Mu-ERD reflects action understanding, but the effect is small

Since the mid-2000's, many researchers have provided evidence that mu-ERD measured at the motor cortex may reflect the collective activation of upstream brain regions associated with the human mirror system during action observation paradigms; however, several recent papers have called these findings into question. Our study represents an effort to address these criticisms. In our study, participants watched videos in which the type of grip an actor used to grasp a coffee mug either conveyed the goal with 100 % certainty (unambiguous-goal trials), or offered no predictive information (ambiguous-goal trials). If mu-ERD indexes action understanding, then we predicted that mu-ERD should increase while participants watched the actor grasp the mug for unambiguous-goal trials, but not for ambiguous-goal trials. During the intervals where participants watched the actor execute the goal, mu-ERD for unambiguous-goal trials should remain steady, whereas mu-ERD for ambiguous-goal trials should now increase. Conversely, if mu-ERD does not index action understanding, and instead reflects general motor processes associated with action (such as the activation of population vectors in M1 or planning processes), then mu-ERD should show no difference across conditions. Across most comparisons, we found that mu-ERD mostly reflected general motor processes; however, there was a small effect when participants overserved unambiguous-goal trials while watching the actor execute the goal suggesting that mu-ERD does reflect mirroring, but the effect is small.

Effects of a single session action observation training on hand function in healthy young adults: a randomised controlled assessor and participants-blinded trial

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.

Guidelines for reporting action simulation studies (GRASS): Proposals to improve reporting of research in motor imagery and action observation

Researchers from multiple disciplines have studied the simulation of actions through motor imagery, action observation, or their combination. Procedures used in these studies vary considerably between research groups, and no standardized approach to reporting experimental protocols has been proposed. This has led to under-reporting of critical details, impairing the assessment, replication, synthesis, and potential clinical translation of effects. We provide an overview of issues related to the reporting of information in action simulation studies, and discuss the benefits of standardized reporting. We propose a series of checklists that identify key details of research protocols to include when reporting action simulation studies. Each checklist comprises A) essential methodological details, B) essential details that are relevant to a specific mode of action simulation, and C) further points that may be useful on a case-by-case basis. We anticipate that the use of these guidelines will improve the understanding, reproduction, and synthesis of studies using action simulation, and enhance the translation of research using motor imagery and action observation to applied and clinical settings.

Observational Learning in Surgical Skill Development

Observation plays a key role in the development of surgical skills, as it allows trainees to learn from experts and improve their performance through trial-and-error practice. This process, known as motor learning, involves the creation of new neural pathways that enable precise control of surgical instruments through hand movements. In recent years, there has been a shift towards minimally invasive surgery, which requires surgeons to continually learn new motor skills to control specialized instrumentation. Motor learning can be enhanced through repetition and the observation of expert performances. Observational learning is particularly useful when it is used in combination with physical practice, as it can provide hints and clues about important aspects of the task that may not be immediately apparent through verbal instruction alone. The role of mirror neurons, which are activated both when an action is performed and when it is observed, is also important in the process of observational learning. By understanding the mechanisms behind observational learning and the factors that influence its effectiveness, trainers can optimize the use of this method in surgical training.

Brain-Computer Interface Training of mu EEG Rhythms in Intellectually Impaired Children with Autism: A Feasibility Case Series

Prior studies show that neurofeedback training (NFT) of mu rhythms improves behavior and EEG mu rhythm suppression during action observation in children with autism spectrum disorder (ASD). However, intellectually impaired persons were excluded because of their behavioral challenges. We aimed to determine if intellectually impaired children with ASD, who were behaviorally prepared to take part in a mu-NFT study using conditioned auditory reinforcers, would show improvements in symptoms and mu suppression following mu-NFT. Seven children with ASD (ages 6-8; mean IQ 70.6 ± 7.5) successfully took part in mu-NFT. Four cases demonstrated positive learning trends (hit rates) during mu-NFT (learners), and three cases did not (non-learners). Artifact-creating behaviors were present during tests of mu suppression for all cases, but were more frequent in non-learners. Following NFT, learners showed behavioral improvements and were more likely to show evidence of a short-term increase in mu suppression relative to non-learners who showed little to no EEG or behavior improvements. Results support mu-NFT's application in some children who otherwise may not have been able to take part without enhanced behavioral preparations. Children who have more limitations in demonstrating learning during NFT, or in providing data with relatively low artifact during task-dependent EEG tests, may have less chance of benefiting from mu-NFT. Improving the identification of ideal mu-NFT candidates, mu-NFT learning rates, source analyses, EEG outcome task performance, population-specific artifact-rejection methods, and the theoretical bases of NFT protocols, could aid future BCI-based, neurorehabilitation efforts.

Mirror neurons and empathy-related regions in psychopathy: systematic review, meta-analysis, and a working model

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.

Motor cognition in schizophrenia: Control of automatic imitation and mapping of action context are reduced

The ability to imitate is considered impaired in schizophrenia patients. This assumption, however, is based on heterogeneous studies mostly targeting voluntary imitation, e.g., pantomime. Studies on automatic imitation, however, and on underlying mechanisms of top-down inhibition of automatic imitation and contextual modulation in schizophrenia are highly limited. We employed two sensorimotor paradigms to examine imitation-inhibition and action context mapping in 37 schizophrenia patients and 36 matched controls. In the first experiment, participants performed finger lifts while observing a hand executing compatible or incompatible finger lifts from the third-person perspective. The compatibility or incompatibility of these finger lifts affected participants' reaction times (RTs). The comparison of between-condition RT differences shows a larger movement compatibility effect in schizophrenia than in controls. The second experiment involved finger lifts while watching a still hand, from the first-person perspective, with constrained fingers that either corresponded or did not correspond to the participants' response fingers. Here, schizophrenia patients showed a diminished RT slowing in corresponding constraint trials. While the former results provide evidence for an impaired control of imitation in patients with schizophrenia, the latter results indicate a reduced encoding of action context. In conclusion, this study provides the first evidence for deficits of top-down control of imitation and motor context processing in the same sample of schizophrenia patients.

Mirror therapy in upper limb motor recovery and activities of daily living, and its neural correlates in stroke individuals: A systematic review and meta-analysis

Available literature indicates that 30-66% of stroke survivors present persistent upper limb impairment. Considering the importance of upper limb function for activities of daily living, it is necessary to investigate neurorehabilitation therapies that could improve the upper limb function. Among stroke complementary therapies, mirror therapy has shown promising results. Thus, the aim of this systematic review and meta-analyses was to review and synthesize clinical evidence on the use of mirror therapy on motor recovery of the upper limb and activities of daily living, and its neural correlates in stroke patients. The literature search was carried out in PubMed, ISI Web of Science, and Scopus databases. Twenty-nine studies met all the inclusion criteria. Two meta-analyses were conducted to compare mirror therapy with sham therapy on two general measures, upper limb assessment and activities of daily living. Results suggest that mirror therapy was better than sham therapy, mainly in the subacute phase, but the meta-analyses were nonsignificant. In addition, mirror therapy and cortical reorganization showed potential neural correlates, such as the primary motor cortex, precuneus, and posterior cingulate cortex.

