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PubMed2005

Kinematical measure for spastic reaching in children with cerebral palsy.

BACKGROUND: Practitioners need more sensitive measure to quantify reaching movement for judgment of the treatment effects and reflecting the degrees of motor impairment in upper extremities. The purposes of this study were to identify the specific kinematic characteristics between normal and spastic reaching under different levels of accuracy, and to determine the most sensitive kinematic variable for quantifying the interference of spasticity on reaching. METHODS: Ten normal subjects as control group and ten subjects with spastic cerebral palsy as experimental group were studied. Participants were asked to reach, at a self-selected pace, toward two different sizes of buttons (one with accuracy constraint and the other with non-accuracy constraint) away from normalized distance. Motion analysis system was used to record the trajectory of reaching performance. Kinematic variables of reaching movement were computed and analyzed. FINDINGS: Measure for movement smoothness presented larger effect size (0.24-0.43) than other kinematic variables adopted in this study. Under high-accuracy reaching, children with spastic cerebral palsy had a prolonged movement time than normal children (P<0.05). Modified Ashworth score was significantly correlated to normalized jerk score, number of movement unit and movement time (r=0.56-0.75). Number of movement unit was the most sensitive kinematic variable to discriminate between normal and spastic reaching. INTERPRETATION: Development of reliable, valid, and sensitive multi-joint biomechanical evaluation is required, particularly for natural and goal-oriented reaching movement. It is concluded that measure of movement smoothness may be applied as valid and sensitive index to quantify the level of coordinative motor performance for subjects with spastic movement disorder.

Adolescent↗

PubMed2007

The coupling between upper and lower extremity synergies during whole body reaching.

When performing whole body reaching movements, all four limbs participate in the task. We hypothesized that the synergies that characterize upper and lower extremity movement are flexible and become coupled into one functional unit to transport the body towards the target. To test this hypothesis, subjects reached to three targets, one within and two beyond arm's length. In addition, subjects reached at two speeds and either stopped at the target or returned to the original start position. To assess the coupling during the various whole body reaches, a principal component analysis was performed on the displacements of the five primary joints used to accomplish the task (ankle, knee, hip, shoulder and elbow). Analysis of the loadings from the principal component analysis indicated that the first component represented the reaching element of the task, while the second and third components represented the postural element. When reaching within arm's length the variance explained by the joint coupling was distributed between the first three principal components. However, as reach distance increased, the distribution shifted with most of the variance being explained by the first principal component. Neither movement velocity nor final joint configuration affected the coupling between the joints. Analysis of center of mass indicated that it shifted progressively forward as reached distance increased. We conclude that as target distance increased, the reach and postural synergies became coupled resulting in the arms, legs and trunk working together as one functional unit to move the whole body forward.

Adult↗

PubMed2004

Background visual cues and memory-guided reaching.

Recent research [e.g., Carrozzo, M., Stratta, F., McIntyre, J., & Lacquaniti, F. (2002). Cognitive allocentric representations of visual space shape pointing errors. Experimental Brain Research 147, 426-436; Lemay, M., Bertrand, C. P., & Stelmach, G. E. (2004). Pointing to an allocentric and egocentric remembered target. Motor Control, 8, 16-32] reported that egocentric and allocentric visual frames of reference can be integrated to facilitate the accuracy of goal-directed reaching movements. In the present investigation, we sought to specifically examine whether or not a visual background can facilitate the online, feedback-based control of visually-guided (VG), open-loop (OL), and memory-guided (i.e. 0 and 1000 ms of delay: D0 and D1000) reaches. Two background conditions were examined in this investigation. In the first background condition, four illuminated LEDs positioned in a square surrounding the target location provided a context for allocentric comparisons (visual background: VB). In the second condition, the target object was singularly presented against an empty visual field (no visual background: NVB). Participants (N=14) completed reaching movements to three midline targets in each background (VB, NVB) and visual condition (VG, OL, D0, D1000) for a total of 240 trials. VB reaches were more accurate and less variable than NVB reaches in each visual condition. Moreover, VB reaches elicited longer movement times and spent a greater proportion of the reaching trajectory in the deceleration phase of the movement. Supporting the benefit of a VB for online control, the proportion of endpoint variability explained by the spatial location of the limb at peak deceleration was less for VB as opposed to NVB reaches. These findings suggest that participants are able to make allocentric comparisons between a VB and target (visible or remembered) in addition to egocentric limb and VB comparisons to facilitate online reaching control.

