Action Imitation Research Articles

Developmental Coordination Disorder: State of the Art and Future Directions from a Neurophysiological Perspective

Developmental coordination disorder (DCD) is a common neurodevelopmental condition characterized by disabling motor impairments being visible from the first years of life. Over recent decades, research in this field has gained important results, showing alterations in several processes involved in the regulation of motor behavior (e.g., planning and monitoring of actions, motor learning, action imitation). However, these studies mostly pursued a behavioral approach, leaving relevant questions open concerning the neural correlates of this condition. In this narrative review, we first survey the literature on motor control and sensorimotor impairments in DCD. Then, we illustrate the contributions to the field that may be achieved using transcranial magnetic stimulation (TMS) of the motor cortex. While still rarely employed in DCD research, this approach offers several opportunities, ranging from the clarification of low-level cortical electrophysiology to the assessment of the motor commands transmitted throughout the corticospinal system. We propose that TMS may help to investigate the neural correlates of motor impairments reported in behavioral studies, thus guiding DCD research toward a brain-oriented acknowledgment of this condition. This effort would help translational research to provide novel diagnostic and therapeutic tools.

Action imitation via trajectory-based or posture-based planning.

Imitation is a significant daily activity involved in social interaction and motor learning. Imitation has been theorized to be performed in at least two ways. In posture-based imitation, individuals reproduce how the body should look and feel, and are sensitive to the relative positioning of body parts. In trajectory imitation, individuals mimic the spatiotemporal motion path of the end effector. There are clear anecdotal situations in which one might benefit from imitating postures (when learning ballet) or trajectories (when learning to reach around objects). However, whether these are in fact distinct methods of imitation, and if so, whether they may be applied interchangeably to perform the same task, remain unknown. If these are indeed separate mechanisms that rely on different computational and neural resources, a cost should be incurred when switching from using one mechanism to the other within the context of a single task. Therefore, observing a processing cost would both provide evidence that these are indeed two distinct mechanisms, and that they may be used interchangeably when trying to imitate the same stimulus. To test this, twenty-five healthy young adults performed a sequential multitasking imitation task. Participants were first instructed to pay attention to the limb postures or the hand path of a video-recorded model, then performed a neutral, congruent, or incongruent intervening motor task. Finally, participants imitated the modeled movement. We examined both spatial and temporal imitation accuracy as well as individual spatial consistency. When the primary task involved imitating trajectories, analysis of individual consistency suggested a processing cost: movements following the posture-matching intervening task were less consistent with baseline (neutral) performance, suggesting performance may be disrupted by the incongruence. This effect was not observed when imitating limb postures. In summary, we present initial evidence for a difference between posture matching and trajectory imitation as a result of instructions and intervening tasks that is consistent with the existence of two computationally distinct imitation mechanisms.

Distinct neural couplings to shared goal and action coordination in joint action: evidence based on fNIRS hyperscanning.

Joint action is central to human nature, enabling individuals to coordinate in time and space to achieve a joint outcome. Such interaction typically involves two key elements: shared goal and action coordination. Yet, the substrates entrained to these two components in joint action remained unclear. In the current study, dyads performed two tasks involving both sharing goal and action coordination, i.e. complementary joint action and imitative joint action, a task only involving shared goal and a task only involving action coordination, while their brain activities were recorded by the functional near-infrared spectroscopy hyperscanning technique. The results showed that both complementary and imitative joint action (i.e. involving shared goal and action coordination) elicited better behavioral performance than the task only involving shared goal/action coordination. We observed that the interbrain synchronization (IBS) at the right inferior frontal cortex (IFC) entrained more to shared goal, while left-IFC IBS entrained more to action coordination. We also observed that the right-IFC IBS was greater during completing a complementary action than an imitative action. Our results suggest that IFC plays an important role in joint action, with distinct lateralization for the sub-components of joint action.

The role of social signals in segmenting observed actions in 18-month-old children.

Learning about actions requires children to identify the boundaries of an action and its units. Whereas some action units are easily identified, parents can support children's action learning by adjusting the presentation and using social signals. However, currently, little is understood regarding how children use these signals to learn actions. In the current study, we investigate the possibility that communicative signals are a particularly suitable cue for segmenting events. We investigated this hypothesis by presenting 18-month-old children (N=60) with short action sequences consisting of toy animals either hopping or sliding across a board into a house, but interrupting this two-step sequence either (a) using an ostensive signal as a segmentation cue, (b) using a non-ostensive segmentation cue and (c) without additional segmentation information between the actions. Marking the boundary using communicative signals increased children's imitation of the less salient sliding action. Imitation of the hopping action remained unaffected. Crucially, marking the boundary of both actions using a non-communicative control condition did not increase imitation of either action. Communicative signals might be particularly suitable in segmenting non-salient actions that would otherwise be perceived as part of another action or as non-intentional. These results provide evidence of the importance of ostensive signals at event boundaries in scaffolding children's learning.

