Spontaneous firing of nigrostriatal dopaminergic neurons in split-brain rats

The regulatory action of the contralateral brain side on nigrostriatal dopaminergic (NSDA) neurons was examined in anesthetized rats using extracellular single-unit recording techniques. The spontaneous activity of NSDA cells was recorded from split-brain, sham-lesioned or intact-brain rats. The three groups of cells did not differ in antidromic latency and firing rate. However, cells from split-brain rats exhibited a more regular pattern of discharge than those recorded in the two control groups as shown by autocorrelograms and the standard deviation and variation coefficient of the interspike intervals. In addition, burst firing was found to be markedly reduced in the split-brain group. It is concluded that decussating pathways are involved in the regulation of the discharge pattern of NSDA neurons.