DOPAMINE AGONISTS REORIENT VISUAL EXPLORATION AWAY FROM THE NEGLECTEDHEMISPACE

Objective: To study the effects of bromocriptine, a dopamine agonist, on visual search. Background: The anatomic substrate of spatial attent ion takes the form of a distributed network with interconnected cortic al (frontal, parietal, and cingulate) and subcortical (striatal and th alamic) components. Dopamine appears to exert a modulatory effect on t he function of this network. Methods: Seven consecutive right-handed s ubjects with right-sided cerebral lesions were studied using a compute rized target search paradigm. Eye movements were recorded. Results: Br omocriptine caused the subjects to spend more time exploring the ipsil esional hemispace and therefore increased the relative neglect of the contralesional left hemispace. However, target detection accuracy did not change. Bromocriptine thus had a differential impact on the explor atory-motor versus sensory-perceptual components of directed attention . Conclusions: Our results show that bromocriptine may worsen same asp ects of hemispatial neglect in patients with lesions that include the postsynaptic components of ascending dopaminergic pathways.