Motivation modulates the activity of the human mirror-neuron system.
ABSTRACT It is not known whether the mirror-neuron system is modulated by motivation, such as hunger. In this study, 2 groups of healthy participants underwent 2 functional magnetic resonance imaging scanning sessions separated by 1.5 h interval. During each session, participants were presented with video clips of another person grasping objects or grasping food. The first session was conducted after participants from group 1 had fasted. Then these participants were allowed to eat and were scanned again. Participants from group 2 had a meal before the first session. Food-related stimuli elicited specific hemodynamic response in the parahippocampal gyrus, orbitofrontal cortex, and amygdala, when participants were in a hungry state as compared with a satiated state. In addition, regions that belong to the mirror-neuron system, including the inferior frontal gyrus, and the posterior parietal cortex showed greater response when participants were hungry. Increased activity was also detected in the extrastriate body area. A positive correlation was observed between the self-report ratings of hunger and the hemodynamic activity in the inferior frontal gyrus as well as in the amygdala. Our results suggest that motivation to eat modulates the neural activity in the mirror-neuron system, facilitating the preparation or the intention to act.
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ABSTRACT: It has been suggested that cortical neural systems for language evolved from motor cortical systems, in particular from those fronto-parietal systems responding also to action observation. While previous studies have shown shared cortical systems for action--or action observation--and language, they did not address the question of whether linguistic processing of visual stimuli occurs only within a subset of fronto-parietal areas responding to action observation. If this is true, the hypothesis that language evolved from fronto-parietal systems matching action execution and action observation would be strongly reinforced. We used functional magnetic resonance imaging (fMRI) while subjects watched video stimuli of hand-object-interactions and control photo stimuli of the objects and performed linguistic (conceptual and phonological), and perceptual tasks. Since stimuli were identical for linguistic and perceptual tasks, differential activations had to be related to task demands. The results revealed that the linguistic tasks activated left inferior frontal areas that were subsets of a large bilateral fronto-parietal network activated during action perception. Not a single cortical area demonstrated exclusive--or even simply higher--activation for the linguistic tasks compared to the action perception task. These results show that linguistic tasks do not only share common neural representations but essentially activate a subset of the action observation network if identical stimuli are used. Our findings strongly support the evolutionary hypothesis that fronto-parietal systems matching action execution and observation were co-opted for language, a process known as exaptation.PLoS ONE 02/2007; 2(9):e891. · 4.09 Impact Factor
Article: Modulation of brain activity during action observation: influence of perspective, transitivity and meaningfulness.[show abstract] [hide abstract]
ABSTRACT: The coupling process between observed and performed actions is thought to be performed by a fronto-parietal perception-action system including regions of the inferior frontal gyrus and the inferior parietal lobule. When investigating the influence of the movements' characteristics on this process, most research on action observation has focused on only one particular variable even though the type of movements we observe can vary on several levels. By manipulating the visual perspective, transitivity and meaningfulness of observed movements in a functional magnetic resonance imaging study we aimed at investigating how the type of movements and the visual perspective can modulate brain activity during action observation in healthy individuals. Importantly, we used an active observation task where participants had to subsequently execute or imagine the observed movements. Our results show that the fronto-parietal regions of the perception action system were mostly recruited during the observation of meaningless actions while visual perspective had little influence on the activity within the perception-action system. Simultaneous investigation of several sources of modulation during active action observation is probably an approach that could lead to a greater ecological comprehension of this important sensorimotor process.PLoS ONE 01/2011; 6(9):e24728. · 4.09 Impact Factor