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Background. Imagined motor movement is a cognitive process in which a subject imagines a movement without doing it, which activates similar brain regions as during actual motor movement. Brain gamma band activity (GBA) is linked to cognitive functions such as perception, attention, memory, awareness, synaptic plasticity, motor control, and Imagination. Motor imagery can be used in sports to improve performance, raising the possibility of using it as a rehabilitation method through brain plasticity through mirror neurons. Method. A comparative observational study was conducted on 56 healthy male subjects after obtaining clearance from the Ethics Committee. EEG recordings for GBA were taken for resting, real, and imaginary motor movements and compared. The power spectrum of gamma waves was analyzed using the Kruskal-Wallis test; a p-value <.05 was considered significant. Results. The brain gamma rhythm amplitude was statistically increased during both actual and imaginary motor movement compared to baseline (resting stage) in most of the regions of the brain except the occipital region. There was no significant difference in GBA between real and imaginary movements. Conclusions. Increased gamma rhythm amplitude during both actual and imaginary motor movement than baseline (resting stage) indicating raised brain cognitive activity during both types of movements. There was no potential difference between real and imaginary movements suggesting that the real movement can be replaced by the imaginary movement to enhance work performance through mirror therapy., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Acquired Brain Injuries are one of the leading causes of mortality and disability worldwide. One of the most frequent sequelae is motor impairment of the upper limbs, which affects people's functionality and quality of life. Following the discovery of mirror neurons, new techniques were developed based on the mechanisms of neuronal plasticity, such as motor imagery (MI) and action observation (AO). We propose a protocol using electromyographic recordings of forearm muscles in people who have suffered a stroke during an MI task and an AO task. Three different experimental conditions will be studied during the electromyographic recordings: control recording, recording during MI, and recording during AO. Understanding the muscle activation in each technique will allow us to develop future protocols and intervention plans, improving the quality of care for people who have suffered a stroke.

Purpose: The aim was to investigate the effects of a single session action observation training (AOT) on hand function and evaluate whether observing self-actions would be more effective than observing someone else., Materials and Methods: A total of 60 right-handed healthy young adults, (32 female, 28 males and the mean age was 21.32 ± 1.07 years) were included in the study. The participants were randomly divided into five groups, self-action observation (sAO), observation of a third person (AO), action practice (AP), non-action observation (nAO), and control. A single session was performed for all participants. The primary outcome was the Jebsen Taylor Hand Function Test (JTHFT) assessed by a masked assessor., Results: Significant differences were observed between the sAO and control group in total left side JTHFT performance ( p  < 0.001). Additionally, there were significant differences between the AO and control group ( p  < 0.001), and AP and nAO group ( p  = 0.003) and AP and control group ( p  < 0.001) in total JTHFT performance change of the left side. Significant differences were found between the sAO and nAO ( p  = 0.001) and control groups ( p  < 0.001) in dominant side total JTHFT performance change. No difference between sAO and AP groups were observed ( p  > 0.05)., Conclusion: It was observed that a single session of action observation training improved hand function in healthy adults. The better performance achieved in the group watching the self-video may suggest that watching the self-image activates more mirror neurons.

The production of facial emotions is an important conveyor of social communication. The present review of the literature concerns the congruence of facial emotions, that is the facial muscular activation that takes place in response to the emotional facial expression perceived in others. Although scientific interest in facial emotions has increased exponentially in the last few years, the production of facial emotions is still underexplored as compared to emotional perception. Several studies, mainly conducted with electromyography, have shown that facial emotional congruence exists in a robust way, largely for anger and happiness. While facial emotional congruence was long considered as innate and automatic, recent work has demonstrated that several sociocultural factors may influence or reduce this ability, challenging its automaticity. From a neuroanatomical point of view, studies have clearly highlighted the implication of mirror neurons but our knowledge is still limited because of the few methodologies assessing this system and the lack of homogeneity between the protocols used. Many explanatory, and probably not mutually exclusive, theories of emotional facial congruence have been put forward. In experimental neuropsychology, emotional facial congruence has seldom been investigated but the few available results suggest an impairment in psychiatric and neurological patients. In view of the important role of emotional facial productions in human relations and social interactions, new methods for easy clinical assessment need to be designed for the diagnosis and the cognitive care of these abilities. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

