title: Projections from Gudden's tegmental nuclei to the mammillary body region in the cynomolgus monkey (Macaca fascicularis).
abstract: Gudden's tegmental nuclei provide major inputs to the rodent mammillary bodies, where they are thought to be important for learning and navigation. Comparable projections have yet to be described in the primate brain, where part of the problem has been in effectively delineating these nuclei. Immunohistochemical staining of tissue from a series of macaque monkeys (Macaca mulatta) showed that cells in the region of both the ventral and dorsal tegmental nuclei selectively stain for parvalbumin, thus helping to reveal these nuclei. These same tegmental nuclei were not selectively revealed when tissue was stained for SMI32, acetylcholinesterase, calbindin, or calretinin. In a parallel study, horseradish peroxidase was injected into the mammillary bodies of five cynomolgus monkeys (Macaca fascicularis). Retrogradely labeled neurons were consistently found in the three subdivisions of the ventral tegmental nucleus of Gudden, which are located immediately below, within, and above the medial longitudinal fasciculus. Further projections to the mammillary body region arose from cells in the anterior tegmental nucleus, which appears to be a rostral continuation of the infrafascicular part of the ventral tegmental nucleus. In the dorsal tegmental nucleus of Gudden, labeled cells were most evident when the tracer injection was more laterally placed in the mammillary bodies, consistent with a projection to the lateral mammillary nucleus. The present study not only demonstrates that the primate mammillary bodies receive parallel inputs from the dorsal and ventral tegmental nuclei of Gudden, but also helps to confirm the extent of these poorly distinguished nuclei in the monkey brain.
authors.affiliation: Laboratory of Neuropsychology, National Institutes of Mental Health, Bethesda, Maryland 20892, USA.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Saunders
authors.forename: Seralynne D
authors.initials: SD
authors.lastname: Vann
authors.forename: John P
authors.initials: JP
authors.lastname: Aggleton
mesh_terms: D000818:Animals; D008252:Macaca fascicularis / Q000033:anatomy & histology* / Q000502:physiology; D008253:Macaca mulatta; D008297:Male; D008326:Mammillary Bodies / Q000166:cytology* / Q000502:physiology; D009434:Neural Pathways / Q000166:cytology / Q000502:physiology; D011149:Pons / Q000166:cytology* / Q000502:physiology; D013681:Tegmentum Mesencephali / Q000166:cytology* / Q000502:physiology