In JoVE (1)

Other Publications (58)

Articles by Antonia Hamilton in JoVE

 JoVE Behavior

Using Fiberless, Wearable fNIRS to Monitor Brain Activity in Real-world Cognitive Tasks

1Department of Medical Physics and Biomedical Engineering, Malet Place Engineering Building, University College London, 2Infrared Imaging Lab, Institute for Advanced Biomedical Technology (ITAB), Department of Neuroscience, Imaging and Clinical Sciences, University of Chieti-Pescara, 3Institute of Cognitive Neuroscience, Alexandra House, University College London

JoVE 53336

Other articles by Antonia Hamilton on PubMed

Controlling the Statistics of Action: Obstacle Avoidance

Journal of Neurophysiology. May, 2002  |  Pubmed ID: 11976380

Task optimization in the presence of signal-dependent noise (TOPS) has been proposed as a general framework for planning goal-directed movements. Within this framework, the motor command is assumed to be corrupted by signal-dependent noise, which leads to a distribution of possible movements. A task can then be equated with optimizing some function of the statistics of this distribution. We found the optimal trajectory for obstacle avoidance by minimizing the mean-squared error at the end of the movement while keeping the probability of collision with the obstacle below a fixed limit. The optimal paths accurately predicted the empirical trajectories. This demonstrates that controlling the statistics of movements in the presence of signal-dependent noise may be a fundamental and unifying principle of goal-directed movements.

Neurophysiology: Cerebral Carbon Copies

Current Biology : CB. Aug, 2002  |  Pubmed ID: 12194835

Predicting the consequences of our actions is essential for sensorimotor control. A candidate neural pathway underlying the prediction of eye position during saccades has been reported.

Sources of Signal-dependent Noise During Isometric Force Production

Journal of Neurophysiology. Sep, 2002  |  Pubmed ID: 12205173

It has been proposed that the invariant kinematics observed during goal-directed movements result from reducing the consequences of signal-dependent noise (SDN) on motor output. The purpose of this study was to investigate the presence of SDN during isometric force production and determine how central and peripheral components contribute to this feature of motor control. Peripheral and central components were distinguished experimentally by comparing voluntary contractions to those elicited by electrical stimulation of the extensor pollicis longus muscle. To determine other factors of motor-unit physiology that may contribute to SDN, a model was constructed and its output compared with the empirical data. SDN was evident in voluntary isometric contractions as a linear scaling of force variability (SD) with respect to the mean force level. However, during electrically stimulated contractions to the same force levels, the variability remained constant over the same range of mean forces. When the subjects were asked to combine voluntary with stimulation-induced contractions, the linear scaling relationship between the SD and mean force returned. The modeling results highlight that much of the basic physiological organization of the motor-unit pool, such as range of twitch amplitudes and range of recruitment thresholds, biases force output to exhibit linearly scaled SDN. This is in contrast to the square root scaling of variability with mean force present in any individual motor-unit of the pool. Orderly recruitment by twitch amplitude was a necessary condition for producing linearly scaled SDN. Surprisingly, the scaling of SDN was independent of the variability of motoneuron firing and therefore by inference, independent of presynaptic noise in the motor command. We conclude that the linear scaling of SDN during voluntary isometric contractions is a natural by-product of the organization of the motor-unit pool that does not depend on signal-dependent noise in the motor command. Synaptic noise in the motor command and common drive, which give rise to the variability and synchronization of motoneuron spiking, determine the magnitude of the force variability at a given level of mean force output.

The Scaling of Motor Noise with Muscle Strength and Motor Unit Number in Humans

Experimental Brain Research. Aug, 2004  |  Pubmed ID: 15014922

Understanding the origin of noise, or variability, in the motor system is an important step towards understanding how accurate movements are performed. Variability of joint torque during voluntary activation is affected by many factors such as the precision of the descending motor commands, the number of muscles that cross the joint, their size and the number of motor units in each. To investigate the relationship between the peripheral factors and motor noise, the maximum voluntary torque produced at a joint and the coefficient of variation of joint torque were recorded from six adult human subjects for four muscle/joint groups in the arm. It was found that the coefficient of variation of torque decreases systematically as the maximum voluntary torque increases. This decreasing coefficient of variation means that a given torque or force can be more accurately generated by a stronger muscle than a weaker muscle. Simulations demonstrated that muscles with different strengths and different numbers of motor units could account for the experimental data. In the simulations, the magnitude of the coefficient of variation of muscle force depended primarily on the number of motor units innervating the muscle, which relates positively to muscle strength. This result can be generalised to the situation where more than one muscle is available to perform a task, and a muscle activation pattern must be selected. The optimal muscle activation pattern required to generate a target torque using a group of muscles, while minimizing the consequences of signal dependent noise, is derived.

Your Own Action Influences How You Perceive Another Person's Action

Current Biology : CB. Mar, 2004  |  Pubmed ID: 15043814

A growing body of neuroimaging and neurophysiology studies has demonstrated the motor system's involvement in the observation of actions, but the functional significance of this is still unclear. One hypothesis suggests that the motor system decodes observed actions. This hypothesis predicts that performing a concurrent action should influence the perception of an observed action. We tested this prediction by asking subjects to judge the weight of a box lifted by an actor while the subject either lifted or passively held a light or heavy box. We found that actively lifting a box altered the perceptual judgment; an observed box was judged to be heavier when subjects were lifting the light box, and it was judged to be lighter when they were lifting the heavy box. This result is surprising because previous studies have found facilitating effects of movement on perceptual judgments and facilitating effects of observed actions on movements, but here we found the opposite. We hypothesize that this effect can be understood in terms of overlapping neural systems for motor control and action-understanding if multiple models of possible observed and performed actions are processed.

Where Does Your Own Action Influence Your Perception of Another Person's Action in the Brain?

NeuroImage. Jan, 2006  |  Pubmed ID: 16112877

Activation of premotor cortex during the observation and imitation of human actions is now increasingly accepted, but it remains unclear how the CNS is able to resolve potential conflicts between the observation of another person's action and the ongoing control of one's own action. Recent data suggest that this overlap leads to a systematic bias, where lifting a box influences participant's perceptual judgments of the weight of a box lifted by another person. We now investigate the neural basis of this bias effect using fMRI. Seventeen participants performed a perceptual weight judgment task or two control conditions while lifting a light box, a heavy box or no box during scanning. Brain regions related to perceptual bias were localized by correlating individual differences in bias with BOLD signal. Five regions were found to show correlations with psychophysical bias: left inferior frontal gyrus, left central sulcus, left extrastriate body area, left lingual gyrus and right intraparietal sulcus. The cluster in primary motor cortex was also activated by box lifting, and the cluster in extrastriate body area by the observation of hand actions and the weight judgment task. We suggest that these brain areas are part of a network where motor processing modulates perceptual judgment of observed human actions, and thus visual and motor processes cannot be thought of as two distinct systems, but instead interact at many levels.

