Prehension Movements Research Articles

Anticipatory postural adjustment deficits in children with developmental coordination disorder during a self-induced prehension task while standing on one leg

Effective postural control is essential for motor skill development, yet the specific nature of anticipatory control in children with Developmental Coordination Disorder (DCD) remains poorly understood for complex or dynamic stability tasks. This study investigated anticipatory postural adjustments (APA) during a self-initiated dynamic stability task. The Can Placement Task (CPT)—a self-initiated dynamic stability task—was performed by 23 children with DCD and 30 typically developing (TD) children aged 9–12 years. The task involved standing on one leg while also repositioning a can on the floor. Center of pressure (COP) movement was recorded by two force platforms during the five phases of the movement. The ground reaction force measured external support during both descent to pick up the can and ascent after replacing the can. The study used a mixed-design approach with group (DCD, TD) as a between-subject factor and condition (can position close or far) and phase of movement as within-subject. Distinct movement control characteristics were shown for children with DCD including a greater range of COP movement and higher COP velocity in the anterior-posterior direction prior to movement initiation compared with TD. The DCD group also relied more on external support during both the downward and upward phases of the CPT and needed more trials to complete the task. Only two significant interaction effects involving Group and the within-subject factors emerged. Children with DCD swayed significantly more at specific phases of the task, especially when coming up and restoring balance, and did not adapt COP velocity as a function of reaching distance. Dynamic control of posture in children with DCD is impaired as they struggle to generate the effective APAs necessary to maintain dynamic stability which leads to greater reliance on external support and more corrective movements. The CPT provides a valuable assessment of posture and dynamic balance control during a complex prehension movement performed on one leg; the task highlights distinct movement patterns between children with and without DCD.

Time-independent relationship between digits closure velocity and hand transport acceleration during reach-to-grasp movements

Prehension movements in primates have been extensively studied for decades, and hand transport and hand grip adjustment are usually considered as the main components of any object reach-to-grasp action. Evident temporal patterns were found for the velocity of the hand during the transport phase and for the digits kinematics during pre-shaping and enclosing phases. However, such kinematics were always analysed separately in regard to time, and never studied in terms of dependence one from another. Nevertheless, if a reliable one-to-one relationship is proven, it would allow reconstructing the digit velocity (and position) simply by knowing the hand acceleration during reaching motions towards the target object, ceasing the usual dependence seen in literature from time of movement and distance from the target. In this study, the aim was precisely to analyse reach-to-grasp motions to explore if such relationship exists and how it can be formulated. Offline and real-time results not only seem to suggest the existence of a time-independent, one-to-one relationship between hand transport and hand grip adjustment, but also that such relationship is quite resilient to the different intrinsic and extrinsic properties of the target objects such as size, shape and position.

Relation between binocular vision alteration and prehension movements in children: a scoping review.

To investigate, map, and synthesize evidence regarding the correlation between changes in binocular vision and fine motor skills among children. We conducted a scoping review of existing evidence, following the guidelines and checklist outlined in "Preferred Reporting Items for Systematic Reviews and Meta-Analyses - Scoping Reviews" (PRISMAScR). Sixteen papers were systematically included in our scoping review. A predominant focus was placed on assessing the impact of strabismus on motor skills. Most of the studies used motor test batteries for comprehensive analysis, while the remaining employed methodologies, such as questionnaires or laboratory-based tests. Vision stands as a pivotal perceptual modality essential for the optimal development of children. Alterations in visual acuity can significantly affect fine motor skills. Pediatric ophthalmology and orthoptics frequently encounter binocular vision disorders, such as amblyopia and strabismus. Our finding showed that impaired binocular vision affects fine motor skills.

