Ipsiversive turning behaviour after discrete unilateral lesions of the dorsal mesencephalic reticular formation by kainic acid.

Discrete axon-sparing lesions were placed unilaterally in the mesencephalon by the local injection of kainic acid. Unilateral lesions of the dorsal reticular formation just beneath the superior colliculus and lateral to the periacqueductal grey resulted in consistent ipsiversive apomorphine-induced circling. Only weak motor asymmetries were observed after unilateral lesions restricted to the superior colliculus or to the periacqueductal grey. The results indicate that the dorsal mesencephalic reticular formation plays an essential role as an output station for striatal postural functions.