Goal Representation in Human Anterior Intraparietal Sulcus

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Jan, 2006  |  Pubmed ID: 16436599

When a child reaches toward a cookie, the watching parent knows immediately what the child wants. The neural basis of this ability to interpret other people's actions in terms of their goals has been the subject of much speculation. Research with infants has shown that 6 month olds respond when they see an adult reach to a novel goal but habituate when an adult reaches to the same goal repeatedly. We used a similar approach in an event-related functional magnetic resonance imaging experiment. Adult participants observed a series of movies depicting goal-directed actions, with the sequence controlled so that some goals were novel and others repeated relative to the previous movie. Repeated presentation of the same goal caused a suppression of the blood oxygen level-dependent response in two regions of the left intraparietal sulcus. These regions were not sensitive to the trajectory taken by the actor's hand. This result demonstrates that the anterior intraparietal sulcus represents the goal of an observed action.

Action Understanding Requires the Left Inferior Frontal Cortex

Current Biology : CB. Mar, 2006  |  Pubmed ID: 16527749

Numerous studies have established that inferior frontal cortex is active when hand actions are planned, imagined, remembered, imitated, and even observed. Furthermore, it has been proposed that these activations reflect a process of simulating the observed action to allow it to be understood and thus fully perceived. However, direct evidence for a perceptual role for left inferior frontal cortex is rare, and linguistic or motor contributions to the reported activations have not been ruled out. We used repetitive transcranial magnetic stimulation (rTMS) over inferior frontal gyrus during a perceptual weight-judgement task to test the hypothesis that this region contributes to action understanding. rTMS at this site impaired judgments of the weight of a box lifted by a person, but not judgements of the weight of a bouncing ball or of stimulus duration, and rTMS at control sites had no impact. This demonstrates that the integrity of left inferior frontal gyrus is necessary to make accurate perceptual judgments about other people's actions.

Building a Motor Simulation De Novo: Observation of Dance by Dancers

NeuroImage. Jul, 2006  |  Pubmed ID: 16530429

Research on action simulation identifies brain areas that are active while imagining or performing simple overlearned actions. Are areas engaged during imagined movement sensitive to the amount of actual physical practice? In the present study, participants were expert dancers who learned and rehearsed novel, complex whole-body dance sequences 5 h a week across 5 weeks. Brain activity was recorded weekly by fMRI as dancers observed and imagined performing different movement sequences. Half these sequences were rehearsed and half were unpracticed control movements. After each trial, participants rated how well they could perform the movement. We hypothesized that activity in premotor areas would increase as participants observed and simulated movements that they had learnt outside the scanner. Dancers' ratings of their ability to perform rehearsed sequences, but not the control sequences, increased with training. When dancers observed and simulated another dancer's movements, brain regions classically associated with both action simulation and action observation were active, including inferior parietal lobule, cingulate and supplementary motor areas, ventral premotor cortex, superior temporal sulcus and primary motor cortex. Critically, inferior parietal lobule and ventral premotor activity was modulated as a function of dancers' ratings of their own ability to perform the observed movements and their motor experience. These data demonstrate that a complex motor resonance can be built de novo over 5 weeks of rehearsal. Furthermore, activity in premotor and parietal areas during action simulation is enhanced by the ability to execute a learned action irrespective of stimulus familiarity or semantic label.

Imitation and Action Understanding in Autistic Spectrum Disorders: How Valid is the Hypothesis of a Deficit in the Mirror Neuron System?

Neuropsychologia. Apr, 2007  |  Pubmed ID: 17234218

The motor mirror neuron system supports imitation and goal understanding in typical adults. Recently, it has been proposed that a deficit in this mirror neuron system might contribute to poor imitation performance in children with autistic spectrum disorders (ASD) and might be a cause of poor social abilities in these children. We aimed to test this hypothesis by examining the performance of 25 children with ASD and 31 typical children of the same verbal mental age on four action representation tasks and a theory of mind battery. Both typical and autistic children had the same tendency to imitate an adult's goals, to imitate in a mirror fashion and to imitate grasps in a motor planning task. Children with ASD showed superior performance on a gesture recognition task. These imitation and gesture recognition tasks all rely on the mirror neuron system in typical adults, but performance was not impaired in children with ASD. In contrast, the ASD group were impaired on the theory of mind tasks. These results provide clear evidence against a general imitation impairment and a global mirror neuron system deficit in children with autism. We suggest this data can best be understood in terms of multiple brain systems for different types of imitation and action understanding, and that the ability to understand and imitate the goals of hand actions is intact in children with ASD.

Evidence for a Distributed Hierarchy of Action Representation in the Brain

Human Movement Science. Aug, 2007  |  Pubmed ID: 17706312

Complex human behavior is organized around temporally distal outcomes. Behavioral studies based on tasks such as normal prehension, multi-step object use and imitation establish the existence of relative hierarchies of motor control. The retrieval errors in apraxia also support the notion of a hierarchical model for representing action in the brain. In this review, three functional brain imaging studies of action observation using the method of repetition suppression are used to identify a putative neural architecture that supports action understanding at the level of kinematics, object centered goals and ultimately, motor outcomes. These results, based on observation, may match a similar functional-anatomic hierarchy for action planning and execution. If this is true, then the findings support a functional-anatomic model that is distributed across a set of interconnected brain areas that are differentially recruited for different aspects of goal-oriented behavior, rather than a homogeneous mirror neuron system for organizing and understanding all behavior.

Social Cognition: Overturning Stereotypes of and with Autism

Current Biology : CB. Aug, 2007  |  Pubmed ID: 17714653

New data suggest that even children with autism are subject to race and gender stereotypes. This result constrains theories of stereotype acquisition and social cognition in autism.

Interference Effect of Observed Human Movement on Action is Due to Velocity Profile of Biological Motion

Social Neuroscience. 2007  |  Pubmed ID: 18633814

It has previously been shown that observing an action made by a human, but not by a robot, interferes with executed actions (Kilner, Paulignan, & Blakemore, 2003). Here, we investigated what aspect of human movement causes this interference effect. Subjects made arm movements while observing a video of either a human making an arm movement or a ball moving across the screen. Both human and ball videos contained either biological (minimum jerk) or non-biological (constant velocity) movements. The executed and observed arm movements were either congruent (same direction) or incongruent (tangential direction) with each other. The results showed that observed movements are processed differently according to whether they are made by a human or a ball. For the ball videos, both biological and non-biological incongruent movements interfered with executed arm movements. In contrast, for the human videos, the velocity profile of the movement was the critical factor: only incongruent, biological human movements interfered with executed arm movements. We propose that the interference effect could be due either to the information the brain has about different types of movement stimuli or to the impact of prior experience with different types of form and motion.

