Non-lateralized impairments in anti- but not pro-pointing in patients with hemispatial neglect

Abstract

It has been widely shown that hemispatial neglect manifests itself in a rightward perceptual bias, but whether this bias extends to goal-directed movements remains a matter of debate. Here we analysed the ability of 10 patients with hemispatial neglect to perform pro- and anti-pointing movements in response to left and rightwardly presented targets. A group of 10 age-matched healthy controls and 10 patients with right-hemisphere lesions but no neglect served as controls. In the pro-pointing condition, subjects were asked to point directly to the target, whereas in the anti-pointing condition they had to move in the opposite direction of the target (i.e. if a target was illuminated on the right subjects had to point to the equivalent target position on the left and vice-versa). In the pro-pointing condition, no impairments specific to patients with hemispatial neglect where found. However for anti-pointing, neglect specific deficits emerged: neglect patients showed greater directional errors (i.e. anti-pointing movements in the wrong direction) and were also severely disrupted in the end-point accuracy of their movements, in particular when anti-pointing rightwards in response to leftwardly presented targets. We relate these findings to the presence of impairments in movements that require specific location mapping and cannot be performed on-line.

Footnotes

 This work was funded by a grant (SFRH/BD/23230/2005) from the Portuguese Foundation for Science and Technology to S Rossit