Activating the motor system through action observation: is this an efficient approach in adults and children?

Impairment in understanding grasping movements in egocentric and allocentric perspectives in children with cerebral palsy due to periventricular leukomalacia

Recognizing and understanding the actions of others through motion information are vital functions for social adaptation. Conditions like neurological disorders and motor impairments can impact sensitivity to biological motion, highlighting the intricate relationship between perceiving and executing movements. Our study centred on assessing the ability of children, encompassing both those with typical development and those diagnosed with cerebral palsy due to periventricular leukomalacia (PVL), to discriminate between depicted grasping of a small cylinder and a large cube. This discrimination task involved observing a point-light animation depicting an actor grasping the object, presented from either an allocentric perspective (observing others) or an egocentric viewpoint (observing oneself). Notably, children with PVL exhibited a pronounced and specific impairment in this task, irrespective of the viewpoint, as evidenced by thresholds increasing by nearly a factor of two. When comparing this impairment to difficulties in form or motion perception, we identified a robust correlation between egocentric biological motion and form sensitivity. However, there was no similar correlation between motion and biological motion sensitivity, suggesting a deficit in the visual system rather than the visuo-motor control system. These findings contribute to our understanding of the intricate interplay between motor and visual processing in individuals with congenital brain lesions, shedding light on the significant involvement of the visual system in cases of PVL.

The Impact of Limited Previous Motor Experience on Action Possibility Judgments in People with Spinal Muscle Atrophy

Previous studies have shown that people with limited motor capabilities may rely on previous motor experience when making action possibility judgments for others. In the present study, we examined if having limited previous motor experience, as a consequence of spinal muscle atrophy (SMA), alters action possibility judgments. Participants with SMA and neurologically healthy (NH) sex- and age-matched controls performed a perceptual-motor judgment task using the Fitts's law paradigm. Participants observed apparent motion videos of reciprocal aiming movements with varying levels of difficulty. For each movement, participants predicted the shortest movement time (MT) at which a neurologically healthy young adult could accurately perform the task. Participants with SMA predicted significantly longer MTs compared to controls; however, the predicted MTs of both SMA and NH participants exhibited a Fitts's law relationship (i.e., the predicted MTs significantly increased as movement difficulty increased). Overall, these results provide evidence that participants with SMA who have limited, or no motor experience may make more conservative action possibility judgments for others. Critically, our finding that the pattern of action possibility judgments was not different between SMA and NH groups suggests that limited previous motor experience may not completely impair action possibility judgments.

Children with Cerebral Palsy can imagine actions like their normally developed peers

The present study aimed at assessing whether children with Cerebral Palsy (CP) can imagine object directed actions similarly to their normally developed peers. We asked children with CP (n = 12) and paired healthy controls (n = 12) to imagine in first person perspective eight daily actions, after observing them through videoclips presented on a computer screen. During motor imagery (MI) children were interrupted at a specific timepoint (e.g., at 2.5 s) from the start. Two frames extracted from the videoclips were then presented on the screen. One of the two depicted the correct timepoint at which the imagined action was interrupted, while the other represented an earlier or later timepoint. Children had to respond by pressing the key associated to the correct frame. Children also underwent VMIQ-2 questionnaire. Both groups performed similarly in the questionnaire and in the requested task, where they showed the same error rate. Errors mainly concerned the later frame, suggesting a similar strategy to solve the task in the two groups. The results support the view that children with CP can imagine actions similarly to their normally developed peers. This encourages the use of MI as a rehabilitative tool in children with motor impairment.

Action observation for upper limb rehabilitation after stroke

BACKGROUND

Action observation (AO) is a physical rehabilitation approach that facilitates the occurrence of neural plasticity through the activation of the mirror-neural system, promoting motor recovery in people with stroke.

OBJECTIVES

To assess whether AO enhances upper limb motor function in people with stroke.

SEARCH METHODS

We searched the Cochrane Stroke Group Trials Register (last searched 18 May 2021), the Cochrane Central Register of Controlled Trials (18 May 2021), MEDLINE (1946 to 18 May 2021), Embase (1974 to 18 May 2021), and five additional databases. We also searched trial registries and reference lists.