Action Outcomes Are Represented in Human Inferior Frontoparietal Cortex

Cerebral Cortex (New York, N.Y. : 1991). May, 2008  |  Pubmed ID: 17728264

The simple action of pressing a switch has many possible interpretations--the actor could be turning on a light, deleting critical files from a computer, or even turning off a life-support system. In each of these cases, the motor parameters of the action are the same but the physical outcome differs. We report evidence of suppressed responses in right inferior parietal and right inferior frontal cortex when participants saw repeated movies showing the same action outcome, but these regions did not distinguish the kinematic parameters by which the action was accomplished. Thus, these brain areas encode the physical outcomes of human actions in the world. These results are compatible with a hierarchical model of human action understanding in which a cascade of specialized processes from occipital to parietal and frontal regions allow humans to understand the physical consequences of actions in the world and the intentions underlying those actions.

Emulation and Mimicry for Social Interaction: a Theoretical Approach to Imitation in Autism

Quarterly Journal of Experimental Psychology (2006). Jan, 2008  |  Pubmed ID: 18038342

The "broken-mirror" theory of autism argues that dysfunction of the "mirror neuron system" is a root cause of social disability in autism. The present paper aims to scrutinize this theory and, when it breaks down, to provide an alternative. Current evidence suggests that children with autism are able to understand and emulate goal-directed actions, but may have specific impairments in automatic mimicry of actions without goals. These data are not compatible with the broken-mirror theory, but can be accounted for by a new model called EP-M. The EP-M model segments the mirror neuron system into an indirect, parietal route for goal emulation and planning (EP) and a direct occipital-frontal route for mimicry (M). This fractionation is consistent with neuroimaging and behavioural studies of the mirror neuron system in typical children and adults. I suggest that top-down modulation of the direct M route may be dysfunctional in individuals with autism, leading to abnormal behaviours on mimicry tasks as well as other social disabilities.

Unbroken Mirrors: Challenging a Theory of Autism

Trends in Cognitive Sciences. Jun, 2008  |  Pubmed ID: 18479959

The 'broken mirror' theory of autism has received considerable attention far beyond the scientific community. This theory proposes that the varied social-cognitive difficulties characteristic of autism could be explained by dysfunction of the mirror neuron system, thought to play a role in imitation. We examine this theory and argue that explaining typical imitation behavior, and the failure to imitate in autism, requires much more than the mirror neuron system. Furthermore, evidence for the role of the mirror neuron system in autism is weak. We suggest the broken mirror theory of autism is premature and that better cognitive models of social behavior within and beyond the mirror neuron system are required to understand the causes of poor social interaction in autism.

Sensitivity of the Action Observation Network to Physical and Observational Learning

Cerebral Cortex (New York, N.Y. : 1991). Feb, 2009  |  Pubmed ID: 18515297

Human motor skills can be acquired by observation without the benefit of immediate physical practice. The current study tested if physical rehearsal and observational learning share common neural substrates within an action observation network (AON) including premotor and inferior parietal regions, that is, areas activated both for execution and observation of similar actions. Participants trained for 5 days on dance sequences set to music videos. Each day they physically rehearsed one set of dance sequences ("danced"), and passively watched a different set of sequences ("watched"). Functional magnetic resonance imaging was obtained prior to and immediately following the 5 days of training. After training, a subset of the AON showed a degree of common activity for observational and physical learning. Activity in these premotor and parietal regions was sustained during observation of sequences that were danced or watched, but declined for unfamiliar sequences relative to the pretraining scan session. These imaging data demonstrate the emergence of action resonance processes in the human brain based on observational learning without physical practice and identify commonalities in the neural substrates for physical and observational learning.

Repetition Suppression for Performed Hand Gestures Revealed by FMRI

Human Brain Mapping. Sep, 2009  |  Pubmed ID: 19117276

The functional components of the human motor system that are used to retrieve and execute simple intransitive hand gestures were identified with a repetition suppression (RS) paradigm. Participants performed movements with the right hand to text instructions in a rapid event related design with a pseudo-random stimulus order. Brain areas associated with action retrieval were identified by comparing trials where an action was repeated to trials that involved a new action. Performance of a novel action, collapsed across individual actions, resulted in significantly greater activity in a left hemisphere predominant fronto-parietal circuit involving inferior frontal gyrus and inferior parietal cortex (supramarginal gyrus). This is consistent with previous action retrieval tasks using go, no-go paradigms and lesion studies of patients with apraxia that emphasize a role of these areas in action organization. In addition, RS effects were present in left primary sensorimotor cortex. These effects cannot be ascribed to kinematic differences, simple action related activity or differences of cognitive set. Significant RS effects for action retrieval could be identified with as little as 5 min of fMRI data and underscores the potential of using RS to characterize representational structure within the motor system.

Lost in Localization: a Minimal Middle Way

NeuroImage. Oct, 2009  |  Pubmed ID: 19442743

Commentaries by Derrfuss and Mar (Derrfuss, J., Mar, R., 2009. Lost in localization: the need for a universal coordinate database. Neuroimage.) and Nielsen (Nielsen, F.A., 2009. Lost in localization: a solution with neuroinformatics 2.0? Neuroimage.) outline the need for a universal coordinate database and some possible approaches to creating one. I highlight the issue of minimal or maximal database scope and advocate a bottom-up approach to this problem.

Goals, Intentions and Mental States: Challenges for Theories of Autism

Journal of Child Psychology and Psychiatry, and Allied Disciplines. Aug, 2009  |  Pubmed ID: 19508497

The ability to understand the goals and intentions behind other people's actions is central to many social interactions. Given the profound social difficulties seen in autism, we might expect goal understanding to be impaired in these individuals. Two influential theories, the 'broken mirror' theory and the mentalising theory, can both predict this result. However, a review of the current data provides little empirical support for goal understanding difficulties; several studies demonstrate normal performance by autistic children on tasks requiring the understanding of goals or intentions. I suggest that this conclusion forces us to reject the basic broken mirror theory and to re-evaluate the breadth of the mentalising theory. More subtle theories which distinguish between different types of mirroring and different types of mentalising may be able to account for the present data, and further research is required to test and refine these theories.

Visual Perspective Taking Impairment in Children with Autistic Spectrum Disorder

Cognition. Oct, 2009  |  Pubmed ID: 19682673

Evidence from typical development and neuroimaging studies suggests that level 2 visual perspective taking - the knowledge that different people may see the same thing differently at the same time - is a mentalising task. Thus, we would expect children with autism, who fail typical mentalising tasks like false belief, to perform poorly on level 2 visual perspective taking as well. However, prior data on this issue are inconclusive. We re-examined this question, testing a group of 23 young autistic children, aged around 8years with a verbal mental age of around 4years and three groups of typical children (n=60) ranging in age from 4 to 8years on a level 2 visual perspective task and a closely matched mental rotation task. The results demonstrate that autistic children have difficulty with visual perspective taking compared to a task requiring mental rotation, relative to typical children. Furthermore, performance on the level 2 visual perspective taking task correlated with theory of mind performance. These findings resolve discrepancies in previous studies of visual perspective taking in autism, and demonstrate that level 2 visual perspective taking is a mentalising task.