Piano Lessons: Fostering Theory of Mind in ASD Through Imitation

ABSTRACT Individuals with ASD display incompetency in developing the Theory of Mind (ToM), a mechanism that allows humans to interpret others’ intentions and reciprocate actions, leading to difficulty in social communication and interaction. The Simulation Theory of ToM proposes that the brain constructs a simulation of others’ states of mind through neural activities in the mirror neuron system; this neural circuit plays an essential role in action observation and imitation. In ASD, the mirror neuron system is believed to be malfunctioning. Consequently, much effort has been put into finding cures for this deficiency, leading to developing interventions that involve motor imitation, such as music therapy. While the positive effect of music on imitation is profoundly recognised in a therapy setting, other music-based practices such as lessons have not yet been widely explored. This literature review investigates whether piano lessons can become a potential tool to foster action imitation and ToM in ASD by exploring existing evidence regarding piano pedagogy and imitation skills in these individuals.

If I told you everyone picked that (non-affordant) tool, would you? Children attend to conventional language when imitating and transmitting tool use

This study explored how conventional versus instrumental language influenced children’s imitation and transmission of non-affordant tool use. Rather than examining children’s imitation of unnecessary actions that do not impede goal completion, we examined children’s conformity with a modeled behavior that may result in sacrificing goal completion. Children (N = 96 4- to 6-year-olds) were presented with either a conventional or instrumental description of a model’s actions before watching the model choose a non-affordant tool. Children who heard conventional language imitated and transmitted the model’s non-affordant tool choice at significantly higher rates than when they heard instrumental language. The results have implications for children, parents, and teachers regarding the extent to which children will conform with what “we” are “supposed” to do.

The Relationship between Motor Coordination and Imitation: An fNIRS Study.

Although motor coordination and imitation are important factors affecting motor skill learning, few studies have examined the relationship between them in healthy adults. In order to address this in the present study, we used fNIRS to analyze the relationship between motor coordination and imitation in college students. Our results showed that: (1) motor coordination in female students was positively correlated with the average time taken to perform an imitation; (2) the mean imitation time was negatively correlated with the activation level of the supplementary motor cortex, primary somatosensory cortex, and angular gyrus of the mirror neuron system; (3) motor coordination in female students moderated mirror neuron system (MNS) activation and imitation. For women with low rather than high motor coordination, higher MNS activation was associated with a stronger imitation ability. These results demonstrate that motor coordination in female students is closely related to action imitation, and that it moderates the activation of the MNS, as measured via fNIRS.

Impacts of Human Robot Proxemics on Human Concentration-Training Games with Humanoid Robots

The use of humanoid robots within a therapeutic role, that is, helping individuals with social disorders, is an emerging field, but it remains unexplored in terms of concentration training. To seamlessly integrate humanoid robots into concentration games, an investigation into the impacts of human robot interactive proxemics on concentration-training games is particularly important. In the case of an epidemic diffusion especially—for example, during the COVID-19 pandemic—HRI games may help in the therapeutic phase, significantly reducing the risk of contagion. In this paper, concentration games were designed by action imitation involving 120 participants to verify the hypothesis. Action-imitation accuracy, the assessment of emotional expression, and a questionnaire were compared with analysis of variance (ANOVA). Experimental results showed that a 2 m distance and left-front orientation for a human and a robot are optimal for human robot interactive concentration training. In addition, females worked better than males did in HRI imitation games. This work supports some valuable suggestions for the development of HRI concentration-training technology, involving the designs of friendlier and more useful robots, and HRI game scenarios.

Towards strategy evolution in pedestrian room evacuation

Knowing how crowds behave is crucial to understanding pedestrian evacuation. In this work, we study strategy evolution in pedestrian room evacuation using a cellular automaton (CA) model with a spatial game. Agents play the game under certain conditions. While playing the game, they choose one of the three strategies (Patient strategy, Normal strategy and Impatient strategy) according to either fitness or imitation that leads to patient, normal or impatient behavior. Interactions among agents are reflected by the payoffs (related with friction cost) which may depend on agents’ surroundings. Simulation results show how evacuation conditions, agents’ individual actions, and friction cost affect strategy evolution in pedestrian room evacuation. It is found that cooperation exists both in emergency situation and relatively nonemergency situation, but appears more in the latter one. The imitation action has negative impacts either on the evolution of Normal strategy in relatively nonemergency situation or on the evolution of Patient strategy in emergency situation. In addition, uniform evolution phenomena are observed in the evacuation process, despite different composition of initial agents.