Postural control during gait termination and prehension

BackgroundChallenges to postural stability emerge in the transition from locomotion to a standing posture as during gait termination, often accompanied by another task (e.g., opening a door), which may complicate control. However, less is known about postural control during terminating gait while engaged in a secondary manual task. Research questionWhat are the changes in postural control when terminating gait with and without a prehension task? MethodsIn a cross-sectional design, 15 healthy young adults (M=8, F=7; 27±2 years; 69±13 kg; 171±8 cm) underwent both a single task gait termination (GTO) and dual task (gait termination plus reaching; GTR). Postural Time-to-Contact (TtC) was measured using Center of Pressure (CoP) and the sternum position in anterior-posterior (AP) and medial-lateral (ML) directions over two different phases: preparatory phase and stabilization phase. Five successful trials were recorded to obtain a mean TtC. For statistical analysis of TtC, a two-tailed paired t-test was used (p =.05) as normality was satisfied. ResultsFor the preparatory phase, there were no differences for the CoP, but TtC of the sternum position in AP was shorter in GTR than GTO (p =.001). Meanwhile, for the stabilization phase, TtCs of both the CoP and sternum position were longer in GTR in both AP and ML directions (p’s <.001). SignificanceWe suggest that for the preparatory phase, the shorter TtC of the sternum position with intact TtC of the CoP in GTR indicates that healthy young individuals are flexible, in that they smoothly integrate CoP control with the upper body demands required to also perform the prehension task. Meanwhile, for the stabilization phase, the longer TtC in dual termination and prehension task indicates that the perturbation imposed by the prehension movement did not result in reduced stabilization when returning to an upright posture.

Visual Priming Effects for Prehension Movements at Different Time Points

Visual Priming Effects for Prehension Movements at Different Time Points

Corticospinal Modulation of Precision Movements.

Recently we demonstrated a critical role for temporal coding of corticospinal activity in a prehension movement requiring precise forelimb control. Learning of precision isometric pull drives large-scale remodeling of corticospinal motor networks. Optogenetic modulation of corticospinal activity and full transection of the corticospinal tract disrupted critical functions of the network in expert animals resulting in impaired modulation of precise movements. In contrast, we observed more widespread corticospinal co-activation and limited temporal coding on a similar, yet more simplistic prehension task, adaptive isometric pull. Disrupting corticospinal neuron activity had much more limited effects on adaptive isometric pull, which was found to be corticospinal independent by transection of the corticospinal tract. Here we discuss these results in context of known roles for corticospinal and corticostriatal neurons in motor control, as well as some of the questions our study raised.

Deficits in Reach Planning and On-Line Grasp Control in Adults With Amblyopia.

Adults with amblyopia exhibit impairments when reaching to grasp three-dimensional objects. We examined whether their deficits derive from problems with feedforward planning of these prehension movements or in using visual feedback to control them on-line. Twenty-one adults with mild to severe anisometropic and/or strabismic amblyopia and reduced binocularity participated, along with 21 normally sighted age- and gender-matched controls. Subjects used their preferred hand to reach for, precision grasp, and then lift cylindrical table-top objects (two sizes, two distances) using binocular, dominant eye, or amblyopic/non-sighting eye vision just to plan their movements during a 1-second task preview with vision then occluded so feedback was absent or to plan and execute them (i.e., with visual feedback fully available). Kinematic and error measures of the timing and accuracy of the reach and grasp were quantified by view and feedback and compared by ANOVA. The amblyopic adults performed generally worse than controls across all three views in both feedback conditions. With vision for planning only, their movement initiation and duration times were significantly increased, as were their initial reach times and error rates, especially when using the amblyopic eye alone, whatever its visual acuity loss. These relative planning deficits were only partially rectified with visual feedback available on-line. Relative grasp planning deficits were less evident in the amblyopia group, who instead produced significantly increased grip times and errors under binocular and amblyopic eye visual feedback conditions, although the subgroup with unmeasurable stereovision also formed wider (inaccurate) grasps across all conditions. Adults with amblyopia seem to have problems constructing reliable internal spatial representations for the feedforward planning of prehension, particularly with their affected eye and mainly affecting their reach, with additional deficits in on-line grasp control related to poor binocularity.