SELECTION CRITERIA

Randomized controlled trials (RCTs) of AO alone or associated with physical practice in adults after stroke. The primary outcome was upper limb (arm and hand) motor function. Secondary outcomes included dependence on activities of daily living (ADL), motor performance, cortical activation, quality of life, and adverse effects.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials according to the predefined inclusion criteria, extracted data, assessed risk of bias using RoB 1, and applied the GRADE approach to assess the certainty of the evidence. The reviews authors contacted trial authors for clarification and missing information.

MAIN RESULTS

We included 16 trials involving 574 individuals. Most trials provided AO followed by the practice of motor actions. Training varied between 1 day and 8 weeks of therapy, 10 to 90 minutes per session. The time of AO ranged from 1 minute to 10 minutes for each motor action, task or movement observed. The total number of motor actions ranged from 1 to 3. Control comparisons included sham observation, physical therapy, and functional activity practice.

PRIMARY OUTCOMES

AO improved arm function (standardized mean difference (SMD) 0.39, 95% confidence interval (CI) 0.17 to 0.61; 11 trials, 373 participants; low-certainty evidence); and improved hand function (mean difference (MD) 2.76, 95% CI 1.04 to 4.49; 5 trials, 178 participants; low-certainty evidence).

SECONDARY OUTCOMES

AO did not improve ADL performance (SMD 0.37, 95% CI -0.34 to 1.08; 7 trials, 302 participants; very low-certainty evidence), or quality of life (MD 5.52, 95% CI -30.74 to 41.78; 2 trials, 30 participants; very low-certainty evidence). We were unable to pool the other secondary outcomes (motor performance and cortical activation). Only two trials reported adverse events without significant adverse effects.

AUTHORS' CONCLUSIONS

The effects of AO are small for arm function compared to any control group; for hand function the effects are large, but not clinically significant. For both, the certainty of evidence is low. There is no evidence of benefit or detriment from AO on ADL and quality of life of people with stroke; however, the certainty of evidence is very low. As such, our confidence in the effect estimate is limited because it will likely change with future research.

If You Are Old, Videos Look Slow. The Paradoxical Effect of Age-Related Motor Decline on the Kinematic Interpretation of Visual Scenes

Perception and action are tightly coupled. However, there is still little recognition of how individual motor constraints impact perception in everyday life. Here we asked whether and how the motor slowing that accompanies aging influences the sense of visual speed. Ninety-four participants aged between 18 and 90 judged the natural speed of video clips reproducing real human or physical motion (SoS, Sense-of-Speed adjustment task). They also performed a finger tapping task and a visual search task, which estimated their motor speed and visuospatial attention speed, respectively. Remarkably, aged people judged videos to be too slow (speed underestimation), as compared to younger people: the Point of Subjective Equality (PSE), which estimated the speed bias in the SoS task, was +4% in young adults (<40), +12% in old adults (40–70) and +16% in elders. On average, PSE increased with age at a rate of 0.2% per year, with perceptual precision, adjustment rate, and completion time progressively worsening. Crucially, low motor speed, but not low attentional speed, turned out to be the key predictor of video speed underestimation. These findings suggest the existence of a counterintuitive compensatory coupling between action and perception in judging dynamic scenes, an effect that becomes particularly germane during aging.

Gamma frequencies as a predictor for the accomplishment of a motor task guided through the action observation network

BACKGROUND

Action observation describes a concept where the subsequent motor behavior of an individual can be modulated though observing an action. This occurs through the activation of neurons in the action observation network, acting on a variety of motor learning processes. This network has been proven highly useful in the rehabilitation of patients with acquired brain injury, placing "action observation" as one of the most effective techniques for motor recovery in physical neurorehabilitation.

OBJECTIVE

The aim of this paper is to define an EEG marker for motor learning, guided through observation.

METHODS

Healthy subjects (n = 41) participated voluntarily for this research. They were asked to repeat an unknown motor behavior, immediately after observing a video. During the observation, EEG raw signals where collected with a portable EEG and the results were later compared with success and fail on repeating the motor procedure. The comparison was then analyzed with the Mann-Whitney U test for non-parametrical data, with a confidence interval of 95%.

