Cognitive approaches in the rehabilitation of upper limbs function in children with cerebral palsy: a systematic review and meta-analysis.

INTRODUCTION: Cerebral palsy (CP) is the predominant cause of children disability. It is characterized by motor, sensory, and postural deficits due to a non-progressive injury to the developing central nervous system. In recent years, new rehabilitation techniques targeting the central representations of motor patterns have been introduced: the most used are action observation therapy (AOT), motor imagery (MI), and mirror therapy (MT). Aim of this study is to assess the effectiveness of these cognitive strategies on the recovery of upper limb motor functions in children with CP. EVIDENCE ACQUISITION: This study was designed as a systematic review and meta-analysis, registered in PROSPERO (CRD42023403794). For the report and methodological definitions of this study, the recommendations of the PRISMA protocol and the Cochrane collaboration, were followed. A total of 3 electronic databases (PubMed, Scopus, and Web of Science) were searched for relevant Randomized Control Trials (RCT) using the combinations of terms "cerebral palsy" AND "action observation" OR "motor imagery" OR "mirror therapy" OR "cognitive therapy." A meta-analysis was carried out to compare cognitive and conventional approaches and combine direct and indirect effects. A random-effects meta-analysis model was used to derive pooled effect estimates. EVIDENCE SYNTHESIS: Out of 328 records, 12 RCTs were analyzed in this systematic review published from 2012 to 2022, and included 375 children, of whom 195 received cognitive therapies, and 180 underwent conventional rehabilitation. AOT was the most investigated (RCTs N.=7), and showed significant results in the recovery of upper limb motor functions, albeit the meta-analysis demonstrated a non-significant difference in Melbourne Unilateral Upper limb Scale (MUUL) (95% CI: -7.34, 12); in Assisting Hand Assessment (AHA) (95% CI: -4.84, 10.74), and in AbilHand-Kids Questionnaire (95% CI: -1.12, 1.45). Five RCTs investigated MT showing significant improvements in grip and dexterity; none used MI as intervention therapy. CONCLUSIONS: Cognitive therapies provided with encouraging results in the recovery of upper limb motor functions, although not a clinical effect in bimanual or unimanual performance; they could represent a valid therapeutic solution integrated to conventional rehabilitation in the treatment of upper limb motor impairment in children with CP.

Perception of robotic actions and the influence of gender.

In our society interaction with robots is becoming more and more frequent since robots are not only used in the industry, but increasingly often in assistance and in health system. Perception of robots and their movements is crucial for their acceptance. Here we shortly review basic mechanisms of perception of actions, and then of perception of robotic and human movements. The literature demonstrates that there are commonalities, but also differences in the perception of human and robotic movements. Especially interesting are biologic gender differences in the perception of robotic movements. The results show that males seem to be more sensitive to the differences between robotic and anthropomorphic movements, whereas females seem not to perceive such differences. However, females transfer more anthropomorphic features to robotic movements. While looking at the brain activation during perception of humanoid and robotic movements in different genders one can conclude that different strategies are used; female seem to analyse robotic movements online, while male seem to use previous knowledge from interaction with robots. Further research is needed to specify more such gender differences.

Parietal control of hand movement.

The parietal lobe has been implicated in the sensorimotor control and integration that supports the skillful use of our hands to reach for, grasp, and manipulate objects in the environment. This area is involved in several circuits within the classic subdivisions of the dorsal stream. Recently, the dorsal stream has been further divided into a "dorso-dorsal" and a "ventro-dorsal" streams. The ventro-dorsal stream is regarded as functionally linked to object manipulation. The dorso-dorsal stream is proposed to subserve reaching and online control of actions. Affordances indicate action possibilities characterized by object properties the environment provides. Affordances are likely represented by the dorsal stream. They code structural object properties that can elicit actions. A further subdivision of affordances into "stable" and "variable" allows an understanding of the neuronal mechanisms underlying object manipulation. Whereas stable affordances emerge from slow processing of visual information based on knowledge of object properties from previous experiences and object interaction, variable affordances emerge from fast online processing of visual information during actual object interaction, within a changing environment. The relevance of the dorsal stream subdivisions in this context is that the dorso-dorsal stream is associated with coding of variable affordances, while that of the dorso-ventral stream is implicated in action representations elicited by stable affordances. A greater interaction between these and ventral stream perceptual and semantic representations allows the parietal control of hand movement. An understanding of these networks is likely to underlie recovery from complex deficits described in limb apraxias.

Gait Alteration in Individual with Limb Loss: The Role of Inertial Sensors.

