Effect of limb movements on orienting of attention in right-hemisphere stroke

A deficit disengaging attention from the ipsilesional space in order to re-orient toward the contralesional space has been reported after right-hemisphere stroke (disengage deficit) and has been related to the severity of visuospatial neglect. Neglect rehabilitation studies have shown that left limb movements improve leftward orienting; the effect, however, is variable, and the mechanism of improvement is uncertain. Thus, this study examined whether limb movements specifically reduce the underlying disengage deficit of attention after right-hemisphere stroke. The effects of active and passive limb movements (vs. no limb movement) on orienting were examined using a covert exogenously cued orienting task in groups of right-hemisphere stroke patients with and without a significant disengage deficit (DD+, DD?) and healthy older adults. As previously seen, disengage deficit scores of stroke patients were positively correlated with the severity of neglect. The leftward disengage deficit was not affected by either active or passive limb movements, however, although movements did have both alerting and distracting effects on other aspects of orienting. Thus, our results suggest that the benefits of limb movements may not be related to changes in the underlying disengage deficit, but may impact other processes that underlie left-sided orienting (e.g., arousal and voluntary strategies).