RESULTS

A significant relation between motor performance and neural activity was found for Alpha (p = 0,0149) and Gamma (0,0005) oscillatory patterns.

CONCLUSION

Gamma oscillations with frequencies between 41 and 49,75 Hz, seem to be an adequate EEG marker for motor performance guided through the action observation network. The technology used for this paper is easy to use, low-cost and presents valid measurements for the recommended oscillatory frequencies, implying a possible use on rehabilitation, by collecting data in real-time during therapeutic interventions and assessments.

Effectiveness of an intensive, functional, gamified Rehabilitation program in improving upper limb motor function in people with stroke: A protocol of the EnteRtain randomized clinical trial

INTRODUCTION

Game-based rehabilitation is an emerging therapeutic intervention that allows intensive, repetitive, task-based training to improve upper limb (UL) function following stroke, based on the principles of neuro-plasticity and motor (re)learning. Rehabilitation using commercial gaming system will be motivating, enjoyable, challenging and affordable. Therefore, the present study aims at assessing the effectiveness of an intensive, functional, gamified rehabilitation program using the ArmAble™ device in improving UL motor function in people with stroke.

METHOD

In this single-blinded, multi-centric, randomized clinical trial, 120 adults with acute/sub-acute unilateral stroke will be randomized to receive an intensive, functional, gamified training program using the ArmAble™ or task-based training along with a conventional therapy for 2 h/day, 6 days/week for 2 weeks, followed by a home-based, functional rehabilitation program for another 4 weeks (~30 min/day, 6 days/week). Primary outcomes evaluated by a blinded assessor at the baseline, 2 weeks and 6 weeks' post-intervention will include the Fugl-Meyer assessment - upper extremity and the action research arm test. A linear mixed effect regression model or relevant non-parametric tests will be used to analyze the data for all outcomes. An intention-to-treat analysis will be used with missing data handled by multiple imputation.

DISCUSSION

Rehabilitation provided with the ArmAble™ device, if found effective, can be used from the early stages post-stroke to provide intensive, repetitive, gamified training to improve UL motor function.

TRIAL REGISTRATION NUMBER

CTRI/2020/09/027651.

Effect of action observation therapy on motor function in children with cerebral palsy: a systematic review of randomized controlled trials with meta-analysis

Objective:

To evaluate the evidence of using Action Observation Therapy in the rehabilitation of children with Cerebral Palsy.

Study design:

Systematic review with meta-analysis of Randomised Controlled Trials.

Methods:

For the purpose of identifying relevant studies, six databases were searched from inception until July 2020. The methodological quality was assessed by Physiotherapy Evidence Database scale. The outcomes were classified within the framework of the International Classification of Functioning. A pooled meta-analysis was performed on studies that demonstrated homogeneity.

Results:

Twelve randomised controlled trials with 307 participants were included with six of them were included in the meta-analysis. Non-significant difference between the groups was demonstrated by meta-analysis. Results of capacity assessed in post treatment and follow up evaluation were (0.06, –0.22 to 0.34, 95% (CI); P = 0.69 and (–0.35, –0.96 to 0.27, 95% (CI); P = 0.27); respectively. Actual performance in post-treatment and follow up were (0.10, –0.22 to 0.48, 95% (CI); P = 0.62) and (0.01, –0.40 to 0.41, 95% (CI); P = 0.97); respectively. Perceived performance evaluated using (ABILHAND-KIDS) were (0.30, –0.28 to 0.89, 95% (CI); P = 0.31) and (0.15, –0.43 to 0.73, 95% (CI); P = 0.61) for post treatment and follow up; respectively. Overall effect on activity domain was (0.08, –0.11 to 0.28, 95% (CI); P = 0.86) immediately and (0.04, –0.33 to 0.26, 95% (CI); P = 0.49) at follow-up; respectively.

Conclusion:

No evidence of benefit had been found to draw a firm conclusion regarding the effectiveness of action observation therapy in the rehabilitation of children with cerebral palsy due to limitations in methodological quality and variations between studies.