Adolescent↗

PubMedDate not supplied

Effect of a back belt on reaching postures.

OBJECTIVE: The present study investigated the effect of a back belt on reach actions. SUBJECTS: Sixteen undergraduate college students (8 male students, 8 female students) ranging in age from 18 to 22 years. Thirteen subjects were included in the final analysis. SETTING: The Department of Psychology at Miami University, Oxford, Ohio METHODS: Using a well-established set of procedures developed in our laboratory for studying reaching, seated adult participants reached for and retrieved an object placed at various distances from them. Reach distances included values both closer than and farther than each subject's maximum seated reach. The reach task had 2 conditions: picking up and retrieving a small block and skewering and retrieving a small bead with a needle. For each task condition, each subject either wore the belt or did not use a belt. RESULTS: Results indicate that when subjects wore the belt while reaching, they tended to have initial transition points (sitting to nonsitting) closer to their bodies than while not wearing the belt. That is, for a distant object, subjects were more likely to raise their bodies out of the chair rather than perform an extreme seated reach, possibly acting to preserve a greater margin of safety. CONCLUSIONS: The back belt consistently modified reaching postures by limiting extreme ranges of motion during a task that required enhanced stability. Furthermore, the methodology and analysis presented in this article when applied to chiropractic will allow us to begin thoughtful investigation of the effects of chiropractic adjustments on postural transitions and margin of safety.

Adult↗

PubMed2003

Acute alcohol administration improves skilled reaching success in intact but not 6-OHDA dopamine depleted rats: a subsystems analysis of the motoric and anxiolytic effects of alcohol.

Low doses of alcohol impair movement and reduce anxiety. Most assessments of movement under ethyl alcohol (alcohol) in the rat have been tests of whole body movements, however. There has been no examination of the effects of alcohol on skilled limb movements, such as reaching for food with a forelimb. This was the purpose of the present study. Rats were trained to reach through a slot of a box with a forelimb in order to obtain a food pellet located on an external shelf. Once asymptotic performance was achieved, rats were given alcohol (20 ml of 8, 12 or 20% (v/v) solution) in separate tests to establish a relationship between alcohol ingestion and skilled reaching performance. Acute treatment with all doses of alcohol impaired postural support, but doses of 8 and 12% alcohol improved skilled reaching success. Qualitative analysis of the movements used for reaching at doses of 8 and 12% indicated that some limb components of the reaching movement were also impaired, perhaps secondarily due to impaired posture. In contrast, the reaching success of rats with unilateral dopamine depletion, induced with the neurotoxin 6-hydroxydopamine (6-OHDA) in the nigrostriatal bundle, was impaired by the same dose of alcohol that improved reaching success in control rats. The finding of improved success in reaching associated with reduced postural support in normal rats suggests a differential action of alcohol on movement subsystems underlying posture relative to skilled movement that depends upon an intact dopaminergic system. The results are also discussed with respect to the relationship of subsystems of movement and anxiety.

Adaptation, Physiological↗

PubMed1989

Olfaction directs skilled forelimb reaching in the rat.

Rats were trained to reach for food pellets, which varied in size from 20 to 300 mg, from one of 21 locations on a shelf located just outside a test cage. After a barrier was lifted, giving access to a food pellet, latency to contact the food was timed, number of reaches to contact the food were counted, the distance of each misplaced reach from the food was measured and the success or failure of each attempt was noted. Control rats walked along the front of the cage sniffing to locate the food. Once they located a food pellet, they inserted their nose between the bars of the cage, sniffed the food for one to three respiratory cycles, raised their snout slightly, and then inserted a forepaw to grasp the food. They seldom required more than three reaches to contact the food and on about half of all trials they were successful in grasping the food. They were more successful in grasping medium-sized food pellets. Performance was unchanged on all measures after vision was occluded with eye patches. Following olfactory bulb removal, however, the rats no longer sniffed to locate the food or sniffed the food prior to initiating a reach. Rather they systematically moved along the length of the cage inserting their snout between the bars at each possible food location and without sniffing reached for the food 'as if blind'. Latency, number of reaches to contact the food and the distance of misplaced reaches increased whereas success rate remained unchanged. Substantial additional impairments were not produced when the bulbectomized rats were given visual occlusion. The study demonstrates that rats locate food and direct reaching using olfaction. The results are discussed in terms of the sensory control of skilled limb use and their relevance to the evolution of the sensory guidance of limb use.

