| Abstract: | Afferent projections to the functionally identified mesencephalic locomotor region were investigated in cats using the horseradish peroxidase retrograde axonal transport technique. Sources of afferent projections to this region were discovered in different structures of the fore-, mid-, and hindbrain. Numbers of horseradish peroxidase-labeled neurons were calculated in different brain structures after injecting this enzyme into the mesencephalic locomotor region. Apart from the endopeduncular nucleus, different hypothalamic structures, and the substantia nigra, labeled neurons were discovered in the central tegmental region, the central gray, raphe and vestibular nuclei, the solitary tract nucleus, and the brain stem reticular formation. Neurons accumulating horseradish peroxidase were also discovered in nuclei where ascending sensory tracts originate. This fact serves to bring out the structural inhomogeneity of the midbrain locomotor region; electrical stimulation of this area is an effect which may be attributed to excitation of neurons found within it and activation of accompanying fiber tracts.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev Translated from Neirofiziologiya, Vol. 18, No. 6, pp. 763–773, November–December, 1986. |