Task-specific modulation of corticospinal neuron activity during motor learning in mice

Motor skill learning relies on the plasticity of the primary motor cortex as task acquisition drives cortical motor network remodeling. Large-scale cortical remodeling of evoked motor outputs occurs during the learning of corticospinal-dependent prehension behavior, but not simple, non-dexterous tasks. Here we determine the response of corticospinal neurons to two distinct motor training paradigms and assess the role of corticospinal neurons in the execution of a task requiring precise modulation of forelimb movement and one that does not. In vivo calcium imaging in mice revealed temporal coding of corticospinal activity coincident with the development of precise prehension movements, but not more simplistic movement patterns. Transection of the corticospinal tract and optogenetic regulation of corticospinal activity show the necessity for patterned corticospinal network activity in the execution of precise movements but not simplistic ones. Our findings reveal a critical role for corticospinal network modulation in the learning and execution of precise motor movements.

Visual priming effects for prehension movements

There are known to be two major visual processing pathways from the occipital lobe to the temporal and parietal lobes: the ventral visual processing system, which is involved in conscious object identification, and the dorsal visual processing system, which is involved in spatial, attentional, and behavioral processing, both conscious and unconscious. However, little is known about how these pathways are employed in reaching and grasping movements. In the present study, we attempted to tease apart contributions of the two pathways by manipulating two aspects of visual stimuli, i.e. object identity, which is expected to engage the ventral pathway, and object orientation, which is relevant for grasping actions and is thus expected to engage the dorsal pathway. In the experiment we conducted, healthy subjects performed reaching and grasping movements after being briefly exposed to a visual stimulus, and we measured the priming effects that the visual stimulus had for the reaching and grasping movements. In doing so, we distinguished four conditions, depending on (i) whether the preceding visual stimulus consisted of the same type of image as the image that the subject was subsequently shown and was to try to grasp and (ii) whether the orientation of the preceding visual stimulus was such that it was likely to elicit movement of the hand that the subject was to move in the grasping action subsequently. The results showed significant priming effects of both types with no interaction between them, suggesting that both visual pathways are independently involved in reaching and grasping movements.

The role of binocular vision in the control and development of visually guided upper limb movements.

Vision provides a key sensory input for the performance of fine motor skills, which are fundamentally important to daily life activities, as well as skilled occupational and recreational performance. Binocular visual function is a crucial aspect of vision that requires the ability to combine inputs from both eyes into a unified percept. Summation and fusion are two aspects of binocular processing associated with performance advantages, including more efficient visuomotor control of upper limb movements. This paper uses the multiple processes model of limb control to explore how binocular viewing could facilitate the planning and execution of prehension movements in adults and typically developing children. Insight into the contribution of binocularity to visuomotor control also comes from examining motor performance in individuals with amblyopia, a condition characterized by reduced visual acuity and poor binocular function. Overall, research in this field has advanced our understanding of the role of binocular vision in the development and performance of visuomotor skills, the first step towards developing assessment tools and targeted rehabilitation for children with neurodevelopment disorders at risk of poor visuomotor outcomes. This article is part of a discussion meeting issue 'New approaches to 3D vision'.

427.9: Total Bilateral Arm Transplantation: Functional Recovery and Psychosocial Outcomes at One Year

