Afferent and efferent connections of the oculomotor cerebellar vermis in the macaque monkey

Abstract

Saccadic eye movements were evoked with weak currents applied to a circumscribed vermal area. The area was confined to lobule VII in the majority of the monkeys and coincided with the distribution of saccade-related neural activity. We defined this area as the oculomotor vermis and studied its anatomical connections with wheat germ-agglutinin conjugated horseradish peroxidase (WGA/HRP) and HRP. When injected HRP was confined to the oculomotor vermis, most labeled Purkinje axons terminated ipsilaterally in an ellipsoidal region in the mediocaudal aspect of the fastigial nucleus. Retrogradely labeled cells were found in two relatively circumscribed regions in the fastigial nucleus: one group was in the lateral half of the ellipsoidal terminal region and the other group was in a spherical region near the lateral margin of the nucleus. Following the injection of HRP into the oculomotor vermis, the largest population of retrogradely labeled neurons was found in the nucleus reticularis tegmenti pontis. Labeled cells were located only in the medial and dorsolateral portions of the nucleus. The cell aggregates in the dorsolateral portion merged with densely labeled cells of the processus tegmentosus lateralis. The second largest population of labeled cells was found in the pontine nuclei. Approximately 28% of the labeled pontine cells aggregated in the paramedian pontine nucleus, whereas the other labeled pontine cells were widely distributed in the dorsal part of the pontine peduncular nucleus and the dorsolateral pontine nucleus. Labeled cells were scattered also in the pontine raphe, the paramedian pontine reticular formation, and the interfascicular nucleus at the rostral level of the hypoglossal nucleus. Fewer labeled cells were discovered in the vestibular nuclear complex and the prepositus hypoglossi. In the inferior olivary nucleus, labeled cells were located in the subnucleus b of the medial accessory nucleus.

Discharge of Monkey Nucleus Reticularis Tegmenti Pontis Neurons Changes During Saccade Adaptation

“…CFN neurons are inhibited by Purkinje cells (P-cells) of the oculomotor vermis (OMV; Ohtsuka and Noda 1991), which, in turn, receives a major input from the NRTP (Yamada and Noda 1987). P-cell firing has not yet been studied during adaptation.…”

“…However, saccade adaptation might influence neurons in the NRTP, which receives direct inputs from the SC (Harting 1977;Kawamura et al 1974;Scudder et al 1996), and, in turn, projects directly to the oculomotor vermis (Brodal 1980;Shinnar et al 1975;Thielert and Thier 1993;Yamada and Noda 1987) and to the CFN (Gonzalo-Ruiz and Leichnetz 1990;Noda et al 1990). Therefore, we investigated whether activity in the NRTP is changed during saccade adaptation.…”

Complex Spike Activity in the Oculomotor Vermis of the Cerebellum: A Vectorial Error Signal for Saccade Motor Learning?

“…The midline cerebellum, which is part of a parallel route for oculomotor information from the superior colliculus (SC) to reach the premotor brain stem generator for saccades (Harting 1977;Kralj-Hans et al 2007;Noda et al 1990;Yamada and Noda 1987), has been implicated as a structure where signals are adapted to reduce saccade dysmetria. It consists of the oculomotor vermis (lobules VIc and VII) and the caudal fastigial nucleus to which they project.…”

“…CS activity to the oculomotor vermis originates in the b nucleus of the medial accessory olive (Kralj-Hans et al 2007;Yamada and Noda 1987), which in turn, receives a strong input from the intermediate layer of the SC (Harting 1977;Huerta and Harting 1984). The intermediate layer of the SC contains neurons that have both visual receptive and motor movement fields, i.e., they discharge maximally for stimuli falling on a particular area of the contralateral hemifield and for contralateral saccades of a certain direction and size (for review, see Sparks and Hartwich-Young 1989).…”

Neural dynamics of saccadic and smooth pursuit eye movement coordination during visual tracking of unpredictably moving targets

“…(Suzuki et al, 1999;Suzuki et al, 2003;T. Yamada et al, 1996) DLPN to CBM (Mustari et al, 1988;Ono et al, 2005;Ono et al, 2004) DLPN to Vermis (Thielert & Thier, 1993;J. Yamada & Noda, 1987) DLPN to VPF Target and background speed and direction input is transferred.…”