Lateralizing effects of apomorphine on taxis, postural support and rotation in rats.

Subcutaneous injections of apomorphine, a dopamine receptor agonist, induced a lateralization of taxis for edges in 16% of rats and a reliable lateralization of postural support in 82% of rats. The relation among these effects and the lateralizing effects of apomorphine on rotational behavior were examined. Lateralized rotation did not reliably correlate with lateralized taxis. However, it correlated with a relatively large asymmetry of postural support. The lateralizing effects of apomorphine on taxis and rotation may reflect attentional and directional asymmetries, respectively. It is proposed that apomorphine can induce different types of lateralizations, including attentional, postural and directional, and that the lateralizing effects of apomorphine on posture and locomotor direction are interrelated. Regional brain interhemispheric asymmetries in the responsiviness of dopamine receptors may underlie different types of apomorphine-induced lateralizations.