Philosophy and neuroscience: relation between mirror neurons and empathy

Visual and motor properties of single neurons of monkey ventral premotor cortex (area F5) were studied in a behavioral paradigm consisting of four conditions: object grasping in light, object grasping in dark, object fixation, and fixation of a spot of light. The employed objects were six different three-dimensional (3-D) geometric solids. Two main types of neurons were distinguished: motor neurons (n = 25) and visuomotor neurons (n = 24). Motor neurons discharged in association with grasping movements. Most of them (n = 17) discharged selectively during a particular type of grip. Different objects, if grasped in similar way, determined similar neuronal motor responses. Visuomotor neurons also discharged during active movements, but, in addition, they fired also in response to the presentation of 3-D objects. The majority of visuomotor neurons (n = 16) showed selectivity for one or few objects. The response was present both in object grasping in light and in object fixation conditions. Visuomotor neurons that selectively discharged to the presentation of a given object discharged also selectively during grasping of that object. In conclusion, object shape is coded in F5 even when a response to that object is not required. The possible visual or motor nature of this object coding is discussed.

The finding of mirror neurons (MNs) has provided a biological substrate to a new concept of cognition, relating data on actions and perceptions not only to integrate perception in action planning and execution but also as a neural mechanism supporting a wide range of cognitive functions. Here we first summarize data on MN localization and role in primates, then we report findings in normal human subjects: functional magnetic resonance imaging and neurophysiological studies sustain that MNs have a role in motor learning and recognizing actions and intentions of others, and they also support an embodied view of language, empathy, and memory. Then, we detail the results of literature searching on MNs and embodied cognition in Parkinson's disease (PD), frontotemporal dementia (FTD)/amyotrophic lateral sclerosis (ALS), and in mild cognitive impairment (MCI)/Alzheimer's disease (AD). In PD the network of MN could be altered, but its hyperactivation might support motor and cognitive performances at least in early stages. In the ALS/FTD continuum, preliminary evidence points out to an involvement of the MN network, which could explain language and inter-subjectivity deficits shown in patients affected by these clinical entities. In the MCI/AD spectrum, a few recent studies suggest a possible progressive involvement from posterior to anterior areas of the MN network, with the brain putting in place compensatory mechanisms in early stages. Reinterpreting neurodegenerative diseases at the light of the new views about brain organization stemming from the discovery of MN could help to better comprehend clinical manifestations and open new pathways to rehabilitation.

Watch your favorite athlete take a shot for the goal, or your favorite actor lean in for a kiss, and chances are that some of the same neurons that would be active if you were performing that action are firing as well. These mirror neurons – neurons in premotor and parietal cortex that fire both when an animal performs a goal-directed action and when observing such actions – provide a link between representations of the other and selfrepresentations (di Pellegrino et al., 1992). Along with their proximity to Broca’s area, this has led to the suggestion that the mirror system is fundamental for the development of language and complex social-cognitive constructs including empathy and theory of mind (Iacoboni & Dapretto, 2006). But how does the mirror system acquire its reflective properties? Are the patterns it shows in response to observing a particular movement pre-set by evolution, or the product of experience? In this issue, Catmur et al. address this question by using fMRI to assess activation patterns within the mirror system after sensorimotor training. They first trained participants to either flex their hand when they saw a picture of a flexed hand and flex their foot in response to the picture of a flexed foot (Compatible condition), or to reverse their responses (Incompatible condition; flex hand in response to foot picture and vice versa). Following training, participants were scanned while simply observing pictures of flexed hands or feet, while themselves remaining stationary. The results show that the mirror system can be trained: Areas that showed greater activity to hand-action displays for the Compatible group showed greater reactivity to foot-action displays in the Incompatible group. Both groups showed stronger activations for the stimuli that predicted performance of the hand action, suggesting some pre-existing bias towards the representation of such actions. However, the critical finding is that the mirror system’s mapping to which stimuli predicted such movements was flexible, showing a complete reversal after only 3 days of training. It appears that the representations linking others’ actions and our own within the mirror system are not hardwired, but instead are easily changed. Is the mirroring system truly unique, or more properly seen as a special case of experience-based associations? Is the urge to make a kick while watching a player do so during a televised game that different from ‘feeling it in your bones’ when you visit the soccer field you frequented in your youth? The results of Catmur et al. suggest that it may not be: In both cases mirror neurons may be responding to the experienced relationship between those cues and the motor programs you have used during a game. The links between the mirror system and more traditional learning and memory principles have important implications. As described above, the mirror system is thought to be fundamental to empathy and social cognition, and disruptions in it may be related to autism, schizophrenia, and other disorders. The possibility of a trainable mirror system opens the door to treatments that ‘iron out’ such distortions.