Individuals with autism spectrum disorder are impaired in absolute but not relative pitch and duration matching in speech and song imitation.

Individuals with autism spectrum disorder (ASD) often exhibit atypical imitation. However, few studies have identified clear quantitative characteristics of vocal imitation in ASD. This study investigated imitation of speech and song in English-speaking individuals with and without ASD and its modulation by age. Participants consisted of 25 autistic children and 19 autistic adults, who were compared to 25 children and 19 adults with typical development matched on age, gender, musical training, and cognitive abilities. The task required participants to imitate speech and song stimuli with varying pitch and duration patterns. Acoustic analyses of the imitation performance suggested that individuals with ASD were worse than controls on absolute pitch and duration matching for both speech and song imitation, although they performed as well as controls on relative pitch and duration matching. Furthermore, the two groups produced similar numbers of pitch contour, pitch interval-, and time errors. Across both groups, sung pitch was imitated more accurately than spoken pitch, whereas spoken duration was imitated more accurately than sung duration. Children imitated spoken pitch more accurately than adults when it came to speech stimuli, whereas age showed no significant relationship to song imitation. These results reveal a vocal imitation deficit across speech and music domains in ASD that is specific to absolute pitch and duration matching. This finding provides evidence for shared mechanisms between speech and song imitation, which involves independent implementation of relative versus absolute features. LAY SUMMARY: Individuals with autism spectrum disorder (ASD) often exhibit atypical imitation of actions and gestures. Characteristics of vocal imitation in ASD remain unclear. By comparing speech and song imitation, this study shows that individuals with ASD have a vocal imitative deficit that is specific to absolute pitch and duration matching, while performing as well as controls on relative pitch and duration matching, across speech and music domains.

The effect of action observation on aesthetic preference of Chinese calligraphy: An fMRI study.

IntroductionThere is some evidence suggesting that movement perception has an effect on aesthetic experience. However, the neural mechanisms underlying the observation of creators’ creative action (the process that calligraphers create calligraphy) remain unclear.MethodsIn this study, participants were scanned with fMRI while performing aesthetic judgments on Chinese calligraphy images with/without action observation.ResultsBehavioral results showed that both the work by the expert and novice with action observation were rated significantly higher on aesthetic preference than those without action observation. Imaging results showed that brain regions associated with perceptual, cognitive, and emotional processing were commonly activated by calligraphy images with/without action observation. However, compared with no action observation, aesthetic judgments of calligraphy images with action observation elicited stronger activation in the anterior cingulate cortex and the bilateral insula. Meanwhile, the superior parietal lobe which is associated with relevant inner action imitation, was also activated when observing the creator's action.ConclusionsBrain activation in the superior parietal lobe, anterior cingulate cortex, and the bilateral insula indicated that observing the creative action of the creators contributed to the aesthetic experience of the observer.

Smaller Than Expected.

. In two pre-registered studies, we investigated whether processes of imitative action regulation are facilitated after experiencing an episode of social exclusion. We reasoned that imitative action regulation effects should be more pronounced for participants who were socially excluded, providing them with an “automatic means” to socially reconnect with others. Participants played a virtual ball-tossing game to experimentally induce social exclusion or inclusion experiences. Subsequently, pairs of two participants engaged in an observational stimulus–response (SR) binding paradigm modeled after Giesen et al. (2014): Participants observed color categorization responses in their interaction partner (trialn-1) and then executed (in)compatible responses in the subsequent trial (trialn), with observation and responding occurring in alternation. Stimulus relation (repetition vs. change) from trialn-1 to trialn was orthogonally manipulated. In both studies, stimulus-based retrieval effects of observationally acquired SR bindings were descriptively larger in socially excluded (compared with socially included) participants. However, none of the effects were statistically significant. Even a joint analysis of both experiments did not show the expected modulation. We discuss the implications of our findings for research on social exclusion effects on imitative action regulation processes.

Does sonification of action simulation training impact corticospinal excitability and audiomotor plasticity?