Introduction: Although arm loss causes severe disability and compromission of body image, functional recovery after allotransplantation still presents many challenges. Objective: A bilateral arm transplantation including reconstruction of the left shoulder was performed on January 13, 2021 in Lyon (France). Functional recovery and psychosocial outcomes are reported one year after the transplantation. Materials and Methods: The recipient was a 48-year old patient with bilateral amputation at proximal arm level after electric shock in January 1998, who underwent liver transplantation in 2002. The patient used mechanic prostheses with poor satisfaction. The surgical procedure consisted in a total arm transplantation on the left side with reconstruction of the gleno-humeral joint. The maintenance immunosuppressive therapy included tacrolimus, mycophenolate mofetil and prednisone. Rehabilitation therapy started on day one. It progressively included manual lymphatic drainage, passive motion of all joints in a total range except limitations for the shoulders during the first 6 weeks. Then, electrostimulation on denervated muscles was performed. After 6 weeks the protocol included hand therapy, psychomotricity, physical activities, occupational therapy and sensory-motor simulation training approaches (motor imagery, virtual mirror therapy, virtual reality). Results: Motor recovery was already appreciated 8 months after the transplantation. At one year, passive ranges of motion of upper limbs are subnormal. According to MRC scale, muscular strength at shoulder level is from 3 to 4/5 on the right side and from 1 to 2/5 on the left side; from 3 to 4/5 for elbow flexors and from 1 to 2 for elbow extensors on both sides; 3/5 for wrist flexors on the right side and 0/5 on the left side; 1 to 2/5 for wrist extensors on both sides; 3/5 for pronators and supinators on the right side and 1/5 on the left side. Slight contraction and movements of the extrinsic flexors and extensor muscles of the fingers have been evidenced on both sides, and the first prehension movements started on the right hand. The Semmes-Weinstein monofilament test for sensory threshold was 6.65 in the right palm and below the left elbow; deep pressure sensation is recovered in both hands. Functional Independence Measure is 96/126 and the DASH score 75.8. The patient is able to perform the same daily activities as with the prostheses before the transplantation.The patient was psychologically tested during the follow-up using a specific questionnaire for upper extremity allotransplantation and MADRS, Hamilton and Rosenberg tests. The results (Table 1) show the difficulties, the patient’s strong motivation and capacity to cope, and his satisfaction reached at the first year of follow-up. Conclusions: The patient is very satisfied of his grafts and of his restored body image, which was his main expectation.

Falls and motor behavior in older adults

This mini-review focuses on intrinsic risk factors for falls, particularly the changes in motor behavior of faller older adults. Our purpose is to present evidence that faller older adults exhibit motor behavior changes beyond the typically investigated standing and walking tasks. We showed initially that postural control alterations with more prominent differences for fallers than non-fallers seem to depend on postural demands, availability of sensory information, and tasks performed concomitantly with the balancing task. We also provided evidence that walking speed is the most consistent aspect to differentiate fallers from non-fallers. This reduction in walking speed may be a strategy to improve gait stability to avoid a fall. More recent studies have shown that fallers presented modifications in the control of the prehension movement. These changes suggest that fallers have changes in movement categories other than balancing and walking, suggesting that fallers’ difficulties are broader than previously thought. The fact that faller older adults have modifications in the control of upper and lower limbs is indicative of a change in motor behavior involving gross and fine motor behaviors. The understanding of a faller as an individual with global changes in motor behavior has important implications for fall prevention and rehabilitation programs for these individuals.

Visual cues two-steps ahead are adequate to grasp an object while walking without compromising stability.

In our prior studies, participants walked and grasped a dowel using an anticipatory mode of control. However, it is unknown how this combined task would change in a less predictable environment. We investigated the online control aspects involved in the combined task of walking and grasping under different coordination patterns between upper- and lower-limbs in young adults. Fifteen young adults walked and grasped a dowel under several experimental conditions combining the instant of visual cue appearance and coordination pattern of upper and lower limbs used to grasp the dowel. Visual cues provided two steps ahead or earlier were enough for executing the combined task of walking and prehension appropriately. Visual cues provided within this window impacted both walking stability and the execution of the prehension movement. Although an ipsilateral arm-leg coordination pattern increased mediolateral stability, a contralateral pattern significantly decreased mediolateral center of mass stability when the visual cue appeared one-step before grasping the object. These results imply that acquiring information to plan the combined task of walking and reaching for an object two steps ahead allows the maintenance of the general movement characteristics present when the decision to reach out for the object is defined two or more steps ahead. These results indicate that the prehension movement is initiated well before heel contact on that side when given sufficient planning time, but that a disruption of the natural arm-leg coordination dynamics emerges to accomplish the task when the cue is provided one step before the object.

