The timing of temporoparietal and frontal activations during mental own body transformations from different visuospatial perspectives.

Abstract

The perspective from where the world is perceived is an important aspect of the bodily self and may break down in neurological conditions such as out-of-body experiences (OBEs). These striking disturbances are characterized by disembodiment, an external perspective and have been observed after temporoparietal damage. Using mental own body imagery, recent neuroimaging work has linked perspectival changes to the temporoparietal cortex. Because the disembodied perspective during OBEs is elevated in the majority of cases, we tested whether an elevated perspective will interfere with such temporoparietal mechanisms mental own body imagery. We designed stimuli of life-sized humans rotated around the vertical axis and rendered as if viewed from three different perspectives: elevated, lowered, and normal. Reaction times (RTs) in an own body transformation task, but not the control condition, were dependent on the rotation angle. Furthermore, RTs were shorter for the elevated as compared with the normal or lowered perspective. Using high-density EEG and evoked potential (EP) mapping, we found a bilateral temporoparietal and frontal activation at approximately 330-420 ms after stimulus onset that was dependent on the rotation angle, but not on the perspective. This activation was also found in response-locked EPs. In the time period approximately 210-330 ms we found a temporally distinct posterior temporal activation with its duration being dependent on the perspective, but not the rotation angle. Collectively, the present findings suggest that temporoparietal and frontal as well as posterior temporal activations and their timing are crucial neuronal correlates of the bodily self as studied by mental imagery.