Spatial attention and the malleability of bodily self in the elderly

A right-hemispheric specificity has been suggested both for spatial attention and for the feeling of body-ownership. Here, we assessed lateralization of spatial attention (Milner landmark task), rubber hand illusion (RHI), and their relationship in a group of 59 healthy elderly subjects. The occurrence of the RHI was assessed by objective (proprioceptive drift) and subjective (questionnaire) measures. Spatial attention was asymmetrical, with a slight, neglect-like overestimation of the right segment of mid-bisected lines. As to the RHI, the proprioceptive drift towards the plastic hand was significantly larger following synchronous compared to asynchronous stroking, but comparable between both sides. Subjective responses indicated an experience of the RHI during synchronous stimulation, without lateralization. On the left hand, however, the proprioceptive drift correlated significantly with the rightward bias of spatial attention. Thus, reduced attention towards sensory signals from one's own limb might facilitate the process of embodiment of an artificial hand into one's body-representation.