Effects of handedness and viewing perspective on Broca's area activity.

Given the fact that we understand observed action by a sensorimotor link that maps the action onto our motor representations, activity of the mirror neuron system may depend on the sensory and motor features of that action. To investigate this hypothesis, we recorded the activity of Broca's area (BCA) in right-handed individuals during observation of chopstick use using near-infrared spectroscopy. Individuals watched the right-handed or left-handed action recorded from the first-person's or third-person's perspective. Results show that the handedness of the observed action influences BCA activity, but the viewing perspective does not. We conclude that the motor aspect of the observed action is critical for BCA activation because this aspect is more relevant for simulating the observed action compared with the visuospatial aspect.