To probe the presence of mirror neurons in the human brain, cross-modal fMRI adaptation has been suggested as a suitable technique. The rationale behind this suggestion is that this technique allows making more accurate inferences about neural response properties underlying fMRI voxel activations, beyond merely showing shared voxels that are active during both action observation and execution. However, the validity of using cross-modal fMRI adaptation to demonstrate the presence of mirror neurons in parietal and premotor brain regions has been questioned given the inconsistent and weak results obtained in human studies. A better understanding of cross-modal fMRI adaptation effects in the macaque brain is required as the rationale for using this approach is based on several assumptions related to macaque mirror neuron response properties that still need validation. Here, we conducted a cross-modal fMRI adaptation study in macaque monkeys, using the same action execution and action observation tasks that successfully yielded mirror neuron region cross-modal action decoding in a previous monkey MVPA study. We scanned two male rhesus monkeys while they first executed a sequence of either reach-and-grasp or reach-and-touch hand actions and then observed a video of a human actor performing these motor acts. Both whole-brain and region-of-interest analyses failed to demonstrate cross-modal fMRI adaptation effects in parietal and premotor mirror neuron regions. Our results, in line with previous findings in non-human primates, show that cross-modal motor-to-visual fMRI adaptation is not easily detected in monkey brain regions known to house mirror neurons. Thus, our results advocate caution in using cross-modal fMRI adaptation as a method to infer whether mirror neurons can be found in the primate brain.

In this chapter, I critically assess the thesis that the discovery of mirror neurons (MNs) provides empirical support for the simulation theory (ST) of social cognition. This thesis can be analyzed into two claims: (i) MNs are involved in understanding others’ intentions or emotions. (ii) The way in which they do so supports a simulationist viewpoint. I will be giving qualified support to both (i) and (ii). Starting with (i), I will present theoretical and empirical points in support of the view that MNs play a substantial role and are perhaps necessary although not sufficient for understanding at least some intentions or emotions.

Mirror neurons (MNs) are a fascinating class of cells originally discovered in the ventral premotor cortex (PMv) and, subsequently, in the inferior parietal lobule (IPL) of the macaque, which become active during both the execution and observation of actions. In this review, I will first highlight the mounting evidence indicating that mirroring others’ actions engages a broad system of reciprocally connected cortical areas, which extends well beyond the classical IPL-PMv circuit and might even include subcortical regions such as the basal ganglia. Then, I will present the most recent findings supporting the idea that the observation of one’s own actions, which might play a role in the ontogenetic origin and tuning of MNs, retains a particular relevance within the adult MN system. Finally, I will propose that both cortical and subcortical mechanisms do exist to decouple MN activity from the motor output, in order to render it exploitable for high-order perceptual, cognitive, and even social functions. The findings reviewed here provide an original framework for envisaging the main challenges and experimental directions of future neurophysiological and neuroanatomical studies of the monkey MN system.