Amputation has a big impact on the functioning of patients, with negative effects on locomotion and dexterity. In this context, inertial measurement units represent a useful tool in clinical practice for motion analysis, and in the development of personalized aids to improve a patient's function. To date, there is still a gap of knowledge in the scientific literature on the application of inertial sensors in amputee patients. Thus, the aim of this narrative review was to collect the current knowledge on this topic and stimulate the publication of further research. Pubmed, Embase, Scopus, and Cochrane Library publications were screened until November 2022 to identify eligible studies. Out of 444 results, we selected 26 articles focused on movement analysis, risk of falls, energy expenditure, and the development of sensor-integrated prostheses. The results showed that the use of inertial sensors has the potential to improve the quality of life of patients with prostheses, increasing patient safety through the detection of gait alteration; enhancing the socio-occupational reintegration through the development of highly technologic and personalized prosthesis; and by monitoring the patients during daily life to plan a tailored rehabilitation program.

Immersive Virtual Reality in Post-Stroke Rehabilitation: A Systematic Review.

In recent years, next to conventional rehabilitation's techniques, new technologies have been applied in stroke rehabilitation. In this context, fully immersive virtual reality (FIVR) has showed interesting results thanks to the level of immersion of the subject in the illusional world, with the feeling of being a real part of the virtual environment. This study aims to investigate the efficacy of FIVR in stroke rehabilitation. PubMed, Web of Science and Scopus were screened up to November 2022 to identify eligible randomized controlled trials (RCTs). Out of 4623, we included 12 RCTs involving post-acute and chronic stroke survivors, with a total of 350 patients (234 men and 115 women; mean age 58.36 years). High heterogeneity of the outcomes considered, the results showed that FIVR provides additional benefits, in comparison with standard rehabilitation. In particular, results showed an improvement in upper limb dexterity, gait performance and dynamic balance, influencing patient independence. Therefore, FIVR represents an adaptable, multi-faceted rehabilitation tool that can be considered in post-stroke rehabilitation, improving the compliance of the patients to the treatment and increasing the level of functioning and quality of life of stroke survivors.

Grasping the semantic of actions: a combined behavioral and MEG study.

There is experimental evidence that the brain systems involved in action execution also play a role in action observation and understanding. Recently, it has been suggested that the sensorimotor system is also involved in language processing. Supporting results are slower response times and weaker motor-related MEG Beta band power suppression in semantic decision tasks on single action verbs labels when the stimulus and the motor response involve the same effector. Attenuated power suppression indicates decreased cortical excitability and consequent decreased readiness to act. The embodied approach forwards that the simultaneous involvement of the sensorimotor system in the processing of the linguistic content and in the planning of the response determines this language-motor interference effect. Here, in a combined behavioral and MEG study we investigated to what extent the processing of actions visually presented (i.e., pictures of actions) and verbally described (i.e., verbs in written words) share common neural mechanisms. The findings demonstrated that, whether an action is experienced visually or verbally, its processing engages the sensorimotor system in a comparable way. These results provide further support to the embodied view of semantic processing, suggesting that this process is independent from the modality of presentation of the stimulus, including language.

Enhancing motor imagery practice using synchronous action observation.

In this paper, we discuss a variety of ways in which practising motor actions by means of motor imagery (MI) can be enhanced via synchronous action observation (AO), that is, by AO + MI. We review the available research on the (mostly facilitatory) behavioural effects of AO + MI practice in the early stages of skill acquisition, discuss possible theoretical explanations, and consider several issues related to the choice and presentation schedules of suitable models. We then discuss considerations related to AO + MI practice at advanced skill levels, including expertise effects, practical recommendations such as focussing attention on specific aspects of the observed action, using just-ahead models, and possible effects of the perspective in which the observed action is presented. In section "Coordinative AO + MI", we consider scenarios where the observer imagines performing an action that complements or responds to the observed action, as a promising and yet under-researched application of AO + MI training. In section "The dual action simulation hypothesis of AO + MI", we review the neurocognitive hypothesis that AO + MI practice involves two parallel action simulations, and we consider opportunities for future research based on recent neuroimaging work on parallel motor representations. In section "AO + MI training in motor rehabilitation", we review applications of AO, MI, and AO + MI training in the field of neurorehabilitation. Taken together, this evidence-based, exploratory review opens a variety of avenues for future research and applications of AO + MI practice, highlighting several clear advantages over the approaches of purely AO- or MI-based practice.