[Mirror neurons, neural substrate of action understanding?]

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.

What modulates the Mirror Neuron System during action observation?: Multiple factors involving the action, the actor, the observer, the relationship between actor and observer, and the context

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.

Age-related Differences in Mu rhythm during Emotional Destination Memory

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 on development of affect and research findings have shown that emotional charge improves performance in 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 the 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, a difference in 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. With regard to the 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 a better cognitive state and adaptive bias. On a neurophysiological level, it is suggested that older adults employ Mu suppression, thus activation of mirror neurons is a possible compensatory mechanism while mirroring properties are not spontaneously activated in young adults.

The role of mirror mechanism in the recovery, maintenance, and acquisition of motor abilities

While it is well documented that the motor system is more than a mere implementer of motor actions, the possible applications of its cognitive side are still under-exploited, often remaining as poorly organized evidence. Here, we will collect evidence showing the value of action observation treatment (AOT) in the recovery of impaired motor abilities for a vast number of clinical conditions, spanning from traumatological patients to brain injuries and neurodegenerative diseases. Alongside, we will discuss the use of AOT in the maintenance of appropriate motor behavior in subjects at risk for events with dramatic physical consequences, like fall prevention in elderly people or injury prevention in sports. Finally, we will report that AOT can help to tune existing motor competencies in fields requiring precise motor control. We will connect all these diverse dots into the neurophysiological scenario offered by decades of research on the human mirror mechanism, discussing the potentialities for individualization. Empowered by modern technologies, AOT can impact individuals' safety and quality of life across the whole lifespan.

Is the Putative Mirror Neuron System Associated with Empathy? A Systematic Review and Meta-Analysis

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.

Beyond action observation: Neurobehavioral mechanisms of memory for visually perceived bodies and actions

Examining the processing of others' body-related information in the perceivers' brain (action observation) is a key topic in cognitive neuroscience. However, what happens beyond the perceptual stage, when the body is not within view and it is transformed into an associative form that can be stored, updated, and later recalled, remains poorly understood. Here we examine neurobehavioural evidence on the memory processing of visually perceived bodily stimuli (dynamic actions and images of bodies). The reviewed studies indicate that encoding and maintaining bodily stimuli in memory recruits the sensorimotor system. This process arises when bodily stimuli are either recalled through action recognition or reproduction. Interestingly, the memory capacity for these stimuli is rather limited: only 2 or 3 bodily stimuli can be simultaneously held in memory. Moreover, this process is disrupted by increasing concurrent bodily operations; i.e., moving one's body, seeing or memorising additional bodies. Overall, the evidence suggests that the neural circuitry allowing us to move and feel ourselves supports the encoding, retention, and memory recall of others' visually perceived bodies.

I'll cry instead: Mu suppression responses to tearful facial expressions

Tears are a facial expression of emotion that readily elicit empathic responses from observers. It is currently unknown whether these empathic responses to tears are influenced by specific neural substrates. The EEG mu rhythm is one method of investigating the human mirror neuron system, purported to underlie the sharing of affective states and a facilitator of social cognition. The purpose of this research was to explore the mu response to tearful expressions of emotion. Sixty-eight participants viewed happy and sad faces, both with and without tears, in addition to a neutral control condition. Participants first completed an emotion discrimination task, and then an imitation condition where they were required to mimic the displayed expression. Mu enhancement was found in response to the discrimination task, whilst suppression was demonstrated in response to the imitation condition. Examination of the suppression scores revealed that greater suppression was observed in response to happy-tear and sad tear-free expressions. Planned contrasts exploring suppression to neutral faces revealed no significant differences between emotional and neutral conditions. The mu response to neutral expressions resembled that of the happy-tear and the sad tear-free conditions, lending support to the idea that ambiguous emotional expressions require greater sensorimotor engagement. This study provides preliminary evidence for the role of the mirror neuron system in discerning tearful expressions of emotion in the absence of context.

A sensorimotor control framework for understanding emotional communication and regulation

Our research team was asked to consider the relationship of the neuroscience of sensorimotor control to the language of emotions and feelings. Actions are the principal means for the communication of emotions and feelings in both humans and other animals, and the allostatic mechanisms controlling action also apply to the regulation of emotional states by the self and others. We consider how motor control of hierarchically organised, feedback-based, goal-directed action has evolved in humans, within a context of consciousness, appraisal and cultural learning, to serve emotions and feelings. In our linguistic analysis, we found that many emotion and feelings words could be assigned to stages in the sensorimotor learning process, but the assignment was often arbitrary. The embodied nature of emotional communication means that action words are frequently used, but that the meanings or senses of the word depend on its contextual use, just as the relationship of an action to an emotion is also contextually dependent.

Visual feedback therapy for restoration of upper limb function of stroke patients

Objective

To investigate the effects of mirror neuron theory-based visual feedback therapy (VFT) on restoration of upper limb function of stroke patients and motor-related cortical function using functional magnetic resonance imaging (fMRI).

Methods

Hemiplegic stroke patients were randomly divided into two groups: a VFT group and a control (CTL) group. Sixteen patients in the VFT group received conventional rehabilitation (CR) and VFT for 8 weeks, while 15 patients in the CTL group received only CR. The Barthel Index (BI) was used to assess the activities of daily living at baseline and the 8^th week of the recovery training period. The Fugl–Meyer assessment (FMA) scale, somatosensory evoked potential (SEP), and fMRI were used to evaluate the recovery effect of the training therapies. The latencies and amplitudes of N9 and N20 were measured. Before recovery training, fMRI was performed for all patients in the VFT and CTL groups. In addition, 17 patients (9 in the VFT group and 8 in the CTL group) underwent fMRI for follow-up 2 months after treatment. Qualitative data were analyzed using the χ² test. The independent sample t-test was used to compare normally distributed data among different groups, the paired sample t-test was used to compare data between groups, and the non-parametric test was used to comparing data without normal distribution among groups.

Results

There were no significant differences between the VFT and CTL group in all indexes. However, after 8 weeks of recovery training, these indexes were all significantly improved (P < 0.05). As compared with the CTL group, the FMA scores, BI, and N9/N20 latencies and amplitudes of SEP in the VFT group were significantly improved (P < 0.05). Two months after recovery training, fMRI showed that the degree of activation of the bilateral central anterior gyrus, parietal lobe, and auxiliary motor areas was significantly higher in the VFT group than the CTL group (P < 0.05).