The Causal Role of Three Frontal Cortical Areas in Grasping.

Efficient object grasping requires the continuous control of arm and hand movements based on visual information. Previous studies have identified a network of parietal and frontal areas that is crucial for the visual control of prehension movements. Electrical microstimulation of 3D shape-selective clusters in AIP during functional magnetic resonance imaging activates areas F5a and 45B, suggesting that these frontal areas may represent important downstream areas for object processing during grasping, but the role of area F5a and 45B in grasping is unknown. To assess their causal role in the frontal grasping network, we reversibly inactivated 45B, F5a, and F5p during visually guided grasping in macaque monkeys. First, we recorded single neuron activity in 45B, F5a, and F5p to identify sites with object responses during grasping. Then, we injected muscimol or saline to measure the grasping deficit induced by the temporary disruption of each of these three nodes in the grasping network. The inactivation of all three areas resulted in a significant increase in the grasping time in both animals, with the strongest effect observed in area F5p. These results not only confirm a clear involvement of F5p, but also indicate causal contributions of area F5a and 45B in visually guided object grasping.

Functional Electrical Stimulation for Upper Limbs Flexion-Extension and Prehension Movements in Rehabilitation

Functional Electrical Stimulation (FES), is a tecnique that uses low-energy electrical pulses to artificially generate muscle contractions, in individuals with damages regarding the central nervous system. The application of FES in clinical environment involves both patients care and rehabilitation. Aim of this work is to introduce a clinical FES protocol for upper limbs rehabilitation, in order to assist and train the execution of complex movement, such as flexion- extension of wrist and fingers and palmar prehension. The new FES protocol has been tested on a cohort of five subjects with different upper limb neuromotor deficits, during their rehabilitation. The benefits deriving from the application of the new FES protocol have been evaluated by comparing specific quantitative electromyographic parameters assessed before and after the treatment. Results show effective improvements in performances of 4 patients out of 5.

Functional Electrical Stimulation for Upper Limbs Flexion-Extension and Prehension Movements in Rehabilitation

Functional Electrical Stimulation (FES), is a tecnique that uses low-energy electrical pulses to artificially generatemuscle contractions, in individuals with damages regarding the central nervous system. The application of FES inclinical environment involves both patients care and rehabilitation. Aim of this work is to introduce a clinical FESprotocol for upper limbs rehabilitation, in order to assist and train the execution of complex movement, such asflexion- extension of wrist and fingers and palmar prehension. The new FES protocol has been tested on a cohort offive subjects with different upper limb neuromotor deficits, during their rehabilitation. The benefits deriving from theapplication of the new FES protocol have been evaluated by comparing specific quantitative electromyographic parameters assessed before and after the treatment. Results show effective improvements in performances of 4 patientsout of 5.

Functional Electrical Stimulation for Upper Limbs Flexion-Extension and Prehension Movements in Rehabilitation

Functional Electrical Stimulation (FES), is a tecnique that uses low-energy electrical pulses to artificially generate muscle contractions, in individuals with damages regarding the central nervous system. The application of FES in clinical environment involves both patients care and rehabilitation. Aim of this work is to introduce a clinical FES protocol for upper limbs rehabilitation, in order to assist and train the execution of complex movement, such as flexion- extension of wrist and fingers and palmar prehension. The new FES protocol has been tested on a cohort of five subjects with different upper limb neuromotor deficits, during their rehabilitation. The benefits deriving from the application of the new FES protocol have been evaluated by comparing specific quantitative electromyographic parameters assessed before and after the treatment. Results show effective improvements in performances of 4 patients out of 5.

Contribution of stereopsis, vergence, and accommodative function to the performance of a precision grasping and placement task in typically developing children age 8-14years.