The code paradigm in biological and social sciences arises to Aristotle. For conscious activity, Aristotle introduced the notion of reflexive self-awareness in sense perception. This reflexive process generates the codes that signify sensual perceptive events and constrain human behavior. Coding systems grow via the generation of hypertextual statements reflecting new meanings in the process defined by Marcello Barbieri as a codepoiesis. It results in the establishment of higher-level codes (metacodes) forming the semiotic screen that has a nature of the set of perceived objects internalized by the conscious subject in encoding the symbolic actions. The characteristic feature of the semiotic screen consists in its property of being shared between the communicating agents. A sufficient complexity of nervous system, through the appearance of mirror neurons that are fired both when a subject executes certain action and when he observes another subject performing a similar action, represents a prerequisite for the emergence of reflexive codes in evolution. The codes appearing as a result of reflexive awareness and establishing different sociotypes, span from the symbolic systems of art and music through the common language to the formal language of logic and mathematics. Social dynamics is based on the implementation of reflexive coding activity and results in the growth and decay of social systems and civilizations., Competing Interests: Declaration of competing interest The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The activation of the Mirror Neuron System (MNS) has been described to reflect visible movements, but not postural, non-visible, adaptations that accompany the observed movements. Since any motor act is the result of a well-tailored dialogue between these two components, we decided to investigate whether a motor resonance to nonvisible postural adaptations could be detected. Possible changes in soleus corticospinal excitability were investigated by eliciting the H-reflex during the observation of three videos, corresponding to three distinct experimental conditions: 'Chest pass', 'Standing' and 'Sitting', and comparing its size with that measured during observation of a control videoclip (a landscape). In the observed experimental conditions, the Soleus muscle has different postural roles: a dynamic role in postural adaptations during the Chest pass; a static role while Standing still; no role while Sitting. The H-reflex amplitude was significantly enhanced in the 'Chest pass' condition compared to the 'Sitting' and 'Standing' conditions. No significant difference was found between 'Sitting' and 'Standing' conditions. The increased corticospinal excitability of the Soleus during the 'Chest pass' condition suggests that the mirror mechanisms produce a resonance to postural components of an observed action, although they may not be visible. This observation highlights the fact that mirror mechanisms echo non intentional movements as well and points to a novel possible role of mirror neurons in motor recovery., (© 2023 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Broadly congruent mirror neurons, responding to any grasp movement, and strictly congruent mirror neurons, responding only to specific grasp movements, have been reported in single-cell studies with primates. Delineating grasp properties in humans is essential to understand the human mirror neuron system with implications for behavior and social cognition. We analyzed electrocorticography data from a natural reach-and-grasp movement observation and delayed imitation task with 3 different natural grasp types of everyday objects. We focused on the classification of grasp types from high-frequency broadband mirror activation patterns found in classic mirror system areas, including sensorimotor, supplementary motor, inferior frontal, and parietal cortices. Classification of grasp types was successful during movement observation and execution intervals but not during movement retention. Our grasp type classification from combined and single mirror electrodes provides evidence for grasp-congruent activity in the human mirror neuron system potentially arising from strictly congruent mirror neurons., (© The Author(s) 2022. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Mirror neurons have been found mainly in neocortical structures of primates and rodents; however, their functions are still debated. A new study has discovered mirror neurons for aggressive behaviors in the ventromedial hypothalamus of mice, an evolutionarily ancient structure, highlighting a new function key for survival., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The association between social cognition and putative mirror neuron system (MNS)-activity in major psychoses might be contingent upon frontal dysregulation. We used a transdiagnostic ecological approach to enrich a specific behavioral phenotype (echophenomena or hyper-imitative states) across clinical diagnoses (mania and schizophrenia) to compare behavioral and physiological markers of social cognition and frontal disinhibition. We examined 114 participants with schizophrenia (N = 53) and mania (N = 61) for the presence and severity of echo-phenomena (echopraxia, incidental, and induced echolalia) using an ecological paradigm to simulate real-life social communication. Symptom severity, frontal release reflexes, and theory of mind performance were also assessed. In a proportion of these participants with (N = 20) and without (N = 20) echo-phenomena, we compared motor resonance (motor evoked potential facilitation during action observation compared to static image viewing) and cortical silent period (CSP) as putative markers of MNS-activity and frontal disinhibition, respectively, using Transcranial Magnetic Stimulation. While the prevalence of echo-phenomena was similar between mania and schizophrenia, incidental echolalia was more severe in mania. Participants with echo-phenomena (compared to those without) had significantly greater motor resonance with singlepulse (not with paired-pulse) stimuli, poorer theory of mind scores, higher frontal release reflexes but similar CSP, and greater symptom severity. None of these parameters significantly differed between participants with mania and schizophrenia. We observed relatively better phenotypic and neurophysiological characterization of major psychoses by categorizing participants based on the presence of echophenomena than clinical diagnoses. Higher putative MNS-activity was associated with poorer theory of mind in a hyper-imitative behavioral state., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Social interactions require awareness and understanding of the behavior of others. Mirror neurons, cells representing an action by self and others, have been proposed to be integral to the cognitive substrates that enable such awareness and understanding. Mirror neurons of the primate neocortex represent skilled motor tasks, but it is unclear if they are critical for the actions they embody, enable social behaviors, or exist in non-cortical regions. We demonstrate that the activity of individual VMHvl PR neurons in the mouse hypothalamus represents aggression performed by self and others. We used a genetically encoded mirror-TRAP strategy to functionally interrogate these aggression-mirroring neurons. We find that their activity is essential for fighting and that forced activation of these cells triggers aggressive displays by mice, even toward their mirror image. Together, we have discovered a mirroring center in an evolutionarily ancient region that provides a subcortical cognitive substrate essential for a social behavior., Competing Interests: Declaration of interests L.L. is a member of the advisory board for Cell., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Fighting is an intense experience not only for the executors but also for the observers. In the current issue of Cell, Yang et al. identified hypothalamic aggression mirror neurons, activated during both physical fighting and witnessing a fight, possibly representing a neural mechanism for understanding social experiences in other minds., Competing Interests: Declaration of interests The author declares no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: This study protocol aims to explore the effectiveness and neural mechanism of the integration of action observation therapy (AOT) and sensory observation therapy (SOT) for post-stroke patients on upper limb sensorimotor function., Methods and Analysis: This is a single-centre, single-blind, randomised controlled trial. A total of 69 patients with upper extremity hemiparesis after stroke will be recruited and randomly divided into an AOT group, a combined action observation and somatosensory stimulation therapy (AOT+SST) group, and a combined AOT and SOT (AOT+SOT) group in a 1:1:1 ratio. Each group will receive 30 min of daily treatment, five times weekly for 4 weeks. The primary clinical outcome will be the Fugl-Meyer Assessment for Upper Extremity. Secondary clinical outcomes will include the Box and Blocks Test, modified Barthel Index and sensory assessment. All clinical assessments and resting-state functional MRI and diffusion tensor imaging data will be obtained at pre-intervention (T1), post-intervention (T2) and 8 weeks of follow-up (T3)., Ethics and Dissemination: The trial was approved by the Ethics Committee of Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Chinese Traditional Medicine (Grant No. 2020-178). The results will be submitted to a peer-review journal or at a conference., Trial Registration Number: ChiCTR2000040568., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Facial expressions are indispensable in daily human communication. Previous neuroimaging studies investigating facial expression processing have presented pre-recorded stimuli and lacked live face-to-face interaction. Our paradigm alternated between presentations of real-time model performance and pre-recorded videos of dynamic facial expressions to participants. Simultaneous functional magnetic resonance imaging (fMRI) and facial electromyography activity recordings, as well as post-scan valence and arousal ratings were acquired from 44 female participants. Live facial expressions enhanced the subjective valence and arousal ratings as well as facial muscular responses. Live performances showed greater engagement of the right posterior superior temporal sulcus (pSTS), right inferior frontal gyrus (IFG), right amygdala and right fusiform gyrus, and modulated the effective connectivity within the right mirror neuron system (IFG, pSTS, and right inferior parietal lobule). A support vector machine algorithm could classify multivoxel activation patterns in brain regions involved in dynamic facial expression processing in the mentalizing networks (anterior and posterior cingulate cortex). These results indicate that live social interaction modulates the activity and connectivity of the right mirror neuron system and enhances spontaneous mimicry, further facilitating emotional contagion., Competing Interests: Declaration of Competing Interest The authors declare no competing financial or non-financial interests., (Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.)