Sonification is a sensory augmentation strategy whereby a sound is associated with, and modulated by, movement. Evidence suggests that sonification could be a viable strategy to maximize learning and rehabilitation. Recent studies investigated sonification of action observation, reporting beneficial effects, especially in Parkinson’s disease. However, research on simulation training—a training regime based on action observation and motor imagery, in which actions are internally simulated, without physical execution—suggest that action observation alone is suboptimal, compared to the combined use of action observation and motor imagery. In this study, we explored the effects of sonified action observation and motor imagery on corticospinal excitability, as well as to evaluate the extent of practice-dependent plasticity induced by this training. Nineteen participants were recruited to complete a practice session based on combined and congruent action observation and motor imagery (AOMI) and physical imitation of the same action. Prior to the beginning, participants were randomly assigned to one of two groups, one group (nine participants) completed the practice block with sonified AOMI, while the other group (ten participants) completed the practice without extrinsic auditory information and served as control group. To investigate practice-induced plasticity, participants completed two auditory paired associative stimulation (aPAS) protocols, one completed after the practice block, and another one completed alone, without additional interventions, at least 7 days before the practice. After the practice block, both groups significantly increased their corticospinal excitability, but sonification did not exert additional benefits, compared to non-sonified conditions. In addition, aPAS significantly increased corticospinal excitability when completed alone, but when it was primed by a practice block, no modulatory effects on corticospinal excitability were found. It is possible that sonification of combined action observation and motor imagery may not be a useful strategy to improve corticospinal, but further studies are needed to explore its relationship with performance improvements. We also confirm the neuromodulatory effect of aPAS, but its interaction with audiomotor practice remain unclear.

Altered Gesture Imitation and Brain Anatomy in Adult Prader-Willi Syndrome Patients.

To explore motor praxis in adults with Prader-Willi syndrome (PWS) in comparison with a control group of people with intellectual disability (ID) and to examine the relationship with brain structural measurements. Thirty adult participants with PWS and 132 with ID of nongenetic etiology (matched by age, sex, and ID level) were assessed using a comprehensive evaluation of the praxis function, which included pantomime of tool use, imitation of meaningful and meaningless gestures, motor sequencing, and constructional praxis. Results support specific praxis difficulties in PWS, with worse performance in the imitation of motor actions and better performance in constructional praxis than ID peers. Compared with both control groups, PWS showed increased gray matter volume in sensorimotor and subcortical regions. However, we found no obvious association between these alterations and praxis performance. Instead, praxis scores correlated with regional volume measures in distributed apparently normal brain areas. Our findings are consistent in showing significant impairment in gesture imitation abilities in PWS and, otherwise, further indicate that the visuospatial praxis domain is relatively preserved. Praxis disability in PWS was not associated with a specific, focal alteration of brain anatomy. Altered imitation gestures could, therefore, be a consequence of widespread brain dysfunction. However, the specific contribution of key brain structures (e.g., areas containing mirror neurons) should be more finely tested in future research.

Machiavellian strategist or cultural learner? Mentalizing and learning over development in a resource-sharing game.

Theorists have sought to identify the key selection pressures that drove the evolution of our species' cognitive abilities, life histories and cooperative inclinations. Focusing on two leading theories, each capable of accounting for many of the rapid changes in our lineage, we present a simple experiment designed to assess the explanatory power of both the Machiavellian Intelligence and the Cultural Brain/Intelligence Hypotheses. Children (aged 3-7 years) observed a novel social interaction that provided them with behavioural information that could either be used to outmanoeuvre a partner in subsequent interactions or for cultural learning. The results show that, even after four rounds of repeated interaction and sometimes lower pay-offs, children continued to rely on copying the observed behaviour instead of harnessing the available social information to strategically extract pay-offs (stickers) from their partners. Analyses further reveal that superior mentalizing abilities are associated with more targeted cultural learning - the selective copying of fewer irrelevant actions - while superior generalized cognitive abilities are associated with greater imitation of irrelevant actions. Neither mentalizing capacities nor more general measures of cognition explain children's ability to strategically use social information to maximize pay-offs. These results provide developmental evidence favouring the Cultural Brain/Intelligence Hypothesis over the Machiavellian Intelligence Hypothesis.

Bio-inspired cognitive model of motor learning by imitation

Learning, and even more so by imitation, is an essential Cognitive Functions because it is carried out throughout life and allows us to adapt our behaviors from other beings through observation. In this work, we propose a model, and implementation of the cognitive function of imitation motor learning (IML), based on psychological and neuroscientific evidence. According to the evidence, learning by imitation includes imitation of action and imitation of action over an object sub-processes. The imitation of action consists of the movement of the limbs. The imitation of action over an object consists of the interaction with an object within the environment. We achieve an implementation of the proposed model for IML and endow a virtual entity with it. In order to validate the proposal, we use a case study to analyze the sub-processes performance. From results, we conclude that both imitation of action and imitation of action over an object sub-processes play an essential role in getting the agent to interact with stimuli within the environment.