Animals↗

PubMedDate not supplied

Investigation of healthcare providers' patterns of referring breast cancer patients to Reach to Recovery.

Providers who referred patients to Reach to Recovery (Reach), an American Cancer Society breast cancer support group, were compared with those who did not to evaluate whether providers who identified problems with the program were less likely to make referrals. Also considered were contact with a Reach volunteer, having a Reach program in the area, years since residency or medical training, perceived value of the Reach program, belief that one's peers refer patients to Reach, urban or rural location of practice, and size of practice. When other variables were considered, physicians who identified problems with Reach were no less likely to refer patients to the program than those who did not. The factors most associated with referral (P < .001) were "having a Reach program in the area" and "having had contact with a Reach volunteer." Implications of these findings and the experience of conducting the evaluation through the Collaborative Evaluations Fellows Project are discussed.

Breast Neoplasms↗

PubMed1978

Reaching in very young infants.

It has been claimed that reaching to visually presented targets is a valid indicator of perceptual capacity in very young infants. In a previous report we failed to replicate the findings on which that claim is based. Here we reanalyze some of the tapes of the first report, using a less restricted criterion for what constitutes a reach, and a much more detailed analysis of the various components of reaching behaviour. A number of components are readily distinguished and reliably observed. Infants of seven to twenty-one days show great individual variation in their reaching, from no such behaviour to a great deal. Certain clusters of the components of reaching can be used to define different reaching "styles". The infants who reached most frequently in our sample all showed a dominant pattern of reaching, which in certain respects appears to be more mature than that of other babies. The finer analysis revealed no differences in the reaching behaviour to objects and pictures of objects, even among the most active reachers.

Arm↗

PubMed2004

The control of memory-guided reaching movements in peripersonal space.

The goal of the present investigation was to explore the putative contributions of feedforward- and feedback-based processes in the control of memory-guided reaching movements. Participants (N = 4) completed an extensive number of reaching movements (2700) to 3 midline targets (20, 30, 40 cm) in 6 visual conditions: full-vision, open-loop, and four memory-guided conditions (0, 200, 400, and 600 ms of delay). To infer limb control, we used a regression technique to examine the within-trial correspondence between the spatial position of the limb at peak acceleration, peak velocity, peak deceleration, and the ultimate movement endpoint. A high degree of within-trial correspondence would suggest that the final position of the limb was largely specified prior to movement onset and not adjusted during the action (i.e., feedforward control); conversely, a low degree of within-trial correspondence would suggest that movements were modified during the reaching trajectory (i.e., feedback control). Full-vision reaches were found to be more accurate and less variable than open-loop and memory-guided reaches. Moreover, full-vision reaches demonstrated only modest within-trial correspondence between the spatial position of the limb at each kinematic marker and the ultimate movement endpoint, suggesting that reaching accuracy was achieved by adjusting the limb trajectory throughout the course of the action. Open-loop and memory-guided movements exhibited strong within-trial correspondence between final limb position and the position of the limb at peak velocity and peak deceleration. This strong correspondence indicates that the final position of the limb was largely determined by processes that occurred before the reach was initiated; errors in the planning process were not corrected during the course of the action. Thus, and contrary to our previous findings in a video-based aiming task, it appears that stored target information is not extensively (if at all) used to modify the trajectory of reaching movements to remembered targets in peripersonal space.

Adult↗

PubMed2003

Coordinated turn-and-reach movements. II. Planning in an external frame of reference.