Event Abstract Back to Event Causal role of ventral premotor cortex during observation of transitive actions Guy Rens1* and Marco Davare1, 2 1 KU Leuven, Department of Kinesiology, Belgium 2 University College London, Sobell Department of Motor Neuroscience and Movement Disorders, United Kingdom In monkeys, neurons in F5 become active both when the monkey performs an action and when the monkey observes a similar action performed by the experimenter (mirror neurons). Using double coil transcranial magnetic stimulation (TMS) in healthy subjects (n=16), we investigated whether short-latency interactions between the ventral premotor cortex (PMv, the homologue of F5 in monkeys) and the primary motor cortex (M1) are modulated by the observation of different types of actions. We further compared PMv-M1 interactions during observation and execution of the same actions. Finally we investigated the causal contribution of PMv to the increase in corticospinal excitability (motor resonance) occurring during action observation. PMv-M1 interactions were tested before and after a train of continuous theta-burst stimulation (cTBS) to PMv during four experimental conditions: (1) object presentation (pen or disc), (2) observation of a transitive action towards an object (goal-directed), (3) observation of an intransitive action and (4) execution of the same actions. We found that both transitive and intransitive action observation modulated PMv-M1 interactions in a grasp-specific fashion (all p<0.011). For example, when observing the grasp of a pen, delivering a conditioning pulse over PMv 6 ms before a test pulse over M1 led to larger motor evoked potentials in muscles specifically required for the grasp. Following PMv cTBS, these grasp-specific PMv-M1 interactions were abolished (all p<0.001); in contrast, grasp-specific M1 resonance was still maintained for intransitive, but not transitive action observation (p=0.003). These results suggest that PMv has a causal role in mediating goal-directed information to M1 during observation of transitive actions. We suggest that other areas of the mirror neuron system enable motor resonance in M1 during intransitive actions. Our results shed new light on complex interactions between the different components of the action observation system. Keywords: TMS, ventral premotor cortex (PMv), action observation, theta burst stimulation, mirror neuron system, motor resonance, goal-directed actions Conference: 12th National Congress of the Belgian Society for Neuroscience, Gent, Belgium, 22 May - 22 May, 2017. Presentation Type: Poster Presentation Topic: Cognition and Behavior Citation: Rens G and Davare M (2019). Causal role of ventral premotor cortex during observation of transitive actions. Front. Neurosci. Conference Abstract: 12th National Congress of the Belgian Society for Neuroscience. doi: 10.3389/conf.fnins.2017.94.00007 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 May 2017; Published Online: 25 Jan 2019. * Correspondence: Mr. Guy Rens, KU Leuven, Department of Kinesiology, Heverlee, België, 3001, Belgium, rensguy1@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Guy Rens Marco Davare Google Guy Rens Marco Davare Google Scholar Guy Rens Marco Davare PubMed Guy Rens Marco Davare Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Mirror neurons are a particular class of visual and motor neurons, first discovered in area F5 of the premotor cortex in monkeys. To humans, brain activity they are involved in mirror neurons occurs in r parietal cortex. An important functional aspect of mirror neurons is the relationship between the motor and visual properties. All mirror neurons show a congruence between actions that respond nd motor responses that encode them. Two important hypothesis have been issued on the functional role of mirror neurons. The first is that mirror neurons activity mediates imitation, the second sustain that mirror neurons are the basis of action understanding. Mechanism makes it possible mediation by understanding others actions mirror neurons is simple. Every time an individual action taken by someone else noticed, neurons that represent that action ed in premotor cortex of the observer. This motor representation of the observed action, which is induced automatically, corresponds to that generated spontaneously during an active action, whose result is known individual. Thus, the mirror system nformation into knowledge. Structural theories are presented and related to mirror neurons and empathy. Empathy is defined as an emotional or intellectual identification with another person, living it indirectly feelings or ideas. Empathy extends beyond simple understanding of the emotional state of a person through to the other living feel. A fundamental concept is that the similarity in the mirror mechanism is activated closely with a stimulus or more from outside. The catalyst may be observing motor actions and ions such as disgust, joy or fear. In conclusion, we believe that this class of specialized cells of the brain is located in parts of its responsiveness to sensory and m (visual, olfactory, auditory, tactile). Using functional MRI to study the influence of different scents on the brain, a team of researchers exposed a subject to three types of olfactory stimuli: bad, pleasant and neutral, in order to obtain a

Examining cross-modal fMRI adaptation for observed and executed actions in the monkey brain

Since their discovery, mirror neurons--units in the macaque brain that discharge both during action observation and execution--have attracted considerable interest. Whether mirror neurons are an innate endowment or acquire their sensorimotor matching properties ontogenetically has been the subject of intense debate. It is widely believed that these units are an innate trait; that we are born with a set of mature mirror neurons because their matching properties conveyed upon our ancestors an evolutionary advantage. However, an alternative view is that mirror neurons acquire their matching properties during ontogeny, through correlated experience of observing and performing actions. The present article re-examines frequently overlooked neurophysiological reports of 'tool-use' and 'audiovisual' mirror neurons within the context of this debate. It is argued that these findings represent compelling evidence that mirror neurons are a product of sensorimotor experience, and not an innate endowment.

