Akinori Tokushige

Topographical projections from the thalamus, subthalamic nucleus and pedunculopontine tegmental nucleus to the striatum in the Japanese monkey, Macaca fuscata

Topographical projections from the thalamus, subthalamic nucleus (STN) and pedunculopontine tegmental nucleus (PPN) to the striatum were examined in the Japanese monkey (Macaca fuscata) by using the retrograde axonal transport technique of WGA-HRP (wheat germ agglutinin-conjugated horseradish peroxidase). After WGA-HRP injection in the head of the caudate nucleus (CN) or putamen (Put), labeled neuronal cell bodies in the thalamus were distributed mainly in the nucleus ventralis anterior (VA)-nucleus ventralis lateralis (VL) complex and the nucleus centrum medianum (CM)-nucleus parafascicularis (Pf) complex, and additionally in the paraventricular, parataenial, rhomboid, reuniens, centrodorsal, centrolateral, paracentral, and centromedial nuclei. The data indicated that the pars principalis of VA (VApc) projected mainly to CN and additionally to Put, and that the pars magnocellularis of VA (VAmc) or pars oralis of VL (VLo) projected selectively to CN or Put, respectively. It was also indicated that CM projected to the middle and caudal parts of Put, while Pf projected to CN and the rostral part of the Put. The data further indicated that the dorsomedial, ventromedial, or lateral part of CM projected respectively to the dorsolateral, ventromedial, or intermediate part of Put, and that the medial or lateral part of Pf projected respectively to the medial or lateral part of the head of CN. Direct projections from STN and PPN to the striatum were confirmed. The subthalamostriatal projections showed a mediolateral topography. The PPN was shown to project bilaterally to the striatum with an ipsilateral predominance.

An autoradiographic study of cortical projections from motor thalamic nuclei in the macaque monkey

The special areal and laminar distributions of cortical afferent connections from various thalamic nuclei in the monkey (Macaca fuscata) were studied by using the anterograde axonal transport technique of autoradiography. The following findings were obtained. The superficial thalamocortical (T-C) projections, terminating in the (superficial half of) cortical layer I, arise mainly from the nucleus ventralis anterior, pars principalis (VApc) and nucleus ventralis lateralis, pars oralis (VLo), and possibly from the nucleus ventralis lateralis, pars medialis (VLm) and nucleus ventralis anterior, pars magnocellularis (VAmc). The VApc gives rise to the superficial T-C and deep T-C projections onto the postarcuate premotor area around the arcuate genu and spur, and onto the dorsomedial part of the caudal premotor area as well as the supplementary motor area (SMA). The VApc also gives rise to only deep T-C projections onto the remaining premotor area and onto the rostral bank of the arcuate sulcus as well as the ventral bank of the cingulate sulcus at the level of the premotor area. The VLo gives rise to the superficial T-C projections onto the ventrolateral part of the motor area (mainly to the forelimb motor area) and onto the dorsomedial part to the mesial cortex at the rostral level of the motor area. The VAmc gives rise to the superficial T-C projections onto the banks of the arcuate genu and adjacent region of area 8. Area X, the nucleus ventralis posterolateralis, pars oralis (VPLo), nucleus ventralis posterolateralis, pars caudalis (VPLc), nucleus ventralis posteromedialis (VPM) and possibly the nucleus ventralis lateralis, pars caudalis (VLc) send only deep T-C projections. The dorsal and medial parts of the VLc project onto the premotor area, the rostral part of the motor area and the SMA, and also the ventral bank of the cingulate sulcus. Area X projects onto the premotor area, the SMA, and the caudal part of area 8. The thalamic relay nuclei projecting onto the frontal association cortex were found to be the VAmc, medial VLc and area X.

Cortical connections of the motor thalamic nuclei in the Japanese monkey, Macaca fuscata.

Our findings revealed the nucleus ventralis lateralis pars oralis (VLo) projection to motor area, and the nucleus ventralis anterior pars principalis (VApc) projections to the premotor and supplementary motor areas (SMA). The VLo gave rise to thalamocortical projections terminating in the superficial half of layer I, mainly in the forelimb motor area. The VApc gave rise to the superficial projections to the post-arcuate premotor area around the arcuate genu and arcuate spur as well as SMA. We suggested that the medial pallidal segment projects to the motor area via VLo, and to the premotor area and SMA via VApc. We also proposed that the premotor area and SMA receive cerebellar afferents via nucleus ventralis lateralis pars caudalis and area X.

Topographical organization of the projections from the cerebral cortex to the head of the caudate nucleus. A horseradish peroxidase study in the cat.

The topographical organization of the projections from the cerebral cortex to the head of the caudate nucleus was studied in the cat using the horseradish peroxidase method. Various amounts of horseradish peroxidase were injected into several sites of the head portion of the caudate nucleus at about the frontal level where its cross section was widest. Injections of small amounts of horseradish peroxidase retrogradely labeled neurons in rather limited cortical areas bilaterally, showing the localized organization of the projections. Neurons in the lateral portions of the ventral bank of the cruciate sulcus and in the dorsal bank (areas 4 gamma and 4 delta) were labeled after horseradish peroxidase injections into the dorsolateral part of the head of the caudate nucleus. Neurons in the intermediate portions of the ventral bank (areas 6 a delta and 6 infra fundum) were strongly labeled after dorsolateral or ventrointermediate injections, and neurons in the medial portion (area 6a beta), after dorsomedial, dorsointermediate, ventrointermediate or central injections. These findings indicate that areas 4 gamma and 4 delta project to the dorsolateral part of the caudate nucleus, areas 6a delta and 6 infra fundum to the lateral half, and area 6a beta to a more medial portion. Other findings revealed that the gyrus proreus projects to the medial part of the caudate nucleus and the anterior cingulate gyrus to the dorsal region.

Entopeduncular nucleus projections to the contralateral thalamic nuclei: an HRP study.

Abstract Neurons of the entopeduncular nucleus projecting to the ventral anterior, ventral lateral and centromedian nuclei of the thalamus were identified on the contralateral, as well as the ipsilateral side, by the retrograde transport of horseradish peroxidase in the cat.

Retinal projection to the formatio reticularis tegmenti mesencephali in the Old World monkeys.

SummaryWe studied the retinal projections of Old World monkeys using the anterograde transport of tritiated amino acid and wheat germ agglutinin conjugated to horseradish peroxidase. In addition to well-known retinal connections, these methods revealed that a small number of labeled retinofugal fibers might terminate in a small area of the contralateral formatio reticularis tegmenti mesencephali between the red nucleus and the substantia nigra. In the autoradiographic cases, a few labeled retinal terminals were also found in the same area on the ipsilateral side. In order to reach their terminal field, these labeled fibers appeared to leave the accessory optic tract in the vicinity of the dorsal border of the lateral terminal nucleus and run medially through the substantia nigra.

An autoradiographic study of the spinofacial projection in the monkey

The spinofacial projection was revealed using anterograde transport of radioactively labeled protein in the monkey. The projection arises from cells in the lateral part of the spinal dorsal horn (i.e. the lateral part of lamina V of Rexed) at the upper cervical cord, mainly C1 segment, ascends in the medial or ventromedial part of the anterior funiculus after crossing the anterior white commissure, then courses through the dorsolateral part of the inferior olivary complex. Finally, it terminates within the medial parts of the facial nuclei bilaterally, with the cells from the side ipsilateral to the injection contributing more heavily. Some fibers of this projection cross initially at spinal levels and recross again at levels through the rostral medulla and caudal pons.