Motor imagery and action-observation in neurorehabilitation: A study protocol in Parkinson's disease patients.

Introduction: Action Observation Treatment (AOT) and Motor Imagery (MI) represent very promising cognitive strategies in neuro-rehabilitation. This study aims to compare the effectiveness of the two cognitive strategies, taken alone or combined, in Parkinson's disease patients. Material and methods: This study is designed as a prospective randomized controlled trial, with four arms. We estimated a sample size of 64 patients (16 in each treatment group) to be able to detect an effect size of F = 0.4 with a statistical significance of 0.05. Primary outcomes will be functional gains in the FIM and UPDRS scales. Secondary outcome measure will be functional gain as revealed by kinematic parameters measured at Gait Analysis. Discussion: The results of this trial will provide insights into the use of AOT and MI, taken alone or combined, in the rehabilitation of Parkinson's disease patients. Ethics and dissemination: The study protocol was approved by the Ethics Committee of the Don Gnocchi Foundation. The study will be conducted in accordance with the 1996 World Medical Association guidelines and according to good clinical practice. The study has been registered on clinicaltrial.gov under the following code: AOTPRFDG. Dissemination will include both submission of the study to peer-reviewed journals and discussion of the study protocol at conferences.

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.

The Semantics of Natural Objects and Tools in the Brain: A Combined Behavioral and MEG Study.

Current literature supports the notion that the recognition of objects, when visually presented, is sub-served by neural structures different from those responsible for the semantic processing of their nouns. However, embodiment foresees that processing observed objects and their verbal labels should share similar neural mechanisms. In a combined behavioral and MEG study, we compared the modulation of motor responses and cortical rhythms during the processing of graspable natural objects and tools, either verbally or pictorially presented. Our findings demonstrate that conveying meaning to an observed object or processing its noun similarly modulates both motor responses and cortical rhythms; being natural graspable objects and tools differently represented in the brain, they affect in a different manner both behavioral and MEG findings, independent of presentation modality. These results provide experimental evidence that neural substrates responsible for conveying meaning to objects overlap with those where the object is represented, thus supporting an embodied view of semantic processing.

What matters is the underlying experience: Similar motor responses during processing observed hand actions and hand-related verbs.

It is well-accepted that processing observed actions involves at some extent the same neural mechanisms responsible for action execution. More recently, it has been forwarded that also the processing of verbs expressing a specific motor content is subserved by the neural mechanisms allowing individuals to perform the content expressed by that linguistic material. This view is also known as embodiment and contrasts with a more classical approach to language processing that considers it as amodal. In the present study, we used a go/no-go paradigm, in which participants were requested to respond to real words and pictures and refrain from responding when presented stimuli were pseudowords and scrambled images. Real stimuli included pictures depicting hand- and foot-related actions and verbs expressing hand- and foot-related actions. We, therefore, directly compared the modulation of hand motor responses during the observation of actions and the presentation of verbs, expressing actions in the same category. The results have shown that participants gave slower hand motor responses during the observation of hand actions and the processing of hand-related verbs as than observed foot actions and related verbs. These findings support embodiment showing that whatever the modality of presentation (observed action or verb), the modulation of hand motor responses was similar, thus suggesting that processing seen actions and related verbs shares common mechanisms most likely involving the motor system and the underlying motor experience.

Action Observation Treatment in a tele-rehabilitation setting: a pilot study in children with cerebral palsy.

OBJECTIVE: Action Observation Treatment is a novel rehabilitation approach exploiting a neurophysiological mechanism that allows one to recruit the neural structures sub-serving action execution during the mere observation of those same actions. Action Observation Treatment is effective in the rehabilitation of several neurological diseases. In this pilot study, we used Action Observation Treatment in a telerehabilitation setting in children with Cerebral Palsy. MATERIALS AND METHODS: Ten children with Cerebral Palsy, aged 5-12 years, entered the study. They followed the Action Observation Treatment rehabilitation program at home with remote supervision by a child neurologist located at the hospital. Outcome measures were the scores at the Melbourne Assessment of Unilateral Upper Limb Function Scale and the Assisting Hand Assessment. RESULTS: Scores obtained after treatment and at a two months' follow-up significantly differed from baseline and overlapped those obtained in randomized controlled studies carried out in a conventional setting. CONCLUSIONS: Action Observation Treatment is therefore a promising approach that can be used on a large scale in a telerehabilitation setting.IMPLICATIONS FOR REHABILITATIONTele-rehabilitation has the potential to enhance early intervention service provision for children with Cerebral Palsy.Action Observation Treatment has the potential to become a routine approach in a telerehabilitation setting.

