Figure 2. Mirror responses: activity common to execution and observation.
Inclusive masking was used in order to look at significant activity common to both execution and observation conditions. BOLD responses to ObserveTrans+ExecuteTrans were seen in premotor cortex, dorsal parietal cortex in both hemispheres and right lateral occipital cortex (a, orange). The same approach for ObserveIntrans+ExecuteIntrans revealed significant activity in both contrasts in left occipital cortex only (a, blue). A direct comparison of activity common to execution and observation of an object directed actions more than an non-object directed action (ObserveTrans>ObserveIntrans)+(ExecuteTrans>ExecuteIntrans) allowed us to highlight voxels that are commonly activated in observing and executing an object-directed grasp more than executing and observing non-object directed movement. This analysis revealed significant activations in bilateral premotor and parietal cortices (b) (28 −48 56, −28 −52 58, 28 −14 56, −30 −4 60, −36 −38 52). The reverse comparison, (ObserveIntrans>ObserveTrans)+(ExecuteIntrans>ExecuteTrans), revealed no significant activity.