Dissociable Substrates for Body Motion and Physical Experience in the Human Action Observation Network

The European Journal of Neuroscience. Oct, 2009  |  Pubmed ID: 19788567

Observation of human actions recruits a well-defined network of brain regions, yet the purpose of this action observation network (AON) remains under debate. Some authors contend that this network has developed to respond specifically to observation of human actions. Conversely, others suggest that this network responds in a similar manner to actions prompted by human and non-human cues, and that one's familiarity with the action is the critical factor that drives this network. Previous studies investigating human and non-human action cues often confound novelty and stimulus form. Here, we used a dance-learning paradigm to assess AON activity during observation of trained and untrained dance cues where a human model was present or absent. Results show that individual components of the AON respond differently to the human form and to dance training. The bilateral superior temporal cortex responds preferentially to videos with a human present, regardless of training experience. Conversely, the right ventral premotor cortex responds more strongly when observing sequences that had been trained, regardless of the presence of a human. Our findings suggest that the AON comprises separate and dissociable components for motor planning and observing other people's actions.

Contorted and Ordinary Body Postures in the Human Brain

Experimental Brain Research. Jul, 2010  |  Pubmed ID: 19943038

Social interaction and comprehension of non-verbal behaviour requires a representation of people's bodies. Research into the neural underpinnings of body representation implicates several brain regions including extrastriate and fusiform body areas (EBA and FBA), superior temporal sulcus (STS), inferior frontal gyrus (IFG) and inferior parietal lobule (IPL). The different roles played by these regions in parsing familiar and unfamiliar body postures remain unclear. We examined the responses of this body observation network to static images of ordinary and contorted postures by using a repetition suppression design in functional neuroimaging. Participants were scanned whilst observing static images of a contortionist or a group of objects in either ordinary or unusual configurations, presented from different viewpoints. Greater activity emerged in EBA and FBA when participants viewed contorted compared to ordinary body postures. Repeated presentation of the same posture from different viewpoints lead to suppressed responses in the fusiform gyrus as well as three regions that are characteristically activated by observing moving bodies, namely STS, IFG and IPL. These four regions did not distinguish the image viewpoint or the plausibility of the posture. Together, these data define a broad cortical network for processing static body postures, including regions classically associated with action observation.

Understanding Actors and Object-goals in the Human Brain

NeuroImage. Apr, 2010  |  Pubmed ID: 20060912

When another person takes 10 pounds from your hand, it matters if they are a shopkeeper or a robber. That is, the meaning of a simple, goal-directed action can vary depending on the identity of the actors involved. Research examining action understanding has identified an action observation network (AON) that encodes action features such as goals and kinematics. However, it is not yet known how or where the brain links actor identity to action goal. In the present paper, we used a repetition suppression paradigm during functional magnetic resonance imaging (fMRI) to examine the neural representation of actor identity within the context of object-directed actions. Participants watched video clips of two different actors with two different object-goals. Repeated presentation of the same actor suppressed the blood oxygen level-dependent (BOLD) response in fusiform gyrus and occipitotemporal cortex. In contrast, repeated presentation of an action with the same object-goal suppressed the BOLD response throughout the AON. Our data reveal an extended brain network for understanding other people and their everyday actions that go beyond the traditional action observation network.

Triangles Have Goals Too: Understanding Action Representation in Left AIPS

Neuropsychologia. Jul, 2010  |  Pubmed ID: 20434468

Humans freely interpret moving shapes as being "alive" and having social intentions, such as beliefs and desires. The brain systems underpinning these processes are the same as those used to detect animacy and infer mental states from human behaviour. However, it is not yet known if the brain systems that respond to human action-goals also respond to the action-goals of shapes. In the present paper, we used a repetition suppression paradigm during functional magnetic resonance imaging (fMRI) to examine brain systems that respond to the action-goals of shapes. Participants watched video clips of simple, geometrical shapes performing different 'take-object' goals. Repeated presentation of the same goal suppressed the blood oxygen level-dependent (BOLD) response in left anterior intraparietal sulcus (aIPS), a brain region known to distinguish the goals of human hand actions. This finding shows that left aIPS shows similar sensitivity to the action-goals of human and non-human agents. Our data complement previous work on animacy perception and mental state inference, which suggest components of the social brain are driven by the type of action comprehension that is engaged rather than by the form of the acting agent (i.e., human or shape). Further, the results have consequence for theories of goal understanding in situations without access to biological form or motion.

Eye Contact Enhances Mimicry of Intransitive Hand Movements

Biology Letters. Feb, 2011  |  Pubmed ID: 20427328

When two people meet in a bar, a subtle interplay of social behaviours, including eye contact and unconscious mimicry of actions play an important role in how much the individuals like each other by the end of the evening. However, it is not known how these different social signals interact. Here, we adopt a rapid mimicry paradigm, to test if eye contact can modulate mimicry on a second by second time scale. Our results show that direct eye contact rapidly and specifically enhances mimicry of hand actions. These findings have implications for understanding the role of eye contact as a controlling signal in human non-verbal social behaviour.

Dissociation of Mirroring and Mentalising Systems in Autism

NeuroImage. Jun, 2011  |  Pubmed ID: 21310248

The role of mirror neuron systems and mentalising systems in causing poor social and communication skills in individuals with autistic spectrum conditions is hotly debated. We studied 18 adults with autistic spectrum conditions in comparison to 19 age and IQ matched typical individuals. Behavioural assessments revealed difficulties in mental state attribution and action comprehension in the autism sample. We examined brain responses when observing rational and irrational hand actions, because these actions engage mirror and mentalising components of the social brain respectively. Both typical and autistic participants activated the left anterior intraparietal sulcus component of the mirror system when viewing hand actions compared to moving shapes. The typical but not autistic participants activated the posterior mid cingulate cortex/supplementary motor area and bilateral fusiform cortex when viewing hand actions. When viewing irrational hand actions, the medial prefrontal cortex of typical participants deactivated but this region did not distinguish the different stimuli in autistic participants. These results suggest that parietal mirror regions function normally in autism, while differences in action understanding could be due to abnormal function of cingulate, fusiform and medial prefrontal regions. Thus, brain regions associated with mirroring and mentalising functions are differentially affected in autistic spectrum conditions.

Tools from the Past in the Modern Brain (Commentary on Stout Et Al.)