Mirror neurons have been associated with empathy. People with psychopathic traits present low levels of empathy. To analyze this, a systematic review of fMRI studies of people with psychopathic traits during an emotional facial expression processing task was performed. The regions of interest were structures associated with the mirror neuron system: ventromedial prefrontal cortex (vmPFC), inferior parietal lobe (IPL), inferior frontal gyrus and superior temporal sulcus. The analysis was also extended to structures related to affective empathy (insula, amygdala and anterior cingulate cortex) and to two more emotional processing areas (orbitofrontal cortex and fusiform gyrus). Hypoactivation was more frequently observed in regions of the mirror neuron system from people with high psychopathic traits, as well as in the emotional processing structures, and those associated with affective empathy, except for the insula, where it presented higher activity. Differences were observed for all types of emotions. The results suggest that the mirror neuron system is altered in psychopathy and their relationship with affective empathy deficits is discussed.

The embodied self is rooted in the self-body in the "here and now". The senses of self-ownership and self-agency have been proposed as the basis of the sense of embodied self, and many experimental studies have been conducted on this subject. This review summarizes the experimental research on the embodied self that has been conducted over the past 20 years, mainly from the perspective of multisensory integration and sensorimotor integration regarding the self-body. Furthermore, the phenomenon of back projection, in which changes in an external object (e.g., a rubber hand) with which one has a sense of ownership have an inverse influence on the sensation and movement of one's own body, is discussed. This postulates that the self-body illusion is not merely an illusion caused by multisensory and/or sensorimotor integration, but is the incorporation of an external object into the self-body representation in the brain. As an extension of this fact, we will also review research on the mirror neuron system, which is considered to be the neural basis of recognition of others, and discuss how the neural basis of self-body recognition and the mirror neuron system can be regarded as essentially the same.

Empathy is the ability to understand (cognitive empathy) and to feel (affective empathy) what others feel. The aim of the study was to assess empathy deficit and neuronal correlates in Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI) and Alzheimer's Disease (AD) dementia. Twenty-four SCD, 41 MCI and 46 CE patients were included. Informer-rated Interpersonal Reactivity Index was used to explore cognitive (Perspective Taking-PT, Fantasy-FT) and affective (Empathic Concern-EC, Personal Distress-PD) empathy, before (T0) and after (T1) cognitive symptoms' onset. Emotion recognition ability was tested through Ekman-60 Faces Test. Cerebral FDG-PET SPM analysis was used to explore neural correlates underlying empathy deficits. FT-T1 scores were lower in AD compared to SCD (13.0 ± 8.0 vs 19.1 ± 4,7 p = 0.008), PD-T1 score were higher in AD compared to MCI and to SCD (27.00 ± 10.00 vs 25.3 ± 5.9 vs 20.5 ± 5.6, p = 0.001). A positive correlation was found between PT-T1 and metabolic disfunction of right middle gyrus (MFG) in MCI and AD. In AD group, a positive correlation between PT-T1 and insula and superior temporal gyrus (STG) metabolism was detected. A negative correlation was found between PD-T1 and superior parietal lobule metabolism in MCI, and between PD-T1 and STG metabolism in AD. Impairment of cognitive empathy starts at MCI stage. Increase of PD starts from preclinical phases and seems to be to be dissociated from cognitive decline. Loss of PT is related to a progressive involvement starting from right MFG in prodromal stage, extending to insula and STG in dementia. Heightened emotional contagion is probably related to derangement of mirror neurons systems in parietal regions in prodromal stages, and to impairment of temporal emotion inhibition system in advanced phases. Further studies are needed to clarify if alterations in emotional contagion might be a predictive feature of a cognitive decline driven by AD., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The amygdala is a core node in the social brain which exhibits structural and functional abnormalities in Autism spectrum disorder and there is evidence that the mirror neuron system (MNS) can functionally compensate for impaired emotion processing following amygdala lesions. In the current study, we employed an fMRI paradigm in 241 subjects investigating MNS and amygdala responses to observation, imagination and imitation of dynamic facial expressions and whether these differed in individuals with higher (n = 77) as opposed to lower (n = 79) autistic traits. Results indicated that individuals with higher compared to lower autistic traits showed worse recognition memory for fearful faces, smaller real-life social networks, and decreased left basolateral amygdala (BLA) responses to imitation. Additionally, functional connectivity between the left BLA and the left inferior frontal gyrus (IFG) as well as some other MNS regions was increased in individuals with higher autistic traits, especially during imitation of fearful expressions. The left BLA-IFG connectivity significantly moderated the autistic group differences on recognition memory for fearful faces, indicating that increased amygdala-MNS connectivity could diminish the social behavioral differences between higher and lower autistic trait groups. Overall, findings demonstrate decreased imitation-related amygdala activity in individuals with higher autistic traits in the context of increased amygdala-MNS connectivity which may functionally compensate for amygdala dysfunction and social deficits. Training targeting the MNS may capitalize on this compensatory mechanism for therapeutic benefits in Autism spectrum disorder., (Copyright © 2022. Published by Elsevier Inc.)

Embodied cognition is a theoretical perspective that considers every form of human knowledge and cognition "embodied", as they pass through bodily experience. The aim of this narrative review is to investigate the importance of mirror neurons system in EC, as well as the EC role in neurodegenerative diseases. This narrative review shows deep connections between body and mind: body states influence mental functions such as perception and reasoning, while mental states cause changes in the body, especially in neurodegenerative disorders. Indeed, abnormalities in EC were found in dementia, Parkinson's Disease and Amyotrophic Lateral sclerosis, also in the absence of other cognitive deficits, negatively affecting patients' outcomes. Exploiting EC mechanisms for rehabilitation purposes, also using innovation technologies, could be a promising therapeutic way to increase motor and cognitive outcomes in patients affected by different neurological disorders., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Background: The rehabilitation of paretic stroke patients uses a wide range of intervention programs to improve the function of impaired upper limb. A new rehabilitative approach, called action observation therapy (AOT) is based on the discovery of mirror neurons and has been used to improve the motor functions of adult stroke patients and children with cerebral palsy. Recently, virtual reality (VR) has provided the potential to increase the frequency and effectiveness of rehabilitation treatment by offering challenging and motivating tasks.  METHODS: The purpose of the present project is to design a randomized controlled six-month follow-up trial (RCT) to evaluate whether action observation (AO) added to standard VR (AO + VR) is effective in improving upper limb function in patients with stroke, compared with a control treatment consisting of observation of naturalistic scenes (CO) without any action content, followed by VR training (CO + VR)., Discussion: AO + VR treatment may provide an addition to the rehabilitative interventions currently available for recovery after stroke and could be utilized within standard sensorimotor training or in individualized tele-rehabilitation., Trial Registration: The trial has been prospectively registered on ClinicalTrials.gov. NCT05163210 . 17 December 2021., (© 2022. The Author(s).)