When we see or hear another person execute an action, we tend to automatically simulate that action. Evidence for this has been found at the neural level, specifically in parietal and premotor brain regions referred to collectively as the mirror neuron system (MNS), and the behavioural level, through an observer's tendency to mimic observed movements. This simulation process may play a key role in emotional understanding. It is currently unclear the extent to which the MNS is driven by bottom-up automatic recruitment of movement simulation, or by top-down (task driven) mechanisms. The present dissertation examines the role of the MNS in the bottom-up and top-down processing of action in the auditory and visual modalities, in response to emotional and neutral movements performed by humans. Study 1 used EEG to demonstrate that the MNS is affected by bottom-up manipulations of modality, and shows that the MNS is activated to a greater extent towards multi-modal versus unimodal sensory input. Study 2 employed an EEG paradigm utilizing a top-down emotion judgment manipulation. It was found that the left STG, part of the extended MNS, is affected by top-down manipulations of emotionality, but there were no areas in classical MNS that met the statistical threshold to be affected by top-down forces. Study 3 employed an fMRi paradigm combining bottom-up and top-down manipulations. It was found that the classical MNS was strongly affected by bottom-up differences in emotionality and modality, and minimally affected by the top-down manipulation. Together, the three studies presented in this dissertation support the premise that the classical mirror neuron system is primarily automatic. More research is needed to determine whether top-down manipulations can uniquely engage the MNS.

Functional imaging of face and hand imitation: towards a motor theory of empathy

&nbsp; When the music moves you, you dance. The bodily movement that develops in response to music is what is here considered &ldquo;dance.&rdquo; Philosophers have long understood music as possessing the power to move us. This paper employs Heinrich Wolfflin&rsquo;s theory of &ldquo;sympathetic modeling&rdquo;&mdash;a theory recently validated by neuroscientists&rsquo; discovery of mirror neurons in humans&mdash;and Antonio Damasio&rsquo;s neurobiological model of emotion to establish the mediating links between music and the bodily movements made in response. The first &ldquo;motion&rdquo; elicited by hearing music is, as Wolfflin suggested, an unconscious &ldquo;sympathetic modeling,&rdquo; an internal vocalization of what is heard; this activity involves muscular expansions and contractions. Signals of muscle movement are relayed to the brain by receptor cells imbedded in the muscles. In complex responses, the brain receives patterns of movement from throughout the entire body. When these whole-body kinesthetic sensations are made conscious as perceptions of a unified self, they enter awareness as subjectively felt emotion: the felt response to music. Such patterns of muscular stretching can be abstracted from the sort of external experience that produces emotion in ordinary life experience and reproduced at will. Thus, a dancer, by deliberately reproducing a pattern of muscle stretching, can re-create a chosen specific emotion. This activity constitutes &ldquo;expressing&rdquo; emotion in bodily movement. Performed in response to the emotion elicited by music, it is the expressive gesture of dance. One viewing the dance &ldquo;understands&rdquo; the emotion expressed by, once again, employing sympathetic modeling to reconstruct the internal pattern of movement associated with that emotion. In popular, social, dancing, dancers model one another&rsquo;s movements and, together, model the muscle tension patterns of particular rhythms and melodic lines; this situation is easily accounted for by what is now known about mirror neurons. Neuroscience thus explains what happens when the music moves you. &nbsp; Key words: Emotion, movement, music, dance, aesthetics, neuroscience.

The visual recognition of goal-directed movements is crucial for the learning of actions, and possibly for the understanding of the intentions and goals of others. The discovery of mirror neurons has stimulated a vast amount of research investigating possible links between action perception and action execution [1,2]. However, it remains largely unknown what is the real extent of this putative visuo-motor interaction during visual perception of actions and which relevant computational functions are instead accomplished by possibly purely visual processing.

Neurons in macaque ventral premotor cortex and inferior parietal lobe discharge during both the observation and the execution of motor acts. It has been claimed that these so-called mirror neurons form the basis of action understanding by matching the visual input with the corresponding motor program (direct matching). Functional magnetic resonance imaging (fMRI) adaptation can be used to test the direct matching account of action recognition by determining whether putative mirror neurons show adaptation for repeated motor acts independently of whether they are observed or executed. An unambiguous test of the hypothesis requires that the motor acts be meaningless to ensure that any adaptation effect is directly because of movement recognition/motor execution and not contextually determined inferences. We found adaptation for motor acts that were repeatedly observed or repeatedly executed. We also found adaptation for motor acts that were first observed and then executed, as would be expected if a previously seen act primed the subsequent execution of that act. Crucially, we found no signs of adaptation for motor acts that were first executed and then observed. Failure to find cross-modal adaptation for executed and observed motor acts is not compatible with the core assumption of mirror neuron theory, which holds that action recognition and understanding are based on motor simulation.