Conclusions

VFT based on mirror neuron theory is an effective approach to improve upper extremity motor function and daily activity performance of stroke patients. The therapeutic mechanism promotes motor relearning by activating the mirror neuron system and motor cortex. SEP amplitudes increased only for patients who participated in visual feedback. VFT promotes sensory-motor plasticity and behavioral changes in both the motor and sensory domains.

Action observation training for rehabilitation in brain injuries: a systematic review and meta-analysis

Background

To systematically review and analyse the effects of Action Observation Training on adults and children with brain damage.

Methods

Seven electronic databases (Cochrane, EBSCO, Embase, Eric, PubMed, Scopus and Web of Science) were searched up to 16 September 2018 to select Randomized Controlled Trials focused on adults and children with brain damage that included AOT training on upper and/or lower limb carried out for at least 1 week. Identification of studies and data extraction was conducted with two reviewers working independently. Oxford Centre for Evidence-based Medicine (March2009) – Levels of Evidence and Physiotherapy Evidence Database scale were used to grade studies. The data collected from the articles were analysed using software R, version 3.4.3. Hedge’s g values were calculated and effect size estimates were pooled across studies. Separate meta-analyses were carried out for each ICF domain (i.e. body function and activity) for upper and lower limb.

Results

Out of the 210 records identified after removing duplicates, 22 were selected for systematic review and 19 were included in the meta-analysis. Thirteen studies included in the meta-analysis focused on upper limb rehabilitation (4 in children and 9 in adults) and 6 on lower limb rehabilitation (only studies in adults). A total of 626 patients were included in the meta-analysis. An overall statistically significant effect size was found for upper limb body function (0.44, 95% CI: [0.24, 0.64], p < 0.001) and upper limb activity domain (0.47, 95% CI: [0.30, 0.64], p < 0.001). For lower limb, only the activity domain was analysed, revealing a statistically significant overall effect size (0.56, 95% CI: [0.28, 0.84], p < 0.001).

Conclusions

Action Observation Training (AOT) is an innovative rehabilitation tool for individuals with brain damage, which shows promising results in improving the activity domain for upper and lower limbs, and also the body function domain for the upper limb. However, the examined studies lack uniformity and further well-designed, larger controlled trials are necessary to determine the most suitable type of AOT particularly in children.

Systematic review registration

CRD42019119600.

The Role of Sensorimotor Processes in Pain Empathy

Pain is a salient, aversive sensation which motivates avoidance, but also has a strong social signaling function. Numerous studies have shown that regions of the nervous system active in association with first-hand pain are also active in response to the pain of others. When witnessing somatic pain, such as seeing bodies in painful situations, significant activations occur not only in areas related to the processing of negative emotions, but also in neuronal structures engaged in somatosensation and the control of skeletal muscles. These empathy-related sensorimotor activations are selectively reviewed in this article, with a focus on studies using electrophysiological methods and paradigms investigating responses to somatic pain. Convergent evidence from these studies shows that these activations (1) occur at multiple levels of the nervous system, from the spinal cord up to the cerebral cortex, (2) are best conceptualized as activations of a defensive system, in line with the role of pain to protect body from injury, and (3) contribute to establishing a matching of psychological states between the sufferer and the observer, which ultimately supports empathic understanding and motivate prosocial action. Future research should thus focus on how these sensorimotor responses are related to higher-order empathic responses, including affective sharing and emotion regulation, and how this motivates approach-related prosocial behaviors aimed at alleviating the pain and suffering of others.

Does rTMS on brain areas of mirror neurons lead to higher improvements on symptom severity and empathy compared to the rTMS standard procedure? - Results from a double-blind interventional study in individuals with major depressive disorders

BACKGROUND

A key feature of major depressive disorders is the lack of emotional processing such as empathy. To counter this, we tested, if brain stimulation on areas rich of mirror neurons on the left inferior parietal lobe (lIPL) might improve emotional processing, including empathy, compared to a standard brain stimulation on the left dorsolateral prefrontal cortex (lDLPFC).

METHODS

Twenty inpatients (mean age: 38.9 years; 55% females) with severe major depressive disorders and stable treatment of sertraline at therapeutic dosages were randomly assigned to either the rTMS condition on areas of mirror neuron stimulation, that is, the left inferior parietal lobe (rTMS-lIPL), or to the left dorsolateral prefrontal cortex (rTMS-lDLPFC; control condition). Interventions lasted for two consecutive weeks (2 × 5 interventions of 30'). At baseline and at the end of the study, patients completed questionnaires on current mood state and emotion regulation. In parallel, experts rated patients' depression severity.

RESULTS

Mood improved over time, but more so in the control condition, compared to the rTMS-lIPL condition (medium-large effect sizes). Emotion regulation improved over time; specifically, empathy improved, but only in the rTMS-lIPL condition, compared to the control condition. Symptoms of depression decreased over time, but more so in the rTMS- lIPL condition.

CONCLUSIONS

The pattern of results suggests that among inpatients with severe major depressive disorders, and compared to a standard procedure of rTMS, rTMS targeting on areas rich of mirror neurons appeared to improve emotion regulation, and specifically empathy, while there was no advantage on acute mood.

Anticipatory effect of execution on observation: an approach using ExoPinch finger robot

Background/aim

This study aims to explore the mirror neuron system (MNS) involvement using mu (8–12 Hz)/beta (15–25 Hz) band suppression in an action observation-execution paradigm.

Materials and methods

Electrophysiological (EEG) data from 16 electrodes were recorded while 8 participants observed video clips of a hand squeezing a spring. Specifically, the effect of anticipated execution on observation was studied. For this purpose, a fully actuated finger exoskeleton robot was utilized to synchronize observation and execution and to control the execution condition for the partici-pants. Anticipatory effect was created with a randomized robot accompany session.

Results

The results showed that the observational condition (with or without anticipation) interacted with hemisphere at central chan-nels near somatosensory cortex. Additionally, we explored the response of MNS on the kinetics features of visual stimuli (hard or soft spring).

Conclusion

he results showed an interaction effect of kinetics features and hemisphere at frontal channels corresponding nearly to the ventral premotor cortex area of the brain. The activation of mirror neurons in this area plays a crucial role in observational learning. Based on our results, we propose that specific type of visual stimuli can be combined with the functional abilities of the MNS in the ac-tion observation based treatment of hand motor dysfunction of stroke patients to have a positive additional impact.

