A dual moveable stimulating electrode and its application to the behavioral version of the collision test

The construction and testing of a dual moveable electrode for chronic stimulation in small mammals are described. The assembly is lightweight (0.9 g), its components are completely re-usable, and the two electrodes may be independently advanced in steps as small as 80 microns over a maximum vertical excursion of 6 mm. The unit performed as well as fixed electrodes do in daily behavioral tests conducted over a 3 month period. Ipsiversive rotation was elicited by stimulation of 15 pontine-mesencephalic sites in a single rat. Behavioral evidence for the collision of heterodromic action potentials in circling-relevant fibers was obtained in 4 position sets.