In the macaque monkey ventral premotor cortex (F5), "canonical neurones" are active when the monkey observes an object and when the monkey grasps that object. In the same area, "mirror neurones" fire both when the monkey observes another monkey grasping an object and when the monkey grasps that object. We used event-related fMRI to investigate where in the human brain activation can be found that reflects both canonical and mirror neuronal activity. There was activation in the intraparietal and ventral limbs of the precentral sulcus when subjects observed objects and when they executed movements in response to the objects (canonical neurones). There was activation in the dorsal premotor cortex, the intraparietal cortex, the parietal operculum (SII), and the superior temporal sulcus when subjects observed gestures (mirror neurones). Finally, activations in the ventral premotor cortex and inferior frontal gyrus (area 44) were found when subjects imitated gestures and executed movements in response to objects. We suggest that in the human brain, the ventral limb of the precentral sulcus may form part of the area designated F5 in the macaque monkey. It is possible that area 44 forms an anterior part of F5, though anatomical studies suggest that it may be a transitional area between the premotor and prefrontal cortices.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder associated with impaired social and emotional skills, the anatomical substrate of which is still unknown. In this study, we compared a group of 14 high-functioning ASD adults with a group of controls matched for sex, age, intelligence quotient, and handedness. We used an automated technique of analysis that accurately measures the thickness of the cerebral cortex and generates cross-subject statistics in a coordinate system based on cortical anatomy. We found local decreases of gray matter in the ASD group in areas belonging to the mirror neuron system (MNS), argued to be the basis of empathic behavior. Cortical thinning of the MNS was correlated with ASD symptom severity. Cortical thinning was also observed in areas involved in emotion recognition and social cognition. These findings suggest that the social and emotional deficits characteristic of autism may reflect abnormal thinning of the MNS and the broader network of cortical areas subserving social cognition.

Seeing is doing -- at least it is when mirror neurons are working normally. But in autistic individuals, say researchers from the University of California, San Diego, the brain circuits that enable people to perceive and understand the actions of others do not behave in the usual way. According to the new study, currently in press at the journal Cognitive Brain Research, electroencephalograph (EEG) recordings of 10 individuals with autism show a dysfunctional mirror neuron system: Their mirror neurons respond only to what they do and not to the doings of others.

People with autism experience less activity in the brain neurons that specifically trigger human empathy, according to a new study by University of Montreal researcher Hugo Théoret. The professor in the Department of Psychology is trying to understand the link between 'mirror neurons' and autism. Mirror neurons, a theory developed in the '90s, are at the basis of all imitative learning such as language acquisition. So, a person who watches another performing a certain activity actually experiences the same activity in their brain circuitry. The theory also explains why laughing can become so contagious.

While scientists have yet to pinpoint the precise function of the mirror-neuron system in humans--and what problems a dysfunction could cause--a flurry of new research suggests that autistic people's mirror systems are not as active as those of normal adults. For example, a study by Théoret, Tager-Flusberg and their colleagues, published in the February issue of Current Biology (Vol. 15, No. 3, pages 84�85), shows that when autistic people watch the hand movements of other people, their brains' mirror-neuron areas activate less than the mirror-neuron areas in normal adults' brains.

Contagious yawning, the onset of a yawn triggered by seeing, hearing, reading, or thinking about another person yawn is a well-documented phenomenon. The mechanisms that drive contagious yawning are as yet unknown, but there is recent evidence of a link between contagious yawning and self-processing (S.M. Platek, S.R. Critton, T.E. Myers, G.G. Gallup Jr., Contagious yawning: the role of self-awareness and mental state attribution, Cogn. Brain Res. 17 (2003) 223-227.) that is negatively impacted by schizotypal personality traits. The neural substrates involved in contagious yawning, however, are unknown. Here, using fMRI, we show that viewing someone yawn evokes unique neural activity in the posterior cingulate and precuneus. Because of the role these areas play in self-processing (e.g., self-referential processing, theory of mind, autobiographical memory), our findings provide further support for the hypothesis that contagious yawning may be part of a neural network involved in empathy.