Finger-counting observation interferes with number processing

Aim of this study was to investigate the association between finger and number representation in a task in which students had to perform arithmetic calculations and decide whether the provided solution was correct or incorrect, while a pair of task-irrelevant hands gesturally expressed the same or a different number. In particular we aimed at investigating whether irrelevant finger-counting might interfere with arithmetic computing, thus showing the existence of a strict neural association between the two processes. 20 volunteers took part to the investigation and EEG/ERPs were recorded from 128 scalp sites. P300 amplitude was greater to correct than incorrect solutions. Accuracy was higher when there was no conflict between the two sets of information A numerical error-related negativity (nERN) was elicited by incorrect solutions, and also by correct solutions when the finger-counting was incongruent. Source analysis applied to the incongruent minus congruent difference showed that when finger-counting was incorrect nERN mostly derived from medial and superior prefrontal cortex activity (supporting action monitoring and suppression). Conversely, when finger-counting indicated the correct solution brain activation included occipital areas, somatosensory regions and visuomotor mirror areas, inferior and superior temporal cortex, reflecting attentional orienting toward the hands. In both cases, the left angular gyrus (BA39) was found active during conjoined digit/number processing, suggesting a strict neural association between finger and digit processing. The present findings help explaining why a lesion in the left parietal cortex may simultaneously lead to finger apraxia and acalculia (Gertsmann syndrome).

Diminished modulation of motor cortical reactivity during context-based action observation in schizophrenia

BACKGROUND

Deficient mirror neuron system (MNS)-activity is associated with social cognition deficits in schizophrenia. However, it is not known how socio-emotional contexts modulate the MNS-response. In a Transcranial Magnetic Stimulation (TMS)-experiment, we aimed to compare putative MNS-responses to action observation stimuli with and without a context, in patients with schizophrenia and healthy subjects.

METHOD

TMS-evoked motor cortical reactivity was measured by single and paired [short interval intracortical inhibition (SICI) and facilitation (ICF)] pulse-paradigms in schizophrenia patients (n = 39) and healthy subjects (n = 28) while they observed three experimental-blocks: a static image, a neutral hand action (NA) and a context-based hand action (CA). The degree of cortical reactivity facilitation with the two action observation blocks, relative to the static block provided indirect measures of premotor MNS-activity. A subset of patients (n = 31) also underwent comprehensive social cognition assessments.

RESULTS

RMANOVA demonstrated significantly higher cortical reactivity during the CA-block in both groups (all TMS-paradigms); albeit significantly less pronounced in patients (SICI and ICF paradigms). MNS-activity during the CA-block was significantly higher compared to that during the NA-block in both groups (all TMS-paradigms), but significantly less pronounced in patients (SICI and single-pulse paradigms). MNS-activity during the CA-block measured by the ICF paradigm was positively correlated with social cognition performance.

CONCLUSION

Providing a context to the action modulates MNS-activity. This modulation is diminished in schizophrenia patients, suggestive of a diminished sensorimotor associative learning process. This novel, ecologically valid paradigm to tap into the MNS may serve as a neuro-marker of social cognition performance in schizophrenia.

Empathy is not in our genes

In academic and public life empathy is seen as a fundamental force of morality - a psychological phenomenon, rooted in biology, with profound effects in law, policy, and international relations. But the roots of empathy are not as firm as we like to think. The matching mechanism that distinguishes empathy from compassion, envy, schadenfreude, and sadism is a product of learning. Here I present a dual system model that distinguishes Empathy¹, an automatic process that catches the feelings of others, from Empathy², controlled processes that interpret those feelings. Research with animals, infants, adults and robots suggests that the mechanism of Empathy¹, emotional contagion, is constructed in the course of development through social interaction. Learned Matching implies that empathy is both agile and fragile. It can be enhanced and redirected by novel experience, and broken by social change.

A touching Sight: EEG/ERP correlates for the vicarious processing of affectionate touch

Observers can simulate aspects of other people's tactile experiences. We asked whether they do so when faced with full-body social interactions, whether emerging representations go beyond basic sensorimotor mirroring, and whether they depend on processing goals and inclinations. In an EEG/ERP study, we presented line-drawn, dyadic interactions with and without affectionate touch. In an explicit and an implicit task, participants categorized images into touch versus no-touch and same versus opposite sex interactions, respectively. Modulations of central Rolandic rhythms implied that affectionate touch displays engaged sensorimotor mechanisms. Additionally, the late positive potential (LPP) being larger for images with as compared to without touch pointed to an involvement of higher order socio-affective mechanisms. Task and sex modulated touch perception. Sensorimotor responding, indexed by Rolandic rhythms, was fairly independent of the task but appeared less effortful in women than in men. Touch induced socio-affective responding, indexed by the LPP, declined from explicit to implicit processing in women and disappeared in men. In sum, this study provides first evidence that vicarious touch from full-body social interactions entails shared sensorimotor as well as socio-affective experiences. Yet, mental representations of touch at a socio-affective level are more likely when touch is goal relevant and observers are female. Together, these results outline the conditions under which touch in visual media may be usefully employed to socially engage observers.

The introduction of IMITATE-R and its comparison with the IMITATE treatment method in the naming ability of two Persian speaking aphasic patients

Mirror neurons that have properties of audio/visual-acuity play a key role in imitation of movement performance. Since speech is a collection of coordinated movements in the producing organs, observing and imitation of speech movements can stimulate these neurons. In addition, observing hand movements trigger some actions related to the verbal cortex in the network of mirror neurons. According to the hypothesis of mirror neurons, new therapeutic approaches, including IMITATE, have been proposed for patients with aphasia. In the present study, using the IMITATE programme, a new therapeutic approach called IMITATE-R was planned based on observation of oral movements, hand gestures, and imitation of oral movements. Afterward, the IMITATE and IMITATE-R methods were compared with each other on naming skills of two Persian people with aphasia. The results showed that the rate of benefit from each treatment in each client was proportional to its individual and linguistic characteristics; however, in both patients, the IMITATE-R method was more effective in improving the naming skill. The results of this study were aimed at confirming the hypothesis of mirror neurons and the use of methods are based on action-observation for the treatment of patients with aphasia.

Determining the potential sites of neural adaptation to cross-education: implications for the cross-education of muscle strength

Cross-education describes the strength gain in the opposite, untrained limb following a unilateral strength training program. Since its discovery in 1894, several studies now confirm the existence of cross-education in contexts that involve voluntary dynamic contractions, eccentric contraction, electrical stimulation, whole-body vibration and, more recently, following mirror feedback training. Although many aspects of cross-education have been established, the mediating neural mechanisms remain unclear. Overall, the findings of this review show that the neural adaptations to cross-education of muscle strength most likely represent a continuum of change within the central nervous system that involves both structural and functional changes within cortical motor and non-motor regions. Such changes are likely to be the result of more subtle changes along the entire neuroaxis which include, increased corticospinal excitability, reduced cortical inhibition, reduced interhemispheric inhibition, changes in voluntary activation and new regions of cortical activation. However, there is a need to widen the breadth of research by employing several neurophysiological techniques (together) to better understand the potential mechanisms mediating cross-education. This fundamental step is required in order to better prescribe targeted and effective guidelines for the clinical practice of cross-education. There is a need to determine whether similar cortical responses also occur in clinical populations where, perhaps, the benefits of cross-education could be best observed.

