Grasp Posture Variability Leads to Greater Ipsilateral Sensorimotor Beta Activation During Simulated Prosthesis Use.

Motor behaviour using upper-extremity prostheses of different levels is greatly variable, leading to challenges interpreting ideal rehabilitation strategies. Elucidating the underlying neural control mechanisms driving variability benefits our understanding of adaptation after limb loss. In this follow-up study, non-amputated participants completed simple and complex reach-to-grasp motor tasks using a body-powered transradial or partial-hand prosthesis simulator.

Partial-Hand Prosthesis Users Show Improved Reach-to-Grasp Behaviour Compared to Transradial Prosthesis Users with Increased Task Complexity.

Approaches to improve outcomes after upper-extremity amputation remain poorly understood. Examining prosthesis-use at different levels of loss elucidates motor control challenges. Non-amputated participants completed simple and complex reach-to-grasp actions using a body-powered transradial or partial-hand prosthesis simulator.

Alpha-band activity in parietofrontal cortex predicts future availability of vibrotactile feedback in prosthesis use.

Prosthesis disuse and abandonment is an ongoing issue in upper-limb amputation. In addition to lost structural and motor function, amputation also results in decreased task-specific sensory information. One proposed remedy is augmenting somatosensory information using vibrotactile feedback to provide tactile feedback of grasping objects.

Neurorehabilitation in Adults With Traumatic Upper Extremity Amputation: A Scoping Review.

Background: Most of the current literature around amputation focuses on lower extremity amputation or engineering aspects of prosthetic devices. There is a need to more clearly understand neurobehavioral mechanisms related to upper extremity amputation and how such mechanisms might influence recovery and utilization of prostheses.

Objective: This scoping review aims to identify and summarize the current literature on adult traumatic upper limb amputation in regard to recovery and functional outcomes and how neuroplasticity might influence these findings.

Emergence of perceptuomotor relationships during paleolithic stone toolmaking learning: intersections of observation and practice.

Stone toolmaking is a human motor skill which provides the earliest archeological evidence motor skill and social learning. Intentionally shaping a stone into a functional tool relies on the interaction of action observation and practice to support motor skill acquisition. The emergence of adaptive and efficient visuomotor processes during motor learning of such a novel motor skill requiring complex semantic understanding, like stone toolmaking, is not understood.

Flexible constraint hierarchy during the visual encoding of tool-object interactions.

Tools and objects are associated with numerous action possibilities that are reduced depending on the task-related internal and external constraints presented to the observer. Action hierarchies propose that goals represent higher levels of the hierarchy while kinematic patterns represent lower levels of the hierarchy. Prior work suggests that tool-object perception is heavily influenced by grasp and action context.

Role of Interhemispheric Cortical Interactions in Poststroke Motor Function.

. We investigated interhemispheric interactions in stroke survivors by measuring transcranial magnetic stimulation (TMS)-evoked cortical coherence. We tested the effect of TMS on interhemispheric coherence during rest and active muscle contraction and compared coherence in stroke and older adults.

Implicit development of gaze strategies support motor improvements during action encoding training of prosthesis use.

Background: Action observation training has been suggested to facilitate motor improvements in the lives of persons with neural injury. Previous studies have shown that for persons with upper limb amputation, matched limb training, where prosthesis users emulate each other, has shown promise above mismatched training where a prosthesis user emulates actions of a person with sound limbs (most commonly that of a therapist).

Objective: The mechanism underlying the matched limb training benefit is unclear.

The Role of Attention and Saccades on Parietofrontal Encoding of Contextual and Grasp-specific Affordances of Tools: An ERP Study.

The ability to recognize a tool's affordances (how a spoon should be appropriately grasped and used), is vital for daily life. Prior research has identified parietofrontal circuits, including mirror neurons, to be critical in understanding affordances. However, parietofrontal action-encoding regions receive extensive visual input and are adjacent to parietofrontal attention control networks.

Exercise-heat stress with and without water replacement alters brain structures and impairs visuomotor performance.

Effects of exercise-heat stress with and without water replacement on brain structure and visuomotor performance were examined. Thirteen healthy adults (23.6 ± 4.

Neurorehabilitation in upper limb amputation: understanding how neurophysiological changes can affect functional rehabilitation.

Background: Significant advances have been made in developing new prosthetic technologies with the goal of restoring function to persons that suffer partial or complete loss of the upper limb. Despite these technological advances, many challenges remain in understanding barriers in patient adoption of technology, and what critical factors should be of focus in prosthetics development from a motor control perspective. This points to a potential opportunity to improve our understanding of amputation using neurophysiology and plasticity, and integrate this knowledge into the development of prosthetics technology in novel ways.

Novel behavioral indicator of explicit awareness reveals temporal course of frontoparietal neural network facilitation during motor learning.

Deficits in sequential motor learning have been observed in many patient populations. Having an understanding of the individual neural progression associated with sequential learning in healthy individuals may provide valuable insights for effective interventions with these patients. Due to individual variability in motor skill acquisition, the temporal course of such learning will be vary, suggesting a need for a more individualized approach.