Contagious depression is a theory proposing that depression can be induced or triggered by our social environment. This theory is based on emotional contagion, the idea that affective states can be transferred during social interaction, since humans can use emotional contagion to communicate feelings and emotions in conscious and unconscious ways. This review presents behavioral, physiological, and neuroanatomical aspects of two essential contagious depression mechanisms, automatic mimicry and the mirror neuron system., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Learning to interact with the environment not only empowers the agent with manipulation capability but also generates information to facilitate building of action understanding and imitation capabilities. This seems to be a strategy adopted by biological systems, in particular primates, as evidenced by the existence of mirror neurons that seem to be involved in multi-modal action understanding. How to benefit from the interaction experience of the robots to enable understanding actions and goals of other agents is still a challenging question. In this study, we propose a novel method, deep modality blending networks (DMBN), that creates a common latent space from multi-modal experience of a robot by blending multi-modal signals with a stochastic weighting mechanism. We show for the first time that deep learning, when combined with a novel modality blending scheme, can facilitate action recognition and produce structures to sustain anatomical and effect-based imitation capabilities. Our proposed system, which is based on conditional neural processes, can be conditioned on any desired sensory/motor value at any time step, and can generate a complete multi-modal trajectory consistent with the desired conditioning in one-shot by querying the network for all the sampled time points in parallel avoiding the accumulation of prediction errors. Based on simulation experiments with an arm-gripper robot and an RGB camera, we showed that DMBN could make accurate predictions about any missing modality (camera or joint angles) given the available ones outperforming recent multimodal variational autoencoder models in terms of long-horizon high-dimensional trajectory predictions. We further showed that given desired images from different perspectives, i.e. images generated by the observation of other robots placed on different sides of the table, our system could generate image and joint angle sequences that correspond to either anatomical or effect-based imitation behavior. To achieve this mirror-like behavior, our system does not perform a pixel-based template matching but rather benefits from and relies on the common latent space constructed by using both joint and image modalities, as shown by additional experiments. Moreover, we showed that mirror learning (in our system) does not only depend on visual experience and cannot be achieved without proprioceptive experience. Our experiments showed that out of ten training scenarios with different initial configurations, the proposed DMBN model could achieve mirror learning in all of the cases where the model that only uses visual information failed in half of them. Overall, the proposed DMBN architecture not only serves as a computational model for sustaining mirror neuron-like capabilities, but also stands as a powerful machine learning architecture for high-dimensional multi-modal temporal data with robust retrieval capabilities operating with partial information in one or multiple modalities., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In 1992, the Laboratory of Human Physiology at the University of Parma (Italy) publish a study describing "mirror" neurons in the macaque that activate both when the monkey performs an action and when it observes an experimenter performing the same action. The research team behind this discovery postulates that the mirror neurons system is the neural basis of our ability to understand the actions of others, through the motor mapping of the observed action on the observer's motor repertory (direct-matching hypothesis). Nevertheless, this conception met serious criticism. These critics attempt to relativize their function by placing them within a network of neurocognitive and sensory interdependencies. In short, the essential characteristic of these neurons is to combine the processing of sensory information, especially visual, with that of motor information. Their elementary function would be to provide a motor simulation of the observed action, based on visual information from it. They can contribute, with other non-mirror areas, to the identification/prediction of the action goal and to the interpretation of the intention of the actor performing it. Studying the connectivity and high frequency synchronizations of the different brain areas involved in action observation would likely provide important information about the dynamic contribution of mirror neurons to "action understanding". The aim of this review is to provide an up-to-date analysis of the scientific evidence related to mirror neurons and their elementary functions, as well as to shed light on the contribution of these neurons to our ability to interpret and understand others' actions., (Copyright © 2021 L'Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.)

In order to inform the debate whether cortical areas related to action observation provide a pragmatic or a semantic representation of goal-directed actions, we performed 2 functional magnetic resonance imaging (fMRI) experiments in humans. The first experiment, involving observation of aimless arm movements, resulted in activation of most of the components known to support action execution and action observation. Given the absence of a target/goal in this experiment and the activation of parieto-premotor cortical areas, which were associated in the past with direction, amplitude, and velocity of movement of biological effectors, our findings suggest that during action observation we could be monitoring movement kinematics. With the second, double dissociation fMRI experiment, we revealed the components of the observation-related cortical network affected by 1) actions that have the same target/goal but different reaching and grasping kinematics and 2) actions that have very similar kinematics but different targets/goals. We found that certain areas related to action observation, including the mirror neuron ones, are informed about movement kinematics and/or target identity, hence providing a pragmatic rather than a semantic representation of goal-directed actions. Overall, our findings support a process-driven simulation-like mechanism of action understanding, in agreement with the theory of motor cognition, and question motor theories of action concept processing., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Objective: Stroke is one of the most debilitating neurological disorders that commonly results in both cognitive and motor dysfunctions. Although the recovery of gait is one of the main goals of patients with stroke, only 50-60% of the patients commonly reach this target. This study aimed to evaluate the effects of action observation training, based on mirror neurons, as an add-on therapy to the conventional physical rehabilitation on the gait performance of patients with stroke., Methods: Fourteen patients with chronic stroke were randomly assigned to the sham or the experimental group. Both groups received a 40-min conventional physical training following a 12-min observation training depicting exercises for the experimental group but nature pictures for the sham group each session. The patients' walking was recorded using a motion analysis system at baseline and after the 12-session intervention. Spatiotemporal parameters of gait and ground reaction forces were measured., Results: Significant improvements were found in most measured spatiotemporal parameters of gait on the unaffected side of the patients in the experimental group, while in the sham group, the recovery was observed only in the percentage of the stance phase. Regarding the affected side, the stride and step length of the patients in the experimental group were parameters with a significant amelioration., Conclusion: The results of this study showed that the action observation training had the potential to improve the walking quality of the patients with hemiplegia in the chronic phase of stroke., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Human cognitive and motor behavior is influenced by the social contexts. The aim of this systematic review is to investigate the impact of the social contexts on human behaviors. A systematic search of the literature was performed via Pub-Med/Medline, Web of sciences, Google scholar, Science direct, Springer-Link and EMBASE and 68 articles were selected. After applying all the inclusion and exclusion criteria, 16 articles were retained. The results show that the presence of other people and the social context influence motor behavior (i.e. movement duration, trajectory behavior, maximum speed) and cognitive behavior (reaction time). Studies have shown an improvement in performance in the presence of other people compared to the individual situation. However, other studies showed that the presence of other people led to deterioration in performance compared to the individual situation. The improvement of behavior is attributed to the social phenomenon of facilitation while the deterioration was explained by the conduct theory or the distraction conflict theory. These social phenomena of facilitation or inhibition could be related to the perception-action theory, which interferes with interaction with other. This, in turn, seems to be associated with neural circuits of mirror neurons and motor system.