The European Journal of Neuroscience. Apr, 2011  |  Pubmed ID: 21457362

Eye Can See What You Want: Posterior Intraparietal Sulcus Encodes the Object of an Actor's Gaze

Journal of Cognitive Neuroscience. Nov, 2011  |  Pubmed ID: 21671736

In a social setting, seeing Sally look at a clock means something different to seeing her gaze longingly at a slice of chocolate cake. In both cases, her eyes and face might be turned rightward, but the information conveyed is markedly different, depending on the object of her gaze. Numerous studies have examined brain systems underlying the perception of gaze direction, but less is known about the neural basis of perceiving gaze shifts to specific objects. During fMRI, participants observed an actor look toward one of two objects, each occupying a distinct location. Video stimuli were sequenced to obtain repetition suppression (RS) for object identity, independent of spatial location. In a control condition, a spotlight highlighted one of the objects, but no actor was present. Observation of the human actor's gaze compared with the spotlight engaged frontal, parietal, and temporal cortices, consistent with a broad action observation network. RS for gazed object in the human condition was found in posterior intraparietal sulcus (pIPS). RS for highlighted object in the spotlight condition was found in middle occipital, inferior temporal, medial fusiform gyri, and superior parietal lobule. These results suggest that human pIPS is specifically sensitive to the type object that an observed actor looks at (tool vs. food), irrespective of the observed actor's gaze location (left vs. right). A general attention or lower-level object feature processing mechanism cannot account for the findings because a very different response pattern was seen in the spotlight control condition. Our results suggest that, in addition to spatial orienting, human pIPS has an important role in object-centered social orienting.

The Control of Mimicry by Eye Contact is Mediated by Medial Prefrontal Cortex

The Journal of Neuroscience : the Official Journal of the Society for Neuroscience. Aug, 2011  |  Pubmed ID: 21849560

Spontaneous mimicry of other people's actions serves an important social function, enhancing affiliation and social interaction. This mimicry can be subtly modulated by different social contexts. We recently found behavioral evidence that direct eye gaze rapidly and specifically enhances mimicry of intransitive hand movements (Wang et al., 2011). Based on past findings linking medial prefrontal cortex (mPFC) to both eye contact and the control of mimicry, we hypothesized that mPFC might be the neural origin of this behavioral effect. The present study aimed to test this hypothesis. During functional magnetic resonance imaging (fMRI) scanning, 20 human participants performed a simple mimicry or no-mimicry task, as previously described (Wang et al., 2011), with direct gaze present on half of the trials. As predicted, fMRI results showed that performing the task activated mirror systems, while direct gaze and inhibition of the natural tendency to mimic both engaged mPFC. Critically, we found an interaction between mimicry and eye contact in mPFC, superior temporal sulcus (STS) and inferior frontal gyrus. We then used dynamic causal modeling to contrast 12 possible models of information processing in this network. Results supported a model in which eye contact controls mimicry by modulating the connection strength from mPFC to STS. This suggests that mPFC is the originator of the gaze-mimicry interaction and that it modulates sensory input to the mirror system. Thus, our results demonstrate how different components of the social brain work together to on-line control mimicry according to the social context.

How Does Your Own Knowledge Influence the Perception of Another Person's Action in the Human Brain?

Social Cognitive and Affective Neuroscience. Feb, 2012  |  Pubmed ID: 21183458

When you see someone reach into a cookie jar, their goal remains obvious even if you know that the last cookie has already been eaten. Thus, it is possible to infer the goal of an action even if you know that the goal cannot be achieved. Previous research has identified distinct brain networks for processing information about object locations, actions and mental-state inferences. However, the relationship between brain networks for action understanding in social contexts remains unclear. Using functional magnetic resonance imaging, this study assesses the role of these networks in understanding another person searching for hidden objects. Participants watched movie clips depicting a toy animal hiding and an actor, who was ignorant of the hiding place, searching in the filled or empty location. When the toy animal hid in the same location repeatedly, the blood oxygen level-dependent (BOLD) response was suppressed in occipital, posterior temporal and posterior parietal brain regions, consistent with processing object properties and spatial attention. When the actor searched in the same location repeatedly, the BOLD signal was suppressed in the inferior frontal gyrus, consistent with the observation of hand actions. In contrast, searches towards the filled location compared to the empty location were associated with a greater response in the medial prefrontal cortex and right temporal pole, which are both associated with mental state inference. These findings show that when observing another person search for a hidden object, brain networks for processing information about object properties, actions and mental state inferences work together in a complementary fashion. This supports the hypothesis that brain regions within and beyond the putative human mirror neuron system are involved in action comprehension within social contexts.

Robotic Movement Preferentially Engages the Action Observation Network

Human Brain Mapping. Sep, 2012  |  Pubmed ID: 21898675

As humans, we gather a wide range of information about other people from watching them move. A network of parietal, premotor, and occipitotemporal regions within the human brain, termed the action observation network (AON), has been implicated in understanding others' actions by means of an automatic matching process that links observed and performed actions. Current views of the AON assume a matching process biased towards familiar actions; specifically, those performed by conspecifics and present in the observer's motor repertoire. In this study, we test how this network responds to form and motion cues when observing natural human motion compared to rigid robotic-like motion across two independent functional neuroimaging experiments. In Experiment 1, we report the surprising finding that premotor, parietal, occipitotemporal regions respond more robustly to rigid, robot-like motion than natural human motion. In Experiment 2, we replicate and extend this finding by demonstrating that the same pattern of results emerges whether the agent is a human or a robot, which suggests the preferential response to robot-like motion is independent of the agent's form. These data challenge previous ideas about AON function by demonstrating that the core nodes of this network can be flexibly engaged by novel, unfamiliar actions performed by both human and non-human agents. As such, these findings suggest that the AON is sensitive to a broader range of action features beyond those that are simply familiar.

Predicting Others' Actions Via Grasp and Gaze: Evidence for Distinct Brain Networks

Psychological Research. Jul, 2012  |  Pubmed ID: 22120203

During social interactions, how do we predict what other people are going to do next? One view is that we use our own motor experience to simulate and predict other people's actions. For example, when we see Sally look at a coffee cup or grasp a hammer, our own motor system provides a signal that anticipates her next action. Previous research has typically examined such gaze and grasp-based simulation processes separately, and it is not known whether similar cognitive and brain systems underpin the perception of object-directed gaze and grasp. Here we use functional magnetic resonance imaging to examine to what extent gaze- and grasp-perception rely on common or distinct brain networks. Using a 'peeping window' protocol, we controlled what an observed actor could see and grasp. The actor could peep through one window to see if an object was present and reach through a different window to grasp the object. However, the actor could not peep and grasp at the same time. We compared gaze and grasp conditions where an object was present with matched conditions where the object was absent. When participants observed another person gaze at an object, left anterior inferior parietal lobule (aIPL) and parietal operculum showed a greater response than when the object was absent. In contrast, when participants observed the actor grasp an object, premotor, posterior parietal, fusiform and middle occipital brain regions showed a greater response than when the object was absent. These results point towards a division in the neural substrates for different types of motor simulation. We suggest that left aIPL and parietal operculum are involved in a predictive process that signals a future hand interaction with an object based on another person's eye gaze, whereas a broader set of brain areas, including parts of the action observation network, are engaged during observation of an ongoing object-directed hand action.