Individuals with ASD showed mu wave suppression to self-movement, but not to watching other's movements, suggesting a dysfunction in the mirror neuron system.

Autism spectrum disorders (ASD) are largely characterized by deficits in imitation, pragmatic language, theory of mind, and empathy. Previous research has suggested that a dysfunctional mirror neuron system may explain the pathology observed in ASD. Because EEG oscillations in the mu frequency (8-13 Hz) over sensorimotor cortex are thought to reflect mirror neuron activity, one method for testing the integrity of this system is to measure mu responsiveness to actual and observed movement. It has been established that mu power is reduced (mu suppression) in typically developing individuals both when they perform actions and when they observe others performing actions, reflecting an observation/execution system which may play a critical role in the ability to understand and imitate others' behaviors. This study investigated whether individuals with ASD show a dysfunction in this system, given their behavioral impairments in understanding and responding appropriately to others' behaviors. Mu wave suppression was measured in ten high-functioning individuals with ASD and ten age- and gender-matched control subjects while watching videos of (1) a moving hand, (2) a bouncing ball, and (3) visual noise, or (4) moving their own hand. Control subjects showed significant mu suppression to both self and observed hand movement. The ASD group showed significant mu suppression to self-performed hand movements but not to observed hand movements. These results support the hypothesis of a dysfunctional mirror neuron system in high-functioning individuals with ASD.

Imitation guides the behaviour of a range of species. Recent scientific advances in the study of imitation at multiple levels from neurons to behaviour have far-reaching implications for cognitive science, neuroscience, and evolutionary and developmental psychology. This volume provides a state-of-the-art summary of the research on imitation in both Europe and America, including work on infants, adults, and nonhuman primates, with speculations about robotics. A special feature of the book is that it provides a concrete instance of the links between developmental psychology, neuroscience, and cognitive science. It showcases how an interdisciplinary approach to imitation can illuminate long-standing problems in the brain sciences, including consciousness, self, perception-action coding, theory of mind, and intersubjectivity. The book addresses what it means to be human and how we get that way.

Understanding the intentions of others while watching their actions is a fundamental building block of social behavior. The neural and functional mechanisms underlying this ability are still poorly understood. To investigate these mechanisms we used functional magnetic resonance imaging. Twenty-three subjects watched three kinds of stimuli: grasping hand actions without a context, context only (scenes containing objects), and grasping hand actions performed in two different contexts. In the latter condition the context suggested the intention associated with the grasping action (either drinking or cleaning). Actions embedded in contexts, compared with the other two conditions, yielded a significant signal increase in the posterior part of the inferior frontal gyrus and the adjacent sector of the ventral premotor cortex where hand actions are represented. Thus, premotor mirror neuron areas -- areas active during the execution and the observation of an action -- previously thought to be involved only in action recognition are actually also involved in understanding the intentions of others. To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically.

Instead of merely seeing what other people do and feel, said Christian Keysers of the University of Groningen, the Netherlands, "we start to feel their actions and sensations in our own cortex as if we would be doing these actions and having those sensations." Except when we don't. In children with autism, "there may be a deficit in the mirror-neuron system," says Prof. Iacoboni, which may explain why they are unable to infer the mental state and intentions of others. Without mirror neurons to serve as bridges between minds, everyone seems like a cipher.

At the heart of the ability to imitate lies a mechanism that matches perceived external behaviours with equivalent internal behaviours of its own, recruiting information from the perceptual, motor and memory systems. This mechanism has been shown to be present even in newborn infants, which have been observed to imitate the facial gestures of their caretakers. In humans, malfunctions of this mechanism, surfaced as an inability to imitate, have been used as detectors of pathological disorders including autism and some forms of apraxia. This chapter presents a computational model of this mechanisms.

We focus on an imitative disturbance involving difficulties both in copying actions and in inhibiting more stereotyped mimicking, such as echolalia.

