Neurophysiological mechanisms underlying action observation treatment for upper limb stroke rehabilitation: A mini-review.

Motor resonance, driven by the mirror neuron system, activates brain regions during action observation similarly to execution. Pattern of activation has been shown to be driven by the motor repertoire in conditions like Parkinson's disease and dystonia, but remains unexamined in functional weakness, a common phenotype of functional motor disorder. To investigate motor resonance by assessing corticospinal excitability modulation in patients with upper limb functional weakness during the observation of actions within their motor repertoire versus actions no longer executable due to their disorder. In this exploratory study, 19 adult patients with functional weakness and 21 healthy controls observed videos of hand movements-index finger abduction and power grip-performed with strong or weak force. Single-pulse transcranial magnetic stimulation targeted the primary motor cortex, with motor-evoked potentials recorded from first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles. In healthy controls, corticospinal excitability increased significantly in the FDI during strong abduction compared to "static" (P = 0.013) and "weak" (P = 0.027) conditions, and during both "weak" (P = 0.002) and "strong" (P = 0.032) power grips compared to baseline. Conversely, patients with functional weakness showed no significant modulation across any condition. Compared to controls, patients exhibited reduced excitability during strong actions in both FDI (abduction; P = 0.03) and ADM (power grip; P = 0.029). Functional weakness patients demonstrated altered force-dependent motor resonance, suggesting a disruption in the motor system's ability to internally simulate actions, particularly those requiring high muscular contraction. These findings may inform future rehabilitation strategies leveraging action observation in functional motor disorders.

Action understanding requires internal models that link vision to motor goals. In monkeys, mirror neurons demonstrate motor resonance during observation, but single-unit evidence in humans is limited, leaving open whether such representations rely solely on motor resonance. We recorded neural activity from motor cortex (MC) and superior parietal lobule (SPL) in two tetraplegic participants implanted with Utah arrays while they intended or observed hand actions. MC strongly encoded intention but showed only weak, feature-specific overlap during observation, evident primarily at the population level. SPL, in contrast, supported shared models across intended movement and observation formats at both single-unit and population levels. In variants with incongruent instructed and observed actions, SPL encoded observed actions only when behaviorally relevant, whereas MC remained intention-dominant. Our results identify a context-dependent gating mechanism in SPL and suggest a hierarchical organization in which MC maintains intention-specific codes while SPL flexibly links observed input with internal goals to support action understanding.

As apparent as real: alpha and beta bands desynchronization unveils apparent motion perception dynamics.

Background/Objectives: Empathy is essential for successful social functioning, mediating different aspects of social cognition in everyday life. An intriguing aspect is the involvement of empathy even in basic neural mechanisms of action perception, thanks to its association with the Mirror Neuron System (MNS). The present retrospective study explores whether individual differences in cognitive and affective empathy, measured by the Interpersonal Reactivity Index (IRI) questionnaire, can predict motor resonance—the enhancement of motor cortex reactivity during the observation of biological movements—during transitive and intransitive action observation. Methods: Data from 160 healthy subjects who participated in transcranial magnetic stimulation (TMS) experiments assessing corticospinal excitability during action observation were retrospectively analyzed using multiple linear regression models. Participants filled the IRI and observed intransitive single-digit finger movements (n = 80) or grasping actions directed at different targets (intransitive, object-directed, social-directed; n = 80) synchronized with TMS over the primary motor cortex, allowing the investigation of how action features modulate the relationship between participants’ empathic traits and motor resonance magnitude. Results: Results show that empathic traits do not affect motor resonance during intransitive movements, whereas they do when motor resonance is measured during the observation of transitive actions. Cognitive empathy, particularly the perspective-taking scale, significantly predicts motor resonance magnitude when observing goal-directed actions. Meanwhile, affective empathy, specifically the empathic concern scale, predicts motor resonance while observing social action. Conclusions: These findings highlight that different facets of empathy are significantly related to humans’ ability to understand others’ actions through inner simulation mechanisms, particularly concerning action goals and social relevance.