The preceding study demonstrated that normal subjects compensate for the additional interaction torques generated when a reaching movement is made during voluntary trunk rotation. The present paper assesses the influence of trunk rotation on finger trajectories and on interjoint coordination and determines whether simultaneous turn-and-reach movements are most simply described relative to a trunk-based or an external reference frame. Subjects reached to targets requiring different extents of arm joint and trunk rotation at a natural pace and quickly in normal lighting and in total darkness. We first examined whether the larger interaction torques generated during rapid turn-and-reach movements perturb finger trajectories and interjoint coordination and whether visual feedback plays a role in compensating for these torques. These issues were addressed using generalized Procrustes analysis (GPA), which attempts to overlap a group of configurations (e.g., joint trajectories) through translations and rotations in multi-dimensional space. We first used GPA to identify the mean intrinsic patterns of finger and joint trajectories (i.e., their average shape irrespective of location and orientation variability in the external and joint workspaces) from turn-and-reach movements performed in each experimental condition and then calculated their curvatures. We then quantified the discrepancy between each finger or joint trajectory and the intrinsic pattern both after GPA was applied individually to trajectories from a pair of experimental conditions and after GPA was applied to the same trajectories pooled together. For several subjects, joint trajectories but not finger trajectories were more curved in fast than slow movements. The curvature of both joint and finger trajectories of turn-and-reach movements was relatively unaffected by the vision conditions. Pooling across speed conditions significantly increased the discrepancy between joint but not finger trajectories for most subjects, indicating that subjects used different patterns of interjoint coordination in slow and fast movements while nevertheless preserving the shape of their finger trajectory. Higher movement speeds did not disrupt the arm joint rotations despite the larger interaction torques generated. Rather, subjects used the redundant degrees of freedom of the arm/trunk system to achieve similar finger trajectories with differing joint configurations. We examined finger movement patterns and velocity profiles to determine the frame of reference in which turn-and-reach movements could be most simply described. Finger trajectories of turn-and-reach movements had much larger curvatures and their velocity profiles were less smooth and less bell-like in trunk-based coordinates than in external coordinates. Taken together, these results support the conclusion that turn-and-reach movements are controlled in an external frame of reference.

Acceleration↗

PubMed1989

Visual feedback and anticipatory hand orientation during infants' reaching.

Infants 5, 7, and 9 mo. of age were videorecorded while reaching for a dowel that either was stationary or changed orientation after initiation of a reach. Visual fixation and hand orientation were monitored throughout each reach, as was the efficiency with which infants contacted the stimulus. In reaching for the stationary stimulus, the 5-mo.-olds showed significantly poorer hand orientation adjustment throughout their reach than 9-mo.-olds. The 7-mo.-olds began a reach with the hand poorly oriented as did 5-mo.-olds, but just before object contact their performance matched that of the 9-mo.-olds. On change-orientation trials, the 5-mo.-olds' reaching was disrupted. They missed, stopped, or withdrew their reach on over half of these trials, and hand orientation on contact was significantly worse than on no-change trials. By contrast, older infants were more skilled in using visual feedback to make corrective adjustments in hand orientation during execution of the reach to secure a smooth contact with the stimulus. These infants showed no difference in hand orientation on contact for change in comparison to no-change trials. The 9-mo.-olds' performance surpassed that of the 7-mo.-olds only in the efficiency with which they contacted the stimulus and the incidence of grasps on first contact.

Attention↗

PubMed2002

Analytically derived three-dimensional reach volumes based on multijoint movements.

The main objectives of this study were to quantify the range of reaching for the upper body with eight degrees of freedom (the trunk and shoulder, elbow, and wrist joints) and the lower body with six degrees of freedom (the hip, knee, and ankle joints). A sweeping algorithm that included trunk and foot motions was used to generate the analytical total reach volume of the human body for young men. Three types of reach volume--unconstrained arm reach, shoulder-restricted arm reach, and foot reach--were generated depending on the joint involved in reach activities. The robot kinematics methodology was employed to represent the human body as a multilink system, which was needed for calculating three-dimensional coordinates of the involved joints. The statistical test results showed that the total reach volume analytically generated in this study was nearly identical to that obtained from the direct human body measurements. Applications of this research include generating the human body's reach volume for the purpose of designing work spaces and products.

Adult↗

PubMed1990

Prostheses and the forward reach of sitting lower-limb amputees.