It has been suggested that social impairments observed in individuals with autism spectrum disorder (ASD) can be partly explained by an abnormal mirror neuron system. Studies on monkeys have shown that mirror neurons are cells in premotor area F5 that discharge when a monkey executes or sees a specific action or when it hears the corresponding action-related sound. Evidence for the presence of a MNS in humans comes in part from studies using transcranial magnetic stimulation (TMS), where a change in the amplitude of the TMS-induced motor-evoked potentials (MEPs) during action observation has been demonstrated.

In this paper I will show that the same neural circuits involved in action control and in the first person experience of emotions and sensations are also active when witnessing the same actions, emotions and sensations of others, respectively.I will posit that the mirror neuron systems, together with other mirroring neural clusters outside the motor domain, constitute the neural underpinnings of embodied simulation, the functional mechanism at the basis of intentional attunement.

"Observing, imagining, preparing or in any way representing an action excites the motor programs used to perform that action, but below the level which actually causes the action to be performed," says Professor Frith. The group's work has been galvanised in the last decade by the discovery of individual mirror neurons in monkeys, which discharge both when the monkey performs certain hand movements and when it observes another monkey or a human performing similar hand movements. While mirror neurons themselves have not been confirmed in humans, the existence of a mirror system is well established. Portions of the brain regions involved in executing actions are also activated by the mere observation of the action. "There are lots of interesting questions that arise from this idea," says Professor Frith. "What stops the movement actually being performed? What is the mirror system imitating, the actual observed movement or the goal of the movement? And does the mirror system somehow get switched on and off?"

It is not uncommon to recognize a specific action by the sound it creates. Neurons have been discovered in monkey premotor cortex that may contribute to this ability; they respond to both performing an action and hearing its action-related sound, and may be critical for communicating with others, learning gestures and even acquiring language.

Mirror neurons are a type of brain cell that respond equally when we perform an action and when we witness someone else perform the same action. They were first discovered in the early 1990s, when a team of Italian researchers found individual neurons in the brains of macaque monkeys that fired both when the monkeys grabbed an object and also when the monkeys watched another primate grab the same object. Neuroscientist Giacomo Rizzolatti, MD, who with his colleagues at the University of Parma first identified mirror neurons, says that the neurons could help explain how and why we "read" other people's minds and feel empathy for them. If watching an action and performing that action can activate the same parts of the brain in monkeys--down to a single neuron--then it makes sense that watching an action and performing an action could also elicit the same feelings in people.

In the prefrontal cortex of the human and monkey brain there are areas with a specific type of neurons. These "mirror neurons" are activated when a certain action is executed, but also when the same action is observed. When we observe a given action we mentally imitate it. The brain activates a motor plan that is normally used to execute the given action. This motor plan is only inhibited at the base of the muscles that are normally used to execute the observed action. As a result of this mental mimicking of the "other" we acquire a "sense of self" and we gain insight about the desires and intentions of the other. This equipes us humans with the capacity for empathy. A very simple form of such mirror system seems to be a widely spread feature in the animal kingdom and is used as the basis for imitative behaviour. If such an important system as the mirror system does not function properly it has serious consequences. In autism the patient are incapable to understand the emotions and ways of thinking of other people as a result of a poorly functioning mirror system. This might be a reason for the social isolation and introversion in autism patients.

The discovery of premotor and parietal cells known as mirror neurons in the macaque brain that fire not only when the animal is in action, but also when it observes others carrying out the same actions provides a plausible neurophysiological mechanism for a variety of important social behaviours, from imitation to empathy. Recent data also show that dysfunction of the mirror neuron system in humans might be a core deficit in autism, a socially isolating condition. Here, we review the neurophysiology of the mirror neuron system and its role in social cognition and discuss the clinical implications of mirror neuron dysfunction.

One of the more intriguing recent discoveries in brain science is the existence of "mirror neurons," a set of neurons in the premotor area of the brain that are activated not only when performing an action oneself, but also while observing someone else perform that action. It is believed mirror neurons increase an individual's ability to understand the behaviors of others, an important skill in social species such as humans. A critical aspect of understanding the behavior of another person is recognizing the intent of his actions--is he coming to praise me or to bury me? In the premier open-access journal PLoS Biology, Marco Iacoboni and colleagues use functional magnetic resonance imaging (fMRI) to show that the mirror neuron system tracks not only the actions, but also the intentions, of others.