Effect of tool-use observation on metric body representation and peripersonal space

In everyday life, we constantly act and interact with objects and with others' people through our body. To properly perform actions, the representations of the dimension of body-parts (metric body representation, BR) and of the space surrounding the body (peripersonal space, PPS) need to be constantly updated. Previous evidence has shown that BR and PPS representation are highly flexible, being modulated by sensorimotor experiences, such as the active use of tools to reach objects in the far space. In this study, we investigate whether the observation of another person using a tool to interact with objects located in the far space is sufficient to influence the plasticity of BR and PPS representation in a similar way to active tool-use. With this aim, two groups of young healthy participants were asked to perform 20 min trainings based on the active use of a tool to retrieve far cubes (active tool-use) and on the first-person observation of an experimenter doing the same tool-use training (observational tool-use). Behavioural tasks adapted from literature were used to evaluate the effects of the active and observational tool-use on BR (body-landmarks localization task-group 1), and PPS (audio-tactile interaction task - group 2). Results show that after active tool-use, participants perceived the length of their arm as longer than at baseline, while no significant differences appear after observation. Similarly, significant modifications in PPS representation, with comparable multisensory facilitation on tactile responses due to near and far sounds, were seen only after active tool-use, while this did not occur after observation. Together these results suggest that a mere observational training could not be sufficient to significantly modulate BR or PPS. The dissociation found in the active and observational tool-use points out differences between action execution and action observation, by suggesting a fundamental role of the motor planning, the motor intention, and the related sensorimotor feedback in driving BR and PPS plasticity.

The Neural and Behavioral Correlates of Anomia Recovery following Personalized Observation, Execution, and Mental Imagery Therapy: A Proof of Concept

The impact of sensorimotor strategies on aphasia recovery has rarely been explored. This paper reports on the efficacy of personalized observation, execution, and mental imagery (POEM) therapy, a new approach designed to integrate sensorimotor and language-based strategies to treat verb anomia, a frequent aphasia sign. Two participants with verb anomia were followed up in a pre-/posttherapy fMRI study. POEM was administered in a massed stimulation schedule, with personalized stimuli, resulting in significant improvement in both participants, with both trained and untrained items. Given that the latter finding is rarely reported in the literature, the evidence suggests that POEM favors the implementation of a word retrieval strategy that can be integrated and generalized. Changes in fMRI patterns following POEM reflect a reduction in the number of recruited areas supporting naming and the recruitment of brain areas that belong to the language and mirror neuron systems. The data provide evidence on the efficacy of POEM for verb anomia, while pointing to the added value of combined language and sensorimotor strategies for recovery from verb anomia, contributing to the consolidation of a word retrieval strategy that can be better generalized to untrained words. Future studies with a larger sample of participants are required to further explore this avenue.

Mu Suppression Is Sensitive to Observational Practice but Results in Different Patterns of Activation in Comparison with Physical Practice

Research has shown the effectiveness of observational practice for motor learning, but there continues to be debate about the mechanisms underlying effectiveness. Although cortical processes can be moderated during observation, after both physical and observational practice, how these processes change with respect to behavioural measures of learning has not been studied. Here we compared short-term physical and observational practice during the acquisition and retention of a novel motor task to evaluate how each type of practice modulates EEG mu rhythm (8-13 Hz). Thirty healthy individuals were randomly assigned to one of three groups: (1) physical practice (PP), (2) observational practice (OP), and (3) no practice (NP) control. There were four testing stages: baseline EEG, practice, postpractice observation, and delayed retention. There was significant bilateral suppression of mu rhythm during PP but only left lateralized mu suppression during OP. In the postpractice observation phase, mu suppression was bilateral and larger after PP compared to that after OP. NP control showed no evidence of suppression and was significantly different to both the OP and PP groups. When comparing the three groups in retention, the groups did not differ with respect to tracing times, but the PP group showed fewer errors, especially in comparison to the NP group. Therefore, although the neurophysiological measures index changes in the OP group, which are similar but moderated in comparison to PP, changes in these processes are not manifest in observational practice outcomes when assessed in a delayed retention test.

