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Parieto-frontal mechanisms underlying observation of complex hand-object manipulation
Full text linkThe observation of actions performed by others is believed to activate the Action Observation Network (AON). Previous evidence suggests that subjects with a specific motor skill show increased activation of the AON during observation of the same skill. The question arises regarding which modulation of the AON occurs during observation of novel complex manipulative actions that are beyond the personal motor repertoire. To address this issue, we carried out a functional MRI study in which healthy volunteers without specific hand motor skills observed videos displaying hand-object manipulation executed by an expert with high manual dexterity, by an actor with intermediate ability or by a naïve subject. The results showed that the observation of actions performed by a naïve model produced stronger activation in a dorso-medial parieto-premotor circuit including the superior parietal lobule and dorsal premotor cortex, compared to observation of an expert actor. Functional connectivity analysis comparing the observation of the naïve model with that of the expert model, revealed increased connectivity between dorsal areas of the AON. This suggests a possible distinction between ventral and dorsal brain circuits involved in the processing of different aspects of action perception, such as kinematics and final action goal
Activation of cerebellum and basal ganglia during the observation and execution of manipulative actions
Full text linkStudies on action observation mostly described the activation of a network of cortical areas, while less investigation focused specifically on the activation and role of subcortical nodes. In the present fMRI study, we investigated the recruitment of cerebellum and basal ganglia during the execution and observation of object manipulation performed with the right hand. The observation conditions consisted in: (a) observation of manipulative actions; (b) observation of sequences of random finger movements. In the execution conditions, participants had to perform the same actions or movements as in (a) and (b), respectively. The results of conjunction analysis showed significant shared activations during both observation and execution of manipulation in several subcortical structures, including: (1) cerebellar lobules V, VI, crus I, VIIIa and VIIIb (bilaterally); (2) globus pallidus, bilaterally, and left subthalamic nucleus; (3) red nucleus (bilaterally) and left thalamus. These findings support the hypothesis that the action observation/execution network also involves subcortical structures, such as cerebellum and basal ganglia, forming an integrated network. This suggests possible mechanisms, involving these subcortical structures, underlying learning of new motor skills, through action observation and imitation
Evolution of Mirror Neuron Mechanism in Primates
No full textThe mirror mechanism is a basic mechanism that transforms sensory representations of the observed or listened actions into motor representations of the same actions. In the present chapter we review evidence for the role of the mirror mechanism in emotion and in goal-directed actions in nonhuman primates and humans. We examine the functions, such as imitation and language, which are present exclusively or almost exclusively in humans and discuss the role of the mirror mechanism in these functions
Premotor cortex and the recognition of motor actions
No full textIn area F5 of the monkey premotor cortex there are neurons that discharge both when the monkey performs an action and when he observes a similar action made by another monkey or by the experimenter. We report here some of the properties of these 'mirror' neurons and we propose that their activity 'represents' the observed action. We posit, then, that this motor representation is at the basis of the understanding of motor events. Finally, on the basis of some recent data showing that, in man, the observation of motor actions activate the posterior part of inferior frontal gyrus, we suggest that the development of the lateral verbal communication system in man derives from a more ancient communication system based on recognition of hand and face gestures
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