Background: Destination memory defined as the ability to remember to whom we addressed a piece of information is found to be impaired in normal aging. Theories of affect development and research findings have shown that emotional charging improves performance on memory tasks, and also that Mu rhythm is desynchronized as an index of mirror neuron activation during such tasks., Objective: In this paper, we sought to investigate the differences in Mu rhythm during an emotional destination memory task, between younger and older adults., Methods: 16 cognitively normal older adults, recruited from Alzheimer's disease day center and 16 young adults, recruited via advertisements, participated in this experimental study. We investigated destination memory of emotionally charged faces (Emotional Destination Memory, EDM) while applying electroencephalograph (EEG) in real time in young versus older adults. We measured Mu rhythm in frontal, fronto-temporal and central areas. EEG data has been pre-processed, segmented in non-overlapping epochs, and independent component analysis (ICA) has been conducted to reject artifacts., Results: Results showed that young adults performed better than older adults in remembering facts associated with angry faces. Also, different neurophysiological activation was found, with older adults showing Mu suppression in frontal and fronto-temporal regions, specifically in F3, F7 and F8 electrodes, in contrast with young adults who showed Mu enhancement. Regarding within group differences, it was found that in the older adults group, electrodes F8 and central C3 were the most activated, while in the young adults group, C3 was the most activated electrode., Conclusion: The findings suggest better behavioral performance of young adults as a result of better cognitive state and adaptive bias. On a neurophysiological level, it is suggested that older adults employ Mu suppression, thus possible activation of mirror neurons, as a compensatory mechanism while mirroring properties are not spontaneously activated in young adults., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Ten years ago, Perspectives in Psychological Science published the Mirror Neuron Forum, in which authors debated the role of mirror neurons in action understanding, speech, imitation, and autism and asked whether mirror neurons are acquired through visual-motor learning. Subsequent research on these themes has made significant advances, which should encourage further, more systematic research. For action understanding, multivoxel pattern analysis, patient studies, and brain stimulation suggest that mirror-neuron brain areas contribute to low-level processing of observed actions (e.g., distinguishing types of grip) but not to high-level action interpretation (e.g., inferring actors' intentions). In the area of speech perception, although it remains unclear whether mirror neurons play a specific, causal role in speech perception, there is compelling evidence for the involvement of the motor system in the discrimination of speech in perceptually noisy conditions. For imitation, there is strong evidence from patient, brain-stimulation, and brain-imaging studies that mirror-neuron brain areas play a causal role in copying of body movement topography. In the area of autism, studies using behavioral and neurological measures have tried and failed to find evidence supporting the "broken-mirror theory" of autism. Furthermore, research on the origin of mirror neurons has confirmed the importance of domain-general visual-motor associative learning rather than canalized visual-motor learning, or motor learning alone.

The learning process in humans requires continuous contacts with environmental stimuli, especially during neurodevelopmental growth. These functions are assisted by the coding potential of mirror neurons to serve social interactions. This ability to learn imitating the observed behavior is no longer necessary during adulthood, and control mechanisms prevent automatic mirroring. However, children with Gilles de la Tourette syndrome could encounter coding errors at the level of the mirror neurons system as these cortical regions are themselves the ones affected in the syndrome. Combined with impulsivity, the resulting sign would be a manifest echopraxia that persists throughout adulthood, averting these individuals from the appraisal of a spot-on motor control.

The mirror neuron system (MNS) has been theorized to play a neurobiological role in a number of social cognitive abilities and is commonly indexed putatively in humans via interpersonal motor resonance (IMR) and mu suppression. Although both indices are thought to measure similar neuronal populations (i.e., "mirror neurons"), it has been suggested that these methods are unrelated, and therefore, incompatible. However, prior studies reporting no relationships were typically conducted in small and underpowered samples. Thus, we aimed to investigate this potential association in a large sample of neurotypical adults (N = 116; 72 females). Participants underwent transcranial magnetic stimulation (TMS), electromyography (EMG), and electroencephalography (EEG) during the observation of videos of actors performing grasping actions in order to index IMR and mu suppression (in beta, lower alpha, and upper alpha bandwidths). A series of linear regressions revealed no associations between IMR and each of the mu suppression bandwidths. Supplementary Bayesian analyses provided further evidence in favor of the null (B 01  = 8.85-8.93), providing further support for no association between the two indices of MNS activity. Our findings suggest that these two measures may indeed be unrelated indices that perhaps assess different neurophysiological aspects of the MNS. These results have important implications for future studies examining the MNS., (© 2021 Wiley Periodicals LLC.)

Objective: 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., Method: 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: 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., Conclusions: 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.

Objective. Motor imagery (MI), based on the theory of mirror neurons and neuroplasticity, can promote motor cortical activation in neurorehabilitation. The strategy of MI based on brain-computer interface (BCI) has been used in rehabilitation training and daily assistance for patients with hemiplegia in recent years. However, it is difficult to maintain the consistency and timeliness of receiving external stimulation to neural activation in most subjects owing to the high variability of electroencephalogram (EEG) representation across trials/subjects. Moreover, in practical application, MI-BCI cannot highly activate the motor cortex and provide stable interaction owing to the weakness of the EEG feature and lack of an effective mode of activation. Approach. In this study, a novel hybrid BCI paradigm based on MI and vestibular stimulation motor imagery (VSMI) was proposed to enhance the capability of feature response for MI. Twelve subjects participated in a group of controlled experiments containing VSMI and MI. Three indicators, namely, activation degree, timeliness, and classification accuracy, were adopted to evaluate the performance of the task. Main results. Vestibular stimulation could significantly strengthen the suppression of α and β bands of contralateral brain regions during MI, that is, enhance the activation degree of the motor cortex ( p < 0.01). Compared with MI, the timeliness of EEG feature-response achieved obvious improvements in VSMI experiments. Moreover, the averaged classification accuracy of VSMI and MI was 80.56% and 69.38%, respectively. Significance. The experimental results indicate that specific vestibular activity contributes to the oscillations of the motor cortex and has a positive effect on spontaneous imagery, which provides a novel MI paradigm and enables the preliminary exploration of sensorimotor integration of MI., (© 2021 IOP Publishing Ltd.)