Social Top-down Response Modulation (STORM): a Model of the Control of Mimicry in Social Interaction

Frontiers in Human Neuroscience. 2012  |  Pubmed ID: 22675295

As a distinct feature of human social interactions, spontaneous mimicry has been widely investigated in the past decade. Research suggests that mimicry is a subtle and flexible social behavior which plays an important role for communication and affiliation. However, fundamental questions like why and how people mimic still remain unclear. In this paper, we evaluate past theories of why people mimic and the brain systems that implement mimicry in social psychology and cognitive neuroscience. By reviewing recent behavioral and neuroimaging studies on the control of mimicry by social signals, we conclude that the subtlety and sophistication of mimicry in social contexts reflect a social top-down response modulation (STORM) which increases one's social advantage and this mechanism is most likely implemented by medial prefrontal cortex (mPFC). We suggest that this STORM account of mimicry is important for our understanding of social behavior and social cognition, and provides implications for future research in autism.

Simulating and Predicting Others' Actions

Psychological Research. Jul, 2012  |  Pubmed ID: 22706683

Observation of Another's Action but Not Eye Gaze Triggers Allocentric Visual Perspective

Quarterly Journal of Experimental Psychology (2006). 2012  |  Pubmed ID: 22901326

In the present paper, we investigated whether observation of bodily cues-that is, hand action and eye gaze-can modulate the onlooker's visual perspective taking. Participants were presented with scenes of an actor gazing at an object (or straight ahead) and grasping an object (or not) in a 2 × 2 factorial design and a control condition with no actor in the scene. In Experiment 1, two groups of subjects were explicitly required to judge the left/right location of the target from their own (egocentric group) or the actor's (allocentric group) point of view, whereas in Experiment 2 participants did not receive any instruction on the point of view to assume. In both experiments, allocentric coding (i.e., the actor's point of view) was triggered when the actor grasped the target, but not when he gazed towards it, or when he adopted a neutral posture. In Experiment 3, we demonstrate that the actor's gaze but not action affected participants' attention orienting. The different effects of others' grasping and eye gaze on observers' behaviour demonstrated that specific bodily cues convey distinctive information about other people's intentions.

Physical Experience Leads to Enhanced Object Perception in Parietal Cortex: Insights from Knot Tying

Neuropsychologia. Dec, 2012  |  Pubmed ID: 23022108

What does it mean to "know" what an object is? Viewing objects from different categories (e.g., tools vs. animals) engages distinct brain regions, but it is unclear whether these differences reflect object categories themselves or the tendency to interact differently with objects from different categories (grasping tools, not animals). Here we test how the brain constructs representations of objects that one learns to name or physically manipulate. Participants learned to name or tie different knots and brain activity was measured whilst performing a perceptual discrimination task with these knots before and after training. Activation in anterior intraparietal sulcus, a region involved in object manipulation, was specifically engaged when participants viewed knots they learned to tie. This suggests that object knowledge is linked to sensorimotor experience and its associated neural systems for object manipulation. Findings are consistent with a theory of embodiment in which there can be clear overlap in brain systems that support conceptual knowledge and control of object manipulation.

Motor Abilities in Autism: a Review Using a Computational Context

Journal of Autism and Developmental Disorders. Feb, 2013  |  Pubmed ID: 22723127

Altered motor behaviour is commonly reported in Autism Spectrum Disorder, but the aetiology remains unclear. Here, we have taken a computational approach in order to break down motor control into different components and review the functioning of each process. Our findings suggest abnormalities in two areas--poor integration of information for efficient motor planning, and increased variability in basic sensory inputs and motor outputs. In contrast, motor learning processes are relatively intact and there is inconsistent evidence for deficits in predictive control. We suggest future work on motor abilities in autism should focus on sensorimotor noise and on higher level motor planning, as these seem to have a significant role in causing motor difficulties for autistic individuals.

Recognition of Emotions in Autism: a Formal Meta-analysis

Journal of Autism and Developmental Disorders. Jul, 2013  |  Pubmed ID: 23114566

Determining the integrity of emotion recognition in autistic spectrum disorder is important to our theoretical understanding of autism and to teaching social skills. Previous studies have reported both positive and negative results. Here, we take a formal meta-analytic approach, bringing together data from 48 papers testing over 980 participants with autism. Results show there is an emotion recognition difficulty in autism, with a mean effect size of 0.80 which reduces to 0.41 when a correction for publication bias is applied. Recognition of happiness was only marginally impaired in autism, but recognition of fear was marginally worse than recognition of happiness. This meta-analysis provides an opportunity to survey the state of emotion recognition research in autism and to outline potential future directions.

Reflecting on the Mirror Neuron System in Autism: a Systematic Review of Current Theories

Developmental Cognitive Neuroscience. Jan, 2013  |  Pubmed ID: 23245224

There is much interest in the claim that dysfunction of the mirror neuron system in individuals with autism spectrum condition causes difficulties in social interaction and communication. This paper systematically reviews all published studies using neuroscience methods (EEG/MEG/TMS/eyetracking/EMG/fMRI) to examine the integrity of the mirror system in autism. 25 suitable papers are reviewed. The review shows that current data are very mixed and that studies using weakly localised measures of the integrity of the mirror system are hard to interpret. The only well localised measure of mirror system function is fMRI. In fMRI studies, those using emotional stimuli have reported group differences, but studies using non-emotional hand action stimuli do not. Overall, there is little evidence for a global dysfunction of the mirror system in autism. Current data can be better understood under an alternative model in which social top-down response modulation is abnormal in autism. The implications of this model and future research directions are discussed.

Brain Systems for Visual Perspective Taking and Action Perception

Social Neuroscience. 2013  |  Pubmed ID: 23350907

Taking another person's viewpoint and making sense of their actions are key processes that guide social behavior. Previous neuroimaging investigations have largely studied these processes separately. The current study used functional magnetic resonance imaging to examine how the brain incorporates another person's viewpoint and actions into visual perspective judgments. Participants made a left-right judgment about the location of a target object from their own (egocentric) or an actor's visual perspective (altercentric). Actor location varied around a table and the actor was either reaching or not reaching for the target object. Analyses examined brain regions engaged in the egocentric and altercentric tasks, brain regions where response magnitude tracked the orientation of the actor in the scene and brain regions sensitive to the action performed by the actor. The blood oxygen level-dependent (BOLD) response in dorsomedial prefrontal cortex (dmPFC) was sensitive to actor orientation in the altercentric task, whereas the response in right inferior frontal gyrus (IFG) was sensitive to actor orientation in the egocentric task. Thus, dmPFC and right IFG may play distinct but complementary roles in visual perspective taking (VPT). Observation of a reaching actor compared to a non-reaching actor yielded activation in lateral occipitotemporal cortex, regardless of task, showing that these regions are sensitive to body posture independent of social context. By considering how an observed actor's location and action influence the neural bases of visual perspective judgments, the current study supports the view that multiple neurocognitive "routes" operate during VPT.