Respiratory function modulated during execution, observation, and imagination of walking via SII.

The Mirror Neurons System (MNS) consists of brain areas active during actions execution, as well as observation-imagination of the same actions. MNS represents a potential mechanism by which we understand other's action goals. We investigated MNS activation for legs actions, and its interaction with the autonomic nervous system. We performed a physiological and fMRI investigation on the common neural structures recruited during the execution, observation, and imagination of walking, and their effects on respiratory activity. Bilateral SMA were activated by all three tasks, suggesting that these areas are responsible for the core of the MNS effect for walking. Moreover, we observed in bilateral parietal opercula (OP1, secondary somatosensory cortex-SII) evidence of an MNS subtending walking execution-observation-imagination that also modulated the respiratory function. We suggest that SII, in modulating the vegetative response during motor activity but also during observation-imagination, consists of a re-enacting function which facilitates the understanding of motor actions.

Combining Action Observation Treatment with a Brain-Computer Interface System: Perspectives on Neurorehabilitation.

Action observation treatment (AOT) exploits a neurophysiological mechanism, matching an observed action on the neural substrates where that action is motorically represented. This mechanism is also known as mirror mechanism. In a typical AOT session, one can distinguish an observation phase and an execution phase. During the observation phase, the patient observes a daily action and soon after, during the execution phase, he/she is asked to perform the observed action at the best of his/her ability. Indeed, the execution phase may sometimes be difficult for those patients where motor impairment is severe. Although, in the current practice, the physiotherapist does not intervene on the quality of the execution phase, here, we propose a stimulation system based on neurophysiological parameters. This perspective article focuses on the possibility to combine AOT with a brain-computer interface system (BCI) that stimulates upper limb muscles, thus facilitating the execution of actions during a rehabilitation session. Combining a rehabilitation tool that is well-grounded in neurophysiology with a stimulation system, such as the one proposed, may improve the efficacy of AOT in the treatment of severe neurological patients, including stroke patients, Parkinson's disease patients, and children with cerebral palsy.

How Do We Motorically Resonate in Aging? A Compensatory Role of Prefrontal Cortex.

Aging is the major risk factor for chronic age-related neurological diseases such as neurodegenerative disorders and neurovascular injuries. Exploiting the multimodal nature of the Mirror Neuron System (MNS), rehabilitative interventions have been proposed based on motor-resonance mechanisms in recent years. Despite the considerable evidence of the MNS' functionality in young adults, further investigation of the action-observation matching system is required in aging, where well-known structural and functional brain changes occur. Twenty-one healthy young adults (mean age 26.66y) and 19 healthy elderly participants (mean age 71.47y) underwent a single MRI evaluation including a T1-3D high-resolution and functional MRI (fMRI) with mirror task. Morphological and functional BOLD data were derived from MRI images to highlight cortical activations associated with the task; to detect differences between the two groups (Young, Elderly) in the two MRI indexes (BOLD and thickness z-scores) using mixed factorial ANOVA (Group∗Index analyses); and to investigate the presence of different cortical lateralization of the BOLD signal in the two groups. In the entire sample, the activation of a bilateral MNS fronto-parietal network was highlighted. The mixed ANOVA (pFDR-corr < 0.05) revealed significant interactions between BOLD signal and cortical thickness in left dorsal premotor cortex, right ventral premotor and prefrontal cortices. A different cortical lateralization of the BOLD signal in frontal lobe activity between groups was also found. Data herein reported suggest that age-related cortical thinning of the MNS is coupled with increased interhemispheric symmetry along with premotor and prefrontal cortex recruitment. These physiological changes of MNS resemble the aging of the motor and cognitive neural systems, suggesting specific but also common aging and compensatory mechanisms.

Motor sequence learning in patients with ideomotor apraxia: Effects of long-term training.

