Thalamic projections of the superior colliculus in the rhesus monkey, Macaca mulatta. A light and electron microscopic study

Abstract

The projections of the superior colliculus to the thalamus have been studied in the monkey, Macaca mulatta, with anterograde degeneration techniques. The superior colliculus has been shown to project to the inferior nucleus of the pulvinar in a topographical manner with the lower visual field represented dorsomedially and the upper field ventrolaterally. The peripheral zone is located along the medial border and the fovea at the dorsolateral angle adjacent to the lateral geniculate nucleus. The superior colliculus also sends a dense projection to the ipsilateral intralaminar complex, i.e., to the parafascicular, central lateral and paracentral nuclei, and a lesser projection to the same contralateral nuclei. Degenerating tectal fibers were also found in the lateral geniculate nuclei. Four types of vesicle containing profiles were observed in the inferior pulvinar and paracentral nucleus. The large RL and small RS terminals contain round vesicles of uniform size and form asymmetric contacts mainly with large and small dendrites respectively. The F terminal contains a mixture of small round and flat vesicles. It forms symmetric contacts with dendrites and cell somata. The P profile is very pale and contains a relatively sparse population of vesicles showing a great variation in size. It forms symmetric contacts with medium to large dendrites. It is frequently found postsynaptic to the other types, especially the RL terminal, and is regularly seen as the intermediate element of serial and triadic synaptic arrangements. The experimental electron microscopic study has shown that many fibers from the superior colliculus terminate as RL profiles, undergoing direct dense degeneration, in both the inferior pulvinar and the paracentral nucleus. Others probably end as smaller RS terminals.

Distribution of neurons projecting to the superior colliculus correlates with thick cytochrome oxidase stripes in macaque visual area V2

“…Input from V2 may also reach the pulvinar complex through superior colliculus-pulvinar projections (Benevento and Fallon, 1975;Partlow et al, 1977;Harting et al, 1980;Benevento and Standage, 1983). Tectal-recipient regions in the pulvinar appear to overlap with cortically projecting regions (Benevento and Rezak, 1976), but the specificity of the tectopulvinofugal projections with respect to thick and thin stripes in V2 and with other visual areas of the dorsal or ventral streams remains to be determined.…”

Cell-specific expression of type II calcium/calmodulin-dependent protein kinase isoforms and glutamate receptors in normal and visually deprived lateral geniculate nucleus of monkeys

“…The inferior pulvinar nucleus also contains populations of cells projecting to more than one cortical area, including superficial layers Rezak, 1975, 1976;Ogren and Hendrickson, 1977;Rezak and Benevento, 1979;Lund et al, 1981;Lysakowski et al, 1988;Cusick et al, 1993). Inputs to both the S laminar and interlaminar cells and the inferior pulvinar nucleus arise in the superficial layers of the superior colliculus (Benevento and Fallon, 1975;Partlow et al, 1977;Harting et al, 1978Harting et al, , 1991 and both receive inputs from the retina (a restricted area adjacent to the lateral geniculate in the case of the inferior pulvinar nucleus) (Campos-Ortega et al, 1972;Tigges et al, 1977;Hendrickson et al, 1970;Kaas et al, 1978;Tokunaga et al, 1981). The parallel with the diffusely projecting matrix of the ventral thalamic nuclei seems clear (see also Diamond et al, 1993, andCusick et al, 1993).…”

Visual cortical projections and chemoarchitecture of macaque monkey pulvinar

“…Anatomic studies have shown that the P 1 and P 2 fields have connections with V1, V2, V4, and MT (CamposOrtega and Hayhow, 1972;Benevento and Rezak, 1976;Ogren and Hendrickson, 1976;Benevento and Davis, 1977;Graham, 1982;Maunsell and Van Essen, 1983;Standage and Benevento, 1983;Ungerleider et al, 1983Ungerleider et al, , 1984Cusick et al, 1993;Gutierrez and Cusick, 1997), and both receive inputs from the superficial layers of the superior colliculus (Benevento and Fallon, 1975;Partlow et al, 1977;Harting et al, 1980;Benevento and Standage, 1983;Stepniewska et al, 1999). The P 3 field has connections with MT, MST, and FST (Maunsell and Van Essen, 1983;Standage and Benevento, 1983;Ungerleider et al, 1984;Boussaoud et al, 1992).…”