Dopamine neuron transplants: electrophysiological unit activity of intrastriatal nigral grafts in freely moving cats.

Fetal transplants of substantia nigra dopamine (DA)-containing neurons into the caudate nucleus in cats produced functional synaptic connections, as measured by behavioral analysis. Electrophysiological activity of single units from the intrastriatal nigral grafts revealed that these neurons displayed some of the characteristic electrophysiological parameters of DA neurons, i.e., long duration action potentials and tri-phasic waveform. However, these neurons discharged at a faster rate and never displayed the characteristic decremental burst pattern seen in intact, non-grafted animals. These data are the first electrophysiological recordings of grafted DA neurons in freely moving animals.