Scientists have recently discovered that neurons in the premotor area that fire in preparation for upcoming movements also fire when we observe someone else carry out that action.

In my commentary I will first focus on some properties of the mirror neuron system in monkeys and humans and provide a neuroscientific perspective on an enlarged account of empathy, the shared manifold of intersubjectivity. I will show that the same neural circuits involved in action control and in the first person experience of emotions and sensations are also active when witnessing the same actions, emotions and sensations of others, respectively. I will posit that the mirror neuron systems, together with other mirroring neural clusters outside the motor domain, constitute the neural underpinnings of embodied simulation, the functional mechanism at the basis of "intentional attunement," our capacity to pre-reflexively identify with the others. The implications of this perspective on the dialogue between neuroscience and psychoanalysis will be discussed.

All of these experiments are focused on relatively simple stimuli that researchers can reproduce and measure easily. Whether mirror neurons are involved in more complex calculations of motive�and, most significantly, in those calculations made when someone is trying to manipulate the behaviour of someone else�remains to be seen. But it seems a plausible hypothesis, and the tools to test it more thoroughly are now in place. Understanding what someone else thinks is the necessary first step to deceiving or even controlling them. The actions of mirror cells may have wide ramifications.

Imitation is a basic form of motor learning during development. We have a preference to imitate the actions of others as if looking in a mirror (specular imitation: i.e., when the actor moves the left hand, the imitator moves the right hand) rather than with the anatomically congruent hand (anatomic imitation: i.e., actor and imitator both moving the right hand). We hypothesized that this preference reflects changes in activity in previously described frontoparietal cortical areas involved in directly matching observed and executed actions (mirror neuron areas). We used functional magnetic resonance imaging to study brain activity in normal volunteers imitating left and right hand movements with their right hand. Bilateral inferior frontal and right posterior parietal cortex were more active during specular imitation compared with anatomic imitation and control motor tasks. Furthermore this same pattern of activity was also observed in the rostral part of the supplementary motor area (SMA-proper) of the right hemisphere. These findings suggest that the degree of involvement of frontoparietal mirror areas in imitation depends on the nature of the imitative behavior, ruling out a linguistic mediation of these areas in imitation. Moreover, activity in the SMA appears to be tightly coupled to frontoparietal mirror areas when subjects copy the actions of others.

Recent advances in the cognitive neuroscience of action have considerably enlarged our understanding of human motor cognition. In particular, the activity of mirror neurons first discovered in the premotor cortex of macaque monkeys seems to provide an observer with the understanding of a perceived action by means of the motor simulation of the agent's observed movements. This discovery has raised the prospect of a motor theory of human social cognition. In humans, however, social cognition encompasses the ability to mindread. Many motor theorists of social cognition try to bridge the gap between motor cognition and mindreading by endorsing a simulation account of mindreading. Here, we argue that motor simulation is neither sufficient nor necessary for third-person mindreading.

The most fundamental solution concepts in Game Theory - Nash equilibrium, backward induction, and iterated elimination of dominated strategies - are based on the assumption that people are capable of predicting others' actions. These concepts require people to be able to view the game from the other players' perspectives, i.e. to understand others' motives and beliefs. Economists still know little about what enables people to put themselves into others' shoes and how this ability interacts with their own preferences and beliefs. Social neuroscience provides insights into the neural mechanism underlying our capacity to represent others' intentions, beliefs, and desires, referred to as "Theory of Mind" or "mentalizing", and the capacity to share the feelings of others, referred to as "empathy". We summarize the major findings about the neural basis of mentalizing and empathizing and discuss some implications for economics.

