Neural and behavioral plasticity: crossed nigro-thalamic projections following unilateral substantia nigra lesions.

Unilateral lesions of the substantia nigra of rats by injection of 6-hydroxydopamine or kainic acid induced ipsi- and contraversive turning behavior. Spontaneous turning was no longer exhibited one week after the lesions. This behavioral recovery was correlated in time with the development of crossed projections from the intact contralateral substantia nigra to the ventromedial thalamus of the lesioned hemisphere which, in the intact animal, receives projections only from the ipsilateral substantia nigra.