Cortical activity and egocentric representation: An fMRI study.

OBJECTIVE: Subjects use different referentials for spatial localization, and the egocentric references are very often impaired especially during stroke. The objective is to find the difference between activations induced by 2 egocentric tasks MATERIAL/PATIENTS AND METHODS: Seventeen right-handed healthy subjects (50.4±14.9 years) were tested using fMRI during the realization of 2 egocentric spatial tasks: the perception of the straight ahead (retinocentric) and the longitudinal axis of the body (centered by the trunk).

RESULTS: For both tasks, cerebral activations dominated largely in the right hemisphere and interest essentially the right frontoparietal network. However, the straight ahead task showed more specific activations in insular and thalamic areas.

DISCUSSION - CONCLUSION: The activations areas found for the 2 egocentric tasks are superimposed with a predominance in right frontotemporal-parietal network, however, the straight ahead task activates quite specifically regions that are closed to the areas usually activated for allocentric tasks, which suggests a continuum between spatial perception in personal trunk centered egocentric referential, retinotopic extrapersonal retinocentric egocentric referential and allocentric referential.