Background: For 8 years, we have followed up a birth cohort comprising 241 mother-and-infant pairs living around the Da Nang airbase, a hot spot of dioxin contamination in Vietnam, and have reported the impacts of perinatal dioxin exposure on the neurodevelopment of children at various ages. In the present study, 9 years after birth, we investigated the effects of perinatal dioxin exposure on mu and theta rhythms by analyzing EEG power during the execution and observation of hand movements, which indicate mirror neuron system activity., Methods: One hundred fifty-five 9-year-old children (86 boys and 69 girls) from the Da Nang birth cohort participated in the EEG examination with free viewing of hand movements. The dioxin levels in their mothers' breast milk, measured 1 month after birth, were used as perinatal dioxin exposure markers. A log transform of the ratio of EEG power during execution or observation of the hand movements relative to the power during observation of a bouncing ball for theta and mu rhythms was used to evaluate mirror neuron activity., Results: In both brain hemispheres, the log power ratio in the theta band was significantly higher (i.e., less reduction of power) during observation of hand movements in girls exposed to high levels of TCDD. In boys, however, dioxin congeners other than TCDD, including HxCDDs and several PCDF congeners, contributed to increased log power ratios in the theta band. Particularly for PCDF congeners, the log power ratios in the lowest group among 4 exposure groups were lowest and significantly increased (i.e., decreasing reduction of power) with increasing dose., Conclusion: Perinatal TCDD exposure may influence the mirror neuron system of the brain, which plays an important role for social-emotional behavior in children, particularly in girls living in a hot spot of dioxin contamination in Vietnam., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In non-human primates, a subset of frontoparietal neurons (mirror neurons) respond both when an individual executes an action and when it observes another individual performing a similar action. 1-8 Mirror neurons constitute an observation and execution matching system likely involved in others' actions processing 3 , Here, we show that the forelimb motor cortex of rats contains neurons presenting mirror properties analogous to those observed in macaques. We provide this evidence by event-related potentials acquired by microelectrocorticography and intracortical single-neuron activity, recorded from the same cortical region during grasping execution and observation. Mirror responses are highly specific, because grasping-related neurons do not respond to the observation of either grooming actions or graspable food alone. These results demonstrate that mirror neurons are present already in species phylogenetically distant from primates, suggesting for them a fundamental, albeit basic, role not necessarily related to higher cognitive functions. Moreover, because murine models have long been valued for their superior experimental accessibility and rapid life cycle, the present finding opens an avenue to new empirical studies tackling questions such as the innate or acquired origin of sensorimotor representations and the effects of social and environmental deprivation on sensorimotor development and recovery.5 , 9 and in a large set of complex cognitive functions. 10 , 11 Here, we show that the forelimb motor cortex of rats contains neurons presenting mirror properties analogous to those observed in macaques. We provide this evidence by event-related potentials acquired by microelectrocorticography and intracortical single-neuron activity, recorded from the same cortical region during grasping execution and observation. Mirror responses are highly specific, because grasping-related neurons do not respond to the observation of either grooming actions or graspable food alone. These results demonstrate that mirror neurons are present already in species phylogenetically distant from primates, suggesting for them a fundamental, albeit basic, role not necessarily related to higher cognitive functions. Moreover, because murine models have long been valued for their superior experimental accessibility and rapid life cycle, the present finding opens an avenue to new empirical studies tackling questions such as the innate or acquired origin of sensorimotor representations and the effects of social and environmental deprivation on sensorimotor development and recovery., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

The discovery of mirror neurons in the macaque brain in the 1990s triggered investigations on putative human mirror neurons and their potential functionality. The leading proposed function has been action understanding: Accordingly, we understand the actions of others by 'simulating' them in our own motor system through a direct matching of the visual information to our own motor programmes. Furthermore, it has been proposed that this simulation involves the prediction of the sensory consequences of the observed action, similar to the prediction of the sensory consequences of our executed actions. Here, we tested this proposal by quantifying somatosensory attenuation behaviourally during action observation. Somatosensory attenuation manifests during voluntary action and refers to the perception of self-generated touches as less intense than identical externally generated touches because the self-generated touches are predicted from the motor command. Therefore, we reasoned that if an observer simulates the observed action and, thus, he/she predicts its somatosensory consequences, then he/she should attenuate tactile stimuli simultaneously delivered to his/her corresponding body part. In three separate experiments, we found a systematic attenuation of touches during executed self-touch actions, but we found no evidence for attenuation when such actions were observed. Failure to observe somatosensory attenuation during observation of self-touch is not compatible with the hypothesis that the putative human mirror neuron system automatically predicts the sensory consequences of the observed action. In contrast, our findings emphasize a sharp distinction between the motor representations of self and others., (© 2021 The Authors. European Journal of Neuroscience published by Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Seeing an agent perform an action typically triggers a motor simulation of that action in the observer's Mirror Neuron System (MNS). Over the past few years, it has become increasingly clear that during action observation the patterns and strengths of responses in the MNS are modulated by multiple factors. The first aim of this paper is therefore to provide the most comprehensive survey to date of these factors. To that end, 22 distinct factors are described, broken down into the following sets: six involving the action; two involving the actor; nine involving the observer; four involving the relationship between actor and observer; and one involving the context. The second aim is to consider the implications of these findings for four prominent theoretical models of the MNS: the Direct Matching Model; the Predictive Coding Model; the Value-Driven Model; and the Associative Model. These assessments suggest that although each model is supported by a wide range of findings, each one is also challenged by other findings and relatively unaffected by still others. Hence, there is now a pressing need for a richer, more inclusive model that is better able to account for all of the modulatory factors that have been identified so far., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Background and Objectives : The mirror neuron system in the sensorimotor region of the cerebral cortex is equally activated during both action observation and execution. Action observation training mimics the functioning of the mirror neuron system, requiring patients to watch and imitate the actions necessary to perform activities of daily living. StrokeCare is a user-friendly application based on the principles of action observation training, designed to assist people recovering from stroke. Therefore, when observing the daily life behavior provided in the StrokeCare app, whether the MNS is activated and mu inhibition appears. Materials and Methods : We performed electroencephalography (EEG) on 24 patients with chronic stroke (infarction: 11, hemorrhage: 13) during tasks closely related to daily activities, such as dressing, undressing, and walking. The StrokeCare app provided action videos for patients to watch. Landscape imagery observation facilitated comparison among tasks. We analyzed the mu rhythm from the C3, CZ, and C4 regions and calculated the mean log ratios for comparison of mu suppression values. Results: The EEG mu power log ratios were significantly suppressed during action observation in dressing, undressing, walking, and landscape conditions, in decreasing order. However, there were no significant activity differences in the C3, C4 and CZ regions. The dressing task showed maximum suppression after a color spectrum was used to map the relative power values of the mu rhythm for each task. Conclusions: These findings reveal that the human mirror neuron system was more strongly activated during observation of actions closely related to daily life activities than landscape images.