Perception as a Route for Motor Skill Learning: Perspectives from Neuroscience

Learning a motor skill requires physical practice that engages neural networks involved in movement. These networks have also been found to be engaged during perception of sensory signals associated with actions. Nonetheless, despite extensive evidence for the existence of such sensory-evoked neural activity in motor pathways, much less is known about their contribution to learning and actual changes in behavior. Primate studies usually involve an overlearned task while studies in humans have largely focused on characterizing activity of the action observation network (AON) in the context of action understanding, theory of mind, and social interactions. Relatively few studies examined neural plasticity induced by perception and its role in transfer of motor knowledge. Here, we review this body of literature and point to future directions for the development of alternative, physiologically grounded ways in which sensory signals could be harnessed to improve motor skills.

The Mirror Neurons Network in Aging, Mild Cognitive Impairment, and Alzheimer Disease: A functional MRI Study

The aim of the current study is to investigate the integrity of the Mirror Neurons (MN) network in normal aging, Mild Cognitive Impairment (MCI), and Alzheimer disease (AD). Although AD and MCI are considered “cognitive” diseases, there has been increasing recognition of a link between motor function and AD. More recently the embodied cognition hypothesis has also been developed: it postulates that a part of cognition results from the coupling between action and perception representations. MN represent a neuronal population which links perception, action, and cognition, therefore we decided to characterize MN functioning in neurodegenerative cognitive decline. Three matched groups of 16 subjects (normal elderly-NE, amnesic MCI with hippocampal atrophy and AD) were evaluated with a focused neuropsychological battery and an fMRI task specifically created to test MN: that comprised of an observation run, where subjects were shown movies of a right hand grasping different objects, and of a motor run, where subjects observed visual pictures of objects oriented to be grasped with the right hand. In NE subjects, the conjunction analysis (comparing fMRI activation during observation and execution), showed the activation of a bilateral fronto-parietal network in “classical” MN areas, and of the superior temporal gyrus (STG). The MCI group showed the activation of areas belonging to the same network, however, parietal areas were activated to a lesser extent and the STG was not activated, while the opposite was true for the right Broca's area. We did not observe any activation of the fronto-parietal network in AD participants. They did not perform as well as the NE subjects in all the neuropsychological tests (including tests of functions attributed to MN) whereas the MCI subjects were significantly different from the NE subjects only in episodic memory and semantic fluency. Here we show that the MN network is largely preserved in aging, while it appears involved following an anterior-posterior gradient in neurodegenerative decline. In AD, task performance decays and the MN network appears clearly deficient. The preservation of the anterior part of the MN network in MCI could possibly supplement the initial decay of the posterior part, preserving cognitive performance.

Learning by observing: the effect of multiple sessions of action-observation training on the spontaneous movement tempo and motor resonance

The present study was designed to explore the changes in motor performance and motor resonance after multiple sessions of action observation (AO) training. Subjects were exposed to the observation of a video showing finger tapping movements executed at 3Hz, a frequency higher than the spontaneous one (2Hz) for four consecutive days. Motor performance and motor resonance were tested before the AO training on the first day, and on the last day. Results showed that multiple sessions of AO training induced a shift of the speed of execution of finger tapping movements toward the observed one and a change in motor resonance. Before the 3Hz-AO training cortical excitability was highest during the observation of the 2Hz video. This motor resonance effect was lost after one single session of 3Hz-AO training whereas after multiple sessions of 3Hz-AO training cortical excitability was highest during the observation of the 3Hz video. Our study shows for the first time that multiple sessions of AO training are able not only to induce performance gains but also to change the way by which the observer's motor system recognizes a certain movement as belonging to the individual motor repertoire. These results may encourage the development of novel rehabilitative protocols based on multiple sessions of action observation aimed to regain a correct movement when its spontaneous speed is modified by pathologies or to modify the innate temporal properties of certain movements.

Effects of Action Observation Therapy in Patients Recovering From Total Hip Arthroplasty Arthroplasty: A Prospective Clinical Trial

OBJECTIVE

The purpose of this study was to investigate the effectiveness of action observation therapy (AOT) compared with written information in patients submitted to a physical therapy program after primary total hip arthroplasty (THA).

