Mirror Neuron System and Upper-Limb EMG Activity During Reaching Imitation in Stroke Survivors: Comparing Outcomes After Observing Normal vs. Aberrant Movements.

Background: Task-based action observation and imitation (AOI) is a promising intervention to enhance upper limb (UL) motor function poststroke. However, whether whole/part task must be trained in the AOI therapy needs further substantiation. Objective: The objective of this study is to assess and compare the mirror neuron activity and UL muscle activity during AOI of reaching task in terms of whole task (complete movement) and part task (proximal arm movements and distal arm movements). Methods: In this cross-sectional study, 26 participants with first-time unilateral stroke were asked to observe the prerecorded videos of a reaching task in terms of a whole task and proximal and distal components, followed by imitation of the task, respectively. Electroencephalographic (EEG) mu rhythm suppression and electromyographic amplitude of six UL muscles were measured during the task. Results: The analysis of EEG revealed a statistically significant mu suppression score, indicating mirror neuron system activity, during AOI of the whole task in C3 (p = <0.001) and C4 (p = <0.001) electrodes compared to the part task. Percentage maximum voluntary contraction amplitudes of the deltoid (p = 0.002), supraspinatus (p = <0.001), triceps brachii (p = 0.002), brachioradialis (p = 0.006), and extensor carpi radialis (p = <0.001) muscles showed a significant increase in muscle activity during AOI of the whole task. Also, there seems to be a task observation-specific activation of muscles following AOI of proximal or distal tasks. Conclusion: The practice of the whole task should be given emphasis while framing the AOI treatment module to enhance reaching in people with stroke. Trial registration: Clinical Trials Registry-India (CTRI) identifier: CTRI/2018/04/013466.

Electroencephalographic mu rhythm desynchronization is thought to reflect Mirror Neuron System (MNS) activity and represents an important neural correlate of the coupling between action execution and perception. It is still unclear if the MNS in human ontogeny is already available at the beginning of postnatal life and how early experience impacts its development. Premature birth provides a “natural condition” for investigating the effects of early, atypical extra-uterine experience on MNS. The main aim of the present study was to investigate whether the MNS activity is associated with prematurity. We compared the mu rhythm activity in preterm (PT) and full-term (FT) 14-month old infants during an action observation/execution (AO/AE) task. Mu rhythm desynchronization was computed over frontal, central, parietal and occipital regions. Both groups showed mu rhythm suppression in all the scalp regions during action execution. Different desynchronization patterns emerged during action observation. Specifically, FT infants showed mu suppression in the right frontal, bilateral parietal and occipital regions; whereas PT infants exhibited mu suppression only in the right parietal region. Overall, these preliminary findings indicate that an atypical extra uterine experience might have an impact on the MNS activity.

Action Observation Therapy (AOT) shows promise in pediatric neurorehabilitation for improving upper limb function. Its proposed mechanism, mirror neuron system (MNS) activation, is largely inferred from adult studies, creating a significant evidence gap in children with unilateral cerebral palsy (UCP). This study aimed to directly measure MNS activation via functional MRI (fMRI) in children with UCP during a goal-directed AOT paradigm and correlate it with functional motor improvements. In a randomized controlled trial, 30 children with UCP (ages 6-12, MACS I-III) were allocated to either AOT (n=15) or control (n=15) groups. The AOT group observed goal-directed actions followed by physical practice, while the control group observed geometric shapes followed by the same practice. Pre- and post-intervention assessments included fMRI scans during action observation and the Assisting Hand Assessment (AHA) and Melbourne Assessment 2 (MA2) for functional evaluation. The AOT group demonstrated significantly greater activation in key MNS regions (inferior frontal gyrus, premotor cortex, inferior parietal lobule) on fMRI (p &lt; 0.001, FWE-corrected). This was coupled with significantly greater improvement on the AHA (mean difference +5.6 points, p=0.002) and MA2 (mean difference +7.1%, p=0.005) compared to the control group. A strong positive correlation was found between the change in MNS activation and the change in AHA scores (r = 0.78, p &lt; 0.001). This study provides the first direct evidence in a pediatric population that functional gains from goal-directed AOT are mediated by the activation of the MNS. It validates AOT as a neuroplasticity-based intervention and underscores the importance of goal-directed action observation in designing effective rehabilitation protocols for children with UCP.