Simultaneous scalp recorded EEG and local field potentials from monkey ventral premotor cortex during action observation and execution reveals the contribution of mirror and motor neurons to the mu-rhythm

The desynchronization of alpha and beta oscillations (mu rhythm) in the central scalp EEG during action observation and action execution is thought to reflect neural mirroring processes. However, the extent to which mirror neurons (MNs) or other populations of neurons contribute to such EEG desynchronization is still unknown. Here, we provide the first evidence that, in the monkey, the neuronal activity recorded from the ventral premotor cortex (PMv) strongly contributes to the EEG changes occurring in the beta band over central scalp electrodes, during executed and observed actions. We simultaneously recorded scalp EEG and extracellular activity, Multi Unit Activity (MUA) and Local Field Potentials (LFP), from area F5 of two macaques executing and observing grasping actions. We found that MUA highly correlates with an increase in high gamma LFP power and, interestingly, such LFP power increase also correlates to EEG beta - and in part also to alpha - desynchronization. In terms of timing of signal changes, the increase in high gamma LFP power precedes the EEG desynchronization, during both action observation and execution, thus suggesting a causal role of PMv neuronal activity in the modulation of the alpha and beta mu-rhythm. Lastly, neuronal signals from deeper layers of PMv exert a greater contribution than superficial layers to the EEG beta rhythm modulation, especially during the motor task. Our findings have clear implications for EEG studies in that they demonstrate that the activity of different populations of neurons in PMv contribute to the generation of the mu-rhythm.

From Neurons to Social Beings: Short Review of the Mirror Neuron System Research and Its Socio-Psychological and Psychiatric Implications

The mirror neuron system (MNS) is a brain network activated when we move our body parts and when we observe the actions of other agent. Since the mirror neuron’s discovery in research on monkeys, several studies have examined its network and properties in both animals and humans. This review discusses MNS studies of animals and human MNS studies related to high-order social cognitions such as emotion and empathy, as well as relations between MNS dysfunction and mental disorders. Finally, these evidences are understood from an evolutionary perspective.

The neural exploitation hypothesis and its implications for an embodied approach to language and cognition: Insights from the study of action verbs processing and motor disorders in Parkinson's disease

As it is widely known, Parkinson's disease is clinically characterized by motor disorders such as the loss of voluntary movement control, including resting tremor, postural instability, and bradykinesia (Bocanegra et al., 2015; Helmich, Hallett, Deuschl, Toni, & Bloem, 2012; Liu et al., 2006; Rosin, Topka, & Dichgans, 1997). In the last years, many empirical studies (e.g., Bocanegra et al., 2015; Spadacenta et al., 2012) have also shown that the processing of action verbs is selectively impaired in patients affected by this neurodegenerative disorder. In the light of these findings, it has been suggested that Parkinson disorder can be interpreted within an embodied cognition framework (e.g., Bocanegra et al., 2015). The central tenet of any embodied approach to language and cognition is that high order cognitive functions are grounded in the sensory-motor system. With regard to this point, Gallese (2008) proposed the neural exploitation hypothesis to account for, at the phylogenetic level, how key aspects of human language are underpinned by brain mechanisms originally evolved for sensory-motor integration. Glenberg and Gallese (2012) also applied the neural exploitation hypothesis to the ontogenetic level. On the basis of these premises, they developed a theory of language acquisition according to which, sensory-motor mechanisms provide a neurofunctional architecture for the acquisition of language, while retaining their original functions as well. The neural exploitation hypothesis is here applied to interpret the profile of patients affected by Parkinson's disease. It is suggested that action semantic impairments directly tap onto motor disorders. Finally, a discussion of what theory of language is needed to account for the interactions between language and movement disorders is presented.

Facilitating Neurofeedback in Children with Autism and Intellectual Impairments Using TAGteach

Individuals with autism and intellectual impairments tend to be excluded from research due to their difficulties with methodological compliance. This study focuses on using Teaching with Acoustic Guidance-TAGteach-to behaviorally prepare children with autism and a IQ ≤ 80 to participate in a study on neurofeedback training (NFT). Seven children (ages 6-8) learned the prerequisite skills identified in a task analysis in an average of 5 h of TAGteach training, indicating that this is a feasible method of preparing intellectually-impaired children with autism to participate in NFT and task-dependent electroencephalography measures. TAGteach may thus have the potential to augment this population's ability to participate in less accessible treatments and behavioral neuroscientific studies.

Neural simulation mechanisms and social-emotional function in schizophrenia

Impairment in simulation, i.e., the generation of internal representations of experiences, may contribute to social dysfunction in schizophrenia spectrum disorders (SZ). Using a novel fMRI task, we identified neural representations generated during simulation of sensorimotor experiences and evaluated their associations with socioemotional function in 19 individuals with SZ and 24 psychiatrically-healthy controls (HC). Participants watched videos depicting a painful sensorimotor experience in the hand or foot of another person and were then asked to imagine how unpleasant it would be to undergo that experience themselves, eliciting simulation. A localizer task identified regions-of-interest (ROIs) within each participant's sensorimotor cortices (SC) recruited by firsthand sensory experiences in hands and feet. Simulation engaged these ROIs in HC and SZ. Simulation-related activation in ROIs did not differ between groups but was associated with participants' social function. Findings indicate that simulation elicits specific neural representations within the SC and the strength of these representations might be linked to social function.

Toward the Language-Ready Brain: Biological Evolution and Primate Comparisons

The approach to language evolution suggested here focuses on three questions: How did the human brain evolve so that humans can develop, use, and acquire languages? How can the evolutionary quest be informed by studying brain, behavior, and social interaction in monkeys, apes, and humans? How can computational modeling advance these studies? I hypothesize that the brain is language ready in that the earliest humans had protolanguages but not languages (i.e., communication systems endowed with rich and open-ended lexicons and grammars supporting a compositional semantics), and that it took cultural evolution to yield societies (a cultural constructed niche) in which language-ready brains could become language-using brains. The mirror system hypothesis is a well-developed example of this approach, but I offer it here not as a closed theory but as an evolving framework for the development and analysis of conflicting subhypotheses in the hope of their eventual integration. I also stress that computational modeling helps us understand the evolving role of mirror neurons, not in and of themselves, but only in their interaction with systems "beyond the mirror." Because a theory of evolution needs a clear characterization of what it is that evolved, I also outline ideas for research in neurolinguistics to complement studies of the evolution of the language-ready brain. A clear challenge is to go beyond models of speech comprehension to include sign language and models of production, and to link language to visuomotor interaction with the physical and social world.

