Abstract
Recent evidence suggests the possibility that not all action modes depend on dorsal visual stream processing but that off-line actions, such as anti-pointing, require additional and even distinct neural networks when compared to target-directed on-line actions. Here we explored this potential dissociation in a group of 11 patients with left visual neglect, a syndrome characterized by a loss of awareness of the contralesional side of space. Ten healthy participants and 10 right-hemisphere damaged patients without neglect served as controls. Participants had to either point directly towards targets presented on their left or right (i.e, pro-pointing) or to their mirror position in the opposite hemispace (i.e, anti-pointing). Compared to both control groups, neglect patients showed reduced accuracy when anti-pointing, but not pro-pointing, to both sides of space. Lesion-behaviour mapping revealed that the areas critically associated with these deficits were located in the middle, superior temporal and parahippocampal gyri. We argue that neglect patients present specific deficits only when the visuomotor task taps into more perceptual representations thought to rely on ventral visual stream processing and that our results indicate that temporal brain regions are implicated in these off-line actions. We will also demonstrate that the relatively spared on-line actions can be exploited successfully for rehabilitation.
This work was supported by the Foundation for Science and Technology (FCT), No: SFRBD232302005.