Recent studies show that limb apraxia is a quite frequent, yet often underdiagnosed, higher motor impairment following stroke. Because it adversely affects every-day life and personal independence, successful rehabilitation of apraxia is essential for personal well-being. Nevertheless, evidence of long-term efficacy of training schemes and generalization to untrained actions is still scarce. One possible reason for the tendency of this neurological disorder to persist may be a deficit in planning, conceptualisation and storage of complex motor acts. This pilot study aims at investigating explicit motor learning in apractic stroke patients. In particular, we addressed the ability of apractic patients to learn and to retain new explicit sequential finger movements across 10 training sessions over a 3-week interval. Nine stroke patients with ideomotor apraxia in its chronic stage participated in a multi-session training regimen and were included in data analyses. Patients performed an explicit finger sequence learning task (MSLT - motor sequence learning task), which is a well-established paradigm to investigate motor learning and memory processes. Patients improved task performance in terms of speed and accuracy across sessions. Specifically, they showed a noticeable reduction in the mean time needed to perform a correct sequence and the number of erroneous sequences. We found also a trend for improved performance at the Goldenberg apraxia test protocol: "imitation of meaningless hand and finger gestures" relative to when assessed before the MSLT training. Patients with ideomotor apraxia demonstrated the ability to acquire and maintain a novel sequence of movements; and, this training was associated with hints towards improvement of apraxia symptoms.

Evidence for the Concreteness of Abstract Language: A Meta-Analysis of Neuroimaging Studies.

The neural mechanisms subserving the processing of abstract concepts remain largely debated. Even within the embodiment theoretical framework, most authors suggest that abstract concepts are coded in a linguistic propositional format, although they do not completely deny the role of sensorimotor and emotional experiences in coding it. To our knowledge, only one recent proposal puts forward that the processing of concrete and abstract concepts relies on the same mechanisms, with the only difference being in the complexity of the underlying experiences. In this paper, we performed a meta-analysis using the Activation Likelihood Estimates (ALE) method on 33 functional neuroimaging studies that considered activations related to abstract and concrete concepts. The results suggest that (1) concrete and abstract concepts share the recruitment of the temporo-fronto-parietal circuits normally involved in the interactions with the physical world, (2) processing concrete concepts recruits fronto-parietal areas better than abstract concepts, and (3) abstract concepts recruit Broca's region more strongly than concrete ones. Based on anatomical and physiological evidence, Broca's region is not only a linguistic region mainly devoted to speech production, but it is endowed with complex motor representations of different biological effectors. Hence, we propose that the stronger recruitment of this region for abstract concepts is expression of the complex sensorimotor experiences underlying it, rather than evidence of a purely linguistic format of its processing.

The concreteness of abstract language: an ancient issue and a new perspective.

This paper addresses the debated issue of abstract language in the framework of embodiment. First, we discuss the notion of abstractness in the light of the Western philosophical thought, with a focus on the English empiricist tradition. Second, we review the most relevant psychological models and neuroscientific empirical findings on abstract language. It turns out that abstract words are not such, because their meaning is "far from experience", but, because of the high complexity of the attached experiential clusters. Finally, we spell out the consequences of this understanding of abstractness in relation to the neural mechanisms subserving abstract language processing. If abstract words, as compared to concrete ones, imply an increasing complexity of the associated experiential clusters, then the processing of abstract language relies on the recruitment of several neural substrates coding for those experiences. We forward that, at the neural level, this complexity is coded by means of three main mechanisms: (1) the recruitment of the motor representations of different biological effectors (abstract meaning as effector-unspecific); (2) the recruitment of different systems, including sensory, motor, and emotional ones (abstract meaning as multi-systemic); (3) the recruitment of neural substrates coding for social contexts and levels of self-relatedness (abstract meaning as dynamic). As compared to the current approaches in the literature on abstract language that combine embodiment with some a-modal aspects, our proposal is fully embodied and rules out additional aspects. Our proposal may spur future empirical research on abstract language in the embodied approach.

Action Observation Treatment Improves Upper Limb Motor Functions in Children with Cerebral Palsy: A Combined Clinical and Brain Imaging Study.

The aim of the present study was to assess the role of action observation treatment (AOT) in the rehabilitation of upper limb motor functions in children with cerebral palsy. We carried out a two-group, parallel randomized controlled trial. Eighteen children (aged 5-11 yr) entered the study: 11 were treated children, and 7 served as controls. Outcome measures were scores on two functional scales: Melbourne Assessment of Unilateral Upper Limb Function Scale (MUUL) and the Assisting Hand Assessment (AHA). We collected functional scores before treatment (T1), at the end of treatment (T2), and at two months of follow-up (T3). As compared to controls, treated children improved significantly in both scales at T2 and this improvement persisted at T3. AOT has therefore the potential to become a routine rehabilitation practice in children with CP. Twelve out of 18 enrolled children also underwent a functional magnetic resonance study at T1 and T2. As compared to controls, at T2, treated children showed stronger activation in a parieto-premotor circuit for hand-object interactions. These findings support the notion that AOT contributes to reorganize brain circuits subserving the impaired function rather than activating supplementary or vicariating ones.