Objective: The present study aimed to examine whether the story understanding of a nonexplanatory film affects mirror neuron system (MNS) activity and to discuss the interactive process involved in generating empathy for fictional characters during participants’ viewing of the film under natural viewing conditions. Methods: The material of the experiment was a Japanese film entitled Dolls . It is a nonexplanatory fiction film, in which the two (male and female) main characters show only minimal actions or facial expressions; therefore, the viewers hardly understand the story until it has been developed to some extent. We measured twelve participants’ MNS activity by using near-infrared spectroscopy during the viewing of the first 20 minutes of the film. Additionally, we measured the brain activity while performing their own hand and leg motions after viewing the film to identify their motor cortices. Results: The results showed that the viewer’s MNS activity increased gradually as the introductory part of the story developed. Subsequent analyses revealed a significant increase in MNS activity in the later chapters of the film at the right premotor and supplementary motor cortices ( P <0.05). Furthermore, there was a significant correlation between the MNS activity and the Interpersonal Reactivity Index scores ( P <0.05). Conclusion: These results indicate that the viewer’s MNS activity was enhanced by the story understanding of a fiction film. We suggest that MNS activity during viewing fiction films can be used as a measure of how much the story, and rhetoric of a narrative, induces empathy in the viewers even if characters show only minimal actions or facial expressions. Keywords: mirror neuron system, MNS, empathy, nonexplanatory film, story understanding, premotor cortex

Possible disrupted biological movement processing in Developmental Coordination Disorder

Modulation of putative mirror neuron activity by both positively and negatively valenced affective stimuli: A TMS study

Blindness is a significant condition that triggers the ability of the brain to adapt to environmental changes through plasticity processes. This study examined somatosensory processing, multisensory integration, kinesthetic motor imagery (MI) and mirror neuron system (MNS) activity in response to auditory stimuli in visually impaired (VI) individuals. The study included 21 individuals with total vision loss, and the findings were compared with 21 participants with normal vision. The somatosensory temporal discrimination threshold (STDT) was used to evaluate somatosensory processing, while transcranial magnetic stimulation (TMS) was employed to measure kinesthetic MI activity and MNS activity in response to auditory stimuli. The results showed that VI individuals had significantly lower STDT values than the control group in conventional STDT measurements. STDT values measured 50, 100 and 300ms after auditory stimuli in the auditory-tactile sensory integration paradigm. VI participants have significantly lower STDT values than the control group in the auditory-tactile sensory integration test. Most of the participants, who were congenitally blind, exhibited TMS activity during MI processes similar to that of sighted individuals. However, no TMS measurements indicative of MNS activation in response to auditory stimuli were detected in VI individuals using the stimulus paradigm applied in the study. The findings suggest that VI individuals perform better than sighted individuals in both somatosensory processing and multisensory integration while exhibiting similar MI performance to sighted individuals. KEY POINTS: Visually impaired (VI) individuals have better somatosensory processing capacity than sighted individuals. The multisensory processing capacities of VI individuals are superior to those of sighted individuals. The enhanced sensory processing and multisensory integration capacities observed in VI individuals may be related to secondary cross-modal plasticity that develops due to vision loss.

Yoga therapy for social cognition in schizophrenia: An experimental medicine-based randomized controlled trial.

Activation of mirror neuron system during gait observation in sub-acute stroke patients and healthy persons

BackgroundImpaired imitation has been found to be an important factor contributing to social communication deficits in individuals with autism spectrum disorder (ASD). It has been hypothesized that the neural correlate of imitation, the mirror neuron system (MNS), is dysfunctional in ASD, resulting in imitation impairment as one of the key behavioral manifestations in ASD. Previous MNS studies produced inconsistent results, leaving the debate of whether “broken” mirror neurons in ASD are unresolved.MethodsThis meta-analysis aimed to explore the differences in MNS activation patterns between typically developing (TD) and ASD individuals when they observe biological motions with or without social-emotional components. Effect size signed differential mapping (ES-SDM) was adopted to synthesize the available fMRI data.ResultsES-SDM analysis revealed hyperactivation in the right inferior frontal gyrus and left supplementary motor area in ASD during observation of biological motions. Subgroup analysis of experiments involving the observation of stimuli with or without emotional component revealed hyperactivation in the left inferior parietal lobule and left supplementary motor during action observation without emotional components, whereas hyperactivation of the right inferior frontal gyrus was found during action observation with emotional components in ASD. Subgroup analyses of age showed hyperactivation of the bilateral inferior frontal gyrus in ASD adolescents, while hyperactivation in the right inferior frontal gyrus was noted in ASD adults. Meta-regression within ASD individuals indicated that the right cerebellum crus I activation increased with age, while the left inferior temporal gyrus activation decreased with age.LimitationsThis meta-analysis is limited in its generalization of the findings to individuals with ASD by the restricted age range, heterogeneous study sample, and the large within-group variation in MNS activation patterns during object observation. Furthermore, we only included action observation studies which might limit the generalization of our results to the imitation deficits in ASD. In addition, the relatively small sample size for individual studies might also potentially overestimate the effect sizes.ConclusionThe MNS is impaired in ASD. The abnormal activation patterns were found to be modulated by the nature of stimuli and age, which might explain the contradictory results from earlier studies on the “broken mirror neuron” debate.

