Gracile, cuneate, and spinal trigeminal projections to inferior olive in rat and monkey

Abstract

In the cat, somatosensory nuclei send substantial projections to the inferior olive, where they terminate in a somatotopic fashion. Although the organization of the cat inferior olive has been used to interpret data from other species, published data suggest this organization may not occur universally. The present study investigated whether the inferior olive in albino rats and cynomolgus monkeys receives the same brainstem somatosensory inputs, whether these inputs are organized somatotopically and, if so, how the organization compares with that in the cat. Projections from the gracile, cuneate and spinal trigeminal nuclei were labeled with wheat germ agglutinin conjugated to horseradish peroxidase or with biotinylated dextran. The results were compared with data from cats (Berkley and Hand [1978] J. Comp. Neurol. 180:253-264). In the rat and monkey, the gracile, cuneate and spinal trigeminal nuclei all project to the contralateral inferior olive, where each nucleus has a distinct preferred terminal field. As in the cat, projections to the medial accessory olive and caudal dorsal accessory olive did not terminate in a precisely organized fashion. Projections to the rostral dorsal accessory olive, however, formed a clear somatotopic map. These somatotopic maps differed from those in the cat in that input from the trigeminal nucleus was confined rostrally, so that the caudal end only received input from the gracile and cuneate nuclei. These data indicate that similar organizational principles characterize the somatosensory projections to the inferior olives of the three species. Nevertheless, distinct species differences occur with regard to the details of this organization.

Bilateral stimulation of the caudal zona incerta nucleus for tremor control

“…Physiologically, the IO is thought to act as a “movement error detector”83 – 87 (fig 4) in that it receives information regarding the movement plan via the cerebellum and parvocellular red nucleus (pRN),88 as well as the movement instruction from the motor cortex and can compare this with the proprioceptive feedback that it receives during movement 89 – 91. On detecting a movement error, it modulates a correction via its efferent climbing fibres that synapse directly on purkinje cells in the cerebellar cortex and on the deep cerebellar nuclei (dentate and interpositus) 92 93.…”

Both Cell-Autonomous and Cell Non-Autonomous Functions of GAP-43 are Required for Normal Patterning of the Cerebellum In Vivo

“…In the cerebellum, GAP-43 is required for the topographically organized CF input from the medial accessory olive (MAO) to lobule VIa [57]. Both the ventrobasal nucleus VB and the MAO are innervated in a crudely somatotopic fashion (e.g., [44]), and both lack any obvious structural abnormalities in the absence of GAP-43 ( [37], not shown). The GAP-43 (−/−) phenotype resembles the wv/wv mutation in which the regional specificity that derives from the climbing fiber afferents innervating the CeL is disrupted without olivary topography being grossly affected [4].…”

Compartmentalization of the Deep Cerebellar Nuclei Based on Afferent Projections and Aldolase C Expression

“…5, yellow). Subnucleus b of the c-MAO receives heterogeneous input from the spinal cord and dorsal column nuclei with crude somatotopy [53][54][55][56] and from the vestibular nuclei and the mesodiencephalic junction [45,46,51]. This group may be involved in the control of stance and locomotion, as has been observed in recording from the rostral MN [57], and in lesioning of the deep white matter near the rostral MN [58].…”