Action observation (AO) is a promising strategy for promoting motor function in neural rehabilitation. Recently, brain-computer interface (BCI)-AO game rehabilitation, which combines AO therapy with BCI technology, has been introduced to improve the effectiveness of rehabilitation. This approach can improve motor learning by providing feedback, which can be interactive in an observation task, and the game contents of the BCI-AO game paradigm can affect rehabilitation. In this study, the effects of congruent rather than incongruent feedback in a BCI-AO game on mirror neurons were investigated. Specifically, the mu suppression with congruent and incongruent BCI-AO games was measured in 17 healthy adults. The mu suppression in the central motor cortex was significantly higher with the congruent BCI-AO game than with the incongruent one. In addition, the satisfaction evaluation results were excellent for the congruent case. These results support the fact that providing feedback congruent with the motion of an action video facilitates mirror neuron activity and can offer useful guidelines for the design of BCI-AO games for rehabilitation.

Sensorimotor alpha suppression is present both during the observation and execution of actions, and is a commonly used tool to investigate neural mirroring in infancy. Köster et al. (2020) used this measure to investigate infants' motor cortex activation during the observation of action demonstrations and its relationship to subsequent imitation of these actions. Contrary to what is implied in the paper and to common findings in the literature, the study's results appear to suggest that the motor system was deactivated during the observation of the actions, and that greater deactivation during action observation was associated with a greater tendency to copy the action. Here we present potential methodological explanations for these unexpected findings and discuss them in relation to common recommendations in the field., Competing Interests: Declaration of Competing Interest None, (Copyright © 2021. Published by Elsevier Inc.)

Misophonia is a common disorder characterized by the experience of strong negative emotions of anger and anxiety in response to certain everyday sounds, such as those generated by other people eating, drinking, and breathing. The commonplace nature of these "trigger" sounds makes misophonia a devastating disorder for sufferers and their families. How such innocuous sounds trigger this response is unknown. Since most trigger sounds are generated by orofacial movements (e.g., chewing) in others, we hypothesized that the mirror neuron system related to orofacial movements could underlie misophonia. We analyzed resting state fMRI (rs-fMRI) connectivity ( N = 33, 16 females) and sound-evoked fMRI responses ( N = 42, 29 females) in misophonia sufferers and controls. We demonstrate that, compared with controls, the misophonia group show no difference in auditory cortex responses to trigger sounds, but do show: (1) stronger rs-fMRI connectivity between both auditory and visual cortex and the ventral premotor cortex responsible for orofacial movements; (2) stronger functional connectivity between the auditory cortex and orofacial motor area during sound perception in general; and (3) stronger activation of the orofacial motor area, specifically, in response to trigger sounds. Our results support a model of misophonia based on "hyper-mirroring" of the orofacial actions of others with sounds being the "medium" via which action of others is excessively mirrored. Misophonia is therefore not an abreaction to sounds, per se, but a manifestation of activity in parts of the motor system involved in producing those sounds. This new framework to understand misophonia can explain behavioral and emotional responses and has important consequences for devising effective therapies. SIGNIFICANCE STATEMENT Conventionally, misophonia, literally "hatred of sounds" has been considered as a disorder of sound emotion processing, in which "simple" eating and chewing sounds produced by others cause negative emotional responses. Our data provide an alternative but complementary perspective on misophonia that emphasizes the action of the trigger-person rather than the sounds which are a byproduct of that action. Sounds, in this new perspective, are only a "medium" via which action of the triggering-person is mirrored onto the listener. This change in perspective has important consequences for devising therapies and treatment methods for misophonia. It suggests that, instead of focusing on sounds, which many existing therapies do, effective therapies should target the brain representation of movement., (Copyright © 2021 Kumar et al.)

The mirror neuron system has dominated understanding of observational learning from a cognitive neuroscience perspective. Our review highlights the value of observational learning frameworks that integrate a more diverse and distributed set of cognitive and brain systems, including those implicated in sensorimotor transformations, as well as in more general processes such as executive control, reward, and social cognition. We argue that understanding how observational learning occurs in the real world will require neuroscientific frameworks that consider how visuomotor processes interface with more general aspects of cognition, as well as how learning context and action complexity shape mechanisms supporting learning from watching others., Competing Interests: Declaration of Interests The authors declare no competing interests in relation to this work., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Multi-layer neural networks, mirror neurons, and gnostic neurons are concepts that assign neural representations to mental representations of percepts and inner sensations. However, none of these approaches alone can explain the higher mental functions, which we observe in natural minds from the third and first-person perspectives through introspection. Recent concepts of preservation of chemical traces of sensory stimuli and hierarchical structures of postsynaptic associations represented by specifically organized groups of neurons combine these concepts and effectively explain much more complex mental functions. To find an operative model and understand how knowledge in the mind creates conscious sensations, we explain how perceptions, sensory impressions, and environment models gain their neural representations. It was pointed out ways to detect the similarity of structures representing previously remembered patterns to the mental and neuronal representations of new perceptions, ways of their associations, and principles of information processing. Supplemented, presented in earlier works, concepts of competition of representations stimulation and factors stimulating their action explain the mind's complex functions, including speech production and recognition. We postulate that using new methods of modelling the neural network's functions through the parallel physical process allows creating a physical model of natural and artificial, conscious, intelligent minds.

