target for one lever is presented near its distal part and the target for the other lever is presented near its proximal part. These results show that the dominance of egocentric and allocentric coordinative constraints in bimanual tool use depends on whether movements are coded in terms of body-related coordinates or in an external reference frame.

The Impact of Augmented Information on Visuo-Motor Adaptation in Younger and Older Adults

BackgroundAdjustment to a visuo-motor rotation is known to be affected by ageing. According to previous studies, the age-related differences primarily pertain to the use of strategic corrections and the generation of explicit knowledge on which strategic corrections are based, whereas the acquisition of an (implicit) internal model of the novel visuo-motor transformation is unaffected. The present study aimed to assess the impact of augmented information on the age-related variation of visuo-motor adjustments.Methodology/Principal FindingsParticipants performed aiming movements controlling a cursor on a computer screen. Visual feedback of direction of cursor motion was rotated 75° relative to the direction of hand motion. Participants had to adjust to this rotation in the presence and absence of an additional hand-movement target that explicitly depicted the input-output relations of the visuo-motor transformation. An extensive set of tests was employed in order to disentangle the contributions of different processes to visuo-motor adjustment. Results show that the augmented information failed to affect the age-related variations of explicit knowledge, adaptive shifts, and aftereffects in a substantial way, whereas it clearly affected initial direction errors during practice and proprioceptive realignment.ConclusionsContrary to expectations, older participants apparently made no use of the augmented information, whereas younger participants used the additional movement target to reduce initial direction errors early during practice. However, after a first block of trials errors increased, indicating a neglect of the augmented information, and only slowly declined thereafter. A hypothetical dual-task account of these findings is discussed. The use of the augmented information also led to a selective impairment of proprioceptive realignment in the younger group. The mere finding of proprioceptive realignment in adaptation to a visuo-motor rotation in a computer-controlled setup is noteworthy since visual and proprioceptive information pertain to different objects.

Functional Organization of Human Motor Cortex: Directional Selectivity for Movement

In monkeys, neurons in the hand representation of the primary motor cortex (M1) are often tuned to the direction of hand movement, and there is evidence that these neurons are clustered according to their "preferred" direction of movement. However, this organizational principle has yet to be demonstrated in M1 of humans. We conducted a functional magnetic resonance imaging (fMRI) study in which participants used a joystick to move a cursor from a central origin to one of five equidistant targets. The fMRI signal of individual voxels was sensitive to the directional aspects of the reaching task and manifested direction-specific adaptation. Furthermore, the correlation between multivoxel patterns of responses for different movement directions depended on the angular distance between them. We conclude that M1 neurons are likely to be organized in clusters according to their preferred direction, since only such a coarse-grained representation can lead to directional selectivity of voxels, encompassing millions of neurons. A simple model that estimates cluster size suggests that the diameter of these clusters is on the order of a few hundred micrometers.

Adaptation of eye and hand movements to target displacements of different size

Previous work has documented that the direction of eye and hand movements can be adaptively modified using the double-step paradigm. Here we report that both motor systems adapt not only to small direction steps (5° gaze angle) but also to large ones (28° gaze angle). However, the magnitude of adaptation did not increase with step size, and the relative magnitude of adaptation therefore decreased from 67% with small steps to 15% with large steps. This decreasing efficiency of adaptation may reflect the participation of directionally selective neural circuits in double-step adaptation.

Initial hand position and movement direction affect reaching in a unilateral optic ataxia patient

Initial hand position and movement direction affect reaching in a unilateral optic ataxia patient

Poster 13: Huntington's Disease Disrupts Motor Control Mechanisms That Rely on Internal Models

