Action observation activates premotor and parietal areas in a somatotopic manner: an fMRI study

Abstract

Functional magnetic resonance imaging (fMRI) was used to localize brain areas that were active during the observation of actions made by another individual. Object-and non-object-related actions made with different effectors (mouth, hand and foot) were presented. Observation of both object-and non-object-related actions determined a somatotopically organized activation of premotor cortex. The somatotopic pattern was similar to that of the classical motor cortex homunculus. During the observation of object-related actions, an activation, also somatotopically organized, was additionally found in the posterior parietal lobe. Thus, when individuals observe an action, an internal replica of that action is automatically generated in their premotor cortex. In the case of object-related actions, a further object-related analysis is performed in the parietal lobe, as if the subjects were indeed using those objects. These results bring the previous concept of an action observation/execution matching system (mirror system) into a broader perspective: this system is not restricted to the ventral premotor cortex, but involves several somatotopically organized motor circuits.

Focusing on body sites: the role of spatial attention in action perception

“…Brain areas with mirror properties have also been discovered in the human parietal and premotor cortices (e.g., Grèzes et al 2003;Iacoboni et al 1999;Koski et al 2002;Leslie et al 2004). Consistent with the present findings of body part specific mirroring effects, these brain structures are somatotopically organized and represent foot and hand actions in anatomically distinct areas (Buccino et al 2001).…”

“…Imaging studies have confirmed that a similar system is also present in humans (e.g. Grèzes et al 2003;Buccino et al 2001;Iacoboni et al 1999;Koski et al 2002), and this system has been linked to the automatic imitation of actions by imaging and behavioral studies (e.g., Jackson et al 2006;Leslie et al 2004;Wohlschläger and Bekkering 2002).…”

Exact and approximate judgements of visual and auditory numerosity: An fMRI study

“…In fact the dorsal prefrontal (pre-motor) peaks showing increased activation for counting with respect to estimation in the present study correspond to peaks previously associated to movements of the hand (while more ventral regions are associated with movements of the mouth, congruently with the classical motor organization of the region (Buccino et al, 2001). …”

Cortical activation during executed, imagined, observed, and passive wrist movements in healthy volunteers and stroke patients

“…While frequently ventral premotor cortices have been associated with movement observation (Decety and Grèzes, 1999), the presently observed more dorsal premotor activations have been reported before particularly for the observation of wrist and hand movements (Buccino et al, 2001;Morin and Grezes, 2008;Sakreida et al, 2005). Interestingly, the presently observed areas were part of a network showing increased activation in response to rehabilitation using action observation (Ertelt et al, 2007).…”

“…In more detail, previous research indicated that activation evoked by movement observation may potentially be reduced when the movement is simple (Biagi et al, 2010), does not involve objects (Buccino et al, 2001;Morin and Grezes, 2008), and when the instruction does not stress that the movements are supposed to be imitated after having been watched (Frey and Gerry, 2006) (but see Caspers et al, 2010). Thus, by using other actions and instructions we may have had observed stronger activation of the sensorimotor system, potentially resulting in a better resemblance of Execution.…”