Functional Relationships Between the Red Nucleus and the Brachium Gonjunctivum

Abstract

An attempt was made to determine the physiologic effects of localized lesions of the red nuclei in monkeys with complete and partial degeneration of the superior cerebellar peduncles. Primary lesions were made in the deep cerebellar nuclei and the brachia conjunctiva. After an observations period of 200 days, secondary lesions were produced in the red nuclei. These combined procedures were successful in 5 of 11 monkeys. Serial sections of the brains were prepared according to the Marchi method. Lesions of the red nuclei in the monkey increase the degree of hypokinesis resulting from lesions of the deep cerebellar nuclei and the brachium conjunctivum. With complete, or virtually complete, degeneration of the brachium conjunctivum, lesions of the red nuclei do not significantly alter ataxia, ataxic tremor or asynergic disturbances. Transient choreiform activity may result from lesions of the red nuclei, but only if portions of the brachium conjunctivum are undegenerated. The hypothesis is presented that dyskinesia resulting from localized lesions of the red nucleus in the monkey are a consequence of interruption of the ascending fibers of the brachium conjunctivum rather than destruction of the cells of the red nucleus.