COURSE OF SPINOTHALAMIC AND MEDIAL LEMNISCUS PATHWAYS IN CAT AND RHESUS MONKEY

Abstract

Action potentials were recorded from the medulla, midbrain, thalamus, and internal capsule with stimulation of contralateral and ipsilateral sciatic and saphenous nerves. Impulses from "touch fibers" were conducted lateral to the olive as well as in the medial lemniscus which indicates the lateral position of the ventral spinothalamic tract in the medulla. Touch and proprio-ceptive components in the spinothalamic and medial lemniscus pathways were condensed into a small area caudal to the nucleus ventralis posterolateralis of the thalamus which they entered. The impulses in the ventral spinothalamic tracts were conducted bilaterally in both cat and monkey, but components from the gracilis and cuneatus nuclei completely crossed to the opposite medial lemniscus and thalamus.