Lateralized and compulsive exteroceptive orientation in rats treated with apomorphine

A new behavioral test afforded the original demonstration of a compulsive and extremely lateralized taxis for edges in a minority (16%) of rats treated with the dopamine (DA) receptor agonist apomorphine (APO) (1.25 mg/kg, s.c.). APO also induced a reliable lateralization of locomotor direction in a rotometer in 29% of rats. The lateralizing effects of the drug on taxis for edges and rotational direction were not reliably associated, however, suggesting that these effects of APO are independent of each other. Interhemispheric asymmetries of DA receptors in functionally distinctive brain regions may underlie the diverse lateralizing effects of APO in subpopulations of rats.