Background Previous studies demonstrated that Huntington's disease (HD) impairs the ability to perform to perform online adjustments during reaching movements. It is not clear whether the difficulty is in responding to errors in observed or predicted trajectory. Do patients have trouble observing deviations of the hand from its goal, or does the difficulty lie in predicting where the hand should be based on internal models of the effects of motor commands? Methods We compared corrections made to two visuomotor perturbations that were equivalent in sensory space, but differed in the nature of the resulting error (goal-related vs effector-related). Subjects made planar reaching movements to guide a screen cursor to a target. Interspersed with baseline trials were perturbation trials, in which either the target jumped to a new location (target jump) or the direction of the cursor was rotated relative to the starting point (rotation). The target jump (to a new direction, ±30 degrees away) and the rotation (±30 degrees) were spatially matched so as to require the same change in hand movement direction in order to acquire the target. The target jump required a change in movement goal (external error), whereas rotation introduced a mismatch between actual hand position and hand position predicted by subject's visuomotor map (internal model error). Results and Discussion The corrections made by patients to target jumps were only slightly abnormal, with increased variability and slight undershoot. Their corrections to visuomotor rotation trials, on the other hand, were considerably abnormal. There was a systematic delay in the onset of the correction, and the amplitude of the correction was incomplete. These findings establish a selective impairment in monitoring errors in computation of predicted hand position. A function of the circuits affected by HD may be to monitor internal motor control models that are necessary to guide movements to their targets.

Combining adaptive classification and human learning for detection of hand movement direction in an MEG-BCI

Combining adaptive classification and human learning for detection of hand movement direction in an MEG-BCI

Encoding of speed and direction of movement in the human supplementary motor area

The supplementary motor area (SMA) plays an important role in planning, initiation, and execution of motor acts. Patients with SMA lesions are impaired in various kinematic parameters, such as velocity and duration of movement. However, the relationships between neuronal activity and these parameters in the human brain have not been fully characterized. This is a study of single-neuron activity during a continuous volitional motor task, with the goal of clarifying these relationships for SMA neurons and other frontal lobe regions in humans. The participants were 7 patients undergoing evaluation for epilepsy surgery requiring implantation of intracranial depth electrodes. Single-unit recordings were conducted while the patients played a computer game involving movement of a cursor in a simple maze. In the SMA proper, most of the recorded units exhibited a monotonic relationship between the unit firing rate and hand motion speed. The vast majority of SMA proper units with this property showed an inverse relation, that is, firing rate decrease with speed increase. In addition, most of the SMA proper units were selective to the direction of hand motion. These relationships were far less frequent in the pre-SMA, anterior cingulate gyrus, and orbitofrontal cortex. The findings suggest that the SMA proper takes part in the control of kinematic parameters of endeffector motion, and thus lend support to the idea of connecting neuroprosthetic devices to the human SMA.

Modifying one’s hand’s trajectory when a moving target’s orientation changes

The path that the hand takes to intercept an elongated moving target depends on the target’s orientation. How quickly do people respond to changes in the moving target’s orientation? In the present study, participants were asked to intercept moving targets that sometimes abruptly changed orientation shortly after they started moving. It took the participants slightly more than 150 ms to adjust their hands’ paths to a change in target orientation. This is about 50 ms longer than it took them to respond to a 5-mm jump in the moving target’s position. It is only slightly shorter than it took them to initiate the movement. We propose that responses to changes in visually perceived orientation are not exceptionally fast, because there is no relationship between target orientation and direction of hand movement that is sufficiently general in everyday life for one to risk making an inappropriate response in order to respond faster.

Cortical Mechanisms for Online Control of Hand Movement Trajectory: The Role of the Posterior Parietal Cortex

The parietal mechanisms for the control of hand movement trajectory were studied by recording cell activity in area 5 of monkeys making direct reaches to visual targets and online corrections of movement trajectory, after change of target location in space. The activity of hand-related cells was fitted with a linear model including hand position, movement direction, and speed. The neural activity modulation mostly led, but also followed, hand movement. When a change of hand trajectory occurred, the pattern of activity associated with the movement to the first target evolved into that typical of the movement to the second one, thus following the corresponding variations of the hand kinematics. The visual signal concerning target location in space did not influence the firing activity associated with the direction of hand movement within the first 150 ms after target presentation. This might be the time necessary for the visuo-motor transformation underlying reaching. We conclude that online control of hand trajectory not only resides in the relationships between neural activity and kinematics, but, under specific circumstances, also on the coexistence of signals about ongoing and future hand movement direction.