Background. Recent evidence suggested that Action Observation Therapy (AOT), based on observation of actions followed by immediate reproduction, could be a useful rehabilitative strategy for promoting functional recovery of children affected by unilateral cerebral palsy (UCP). AOT most likely exploits properties of the parieto-premotor mirror neuron system (MNS). This is more intensely activated when participants observe actions belonging to their own motor repertoire. Objective. The aim of the present study was to investigate the issue of whether MNS of UCP children is better activated by actions performed by a paretic hand rather than a healthy one. Methods. Using functional magnetic resonance imaging, we assessed brain activation in a homogeneous group of 10 right UCP children compared with that of 10 right-handed typically developing (TD) children, during observation of grasping actions performed by a healthy or a paretic hand. Results. The results revealed a significant activation within the MNS in both UCP and TD children, more lateralized to the left hemisphere in the TD group. Most important, region of interest (ROI) analysis on parietal and premotor regions showed that, in UCP, the MNS was more strongly activated by observation of actions performed by the paretic hand, a motor model more similar to the observer’s motor repertoire. Conclusions. This study shows that children affected by spastic UCP exhibit enhanced activation of the MNS during observation of goal-directed actions performed by a pathological model with respect to a healthy one.

Modulation of motor area activity during observation of unnatural body movements

Comparing mirror neuron system activity between sporadic and familial cases of schizophrenia.

&lt;p&gt;In normotypic children 4-7 years old and their peers with autism spectrum disorders (ASD), an electroencephalogram (EEG) was recorded in situations of observation of imaginary and real actions of the experimenter, as well as when the action was repeated by children. The relevance of the study is due to the assumption of a violation in children with ASD of the functioning of the so-called mirror neuron system (MNS). In both groups of children in these situations, desynchronization of EEG power was detected in individually defined mu-rhythm ranges in the central, frontal and parietal locus, which indicates the activation of MNS. At the same time, in children with ASD in all experimental situations, there was a greater desynchronization of the mu-rhythm in the areas of the lower frontal gyri of the left and right hemispheres (locus F7 and F8), compared with normotypic children. However, in the central locus of the right hemisphere (C4 locus), under the conditions of observation of a real action in children with ASD, there is significantly less desynchronization of the mu-rhythm compared to the norm group, which is probably due to less activation of MNS when perceiving the purposeful actions of another person. The results obtained are important for understanding social behavior disorders in children with ASD and developing methods for their correction.&lt;/p&gt;

The mirror neuron system (MNS), mainly including the premotor cortex (PMC), inferior frontal gyrus (IFG), superior parietal lobule (SPL), and rostral inferior parietal lobule (IPL), has attracted extensive attention as a possible neural mechanism of social interaction. Owing to high ecological validity, functional near-infrared spectroscopy (fNIRS) has become an ideal approach for exploring the MNS. Unfortunately, for the feasibility of fNIRS to detect the MNS, none of the four dominant regions were found in previous studies, implying a very limited capacity of fNIRS to investigate the MNS. Here, we adopted an experimental paradigm in a real-life situation to evaluate whether the MNS activity, including four dominant regions, can be detected by using fNIRS. Specifically, 30 right-handed subjects were asked to complete a table-setting task that included action execution and action observation. A double density probe configuration covered the four regions of the MNS in the left hemisphere. We used a traditional channel-based group analysis and also a ROI-based group analysis to find which regions are activated during both action execution and action observation. The results showed that the IFG, adjacent PMC, SPL, and IPL were involved in both conditions, indicating the feasibility of fNIRS to detect the MNS. Our findings provide a foundation for future research to explore the functional role of the MNS in social interaction and various disorders using fNIRS.