Explores the role that mirror neurons may play in human actions and interactions and explains how scientists think mirror neurons work.This NOVA scienceNOW segment: * explains the role that mirror neurons may play in how we understand and connect with each other. * reports on experiments indicating that the neurons that "fire" when a monkey does an activity also "fire" when the monkey observes the activity, suggesting that neurologically doing and watching are the same. * suggests that humans use a similar "mirroring" response to translate what we see, so that we can relate to each other and the world. * demonstrates an experiment involving pictures of different facial expressions that may show how mirror neurons tie us to each other's feelings as well as actions. * suggests that mirror neurons may have enhanced humans' evolutionary process and survival success.

These neurons differ in function from previously defined mirror neurons in that they apparently code not current actions, but some aspect of future ones. In this interpretation, an action observed within a familiar context activates mirror neurons for �logically related� actions, those that most likely will follow the observed one. This suggests the mirror neuron system is intimately involved not only with understanding the behavior of others, but predicting it as well.

Starting from a neurobiological standpoint, I will propose that our capacity to understand others as intentional agents, far from being exclusively dependent upon mentalistic/linguistic abilities, be deeply grounded in the relational nature of our interactions with the world. According to this hypothesis, an implicit, prereflexive form of understanding of other individuals is based on the strong sense of identity binding us to them. We share with our conspecifics a multiplicity of states that include actions, sensations and emotions. A new conceptual tool able to capture the richness of the experiences we share with others will be introduced: the shared manifold of intersubjectivity. I will posit that it is through this shared manifold that it is possible for us to recognize other human beings as similar to us. It is just because of this shared manifold that intersubjective communication and ascription of intentionality become possible. It will be argued that the same neural structures that are involved in processing and controlling executed actions, felt sensations and emotions are also active when the same actions, sensations and emotions are to be detected in others. It therefore appears that a whole range of different "mirror matching mechanisms" may be present in our brain. This matching mechanism, constituted by mirror neurons originally discovered and described in the domain of action, could well be a basic organizational feature of our brain, enabling our rich and diversified intersubjective experiences. This perspective is in a position to offer a global approach to the understanding of the vulnerability to major psychoses such as schizophrenia.

"Mirror neurons suggest that we pretend to be in another person's mental shoes," says Marco Iacoboni, a neuroscientist at the University of California, Los Angeles School of Medicine. "In fact, with mirror neurons we do not have to pretend, we practically are in another person's mind." Since their discovery, mirror neurons have been implicated in a broad range of phenomena, including certain mental disorders. Mirror neurons may help cognitive scientists explain how children develop a theory of mind (ToM), which is a child's understanding that others have minds similar to their own. Doing so may help shed light on autism, in which this type of understanding is often missing.

The discovery of mirror neurons has given rise to a number of interpretations of their functions together with speculations on their potential role in the evolution of specifically human capacities. Thus, mirror neurons have been thought to ground many aspects of human social cognition, including the capacity to engage in cooperative collective actions and to understand them. I will propose an evaluation of this latter claim. On the one hand, I will argue that mirror neurons do not by themselves provide a sufficient basis for the forms of agentive understanding and shared intentionality involved in cooperative collective actions. On the other hand, I will also argue that mirror neurons can nevertheless play an important role in an account of the production and understanding of joint action, insofar as they provide the basic constituents of implicit agent-neutral representations and are useful elements in a process of online mutual adjustment of participants' actions.

The main aim of my arguments will be to show that, far from being exclusively dependent upon mentalistic/linguistic abilities, the capacity for understanding others as intentional agents is deeply grounded in the relational nature of action. Action is relational, and the relation holds both between the agent and the object target of the action, as between the agent of the action and his/her observer (see below). Agency constitutes a key issue for the understanding of intersubjectivity and for explaining how individuals can interpret their social world. This account of intersubjectivity, founded on the empirical findings of neuroscientific investigation, will be discussed and put in relation with a classical tenet of phenomenology: empathy. I will provide an "enlarged" account of empathy that will be defined by means of a new conceptual tool: the shared manifold of intersubjectivity.