The hypothesis that prostheses improve the forward reach of sitting lower-limb amputees was tested. While sitting with only ischial support, ten unilateral below-knee (BK) amputees could reach farther when they wore their prostheses than when they did not, when reaching at 45 degrees toward or away from the side of the amputation, with mean differences (+/- 1 SD) of 10.7cm (+/- 6.9, p less than 0.0001) and 4.4cm (+/- 4.1, p less than 0.01), respectively. With ten unilateral above-knee (AK) amputees, the differences were not statistically significant. Seven bilateral amputees (mixed levels) were able to reach farther with their prostheses on than off, with mean differences of 41.2cm (+/- 9.5) and 31.5cm (+/- 7.9) for reaches at 0 degrees and 45 degrees, respectively (p less than 0.0001). With the prostheses off, their reach was significantly greater when their thighs were supported than when they were sitting with only ischial support. These findings suggest that (1) prostheses improve the anterolateral reach of unilateral BK amputees, and the straight forward and anterolateral reach of bilateral amputees; (2) when prostheses are not being worn, a sitting surface which provides support through the residual limbs improves forward reach; and (3) the design of AK prostheses should reflect the patient's needs, both standing and sitting.

Adult↗

PubMed2004

Similar and functionally typical kinematic reaching parameters in 7- and 15-month-old in utero cocaine-exposed and unexposed infants.

This study examined the effects of intrauterine cocaine exposure on the reaches of 19 exposed and 15 unexposed infants at 7 and 15 months using kinematic measures. Infants sat at a table and reached for a rattle, a toy doll, and a chair. Videotaped reaches were digitized using the Peak Performance system. Kinematic movement variables were extracted (e.g., reach duration, peak velocity, movement units, path length) and ratios computed (e.g., path length divided by number of movement units). Regardless of exposure status, reaches of older infants were faster, more direct, had fewer movement units, and covered more distance with the first movement unit. Exposed infants covered more distance per movement unit than unexposed infants, but there were no other significant differences. Reaches of exposed and unexposed infants were essentially similar. Importantly, reach parameters for these high-risk infants were similar to reach parameters for infants at lower social and biological risk.

Adult↗

PubMed1993

Proprioceptive guidance and motor planning of reaching movements to unseen targets.

The ability to make accurate reaching movements toward proprioceptively defined target locations was studied in seven normal subjects who were trained to reach to five different targets in a horizontal plane, with no vision of hand or target. The task consisted of moving a handle from a fixed origin to each target location, fast and accurately. Target locations were learned in training sessions that utilized acoustic cuing. Most movements were rapid, with a bell-shaped velocity profile. The error in target reproduction, which constituted the difference between the position consciously identified as the correct target location and the real target location, was calculated in each trial. This was compared with the error in preprogrammed reaching, which constituted the difference between the point in space where the initial fast movement toward the target ended and the target location. The absence of significant differences between these two error types indicated that the transformation from an internal representation of target location into a motor program for reaching to it did not introduce an additional reaching error. Learning of target locations was done only with the right hand, yet, reaching of both hands was tested. This allowed a comparison between the subjects' ability to utilize a transformed spatial code (reaching with the untrained hand) and their ability to use a direct sensory-motor code (reaching with the trained hand). While transformation of the spatial code was found to reduce it's accuracy, utilization of this code in motor programming again did not appear to introduce an additional error.

Adult↗

PubMed1990

Lateral-posterior and pulvinar reaching cells--comparison with parietal area 5a: a study in behaving Macaca nemestrina monkeys.

In a previous study we have demonstrated the existence of pulvinar (puv) cells which were optimally activated when a monkey executed reaching movements with his limbs (Acuña et al 1983). We now describe further observations in four Macaca nemestrina monkeys trained to perform goal directed reaching movements aimed at four different positions in space. Extracellular unit activity in the lateralis posterior (lp) and puv nuclei, together with electrooculograms were recorded during the execution of the task. Seven hundred and sixty neurons were studied in the lp-puv complex. One hundred and twenty three cells (16%) showed changes in activity related to the reaching movements. Reaching related cells fell into two categories: goal direction sensitive (28/123 = 23%) and pandirectional (95/123 = 77%). Goal direction sensitive cells showed different responses depending on the direction of the goal relative to the starting point of the movement. The responses of the pandirectional cells were independent of goal direction. The activity of the remaining cells (637/760) could not be correlated with reaching movements. In a smaller number of area 5a (PE) cells (n = 109) studied in one monkey, 82 (75%) were classified as reaching related cells. Of these, 76% (62/82) were goal direction sensitive and 24% (20/82) pandirectional. The lp-puv cells were more dependent on the intentionality of movement than area 5a cells, and not reliably activated by passive manipulation of the limb. After injection of HRP-WGA in area 5a, where the reaching cells were recorded, labeled cells and terminals were located in the lp-puv zones where reaching cells were also found.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1997

The development of goal-directed reaching in infants. II. Learning to produce task-adequate patterns of joint torque.