AYNA NÖRON SİSTEMİ VE FONKSİYONLARINA KLİNİK YAKLAŞIM

Mirror neurons were discovered in macaque monkeys in the early 1990s by Rizzolatti and his colleagues at the University of Parma. In studies investigating mirror neurons in humans, noninvasive methods of neuroimaging and electrophysiology have been used because the invasive methods used on macaque monkeys are not available. Several complex functions, including identification, evaluation, and imitation of action, empathy, learning, and memory, have been attributed to this neuron group since its discovery. Thus, the mirror neuron system is thought to be the bridge between cognition and action. This possible role in cognition shows the contribution of this system in some neurological and psychiatric diseases. With this perspective, studies on the pathology of the mirror neuron system in Parkinson’s and Alzheimer’s diseases, amyotrophic lateral sclerosis, and autism-spectrum and psychotic disorders are mentioned in this review, together with research on the possible involvement of the mirror neuron system in congenital mirror movement disorder. A re-evaluation of neurological and psychiatric diseases in light of new opinions on the organization of the brain following the discovery of mirror neurons may be helpful in understanding clinical features and establishing new methods of treatment and rehabilitation.

Motor cortex activity during action observation predicts subsequent action imitation in human infants

From early on, human infants acquire novel actions through observation and imitation. Yet, the neural mechanisms that underlie infants’ action learning are not well understood. Here, we combine the assessment of infants’ neural processes during the observation of novel actions on objects (i.e. transitive actions) and their subsequent imitation of those actions. Most importantly, we found that the 7–10 ​Hz motor cortex activity increased during action observation and predicted action imitation in 20-month-olds (n ​= ​36). 10-month-olds (n ​= ​42), who did not yet reliably imitate others’ actions, showed a highly similar neural activity pattern during action observation. The presence or absence of communicative signals did neither affect infants’ neural processing nor their subsequent imitation behavior. These findings provide first evidence for neural processes in the motor cortex that allow infants to acquire transitive actions from others ‒ and pinpoint a key learning mechanism in the developing brain of human infants.

Motor imagery during action observation enhances imitation of everyday rhythmical actions in children with and without developmental coordination disorder.

Children with developmental coordination disorder (DCD) exhibit deficits both in imitation and motor imagery (MI) compared to typically developing children. Combined action observation and motor imagery (AO+MI) instructions can however enhance automatic imitation in both groups. In the present study we investigated the effects of AO+MI instructions on intentional imitation in children both with (n=13) and without DCD (n=12). On each trial participants observed and/or imagined before executing a familiar rhythmical pantomime action. These target actions were either habitually fast (tooth brushing or window wiping) or habitually slow (paint brushing or face washing), in the vertical or horizontal plane. Within each habitual speed, the target action speed was subtly manipulated across trials (fast vs. slow). Instruction condition was manipulated across three blocks of 16 trials: (1) observe before imitating the target action; (2) observe then imagine the action before imitating; (3) observe while imagining the same action before imitating (AO+MI). Kinematic analyses revealed typically developing children imitated the observed cycle times significantly better than children with DCD. A main effect of instruction showed imitation improved for AO+MI compared to the other two instructions. Within-group analyses found a significant advantage in DCD for AO+MI compared to observe then imagine. In typically developing children, imitation was significantly enhanced for AO+MI compared to observe then imitate. Combined AO+MI instructions therefore represent a promising new approach to refining performance of everyday rhythmical actions in children both with and without DCD, with implications for movement therapy and sports training.

Less imitation of arbitrary actions is a specific developmental precursor to callous-unemotional traits in early childhood.

Callous-unemotional (CU) traits in early childhood explain heterogeneity within conduct problems and are associated with higher risk for later diagnoses of childhood disruptive behavior disorders and antisocial behavior in adulthood. Emerging research implicates impairments in affiliative processes in the etiology of CU traits. The current study tests whether the imitation of intentional actions with no functional significance -a behavior that supports the acquisition of social conventions and affiliative bonds, is a specific developmental precursor to CU traits in early childhood. Data came from a longitudinal twin study of 628 children (Age 2: 47% females; Age 3: 44.9% females) with observations of arbitrary (i.e., nonfunctional actions) and instrumental (i.e., functional actions) imitation and parent reports of CU traits and oppositional defiant (ODD) behaviors at ages 2 and 3. Lower arbitrary imitation at age 2, but not instrumental imitation, was related to increases in CU traits from ages 2 to 3 (β=-.10, p=.02). These findings establish early social and affiliative processes in the etiology of CU traits, highlighting that novel personalized treatment and intervention strategies for CU traits may benefit from targeting these processes to help reduce CU traits and risk for persistent conduct problems in children.