Kinematic analysis of head, trunk, and pelvic motion during mirror therapy for stroke patients

[Purpose] The purpose of this study was to investigate mirror therapy (MT) condition by analyzing kinematic parameters according to mirror size and angle. [Subjects and Methods] Three hemiparesis stroke patients and five healthy adults participated in this cross-sectional study. Kinematic parameters during the MT were collected over a total of 5 trials for each subject (3 mirror angles × 3 mirror sizes). Center of pressure (COP) excursion data was collected by force plate, and other kinematic parameters by infra-red cameras. [Results] The larger the size and smaller the angle, the overall dependent variables decreased in all participants. Particularly, when virtual reality reflection equipment (VRRE) was used, the value of the flexion and the lateral tilt was the closest to the midline compared to all other independent variables. Moreover, it showed tendency of moving towards the affected side. Based on the results, MT for stroke patients has a disadvantage of shifting weight and leaning towards the unaffected side during therapy. [Conclusion] Therefore, it seems to be more effective in terms of clinics to apply VRRE to make up for the weak parts and provide more elaborate visual feedback.

Social modeling of eating mediated by mirror neuron activity: A causal model moderated by frontal asymmetry and BMI

The social modeling of eating effect refers to the consistently demonstrated phenomenon that individuals tend to match their quantity of food intake to their eating companion. The current study sought to explore whether activity within the mirror neuron system (MNS) mediates the social modeling of eating effect as a function of EEG frontal asymmetry and body mass index (BMI). Under the guise of rating empathy, 93 female undergraduates viewed a female video confederate "incidentally" consume either a low or high intake of chips while electroencephalogram (EEG) activity was recorded. Subsequent ad libitum chip consumption was quantified. A first- and second-stage dual moderation model revealed that frontal asymmetry and BMI moderated an indirect effect of model consumption on participants' food consumption as mediated by MNS activity at electrode site C3, a₃b₃=-0.718, SE=0.365, 95% CI [-1.632, -0.161]. Left frontal asymmetry was associated with greater mu activity and a positive association between model and participant chip consumption, while right frontal asymmetry was associated with less mu activity and a negative association between model and participant consumption. Across all levels of frontal asymmetry, the effect was only significant among those with a BMI at the 50th percentile or lower. Thus, among leaner individuals, the MNS was demonstrated to mediate social modeling of eating, as moderated by frontal asymmetry. These findings are integrated within the normative account of social modeling of eating. It is proposed that the normative framework may benefit from consideration of both conscious and unconscious operation of intake norms.

Action observation in the modification of postural sway and gait: Theory and use in rehabilitation

The discovery of cortical neurons responsive to both the observation of another individual's movement and one's own physical movement has spurred scientists into utilising this interplay for rehabilitation. The idea that humans can quickly transfer motor programmes or refine existing motor strategies through observation has only recently gained interest in the context of gait rehabilitation but may offer significant promise as an adjunctive therapy to routine balance training. This review is the first dedicated to action observation in postural control or gait in healthy individuals and patients. The traditional use of action observation in rehabilitation is that the observer has to carefully watch pre-recorded or physically performed actions and thereafter imitate them. Using this approach, previous studies have shown improved gait after action observation in stroke, Parkinson's disease and knee or hip replacement patients. In healthy subjects, action observation reduced postural sway from externally induced balance perturbations. Despite this initial evidence, future studies should establish whether patients are instructed to observe the same movement to be trained (i.e., replicate the observed action(s)) or observe a motor error in order to produce postural countermeasures. The best mode of motor transfer from action observation is yet to be fully explored, and may involve observing live motor acts rather than viewing video clips. Given the ease with which action observation training can be applied in the home, it offers a promising, safe and economical approach as an adjunctive therapy to routine balance training.

Neural mechanisms of vocal imitation: The role of sleep replay in shaping mirror neurons

Learning by imitation involves not only perceiving another individual's action to copy it, but also the formation of a memory trace in order to gradually establish a correspondence between the sensory and motor codes, which represent this action through sensorimotor experience. Memory and sensorimotor processes are closely intertwined. Mirror neurons, which fire both when the same action is performed or perceived, have received considerable attention in the context of imitation. An influential view of memory processes considers that the consolidation of newly acquired information or skills involves an active offline reprocessing of memories during sleep within the neuronal networks that were initially used for encoding. Here, we review the recent advances in the field of mirror neurons and offline processes in the songbird. We further propose a theoretical framework that could establish the neurobiological foundations of sensorimotor learning by imitation. We propose that the reactivation of neuronal assemblies during offline periods contributes to the integration of sensory feedback information and the establishment of sensorimotor mirroring activity at the neuronal level.

Brains for birds and babies: Neural parallels between birdsong and speech acquisition

Language as a computational cognitive mechanism appears to be unique to the human species. However, there are remarkable behavioral similarities between song learning in songbirds and speech acquisition in human infants that are absent in non-human primates. Here we review important neural parallels between birdsong and speech. In both cases there are separate but continually interacting neural networks that underlie vocal production, sensorimotor learning, and auditory perception and memory. As in the case of human speech, neural activity related to birdsong learning is lateralized, and mirror neurons linking perception and performance may contribute to sensorimotor learning. In songbirds that are learning their songs, there is continual interaction between secondary auditory regions and sensorimotor regions, similar to the interaction between Wernicke's and Broca's areas in human infants acquiring speech and language. Taken together, song learning in birds and speech acquisition in humans may provide useful insights into the evolution and mechanisms of auditory-vocal learning.

Sources of mu activity and their functional connectivity in perceiving complexities in reciprocal social interactive motion: An exploratory study using the 'Namaste' task

Cognitive processes underlying reciprocal social interactions are understood by the mechanism of embodiment, which is closely related to the mirror neuron system. Electroencephalographic (EEG) mu activity is a neural marker of the mirror neuron system. This study investigated the mu activity, localization of its sources and functional connectivity, which was induced while watching reciprocal social interactive motion across various degrees of complexity. Eighteen healthy participants underwent high-resolution EEG recording using 256-channels while they watched a specifically designed, culture specific, video task that showed two persons interacting socially using body gestures. Task complexity was determined by (1) whether there was an identical gestural response or a non-identical one; (2) whether the participant watched two persons interacting or was virtually involved in the interaction. Source localization and functional connectivity analysis was conducted for mu activity across various tasks. We also correlated mu activity and functional connectivity measures with serum BDNF. We found that spectral densities in various brain sources of mu activity and their increased functional connectivity distinguished identical and non-identical reciprocal expression observations, while mu suppression alone did not discriminate various degrees of complexities. These findings might have important implications in the understanding of mechanisms underlying mirror neuron dysfunction in various psychiatric disorders.