Nine young infants were followed longitudinally from 4 to 15 months of age. They performed multi-joint reaching movements to a stationary target presented at shoulder height. Time-position data of the hand, shoulder, and elbow were collected using an optoelectronic measurement system. In addition, we recorded electromyographic activity (EMG) from arm extensors and flexors. This paper documents how control problems of proximal torque generation may account for the segmented hand paths seen during early reaching. Our analysis revealed the following results: first, muscular impulse (integral of torque) increased significantly between the ages of 20 (reaching onset) and 64 weeks. That is, as infants got older they produced higher levels of mean muscular flexor torque during reaching. Data were normalized by body weight and movement time, so differences are not explained by anthropometric changes or systematic variations in movement time. Second, while adults produced solely flexor muscle torque to accomplish the task, infants generated flexor and extensor muscle torque at shoulder and elbow throughout a reach. At reaching onset more than half of the trials revealed this latter kinetic profile. Its frequency declined systematically as infants got older. Third, we examined the pattern of muscle coordination in those trials that exhibited elbow extensor muscle torque. We found that during elbow extension coactivation of flexor and extensor muscles was the predominant pattern in 67% of the trials. This pattern was notably absent in comparable adult reaching movements. Fourth, fluctuations in force generation, as measured by the rate of change of total torque (NET) and muscular torque (MUS), were more frequent in early reaching (20-28 weeks) than in the older cohort (52-64 weeks), indicating that muscular torque production became increasingly smoother and task-efficient. Our data demonstrate that young infants have problems in generating smooth profiles of proximal joint torques. One possible reason for this imprecision in infant force control is their inexperience in predicting the magnitude and direction of external forces. That infants learned to consider external forces is documented by their increasing reliance on these forces when performing voluntary elbow extensions. The patterns of muscle coordination underlying active elbow extensions were basically the same as during the prereaching phase, indicating that the formation of functional synergies is based on a basal repertoire of innervation patterns already observable in very early, spontaneous movements.

Child Development↗

PubMed2002

Effect of movement speed on limb segment motions for reaching from a standing position.

The performance of a standing reaching task that necessitates some forward bending requires: (1) the coordination of multiple joints (i.e., the trunk and limb segments) to reach the target, and (2) the preservation of postural stability. It has been proposed that the neural control of multijoint reaching tasks can be simplified by time scaling of joint motions while keeping joint excursions the same. To determine if time scaling of joint motions was used in this more complex reaching task, we had 20 healthy subjects (10 male and 10 female) reach for two targets located in a parasagittal plane while standing on a force platform. Subjects reached for the targets at a comfortable speed and a fast paced speed. Sagittal plane motions of the right shank, thigh, pelvis, trunk, humerus, and forearm were measured. At the fast paced movement speeds subjects had significantly larger excursions of the thigh, pelvis, humerus, and forearm compared to the comfortable speed. Thus, segment motions are not simply time scaled for standing multijoint reaches. We explored three possible reasons for not obeying time scaling: (1) to reduce scaling of peak kinetic energy, (2) to reduce scaling of peak horizontal ground reaction force, and (3) a convergence of movement strategies at faster speeds. While subjects modified their movement strategy in relationship to movement speed, these changes had no significant effect on the expected scaling of peak kinetic energy, or peak horizontal ground reaction forces. Given the intersubject differences in movement strategies used to perform these reaching tasks at the fast speeds, a convergence of movement strategies was ruled out. We propose that the increase in segment motions with speed may be a consequence of rules underlying motor output, the increases being greater for segments in which viscoelastic resistance to movement is more significant compared to inertial resistance.

Adult↗