the diencephalon , the periventricular preoptic area , the supraoptic nucleus , and , in particular , the medial habenular nucleus are densely innervated by nai fibers , whereas in the midbrain nai plexuses are found in the ventral tegmental area , the substantia nigra and its dorsolateral extension ( ra8 ) , and in an area ventral to the nucleus interpeduncularis , pars ventralis .
C0025462
midbrain
C0038590
substantia nigra