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

Schizophrenia is a heterogenous disorder, and has often been subtyped on the basis of family history of psychotic disorders. Compared to those without, a positive family history is associated with an earlier age of onset, greater structural brain abnormalities and poorer clinical course. Given recent emphasis on mirror neuron system (MNS) in attempting to explain psychopathology in schizophrenia; present analysis tried to tease out differences in MNS functioning between these two groups. With ethical approval, 10 consenting right-handed patients with schizophrenia (ICD-10-DCR; M=8; Drug-naïve=2) were recruited and divided into two groups of five each (M=4, F=1): those with (age 29.40±5.85 years, duration of illness 50.80±30.84 months) and without (age 29.60±5.77 years, duration of illness 43.20±43.76 months) family history of schizophrenic illness (group difference p>0.05). MNS activity was assessed using event-related desynchronization of EEG Mu waves in response to biological motion on 192-channel EEG Neurofax EEG-1100K. On comparison, while patients had significantly lower mu suppression compared to controls (p<0.001); two schizophrenia groups did not differ between themselves, neither on MNS activity nor on psychopathology (p>0.05). Present study replicates finding of a dysfunctional MNS in schizophrenia patients, and represents a preliminary attempt at comparing two groups of symptomatic schizophrenia patients. In both these groups, MNS dysfunctions were comparable, and commensurate with respect to psychopathology. Thus, MNS dysfunction in schizophrenia might either be inherited or acquired. However, this abnormality forms a common base, and ultimate vulnerability marker, for development of psychopathology during active disease states.

Biological Motion induced mu suppression is reduced in Early Psychosis (EP) patients with active negative symptoms and Autism Spectrum Disorders (ASD)

There is evidence of genetic and neural system overlap in Autism Spectrum Disorder (ASD) and Early Psychosis (EP). Five datasets were pooled to compare mu suppression index (MSI), a proxy of mirror neuron activity, in EP, high functioning ASD, and healthy subjects (HS). ASDs and EPs with "active" negative symptoms showed significant differences in mu suppression, in response to Biological Motion/point-light display animation, compared to HS. Preliminary findings suggest that similar neural network deficits in ASD and EP could be driven by the expression of negative symptoms in the latter group of patients. These findings may aid future studies on EP and ASD and facilitate the formulation of new hypotheses regarding their pathophysiology.

Mu suppression - A good measure of the human mirror neuron system?

Mu suppression has been proposed as a signature of the activity of the human mirror neuron system (MNS). However the mu frequency band (8–13 Hz) overlaps with the alpha frequency band, which is sensitive to attentional fluctuation, and thus mu suppression could potentially be confounded by changes in attentional engagement. The specific baseline against which mu suppression is assessed may be crucial, yet there is little consistency in how this is defined. We examined mu suppression in 61 typical adults, the largest mu suppression study so far conducted. We compared different methods of baselining, and examined activity at central and occipital electrodes, to both biological (hands) and non-biological (kaleidoscope) moving stimuli, to investigate the involvement of attention and alpha activity in mu suppression. We also examined changes in beta power, another candidate index of MNS engagement. We observed strong mu suppression restricted to central electrodes when participants performed hand movements, demonstrating that mu is indeed responsive to the activity of the motor cortex. However, when we looked for a similar signature of mu suppression to passively observed stimuli, the baselining method proved to be crucial. Selective suppression for biological versus non-biological stimuli was seen at central electrodes only when we used a within-trial baseline based on a static stimulus: this method greatly reduced trial-by-trial variation in the suppression measure compared with baselines based on blank trials presented in separate blocks. Even in this optimal condition, 16–21% of participants showed no mu suppression. Changes in beta power also did not match our predicted pattern for MNS engagement, and did not seem to offer a better measure than mu. Our conclusions are in contrast to those of a recent meta-analysis, which concluded that mu suppression is a valid means to examine mirror neuron activity. We argue that mu suppression can be used to index the human MNS, but the effect is weak and unreliable and easily confounded with alpha suppression.

Neural basis of understanding communicative actions: Changes associated with knowing the actor's intention and the meanings of the actions

People can communicate by using hand actions, e.g., signs. Understanding communicative actions requires that the observer knows that the actor has an intention to communicate and the meanings of the actions. Here, we investigated how this prior knowledge affects processing of observed actions. We used functional MRI to determine changes in action processing when non-signers were told that the observed actions are communicative (i.e., signs) and learned the meanings of half of the actions. Processing of hand actions activated the left and right inferior frontal gyrus (IFG, BA 44 and 45) when the communicative intention of the actor was known, even when the meanings of the actions remained unknown. These regions were not active when the observers did not know about the communicative nature of the hand actions. These findings suggest that the left and right IFG play a role in understanding the intention of the actor, but do not process visuospatial features of the communicative actions. Knowing the meanings of the hand actions further enhanced activity in the anterior part of the IFG (BA 45), the inferior parietal lobule and posterior inferior and middle temporal gyri in the left hemisphere. These left-hemisphere language regions could provide a link between meanings and observed actions. In sum, the findings provide evidence for the segregation of the networks involved in the neural processing of visuospatial features of communicative hand actions and those involved in understanding the actor’s intention and the meanings of the actions.

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Participants observed hand actions before and after learning that they are signs.

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Learning-induced changes in brain activity measured using fMRI.

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No activity in mirror neuron system when actions were not known to be communicative.

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Knowing the actor’s intention to communicate activated IFG and IPL.

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Knowing meanings of the actions increased activity in left IFG (BA 45), IPL and MTG.

Is the human mirror neuron system plastic? Evidence from a transcranial magnetic stimulation study

Virtual lesions in the mirror neuron network using inhibitory low-frequency (1Hz) transcranial magnetic stimulation (TMS) have been employed to understand its spatio-functional properties. However, no studies have examined the influence of neuro-enhancement by using excitatory high-frequency (20Hz) repetitive transcranial magnetic stimulation (HF-rTMS) on these networks. We used three forms of TMS stimulation (HF-rTMS, single and paired pulse) to investigate whether the mirror neuron system facilitates the motor system during goal-directed action observation relative to inanimate motion (motor resonance), a marker of putative mirror neuron activity. 31 healthy individuals were randomized to receive single-sessions of true or sham HF-rTMS delivered to the left inferior frontal gyrus - a component of the human mirror system. Motor resonance was assessed before and after HF-rTMS using three TMS cortical reactivity paradigms: (a) 120% of resting motor threshold (RMT), (b) stimulus intensity set to evoke motor evoked potential of 1-millivolt amplitude (SI1mV) and (c) a short latency paired pulse paradigm. Two-way RMANOVA showed a significant group (true versus sham) X occasion (pre- and post-HF-rTMS motor resonance) interaction effect for SI1mV [F(df)=6.26 (1, 29), p=0.018] and 120% RMT stimuli [F(df)=7.01 (1, 29), p=0.013] indicating greater enhancement of motor resonance in the true HF-rTMS group than the sham-group. This suggests that HF-rTMS could adaptively modulate properties of the mirror neuron system. This neuro-enhancement effect is a preliminary step that can open translational avenues for novel brain stimulation therapeutics targeting social-cognition deficits in schizophrenia and autism.

