Maximum stimulation amplitudes (mA, mean±SEM) in the different experiments.

<p>Stimulation amplitudes were determined by subjecting the animals to a sinusoid current that was increased until head rocking was just visible. During stochastic stimulation the amplitude never exceeded ± this amplitude. A different current delivery system was used for the microdialysis experiments in unlesioned animals. 6-OHDA 6-hydroxy-dopamine, PPN pedunculopontine nucleus, ST striatum, SN substanta nigra, VM ventromedial thalamus.