Understanding the Role of the 'self' in the Social Priming of Mimicry

PloS One. 2013  |  Pubmed ID: 23565208

People have a tendency to unconsciously mimic other's actions. This mimicry has been regarded as a prosocial response which increases social affiliation. Previous research on social priming of mimicry demonstrated an assimilative relationship between mimicry and prosociality of the primed construct: prosocial primes elicit stronger mimicry whereas antisocial primes decrease mimicry. The present research extends these findings by showing that assimilative and contrasting prime-to-behavior effect can both happen on mimicry. Specifically, experiment 1 showed a robust contrast priming effect where priming antisocial behaviors induces stronger mimicry than priming prosocial behaviors. In experiment 2, we manipulated the self-relatedness of the pro/antisocial primes and further revealed that prosocial primes increase mimicry only when the social primes are self-related whereas antisocial primes increase mimicry only when the social primes are self-unrelated. In experiment 3, we used a novel cartoon movie paradigm to prime pro/antisocial behaviors and manipulated the perspective-taking when participants were watching these movies. Again, we found that prosocial primes increase mimicry only when participants took a first-person point of view whereas antisocial primes increase mimicry only when participants took a third-person point of view, which replicated the findings in experiment 2. We suggest that these three studies can be best explained by the active-self theory, which claims that the direction of prime-to-behavior effects depends on how primes are processed in relation to the 'self'.

Second Person Neuroscience Needs Theories As Well As Methods

The Behavioral and Brain Sciences. Aug, 2013  |  Pubmed ID: 23883754

Advancing second-person neuroscience will need strong theories, as well as the new methods detailed by Schilbach et al. I assess computational theories, enactive theories, and cognitive/information processing theories, and argue that information processing approaches have an important role to play in second-person neuroscience. They provide the closest link to brain imaging and can give important insights into social behaviour.

Supramodal and Modality-sensitive Representations of Perceived Action Categories in the Human Brain

Experimental Brain Research. Oct, 2013  |  Pubmed ID: 23963602

Seeing Suzie bite an apple or reading the sentence 'Suzie munched the apple' both convey a similar idea. But is there a common neural basis for action comprehension when generated through video or text? The current study used functional magnetic resonance imaging to address this question. Participants observed videos or read sentences that described two categories of actions: eating and cleaning. A conjunction analysis of video and sentence stimuli revealed that cleaning actions (compared to eating actions) showed a greater response in dorsal frontoparietal regions, as well as within the medial fusiform gyrus. These findings reveal supramodal representations of perceived actions in the human brain, which are specific to action categories and independent of input modality (video or written words). In addition, some brain regions associated with cleaning and eating actions showed an interaction with modality, which was manifested as a greater sensitivity for video compared with sentence stimuli. Together, this pattern of results demonstrates both supramodal and modality-sensitive representations of action categories in the human brain, a finding with implications for how we understand other people's actions from video and written sources.

The Mirror Neuron System Contributes to Social Responding

Cortex; a Journal Devoted to the Study of the Nervous System and Behavior. Nov-Dec, 2013  |  Pubmed ID: 24079916

Why Does Gaze Enhance Mimicry? Placing Gaze-mimicry Effects in Relation to Other Gaze Phenomena

Quarterly Journal of Experimental Psychology (2006). 2014  |  Pubmed ID: 23987097

Eye gaze is a powerful signal, which exerts a mixture of arousal, attentional, and social effects on the observer. We recently found a behavioural interaction between eye contact and mimicry where direct gaze rapidly enhanced mimicry of hand movements ). Here, we report two detailed investigations of this effect. In Experiment 1, we compared the effects of "direct gaze", "averted gaze", and "gaze to the acting hand" on mimicry and manipulated the sequence of gaze events within a trial. Only direct gaze immediately before the hand action enhanced mimicry. In Experiment 2, we examined the enhancement of mimicry when direct gaze is followed by a "blink" or by "shut eyes", or by "occluded eyes". Enhanced mimicry relative to baseline was seen only in the blink condition. Together, these results suggest that ongoing social engagement is necessary for enhanced mimicry. These findings allow us to place the gaze-enhancement effect in the context of other reported gaze phenomena. We suggest that this effect is similar to previously reported audience effects, but is less similar to ostensive cueing effects. This has important implications for our theories of the relationships between social cues and imitation.

Goal Representation in the Infant Brain

NeuroImage. Jan, 2014  |  Pubmed ID: 23994126

It is well established that, from an early age, human infants interpret the movements of others as actions directed towards goals. However, the cognitive and neural mechanisms which underlie this ability are hotly debated. The current study was designed to identify brain regions involved in the representation of others' goals early in development. Studies with adults have demonstrated that the anterior intraparietal sulcus (aIPS) exhibits repetition suppression for repeated goals and a release from suppression for new goals, implicating this specific region in goal representation in adults. In the current study, we used a modified paired repetition suppression design with 9-month-old infants to identify which cortical regions are suppressed when the infant observes a repeated goal versus a new goal. We find a strikingly similar response pattern and location of activity as had been reported in adults; the only brain region displaying significant repetition suppression for repeated goals and a release from suppression for new goals was the left anterior parietal region. Not only does our data suggest that the left anterior parietal region is specialized for representing the goals of others' actions from early in life, this demonstration presents an opportunity to use this method and design to elucidate the debate over the mechanisms and cues which contribute to early action understanding.

The Social Modulation of Imitation Fidelity in School-age Children

PloS One. 2014  |  Pubmed ID: 24465913

Children copy the actions of others with high fidelity, even when they are not causally relevant. This copying of visibly unnecessary actions is termed overimitation. Many competing theories propose mechanisms for overimitation behaviour. The present study examines these theories by studying the social factors that lead children to overimitate actions. Ninety-four children aged 5- to 8-years each completed five trials of an overimitation task. Each trial provided the opportunity to overimitate an action on familiar objects with minimal causal reasoning demands. Social cues (live or video demonstration) and eye contact from the demonstrator were manipulated. After the imitation, children's ratings of action rationality were collected. Substantial overimitation was seen which increased with age. In older children, overimitation was higher when watching a live demonstrator and when eye contact was absent. Actions rated as irrational were more likely to be imitated than those rated as rational. Children overimitated actions on familiar objects even when they rated those actions as irrational, suggesting that failure of causal reasoning cannot be driving overimitation. Our data support social explanations of overimitation and show that the influence of social factors increases with age over the 5- to 8-year-old age range.

Spatial Transformations of Bodies and Objects in Adults with Autism Spectrum Disorder

Journal of Autism and Developmental Disorders. Sep, 2014  |  Pubmed ID: 24658868

Previous research into autism spectrum disorder (ASD) has shown people with autism to be impaired at visual perspective taking. However it is still unclear to what extent the spatial mechanisms underlying this ability contribute to these difficulties. In the current experiment we examine spatial transformations in adults with ASD and typical adults. Participants performed egocentric transformations and mental rotation of bodies and cars. Results indicated that participants with ASD had general perceptual differences impacting on response times across tasks. However, they also showed more specific differences in the egocentric task suggesting particular difficulty with using the self as a reference frame. These findings suggest that impaired perspective taking could be grounded in difficulty with the spatial transformation used to imagine the self in someone else’s place.

