A mirror up to nature

Center for Neural Science, New York University, 4 Washington Place, New York, New York 10003, USA.
Current Biology (Impact Factor: 9.57). 02/2008; 18(1):R13-8. DOI: 10.1016/j.cub.2007.11.004
Source: PubMed


Mirror neurons were first documented in the macaque monkey a little over ten years ago. Their discovery has led to the formulation of several theories about their function in humans, including suggestions that mirror neurons are involved in understanding the meaning and intentions of observed actions, learning by imitation, feeling empathy, formation of a 'theory of mind', and even the development of language. Hypotheses have also been made about the consequences of mirror neuron dysfunction; foremost among these is the notion that such a dysfunction during development leads to many of the social and cognitive symptoms associated with the autism spectrum disorders (ASDs). Yet, despite a decade of prolific research on these appealing theories, there is little evidence to support them. In this essay, we review the current state of 'mirror system' research, point to several weaknesses in the field, and offer suggestions for how better to study these remarkably interesting neurons in both neurotypical and autistic individuals.

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Available from: Ilan Dinstein, Oct 07, 2015
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    • "Some assert that the MNS is responsible for, or implicated in, social cognitive processes such as action/goal/intention understanding (Gallese et al., 2013), imitation (Williams et al., 2001), empathy (Iacoboni and Mazziotta, 2007), and theory of mind (Perkins et al., 2010). Others have challenged these claims (Dinstein et al., 2008; Hickok, 2009). These potential links between the MNS and social cognition have led to hypotheses such as the broken mirror theory of autism spectrum disorder (ASD). "
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    ABSTRACT: The human mirror neuron system (MNS) is hypothesized to be crucial to social cognition. Given that key MNS-input regions such as the superior temporal sulcus are involved in biological motion processing, and mirror neuron activity in monkeys has been shown to vary with visual attention, aberrant MNS function may be partly attributable to atypical visual input. To examine the relationship between gaze pattern and interpersonal motor resonance (IMR; an index of putative MNS activity), healthy right-handed participants aged 18-40 (n = 26) viewed videos of transitive grasping actions or static hands, whilst the left primary motor cortex received transcranial magnetic stimulation. Motor-evoked potentials recorded in contralateral hand muscles were used to determine IMR. Participants also underwent eyetracking analysis to assess gaze patterns whilst viewing the same videos. No relationship was observed between predictive gaze and IMR. However, IMR was positively associated with fixation counts in areas of biological motion in the videos, and negatively associated with object areas. These findings are discussed with reference to visual influences on the MNS, and the possibility that MNS atypicalities might be influenced by visual processes such as aberrant gaze pattern.
    Frontiers in Human Neuroscience 07/2015; 9:396. DOI:10.3389/fnhum.2015.00396 · 2.99 Impact Factor
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    • "An important and unresolved issue concerns the dynamics of spreading activation between sensory and motor systems: in order for the findings from those studies to be taken as support for the motor theory of speech perception, it would have to be argued that the effects of TMS are (only) local to the inactivated region, and do not spread to regions connected to the motor areas. Currently, it remains unknown whether this assumption is correct (Dinstein et al., 2008; Galantucci et al., 2006; Hickok, 2000, 2010; Hickok, Houde, & Rong, 2011a; Lotto, Hickok, & Holt, 2009; Rogalsky, Love, Driscoll, Anderson, & Hickok, 2011; Stasenko, Garcea, & Mahon, 2013; Toni, de Lange, Noordzij, & Hagoort, 2008). It is also theoretically relevant that the effects observed with TMS are present only when stimuli are degraded by noise, and are usually observed in response times rather than accuracy. "
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    ABSTRACT: The debate about the causal role of the motor system in speech perception has been reignited by demonstrations that motor processes are engaged during the processing of speech sounds. Here, we evaluate which aspects of auditory speech processing are affected, and which are not, in a stroke patient with dysfunction of the speech motor system. We found that the patient showed a normal phonemic categorical boundary when discriminating two non-words that differ by a minimal pair (e.g., ADA–AGA). However, using the same stimuli, the patient was unable to identify or label the non-word stimuli (using a button-press response). A control task showed that he could identify speech sounds by speaker gender, ruling out a general labelling impairment. These data suggest that while the motor system is not causally involved in perception of the speech signal, it may be used when other cues (e.g., meaning, context) are not available.
    Cognitive Neuropsychology 05/2015; 32(2):38-57. DOI:10.1080/02643294.2015.1035702 · 2.07 Impact Factor
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    • "Moreover, hypoactivation in the left hemisphere, relative to the right hemisphere, has been found in individuals with ASD [6– 9]. In addition, abnormal synaptic maturation, brain connectivity , and mirror neuron dysfunction have all also been purposed as neurophysiological factors that may underlie the symptoms associated with ASD [10] [11] [12] [13]. "
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    ABSTRACT: Abnormal synaptic maturation and connectivity are possible etiologies of autism. Previous studies showed significantly less alpha activity in autism than normal children. Therefore, we studied the effects of anodal tDCS on peak alpha frequency (PAF) related to autism treatment evaluation checklist (ATEC). Twenty male children with autism were randomly assigned in a crossover design to receive a single session of both active and sham tDCS stimulation (11 mA) over F3 (left dorsolateral prefrontal cortex). Pre- to postsession changes in a measure of cortical activity impacted by tDCS (PAF) and ATEC were compared between groups. We also examined the associations between pre- and postsession changes in the PAF and ATEC. The results show significant pre- to postsession improvements in two domains of ATEC (social and health/behavior domains) following active tDCS, relative to sham treatment. PAF also significantly increased at the stimulation site, and an increase in PAF was significantly associated with improvements in the two domains of ATEC impacted by tDCS. The findings suggest that a single session of anodal tDCS over the F3 may have clinical benefits in children with autism and that those benefits may be related to an increase in PAF.
    Behavioural neurology 04/2015; 2015:1-11. DOI:10.1155/2015/928631 · 1.45 Impact Factor
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