METHODS

We conducted a prospective clinical trial. Twenty-four patients with THA, 62.5% female (aged 69.0 ± 8.5 years), received AOT in addition to conventional physical therapy (experimental group) or written information in addition to conventional physical therapy (exercise and information group) for 10 sessions. Outcomes used were visual analog scale, hip active and passive range of motion, Barthel Index, Short Form 36 (SF-36) Health Survey, Tinetti Scale, and Lequesne Index measurements. All measures were collected at baseline and at the end of the intervention. Repeated measures analysis of variance was used to examine the interventions effects within groups and between groups.

RESULTS

No relevant baseline differences were observed between groups. Both treatments produced statistically significant improvements on visual analog scale, active and passive range of motion, Barthel Index, SF-36, Tinetti Scale, and Lequesne Index immediately after the intervention (all, P < .001). SF-36 (physical functioning subscale) revealed a statistically significant intergroups difference (P = .02) after treatment.

CONCLUSIONS

Both treatments were effective at improving pain, functional status, quality of life, and gait features in patients with primary THA. In addition to conventional physical therapy, AOT improved perceived physical function more than written information.

TRIAL REGISTRATION IDENTIFIER

NCT02861638.

Feasibility and efficacy of a robotic device for hand rehabilitation in hemiplegic stroke patients: a randomized pilot controlled study

OBJECTIVE

The purpose of the study was to evaluate the feasibility and efficacy of robot-assisted hand rehabilitation in improving arm function abilities in sub-acute hemiplegic patients.

DESIGN

Randomized controlled pilot study.

SETTING

Inpatient rehabilitation centers.

PARTICIPANTS

Thirty hemiplegic stroke patients (Ashworth spasticity index <3) were recruited and randomly divided into a Treatment group (TG) and Control group (CG).

INTERVENTIONS

Patients in the TG received intensive hand training with Gloreha, a hand rehabilitation glove that provides computer-controlled, repetitive, passive mobilization of the fingers, with multisensory feedback. Patients in the CG received the same amount of time in terms of conventional hand rehabilitation.

MAIN OUTCOME MEASURES

Hand motor function (Motricity Index, MI), fine manual dexterity (Nine Hole Peg Test, NHPT) and strength (Grip and Pinch test) were measured at baseline and after rehabilitation, and the differences, (Δ) mean(standard deviation), compared between groups. Results Twenty-seven patients concluded the program: 14 in the TG and 13 in the CG. None of the patients refused the device and only one adverse event of rheumatoid arthritis reactivation was reported. Baseline data did not differ significantly between the two groups. In TG, ΔMI 23(16.4), ΔNHPT 0.16(0.16), ΔGRIP 0.27(0.23) and ΔPINCH 0.07(0.07) were significantly greater than in CG, ΔMI 5.2(9.2), ΔNHPT 0.02(0.07), ΔGRIP 0.03(0.06) and ΔPINCH 0.02(0.03)] ( p=0.002, p=0.009, p=0.003 and p=0.038, respectively).

CONCLUSIONS

Gloreha Professional is feasible and effective in recovering fine manual dexterity and strength and reducing arm disability in sub-acute hemiplegic patients.

Cognitive robots in the development and rehabilitation of children with developmental disorders

Cognitive robots constitute a highly interdisciplinary approach to the issue of therapy of children with developmental disorders. Cognitive robots become more popular, especially in action and language integration areas, joining the experience of psychologists, neuroscientists, philosophers, and even engineers. The concept of a robot as a cognitive companion for humans may be very useful. The interaction between humans and cognitive robots may be a mediator of movement patterns, learning behaviors from demonstrations, group activities, and social behaviors, as far as higher-order concepts such as symbol manipulation capabilities, words acquisition, and sensorimotor knowledge organization. Moreover there is an occupation to check many theories, such as transferring the knowledge and skills between humans and robots. Although several robotic solutions for children have been proposed the diffusion of aforementioned ideas is still limited. The review summarizes the current and future role of cognitive robots in the development and rehabilitation of children with developmental disorders.