Vocal smile is recognized but not embodied in autistic adults

Evidence suggests that insects may utilize resonant mechanics during flight to optimize energetic efficiency, though whether this mechanism is universal across all insect species remains debated. Microinsects appear particularly intriguing in this context: they exhibit agility comparable to larger species despite experiencing higher aerodynamic damping forces on their wings. We investigated mechanical resonance dynamics focusing on the miniature waspTiphodytes gerriphagus-a remarkable species capable of both aerial flight and underwater locomotion, using wings in both cases. This dual-mode mobility introduces additional biomechanical constraints that simplify parameter identification in the analysis. We developed a reduced-order model incorporating muscle activation, internal inertial and viscous damping forces, thoracic elasticity, and inertial and fluid-dynamic forces acting on the wing. This model represents the insect flight apparatus as a one-dimensional oscillator. It employs capillary analogy modeling, integrated with a wing-thorax-muscle system undergoing periodic flapping motions. Our results demonstrate limited flight motor resonance potential in air, caused by strong damping effects, and unavoidably overdamped conditions underwater.

BackgroundThe mirror neuron system (MNS) activates during the performance of an action and during the observation of the same action being performed by another. At the motor output level, MNS activation manifests as motor resonance, or a muscle-specific increase in corticospinal excitability during action observation. This study focuses on how and to what extent motor learning alters the initial mirror response and whether the rate of motor learning is associated with pretraining or post-training levels of mirror response. The study involved 23 healthy adults aged 22.7 years on average. The experiment consisted of six sessions. On the first and last days, a transcranial magnetic stimulation session was performed to assess the putative activity of mirror neurons, as reflected in the level of motor-evoked potential facilitation during action observation under various conditions. From the second to the fifth sessions (four sessions), motor learning was performed, as represented in the form of a serial reaction time (SRT) task.ResultsWe observed a statistically significant decrease in reaction time during the process of learning within the SRT task and motor facilitation during action observation, thus reflecting putative mirror neuron activity. We found a significant correlation between the learning speed of the non-dominant hand and mirror neuron activation in the dominant hemisphere during the observation of button presses and pinch gestures.ConclusionThe MNS excitability is not a predictor of motor learning, but motor learning is reflected in the characteristics of the MNS.

The same label, different processes: What lies behind the term "mental simulation" in the embodied cognition literature?

Motor resonance (MoR) refers to the automatic activation of motor circuits during action observation, reflecting an internal simulation of the observed movement. This phenomenon is thought to arise from the activity of mirror neuron regions, which modulate primary motor cortex (M1) excitability via cortico-cortical pathways. MoR, which is believed to be involved in the mechanism underlying action understanding and motor learning, has been widely studied using visual stimuli and transcranial magnetic stimulation (TMS). However, the optimal form of movement presentation and TMS timing remains unclear. This study compared the effects of static photographs and videos on the MoR activation and explored the ideal timing for TMS. Participants observed abduction movements of the index finger (controlled by the first dorsal interosseous muscle, FDI) and the little finger (controlled by the abductor digiti minimi muscle, ADM) presented as photographs or videos. The task included three conditions: Photo (static images), Video (full movement videos), and Postvideo (post-movement period). TMS was applied over the primary motor cortex at 0, 320, or 640 ms from movement onset (Photo, Video) and at the same intervals from movement offset (Postvideo). Motor evoked potentials (MEPs) were recorded from FDI and ADM. The Postvideo condition yielded the strongest MEP modulations, with inhibition in the non-matching muscle and excitation in the muscle corresponding to the observed movement. In contrast, Photo and Video conditions showed time-dependent reductions in cortical excitability, especially in non-matching muscles. These findings suggest that applying TMS after movement observation provides a more accurate approach to studying MoR and highlights the role of motor surround inhibition in motor control.

Abstract The comfort assessment for high-speed train passengers is becoming increasingly stringent, with noise being a key indicator. This paper focuses on the phenomenon of noise exceeding standards in a specific high-speed train, conducting noise testing research to identify the traction system noise as the major contributor. By optimizing the design of the traction motor and its control strategy, considering the motor slot coordination and control strategies, the noise caused by electromagnetic forces leading to motor resonance radiation was eliminated. The optimization results were significant, providing experiential guidance for noise optimization in other high-speed train motors.

This study explores contagious yawning in adult chimpanzees (Pan troglodytes) in the presence of a non-biological humanoid agent, an android. Chimpanzees observed an android portraying specific facial expressions, including yawns and gapes. The results showed that adult chimpanzees exhibited across-agent yawn contagion, with a graded response: the highest contagion occurred when the android displayed a fully wide-open mouth (Yawn condition), a reduced response when the mouth was partially opened (Gape condition), and no contagion when the android’s mouth was closed (Close condition). Additionally, chimpanzees engaged in behaviours associated with drowsiness, such as gathering bedding materials, constructing nests, and lying down, while observing the android yawning. This suggests that yawning by an unfamiliar model may act as a contextual cue for rest, rather than merely triggering a motor resonance response. These findings contribute to the understanding of non-human primates’ susceptibility to contagiously induced behaviours, specifically yawns, even when triggered by an artificial agent. This study highlights the role of social factors in shaping yawn contagion and calls for further research on cross-species and cross-agent interactions.

