Spiroperidol reinstates asymmetries in neglect in rats recovered from left or right dorsomedial prefrontal cortex lesions

The role of dopaminergic mechanisms in spontaneous behavioral recovery from cortical neglect was examined in rats that received lesions of either the left or the right dorsomedial prefrontal cortex (PCm, also referred to as AGm). Neglect was assessed by rating the degree of head orientation to visual, auditory, or tactile stimuli. Following behavioral recovery, separate groups received 0.03, 0.05, 0.07, or 0.10 mg/kg spiroperidol or the vehicle. In accordance with the lateralization of neglect typically seen postsurgery, spiroperidol dose-dependently reinstated contralesional neglect in left PCm operates and ipsilesional neglect in right PCm operates. Neglect was reinstated by spiroperidol in right PCm operates at lower doses than in left PCm operates. Also, only right PCm operates demonstrated asymmetrical bilateral dose-dependent neglect. Spiroperidol did not produce neglect in unilaterally brain-damaged control subjects. The results indicate that dopaminergic mechanisms may underlie spontaneous recovery from cortical neglect and that these mechanisms are asymmetrical in left and right PCm operates.