Motivation modulates the activity of the human mirror-neuron system

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.