Separate non-cholinergic descending projections and cholinergic ascending projections from the nucleus tegmenti pedunculopontinus.

A substantial population of cells from the nucleus tegmenti pedunculopontinus was demonstrated to have descending projections to the spinal cord using fluorescent retrograde axonal tracers. Double-labeling studies showed that separate perikarya in this region have descending versus ascending projections. The distributions of the cell bodies with ascending or descending projections were spatially distinct, but partially overlapping. Some ascending, but not the descending, projections were cholinergic.