Both the mirror and the affordance systems might be impaired in adults with high autistic traits. Evidence from EEG mu and beta rhythms (original) (raw)
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Background: The mirror neuron system (MNS) consists of interconnected brain regions, namely the inferior frontal gyrus (IFG) and the inferior parietal lobe (IPL). First discovered in monkeys, the MNS contains neurons that respond similarly when an individual observes an action, such as reaching for a cup, or executes the same action. One difference between the monkey and human MNS is that the monkey MNS only responds when an object is present as the goal of the action, while the human MNS will respond to meaningless or pantomimed gestures that do not have objects present. It has been hypothesized that this system underlies the ability to understand the actions of others, including their goals and intentions. These are skills that individuals with autism often have demonstrated difficulty, leading to the broken mirror theory of autism (Williams et al., 2001). However, it appears that some skills that rely on the MNS are not compromised in ASD. For instance, the ability to imitate act...
EEG evidence for mirror neuron dysfunction in autism
Poster Session Presented …, 2004
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. D
Neuropsychologia, 2007
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.
Unbroken mirror neurons in autism spectrum disorders
BACKGROUND: The 'broken mirror' theory of autism, which proposes that a dysfunction of the human mirror neuron system (MNS) is responsible for the core social and cognitive deficits in individuals with autism spectrum disorders (ASD), has received considerable attention despite weak empirical evidence. METHODS: In this electroencephalographic study, we examined mu suppression, as an indicator of sensorimotor resonance, concurrent with oculomotor performance while individuals (n = 20) with ASD and control participants (n = 20) either executed hand actions or observed hand actions or a moving dot. No difference in visual attention between groups was found as indicated by fixation duration and normalized fixation number on the presented stimuli. RESULTS: The mu suppression over the sensorimotor cortex was significantly affected by experimental conditions, but not by group membership, nor by the interaction between groups and conditions. Individuals with ASD, similar to the controls, exhibited stronger mu suppression when watching hand actions relative to a moving dot. Notably, participants with ASD failed to imitate the observed actions while their mu suppression indicating the MNS activity was intact. In addition, the mu suppression during the observation of hand actions was positively associated with the communication competence of individuals with ASD. CONCLUSION: Our study clearly challenges the broken mirror theory of autism. The functioning of the mirror neuron system might be preserved in individuals with ASD to a certain degree. Less mu suppression to action observation coupled with more communicational severity can reflect the symptom heterogeneity of ASD. Additional research needs to be done, and more caution should be used when reaching out to the media.
Atypical activation of the mirror neuron system during perception of hand motion in autism
Brain Research, 2010
Disorders in the autism spectrum are characterized by deficits in social and communication skills such as imitation, pragmatic language, theory of mind, and empathy. The discovery of the "mirror neuron system" (MNS) in macaque monkeys may provide a basis from which to explain some of the behavioral dysfunctions seen in individuals with autism spectrum disorders (ASD).We studied seven right-handed high-functioning male autistic and eight normal subjects (TD group) using functional magnetic resonance imaging during observation and execution of hand movements compared to a control condition (rest).
Does the Mirror Neuron System and Its Impairment Explain Human Imitation and Autism
The proposal that the understanding and imitation of observed actions are made possible through the ‘mirror neuron system’ (Rizzolatti, G., Fogassi, L., & Gallese, V., 2001, Neurophysiological mechanisms underlying the understanding of action. Nature Review Neuroscience, 2, 661–670) has led to much speculation that a dysfunctional mirror system may be at the root of the social deficits characteristic of autism (e.g. Ramachandran, V. S., & Oberman, L. M., 2006, Broken mirrors: A theory of autism. Scientific American, November 2006). This chapter will critically examine the hypothesis that those with ASD may be in possession of a ‘broken’ mirror neuron system. We propose that the deficits seen in imitation in individuals with ASD reflect not a dysfunctional MNS, but a lack of sensitivity to those cues that would help them identify what to imitate. In doing this, we will also argue that imitation in typically developing children cannot be explained by appealing to a direct-matching mechanism, and that the process by which young children imitate involves a far more complex yet effortless analysis of the communication of those who they learn from.
CNS Neuroscience and Therapeutics
The Mirror Neuron System (MNS) plays a crucial role in action perception and imitative behavior, which is suggested to be impaired in Autism Spectrum Disorders (ASDs). In this review, we discuss the plausibility and empirical evidence of a neural interaction between the MNS, action perception, empathy, imitative behavior, and their impact on social decision making in ASDs. To date, there is no consensus regarding a particular theory in ASDs and its underlying mechanisms. Some theories have completely focused on social difficulties, others have emphasized sensory aspects. Based on the current studies, we suggest a multilayer neural network model including the MNS on a first layer and transforming this information to a higher layer network responsible for reasoning. Future studies with ASD participants combining behavioral tasks with neuroimaging methods and transcranial brain stimulation as well as computational modeling can help validate and complement this suggested model. Moreover, we propose applying the behavioral paradigms, and the neurophysiological markers mentioned in this review article for evaluating psychiatric treatment approaches in ASDs. The investigation of modulating effects of different treatment approaches on the neurophysiological markers of the MNS can help find specific subgroups of ASDs patients and support tailored psychiatric interventions.