Moving and being moved: differences in cerebral activation during recollection of whole-body motion.

While moving through the world, humans as well as animals can make use of motion cues during both active and passive whole-body motion to track their own position in space. However, the functional neuroanatomy of self-motion processing remains poorly understood. In the present study we aimed to characterize brain networks reflecting whole-body self-motion experience. We used retrieval of previously experienced events, which is known to involve cortical representations of the modalities used to perceive these events. Recollection of self-motion experience may thus engage motor and sensory brain areas, reflecting the active or passive nature of the experienced movement, but may engage also common brain areas processing self-motion. We further compared the retrieval networks of self- and observed motion: even though actual action observation has been shown to recruit brain networks similar to those active during mental simulation, it is unclear to which extent recollection networks of these experiences overlap. Brain activation patterns were recorded using fMRI during mental simulation of recent episodes of (1) experiencing linear whole-body motion (active locomotion and passive transport) and (2) observing another person performing the same tasks. Following the experiential phase, participants recalled the episodes during a MR session. We found that primary sensorimotor brain areas dominate the composition of the recollection network of active walking, while recalling passive transport recruits higher level association areas. Common to both self-motion conditions was activation in the medial temporal lobe. Recollection of self-experienced and observed movement overlapped in motor planning areas. Our results provide evidence that the medial temporal lobe is specifically relevant for retrieval of self-motion information and that motor coding during action observation is reflected in recollection networks.