Perspective Taking: Building a Neurocognitive Framework for Integrating the "social" and the "spatial"

Frontiers in Human Neuroscience. 2014  |  Pubmed ID: 24966824

Responses to Irrational Actions in Action Observation and Mentalising Networks of the Human Brain

NeuroImage. Dec, 2014  |  Pubmed ID: 25241085

By observing other people, we can often infer goals and motivations behind their actions. This study examines the role of the action observation network (AON) and the mentalising network (MZN) in the perception of rational and irrational actions. Past studies in this area report mixed results, so the present paper uses new stimuli which precisely control motion path, the social form of the actor and the rationality of the action. A cluster in medial prefrontal cortex and a large cluster in the right inferior parietal lobule extending to the temporoparietal junction distinguished observation of irrational from rational actions. Activity within the temporoparietal region also correlated on a trial-by-trial basis with each participant's judgement of action rationality. These findings demonstrate that observation of another person performing an irrational action engages both action observation and mentalising networks. Our results advance current theories of action comprehension and the roles of action observation and mentalising networks in this process.

Anterior Medial Prefrontal Cortex Implements Social Priming of Mimicry

Social Cognitive and Affective Neuroscience. Apr, 2015  |  Pubmed ID: 25009194

The neural and cognitive mechanisms by which primed constructs can impact on social behavior are poorly understood. In the present study, we used functional magnetic resonance imaging (fMRI) to explore how scrambled sentence priming can impact on mimicry behavior. Sentences involving pro/antisocial events from a first/third-person point of view were presented in short blocks, followed by a reaction-time assessment of mimicry. Behavioral results showed that both prosociality and viewpoint impact on mimicry, and fMRI analysis showed this effect is implemented by anterior medial prefrontal cortex (amPFC). We suggest that social primes may subtly modulate processing in amPFC in a manner linked to the later behavior, and that this same region also implements the top-down control of mimicry responses. This priming may be linked to processing of self-schemas in amPFC. Our findings demonstrate how social priming can be studied with fMRI, and have important implications for our understanding of the underlying mechanisms of prime-to-behavior effects as well as for current theories in social psychology.

Cognitive Underpinnings of Social Interaction

Quarterly Journal of Experimental Psychology (2006). 2015  |  Pubmed ID: 25405540

Human social interaction is part of what defines us. Here I present an overview of recent studies of imitation, a subdomain of social interaction that can be dissected and examined in a scientific fashion. I use these studies to test two core claims: (a) that there is more than one copying mechanism in the human brain and (b) that mimicry (a form of copying) is particularly relevant for understanding social behaviour. Evidence in favour of the first claim comes from neuroimaging studies that show distinct brain systems for understanding action kinematics, action goals, and irrational actions. Further studies of participants with autism show abnormal copying of irrational actions. Evidence in favour of the second claim comes from behavioural studies of the social cues that prime mimicry and from neuroimaging studies of the pathways involved in this priming. These studies suggest that medial prefrontal cortex has a core role in controlling mimicry responses and support the STORM (social top-down response modulation) model. Future work should determine what organizing principles govern the control of social responses and how these critical mechanisms for interpersonal connection differ in autism.

The Granularity of Grasping: Comment on "Grasping Synergies: a Motor-control Approach to the Mirror Neuron Mechanism" by A. D'Ausilio Et Al

Physics of Life Reviews. Mar, 2015  |  Pubmed ID: 25638446

Cognitive Mechanisms Underlying Visual Perspective Taking in Typical and ASC Children

Autism Research : Official Journal of the International Society for Autism Research. Jun, 2015  |  Pubmed ID: 26052836

Previous research has suggested that people with Autism Spectrum Conditions (ASC) may have difficulty with visual perspective taking (VPT) but it is not clear how this relates to different strategies that can be used in perspective taking tasks. The current study examined VPT in 30 children with autism and 30 verbal mental age matched typical children, in comparison to mental rotation (MR) abilities and body representation abilities. Using a similar paradigm to Hamilton, Brindley, and Frith [2009] all children completed three tasks: a VPT task in which children decided what a toy on a table would look like from a different points of view; a MR task in which the child decided what a toy would look like after it had been rotated; and a body posture matching task, in which children matched pictures of a body shown from different viewpoints. Results showed that children with ASC performed better than the typically developing children on the MR task, and at a similar level on the VPT task and body matching task. Importantly, in the typical children VPT performance was predicted by performance on the body matching task, whereas in the ASC children VPT performance was predicted by MR ability. These findings suggest that differences in VPT in ASC may be explained by the use of a spatial rotation strategy rather than the embodied egocentric transformation strategy used by typical children. Autism Res 2015. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

Measuring the Value of Social Engagement in Adults with and Without Autism

Molecular Autism. 2015  |  Pubmed ID: 26097674

Differences in social communication are commonly reported in autism spectrum condition (ASC). A recent theory attributes this to a reduced motivation to engage with others, that is, deficits in social motivation. However, there are currently few simple, direct, behavioural ways to test this claim. This study uses a new behavioural measure of social motivation to test if preferences for direct gaze and face stimuli are linked to autistic traits or an ASC diagnosis. Our novel choose-a-movie (CAM) paradigm measures the effort participants invest to see particular stimuli. This aspect of social motivation is also known as social seeking.

Automatic Imitation in a Rich Social Context with Virtual Characters

Frontiers in Psychology. 2015  |  Pubmed ID: 26106357

It has been well established that people respond faster when they perform an action that is congruent with an observed action than when they respond with an incongruent action. Here we propose a new method of using interactive Virtual Characters (VCs) to test if social congruency effects can be obtained in a richer social context with sequential hand-arm actions. Two separate experiments were conducted, exploring if it is feasible to measure spatial congruency (Experiment 1) and anatomical congruency (Experiment 2) in response to a VC, compared to the same action sequence indicated by three virtual balls. In Experiment 1, we found a robust spatial congruency effect for both VC and virtual balls, modulated by a social facilitation effect for participants who felt the VC was human. In Experiment 2 which allowed for anatomical congruency, a form by congruency interaction provided evidence that participants automatically imitate the actions of the VC but do not imitate the balls. Our method and results build a bridge between studies using minimal stimuli in automatic interaction and studies of mimicry in a rich social interaction, and open new research venue for future research in the area of automatic imitation with a more ecologically valid social interaction.

Body Constraints on Motor Simulation in Autism Spectrum Disorders

Journal of Autism and Developmental Disorders. Nov, 2015  |  Pubmed ID: 26572656

Developmental data suggested that mental simulation skills become progressively dissociated from overt motor activity across development. Thus, efficient simulation is rather independent from current sensorimotor information. Here, we tested the impact of bodily (sensorimotor) information on simulation skills of adolescents with Autism Spectrum Disorders (ASD). Typically-developing (TD) and ASD participants judged laterality of hand images while keeping one arm flexed on chest or while holding both arms extended. Both groups were able to mentally simulate actions, but this ability was constrained by body posture more in ASD than in TD adolescents. The strong impact of actual body information on motor simulation implies that simulative skills are not fully effective in ASD individuals.

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