Understanding and interpreting non-verbal actions are critical components of social cognition, which are often challenging for autistic individuals. Oxytocin, a neuropeptide known to modulate social behavior and enhance the salience of social stimuli, is being explored as a therapeutic option for improving social mirroring. However, its effects are mediated by context- and person-dependent factors. This study examines the impact of a single intranasal dose of oxytocin (24 IU) on interpersonal motor resonance in young adult men with and without autism. Neurophysiological assessments of corticomotor excitability were performed using transcranial magnetic stimulation while participants observed real-time hand movements displayed by an experimenter demonstrating varying social intent (i.e. showing direct vs averted gaze). While no overall effect of oxytocin on interpersonal motor resonance was observed across groups, person-specific factors significantly influenced outcomes. In the autism group, individuals with higher endogenous oxytocin levels exhibited greater motor resonance during action observation. Autistic individuals with heightened social difficulties or avoidant attachment styles showed enhanced motor resonance following oxytocin administration. These findings highlight the nuanced role of both endogenous and exogenous oxytocin in shaping neurophysiological motor resonance and emphasize the importance of individual variability in assessing oxytocin's therapeutic potential for addressing social challenges in autism.Lay abstractThis study explores how oxytocin, a hormone that influences social behaviors, affects the ability to interpret and respond to non-verbal cues, particularly in autistic adults. Understanding others' actions and intentions, often guided by observing body language and eye contact, is a critical part of social interaction. Autistic individuals frequently face challenges in these areas. Using a safe, non-invasive brain stimulation technique, the study measured participants' brain responses as they observed real-time hand movements paired with the interaction partner's direct eye contact or averted gaze. Participants included young autistic and non-autistic adult men who received a placebo and a single dose of oxytocin via nasal spray. Results showed no overall differences between the two groups in their brain responses to these movements. However, in the autism group, several factors significantly influenced the effects of oxytocin. Participants with higher natural oxytocin levels or those who reported greater social challenges showed stronger responses after oxytocin administration, particularly when observing hand movements combined with direct gaze. These findings suggest that oxytocin may enhance social understanding in autistic individuals, especially for those experiencing greater difficulties. This highlights the potential of personalized approaches when considering oxytocin as a therapeutic option to improve social interactions.

69. Oxytocin Facilitates Interpersonal Motor Resonance in Autistic Individuals With High Social Difficulties: A Transcranial Magnetic Stimulation Study

Background/Objectives: Action observation therapy (AOT) has gained attention as a rehabilitation method for motor function recovery following nerve injury. Although the total observation time and daily session duration have been studied, the effective observation duration per trial remains unclear. This study examined the effect of different observation durations on manual dexterity, mirror neuron system activity, and subjective psychomotor effort in healthy adults. Methods: Twenty-four healthy right-handed adults participated in this crossover study under four conditions: observing ball rotations with the dominant hand for one, two, or three minutes, or geometric patterns (control) for two minutes. The outcomes included maximum rotations and errors by both hands during a ball rotation task and interpersonal motor resonance (IMR), indicating mirror neuron system activity. These measures were compared before and after intervention. Subjective ratings of concentration, physical fatigue, and mental fatigue were assessed post-intervention. Results: Rotation performance significantly increased for the intervention hand after a 2 min observation and showed a notable effect (p = 0.113, r = 0.48) for the non-intervention hand after a 3 min observation compared to the control. The IMR was significantly greater during the 2 min observation than in the control. Compared to the 1 min observation, the 2 min and 3 min observations resulted in higher mental fatigue, and the 3 min observation showed lower concentration levels. Conclusions: These findings indicate that the observation duration has varying effects on manual dexterity and mirror neuron system activity, with optimal effects observed at specific time intervals while also highlighting the relationship between observational learning and psychomotor effort.