The article contributes to the quest to relate global data on brain and behavior (e.g. from PET, Positron Emission Tomography, and fMRI. functional Magnetic Resonance Imaging) to the underpinning neural networks. Models tied to human brain imaging data often focus on a few "boxes" based on brain regions associated with exceptionally high blood flow, rather than analyzing the cooperative computation of multiple brain regions. For analysis directly at the level of such data, a schema-based model may be most appropriate. To further address neurophysiological data, the Synthetic PET imaging method uses computational models of biological neural circuitry based on animal data to predict and analyze the results of human PET studies. This technique makes use of the hypothesis that rCBF (regional cerebral blood flow) is correlated with the integrated synaptic activity in a localized brain region. We also describe the possible extension of the Synthetic PET method to fMRI. The second half of the paper then exemplifies this general research program with two case studies, one on visuo-motor processing for control of grasping (Section 3 in which the focus is on Synthetic PET) and the imitation of motor skills (Sections 4 and 5, with a focus on Synthetic fMRI). Our discussion of imitation pays particular attention to data on the mirror system in monkey (neural circuitry which allows the brain to recognize actions as well as execute them). Finally, Section 6 outlines the immense challenges in integrating models of different portions of the nervous system which address detailed neurophysiological data from studies of primates and other species; summarizes key issues for developing the methodology of Synthetic Brain Imaging; and shows how comparative neuroscience and evolutionary arguments will allow us to extend Synthetic Brain Imaging even to language and other cognitive functions for which few or no animal data are available.

Conducted at the Semel Institute's Ahmanson-Lovelace Brain Mapping Center, the research used functional magnetic resonance imaging (fMRI) to measure brain activity in 10 high-functioning children with autism while they imitated and observed 80 photos depicting different emotions such as anger, fear, happiness or sadness. In addition, the brain activity of 10 typically developing children was studied while performing the same tasks. The study shows that unlike typically developing children, children with autism have virtually no activity in the pars opercularis of the inferior frontal gyrus, identified by previous research as a key part of the mirror neuron system. Importantly, the level of mirror neuron activity seen in children with autism was inversely related to symptom severity in the social domain. Children with autism also showed reduced activity in the emotion centers of the brain, consistent with the hypothesis that this mirroring mechanism may play a crucial role for understanding how others feel and for empathizing with them.

"Understanding the intentions of others while watching their action is a fundamental building block of social behavior," said principal investigator Dr. Marco Iacoboni, an associate professor in-residence of psychiatry and biobehavioral sciences at the UCLA Neuropsychiatric Institute's Ahmanson Lovelace Brain Mapping Center and the David Geffen School of Medicine at UCLA. "Our findings show for the first time that intentions behind actions of others can be recognized by the motor system using a mirror mechanism in the brain. The same area of the brain responsible for understanding behavior can predict behavior as well."

Powerpoint presentation

Brain imaging techniques allow the mapping of cognitive functions onto neural systems, but also the understanding of mechanisms of human behavior. In a series of imaging studies we have described a minimal neural architecture for imitation. This architecture comprises a brain region that codes an early visual description of the action to be imitated, a second region that codes the detailed motor specification of the action to be copied, and a third region that codes the goal of the imitated action. Neural signals predicting the sensory consequences of the planned imitative action are sent back to the brain region coding the early visual description of the imitated action, for monitoring purposes ("my planned action is like the one I have just seen"). The three brain regions forming this minimal neural architecture belong to a part of the cerebral cortex called perisylvian, a critical cortical region for language. This suggests that the neural mechanisms implementing imitation are also used for other forms of human communication, such as language. Indeed, imaging data on warping of chimpanzee brains onto human brains indicate that the largest expansion between the two species is perisylvian. Functional similarities between the structure of actions and the structure of language as it unfolds during conversation reinforce this notion. Additional data suggest also that empathy occurs via the minimal neural architecture for imitation interacting with regions of the brain relevant to emotion. All in all, we come to understand others via imitation, and imitation shares functional mechanisms with language and empathy.

In this article we provide a unifying neural hypothesis on how individuals understand the actions and emotions of others. Our main claim is that the fundamental mechanism at the basis of the experiential understanding of others' actions is the activation of the mirror neuron system. A similar mechanism, but involving the activation of viscero-motor centers, underlies the experiential understanding of the emotions of others.