Incidental Learning and Explicit Recall in Upper Extremity Prosthesis Use: Insights Into Functional Rehabilitation Challenges.

Loss of an upper extremity and the resulting rehabilitation often requires individuals to learn how to use a prosthetic device for activities of daily living. It remains unclear how prostheses affect motor learning outcomes. The authors' aim was to evaluate whether incidental motor learning and explicit recall is affected in intact persons either using prostheses (n = 10) or the sound limb (n = 10), and a chronic amputee on a modified serial reaction time task.

Remodeling of cortical activity for motor control following upper limb loss.

Objective: Upper extremity loss presents immediate and lasting challenges for motor control. While sensory and motor representations of the amputated limb undergo plasticity to adjacent areas of the sensorimotor homunculus, it remains unclear whether laterality of motor-related activity is affected by neural reorganization following amputation.

Methods: Using electroencephalography, we evaluated neural activation patterns of formerly right hand dominant persons with upper limb loss (amputees) performing a motor task with their residual right limb, then their sound left limb.

Influence of Perspective of Action Observation Training on Residual Limb Control in Naïve Prosthesis Usage.

Prior work in amputees and partial limb immobilization have shown improved neural and behavioral outcomes in using their residual limb with prosthesis when undergoing observation-based training with a prosthesis-using actor compared to an intact limb. It was posited that these improvements are due to an alignment of user with the actor. It may be affected by visual angles that allow emphasis of critical joint actions which may promote behavioral changes.

Evaluating interhemispheric cortical responses to transcranial magnetic stimulation in chronic stroke: A TMS-EEG investigation.

TMS-evoked cortical responses can be measured using simultaneous electroencephalography (TMS-EEG) to directly quantify cortical connectivity in the human brain. The purpose of this study was to evaluate interhemispheric cortical connectivity between the primary motor cortices (M1s) in participants with chronic stroke and controls using TMS-EEG. Ten participants with chronic stroke and four controls were tested.

Carbohydrate ingestion but not mouth rinse maintains sustained attention when fasted.

Unlabelled: Carbohydrate (CHO) receptors in the mouth signal brain areas involved in cognitive tasks relying upon motivation and task persistence; however, the minimal CHO dose that improves mental activity is unclear.

Purpose: To determine if CHO (via ingestion or oral rinse) influences sustained attention without eliciting glycemic responses when in a fasted state.

Methods: Study A: Six healthy adults completed five treatment trials, ingesting 0-6% CHO solutions to evaluate glycemic response.

Enhanced Neurobehavioral Outcomes of Action Observation Prosthesis Training.

Background Previous studies have demonstrated improved neurobehavioral outcomes when prosthesis users learn task-specific behaviors by imitating movements of prosthesis users (matched limb) compared with intact limbs (mismatched limb). Objective This study is the first to use a unique combination of neurophysiological and task performance methods to investigate prosthetic device training strategies from a cognitive motor control perspective. Intact nonamputated prosthesis users (NAPUs) donned specially adapted prosthetic devices to simulate the wrist and forearm movement that persons with transradial limb loss experience.

Reliability of Visual and Somatosensory Feedback in Skilled Movement: The Role of the Cerebellum.

The integration of vision and somatosensation is required to allow for accurate motor behavior. While both sensory systems contribute to an understanding of the state of the body through continuous updating and estimation, how the brain processes unreliable sensory information remains to be fully understood in the context of complex action. Using functional brain imaging, we sought to understand the role of the cerebellum in weighting visual and somatosensory feedback by selectively reducing the reliability of each sense individually during a tool use task.

Distinctive laterality of neural networks supporting action understanding in left- and right-handed individuals: An EEG coherence study.

Prior work has demonstrated that perspective and handedness of observed actions can affect action understanding differently in right and left-handed persons, suggesting potential differences in the neural networks underlying action understanding between right and left-handed individuals. We sought to evaluate potential differences in these neural networks using electroencephalography (EEG). Right- and left-handed participants observed images of tool-use actions from egocentric and allocentric perspectives, with right- and left-handed actors performing the actions.

I give you a cup, I get a cup: a kinematic study on social intention.

While affordances have been intensively studied, the mechanisms according to how their activation is modulated by context are poorly understood. We investigated how the Agent׳s reach-to-grasp movement towards a target-object (e.g.

Motor performance benefits of matched limb imitation in prosthesis users.

Our previous work demonstrated that the action encoding parietofrontal network, which is crucial in planning and executing motor tasks, is less active in prosthesis users who imitate movements of intact actors (mismatched limb) versus prosthesis users (matched limb). Such activation could have behavioral consequences in prosthesis users rehabilitating with intact therapists. The goal was to identify behavioral effects of matched versus mismatched limb action imitation in naïve users of prostheses.

Differential mechanisms of action understanding in left and right handed subjects: the role of perspective and handedness.

The ability to comprehend outcomes of skilled action is important for understanding the world around us. Prior studies have evaluated the perspective an action is performed in, but few have evaluated how handedness of the actor and the observer interact with action perspective. Understanding handedness affords the opportunity to identify the role of mirroring and matched limb action encoding, which may display unique strategies of action understanding.