In sports, players constantly engage in understanding others’ actions and intentions. Previous studies have highlighted that possessing the observed action in the individual motor repertoire improves the prediction abilities of the observer. Here, we tested the extent to which players’ ability to predict soccer actions is influenced by their motor repertoire, which is modulated not only by their generic expertise but also by the specific position played on the field. To these aims, two experiments were conducted by asking players to predict the result of typical soccer actions and comparing accuracies with data concerning their soccer career. Results revealed that both general expertise and position-specific experience significantly impacted prediction performance, with the highest accuracy observed when actions aligned with players’ positional expertise. These findings highlight that the motor resonance mechanism is finely attuned to the individual’s motor repertoire, which operates as a continuum – from no experience to advanced expertise in a specific position – enabling a dynamic, experience-driven enhancement of action prediction in sports.

M1 large-scale network dynamics support human motor resonance and its plastic reshaping.

Automatic behavioral matching includes Rapid Facial Mimicry (RFM) and Yawn Contagion (YC) that occur when the facial expression of an individual acts as a ‘mirror social releaser’ and induces the same facial expression in the observer (within 1 s for RFM, and minutes for YC). Motor replication has been linked to coordination and emotional contagion, a basic form of empathy. We investigated the presence and modulating factors of Rapid Smile Mimicry (RSM) and YC in infants/toddlers from 10 to 36 months at the nursery ‘Melis’ (Turin, Italy). In February-May 2022, we gathered audio and/or video of all occurrences data on affiliative behaviors, smiling during play, and yawning during everyday activities. Both RSM and YC were present, as toddlers were most likely to smile (within 1 s) or yawn (within three-min) after perceiving a smile/yawn from another toddler. Sex, age, and parents’ country of origin did not influence RSM and YC occurrence, probably because gonadal maturation was long to come, the age range was skewed towards the early developmental phase, and toddlers had been in the same social group for months. RSM and YC showed social modulation, thus possibly implying more than just motor resonance. Both phenomena were inversely related to affiliation levels (a social bond proxy). Because literature reports that in adults RSM and YC may increase with familiarity, our reversed result suggests that in certain toddler cohorts the same phenomena may help increase socio-emotional coordination and that the function of motoric resonance may be experience- and context-dependent.

Background/Objectives. Mirror properties of the action observation network (AON) can be modulated through Hebbian-like associative plasticity using paired associative stimulation (PAS). We recently introduced a visuomotor protocol (mirror-PAS, m-PAS) that pairs transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) with visual stimuli of ipsilateral (to TMS) movements, leading to atypical corticospinal excitability (CSE) facilitation (i.e., motor resonance) during PAS-conditioned action observation. While m-PAS aftereffects are robust, little is known about markers of associative plasticity during its administration and their predictive value for subsequent motor resonance rewriting. The present study aims to fill this gap by investigating CSE modulations during m-PAS and their relationship with the protocol's aftereffects. Methods. We analyzed CSE dynamics in 81 healthy participants undergoing the m-PAS before and after passively observing left- or right-hand index finger movements. Here, typical and PAS-conditioned motor resonance was assessed with TMS over the right M1. We examined CSE changes during the m-PAS and used linear regression models to explore their relationship with motor resonance modulations. Results. m-PAS transiently reshaped both typical and PAS-induced motor resonance. Importantly, we found a gradual increase in CSE during m-PAS, which predicted the loss of typical motor resonance but not the emergence of atypical responses after the protocol's administration. Conclusions. Our results suggest that the motor resonance reshaping induced by the m-PAS is not entirely predictable by CSE online modulations. Likely, this rewriting is the product of a large-scale reorganization of the AON rather than a phenomenon restricted to the PAS-stimulated motor cortex. This study underlines that monitoring CSE during non-invasive brain stimulation protocols could provide valuable insight into some but not all plastic outcomes.

Modern and ancient literatures reveal that there is a handful of firms that have been in operation for over a millennium year. Their resilience, while fascinating, has triggered academic interests to uncover insights owing to diminishing modern firms’ lifespan. Previous studies have intuitively highlighted key elements of longevity. This study searches for the inner substance of these firms so many other organisations cannot replicate. The review of ten selected millennium-long history firms reveals that they spread from various business sectors. These firms report an “experience of harmony” refer to as “resonance”. Borrowing from natural science together with the integrated evidence from multiple disciplines including psychology and neuroscience, the concept of “motor resonance” was introduced in operations management to forge ahead with the theory of strategic resonance. Until now strategic resonance models were intuitive and metaphoric. The proposed model suggests that “motor resonance” is the driver of the dynamic interplay between internal and external environments of millennium-long history firms. Additionally, leading with foresight guarantee continuous resonance between the environment and the firms’ operational capabilities, while managing with insight guarantee continuous resonance between and within firm functions. Overall, findings contribute novel theoretical and practical insights to strategic resonance.