Upper limb reaching and grasping movements are performed more efficiently during binocular viewing; however, the distinct contribution of stereopsis, fusional vergence, and accommodation (binocular facility, amplitude and accuracy) has not been examined in typically developing children. This study examined binocular visual function in a cohort of 57 typically developing children, 8 to 14years old. Hand kinematics were recorded using a motion capture camera while children performed a prehension task involving threading a bead onto a needle. Results showed that different aspects of binocular vision contribute to the control of distinct phases of upper limb movements. Specifically, fusional vergence was associated with higher peak reach velocity, stereoacuity was associated with shorter grasp execution, and accommodation was associated with shorter placement duration. These findings suggest that different aspects of binocular vision play an important role in optimizing the control of distinct phases of prehension movements during development.

Some binocular advantages for planning reach, but not grasp, components of prehension

Proficient (fast, accurate, precise) hand actions for reaching-to-grasp 3D objects are known to benefit significantly from the use of binocular vision compared to one eye alone. We examined whether these binocular advantages derive from increased reliability in encoding the goal object’s properties for feedforward planning of prehension movements or from enhanced feedback mediating their online control. Adult participants reached for, precision grasped and lifted cylindrical table-top objects (two sizes, 2 distances) using binocular vision or only their dominant/sighting eye or their non-dominant eye to program and fully execute their movements or using each of the three viewing conditions only to plan their reach-to-grasp during a 1 s preview, with vision occluded just before movement onset. Various kinematic measures of reaching and grasping proficiency, including corrective error rates, were quantified and compared by view, feedback and object type. Some significant benefits of binocular over monocular vision when they were just available for pre-movement planning were retained for the reach regardless of target distance, including higher peak velocities, straighter paths and shorter low velocity approach times, although these latter were contaminated by more velocity corrections and by poorer coordination with object contact. By contrast, virtually all binocular advantages for grasping, including improvements in peak grip aperture scaling, the accuracy and precision of digit placements at object contact and shorter grip application times preceding the lift, were eliminated with no feedback available, outcomes that were influenced by the object’s size. We argue that vergence cues can improve the reliability of binocular internal representations of object distance for the feedforward programming of hand transport, whereas the major benefits of binocular vision for enhancing grasping performance derive exclusively from its continuous presence online.

Older Adolescents and Young Adults With Autism Spectrum Disorder Have Difficulty Chaining Motor Acts When Performing Prehension Movements Compared to Typically Developing Peers.

It is known that motor actions performed by individuals with autism spectrum disorders (ASD) are clumsy and a previous study revealed that children with ASD of around 8 years old showed less smooth movement and dysfunction of appropriate usage of online vision for grip aperture control. The present study investigates whether and how the kinematic properties of reach-to-grasp movements in older adolescents and adults with ASD [mean (±SD) age: 18.3 ± 2.1] differ from those in typically developing (TD) peers [mean (±SD) age: 19.1 ± 2.2]. Revealing the kinematic properties of reach-to-grasp movements in older adolescents and adults with ASD is indispensable in determining the developmental trajectory of this motor behavior in individuals with ASD. While wearing liquid crystal shutter goggles, participants reached for and grasped a cylinder with a diameter of either 4 or 6 cm. Two visual conditions were tested: a full vision (FV) condition (the goggles remained transparent during the movement) and a no vision (NV) condition (the goggles were closed immediately after the movement was initiated). These two visual conditions were either alternated with each trial in a single experimental session (alternated condition) or blocked within the session (blocked condition). We found that the reaching movement smoothness calculated as a normalized jerk score (i.e., index of skilled, coordinated human movements) of ASD participants did not differ significantly from that of TD peers although ASD participants showed smoother reaching in the alternated condition than in the blocked condition. The influence of online vision and its visual condition schedule on grip aperture during the in-flight phase was remarkably similar between the ASD and TD groups. Furthermore, we found that ASD group experienced a significant longer transition period from grasping end (i.e., stable holding when touching the surface of the object) to uplift initiation than the TD group. The results suggest that (1) deficits in movement smoothness and the use of online vision for motor control are rectified by the time individuals with ASD reach late adolescence and (2) older adolescents and adults with ASD still have difficulties chaining motor acts.