Association of Nurses' Self-Reported Empathy and Mu Suppression with Patients' Satisfaction

INTRODUCTION

The aim of this study is to explore the association between mu suppression and self-reported empathy in nurses with patients' satisfaction.

METHODS

For this correlational study, 30 male nurses, as well as 30 patients took care by these nurses during the week before data gathering, were selected via accessible and random sampling method, respectively. The tools included Jefferson's Scale of Empathy-health professionals, and patient's satisfaction scale of La Monica-Oberst. Activation of Mirror Neurons System (MNS) was investigated by mu suppression. For this purpose, electroencephalography (EEG) was recorded in three phases: 1) Watching the video of a non-moving hand, 2) Watching the video of a hand being open and closed, and 3) Opening and closing one-self's hand. EEG recordings were analyzed using Matlab R 2014a software. Data were analyzed by Pearson's correlation coefficients and multiple regression analyses.

RESULTS

There was no significant correlation between mu suppression in nurses with nurses' self-reported empathy and patients' satisfaction, however, a significant correlation was found between nurses' self-reported empathy and patients' satisfaction. Regression analysis outcomes showed that nurses' self-reported empathy could predict 18.5% (nearly one fifth) of patients' satisfaction variance while mu suppression did not forecast patients' satisfaction significantly.

CONCLUSION

These findings suggested that mu rhythm was a good biomarker neither for nurses' self-reported empathy nor for patients' satisfaction. In addition, it was manifested that patients' satisfaction, at least partly, depended on skills that nurses could learn, since showing empathy is highly learnable.

No evidence for mirror system dysfunction in schizophrenia from a multimodal TMS/EEG study

Dysfunctional mirror neuron systems have been proposed to contribute to the social cognitive deficits observed in schizophrenia. A few studies have explored mirror systems in schizophrenia using various techniques such as TMS (levels of motor resonance) or EEG (levels of mu suppression), with mixed results. This study aimed to use a novel multimodal approach (i.e. concurrent TMS and EEG) to further investigate mirror systems and social cognition in schizophrenia. Nineteen individuals with schizophrenia or schizoaffective disorder and 19 healthy controls participated. Single-pulse TMS was applied to M1 during the observation of hand movements designed to elicit mirror system activity. Single EEG electrodes (C3, CZ, C4) recorded brain activity. Participants also completed facial affect recognition and theory of mind tasks. The schizophrenia group showed significant deficits in facial affect recognition and higher level theory of mind compared to healthy controls. A significant positive relationship was revealed between mu suppression and motor resonance for the overall sample, indicating concurrent validity of these measures. Levels of mu suppression and motor resonance were not significantly different between groups. These findings indicate that in stable outpatients with schizophrenia, mirror system functioning is intact, and therefore their social cognitive difficulties may be caused by alternative pathophysiology.

Semantic brain areas are involved in gesture comprehension: An electrical neuroimaging study

While the mechanism of sign language comprehension in deaf people has been widely investigated, little is known about the neural underpinnings of spontaneous gesture comprehension in healthy speakers. Bioelectrical responses to 800 pictures of actors showing common Italian gestures (e.g., emblems, deictic or iconic gestures) were recorded in 14 persons. Stimuli were selected from a wider corpus of 1122 gestures. Half of the pictures were preceded by an incongruent description. ERPs were recorded from 128 sites while participants decided whether the stimulus was congruent. Congruent pictures elicited a posterior P300 followed by late positivity, while incongruent gestures elicited an anterior N400 response. N400 generators were investigated with swLORETA reconstruction. Processing of congruent gestures activated face- and body-related visual areas (e.g., BA19, BA37, BA22), the left angular gyrus, mirror fronto/parietal areas. The incongruent-congruent contrast particularly stimulated linguistic and semantic brain areas, such as the left medial and the superior temporal lobe.

Increased premotor cortex activation in high functioning autism during action observation

The mirror neuron (MN) hypothesis of autism has received considerable attention, but to date has produced inconsistent findings. Using functional MRI, participants with high functioning autism or Asperger's syndrome were compared to typically developing individuals (n=12 in each group). Participants passively observed hand gestures that included waving, pointing, and grasping. Concerning the MN network, both groups activated similar regions including prefrontal, inferior parietal and superior temporal regions, with the autism group demonstrating significantly greater activation in the dorsal premotor cortex. Concerning other regions, participants with autism demonstrated increased activity in the anterior cingulate and medial frontal gyrus, and reduced activation in calcarine, cuneus, and middle temporal gyrus. These results suggest that during observation of hand gestures, frontal cortex activation is affected in autism, which we suggest may be linked to abnormal functioning of the MN system.

Motor resonance meets motor performance

The aim of the present work is to explore which of two different models better explains facilitation/interference effects when participants have to conditionally react to an observed action with a movement. The Dimensional Overlap model assumes two parallel routes, an automatic route and a rule-based one, that interact only when the stimulus-set and the response-set share some dimensions. In the alternative model, a motor resonance for rule-based reaction, the automatic visuo-motor transformation is always an obligatory step that provides the correct categorization of the observed action as the input for the rule-based route, thus linking the two routes in a serial fashion. We explicitly tested which of the hypotheses fits better the data by asking participants to perform one of two different actions in a two-choice reaction paradigm. In one condition participants were required to perform the opposite action compared to the one they saw (COUNTER task: see A→do B, see B→do A), while in the other they were required to perform two actions that did not share any dimension with the stimulus-set (NEUTRAL task: see A→do C, see B→do D). We predicted an advantage for the NEUTRAL task if the Dimensional Overlap model was correct, while a similar performance was foreseen if the motor resonance-based model was correct. Since the interpretation of these results was not straightforward, we conducted a distributional analysis of participants' response accuracies in order to understand whether a serial or a general parallel model explained better the data. We found clear evidence that participants responded above chance before the motor representation of the action observed was activated. We conclude that two separate systems in the human brain can transform observed actions in own motor representations. One is stimulus-driven, while the second is rule-driven. Likely, their activity is mutually independent along parallel pathways.

[The motor organization of cerebral cortex and the role of the mirror neuron system. Clinical impact for rehabilitation]

The basic characteristics of Penfield homunculus (somatotopy and unique representation) have been questioned. The existence of a defined anatomo-functional organization within different segments of the same region is controversial. The presence of multiple motor representations in the primary motor area and in the parietal lobe interconnected by parieto-frontal circuits, which are widely overlapped, form a complex organization. Both features support the recovery of functions after brain injury. Regarding the movement organization, it is possible to yield a relevant impact through the understanding of actions and intentions of others, which is mediated by the activation of mirror-neuron systems. The implementation of cognitive functions (observation, image of the action and imitation) from the acute treatment phase allows the activation of motor representations without having to perform the action and it plays an important role in learning motor patterns.