Background: Joint actions, described as a form of social interaction in which individuals coordinate their actions in space and time to bring about a change in the environment, rely on sensory-motor processes that play a role in the development of social skills. Two brain networks, associated with "mirroring" and "mentalizing", are engaged during these actions: the mirror neuron and the theory of mind systems. People with autism spectrum disorder (ASD) showed impairment in interpersonal coordination during joint actions. Studying joint action coordination in ASD will contribute to clarify the interplay between sensory-motor and social processes throughout development and the interactions between the brain and the behavior., Method: This review focused on empirical studies that reported behavioral and kinematic findings related to joint action coordination in people with ASD., Results: Literature on mechanisms involved in the joint action coordination impairment in ASD is still limited. Data are controversial. Different key-components of joint action coordination may be impaired, such as cooperative behavior, temporal coordination, and motor planning., Conclusions: Interpersonal coordination during joint actions relies on early sensory-motor processes that have a key role in guiding social development. Early intervention targeting the sensory-motor processes involved in the development of joint action coordination could positively support social skills., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Theoretical perspectives suggest that the mirror neuron system (MNS) is an important neurobiological contributor to empathy, yet empirical support is mixed. Here, we adopt a summary model for empathy, consisting of motor, emotional, and cognitive components of empathy. This review provides an overview of existing empirical studies investigating the relationship between putative MNS activity and empathy in healthy populations. 52 studies were identified that investigated the association between the MNS and at least one domain of empathy, representing data from 1044 participants. Our results suggest that emotional and cognitive empathy are moderately correlated with MNS activity, however, these domains were mixed and varied across techniques used to acquire MNS activity (TMS, EEG, and fMRI). Few studies investigated motor empathy, and of those, no significant relationships were revealed. Overall, results provide preliminary evidence for a relationship between MNS activity and empathy. However, our findings highlight methodological variability in study design as an important factor in understanding this relationship. We discuss limitations regarding these methodological variations and important implications for clinical and community translations, as well as suggestions for future research.

Previous studies based on an assumption of connectivity stationarity reported disconnections in mirror neuron system (MNS) and mentalizing networks of schizophrenic brains with social cognitive disruptions. However, recent studies demonstrated that functional brain connections are dynamic, and static connectivity metrics fail to capture time-varying properties of functional connections. The present study used a dynamic functional connectivity (dFC) method to test whether alterations of functional connectivity in the two networks are time-varying in adolescent-onset schizophrenia (AOS) patients. We collected resting-state fMRI data from 28 patients with AOS and 22 matched healthy controls. Static functional connectivity and dFC were used to explore the connectivity difference in the MNS and mentalizing networks between the two groups, respectively. Then a Pearson's correlation analysis between the connectivity showing intergroup differences and clinical scores was conducted in the AOS group. Compared with static functional connectivity analyses, dFC revealed state-specific connectivity decreases within the MNS network in the AOS group. Additionally, the dFC between the left middle temporal gyrus and left V5 was negatively correlated with the item2 of PANSS negative scores across all the AOS patients. Our findings suggest that social dysfunctions in AOS patients may be associated with the altered integrity and interaction of the MNS and mentalizing networks, and the functional impairments in the MNS are dynamic over time., (Copyright © 2020 Elsevier B.V. and Japan Neuroscience Society. All rights reserved.)

Lay Abstract: The mirror neuron system has been argued to be a key brain system responsible for understanding the actions of others and for imitation. It has therefore been proposed that problems within this system could explain the social difficulties experienced by people with autism spectrum condition. This idea is referred to as the broken mirror hypothesis. However, research has produced insufficient evidence to support the broken mirror hypothesis in its original form. Therefore, two other models have been suggested: EP-M model and the social top-down response modulation (STORM) model. All models suggest something is different regarding the mirror neuron system in autism spectrum condition: either within the mirror neuron system itself or within the systems that control the activity of the mirror neuron system. This literature review compares these three models in regard to recent neuroscientific investigations. This review concludes that there is insufficient support for both the broken mirror hypothesis, but converging evidence supports an integrated EP-M and STORM model.

Training of a musical skill is known to produce a distributed neural representation of the ability to perceive music and perform musical tasks. In the present study we tested the hypothesis that the audiovisual perception of music involves a wider activation of multimodal sensory and sensorimotor structures in the brain, including those containing mirror neurons. We mapped the activation of brain areas during passive listening and viewing of the first 40 s of "Ode to Joy" being played on the piano by an expert pianist. To do this we performed brain functional magnetic resonance imaging during the presentation of 6 different stimulus contrasts pertaining to that musical melody in a pseudo-randomized order. Group data analysis in musically trained and untrained adults showed robust activation in broadly distributed occipitotemporal, parietal and frontal areas in trained subjects and much restricted activation in untrained subjects. A visual stimulus contrast focusing on the visual motion percept of moving fingers on piano keys revealed selective bilateral activation of a locus corresponding to the V5/MT area, which was significantly more pronounced in trained subjects and showed partial linear dependence on the duration of training on the left side. Quantitative analysis of individual brain volumes confirmed a significantly greater and wider spread of activation in trained compared to untrained subjects. These findings support the view that audiovisual perception of music and musical gestures in trained musicians involves an expanded and widely distributed neural representation formed due to experience-dependent plasticity., (Copyright © 2020 IBRO. Published by Elsevier Ltd. All rights reserved.)

In the search for the function of mirror neurons, a previous study reported that F5 mirror neuron responses are modulated by the value that the observing monkey associates with the grasped object. Yet we do not know whether mirror neurons are modulated by the expected reward value for the observer or also by other variables, which are causally dependent on value (e.g., motivation, attention directed at the observed action, arousal). To clarify this, we trained two rhesus macaques to observe a grasping action on an object kept constant, followed by four fully predictable outcomes of different values (2 outcomes with positive and 2 with negative emotional valence). We found a consistent order in population activity of both mirror and nonmirror neurons that matches the order of the value of this predicted outcome but that does not match the order of the above-mentioned value-dependent variables. These variables were inferred from the probability not to abort a trial, saccade latency, modulation of eye position during action observation, heart rate, and pupil size. Moreover, we found subpopulations of neurons tuned to each of the four predicted outcome values. Multidimensional scaling revealed equal normalized distances of 0.25 between the two positive and between the two negative outcomes suggesting the representation of a relative value, scaled to the task setting. We conclude that F5 mirror neurons and nonmirror neurons represent the observer's predicted outcome value, which in the case of mirror neurons may be transferred to the observed object or action. NEW & NOTEWORTHY Both the populations of F5 mirror neurons and nonmirror neurons represent the predicted value of an outcome resulting from the observation of a grasping action. Value-dependent motivation, arousal, and attention directed at the observed action do not provide a better explanation for this representation. The population activity's metric suggests an optimal scaling of value representation to task setting.