The evolution and functions of nuclei of the visual pulvinar in primates

Abstract

In this review, we outline the history of our current understanding of the organization of the pulvinar complex of mammals. We include more recent evidence from our own studies of both New and Old World monkeys, prosimian galagos, and close relatives of primates, including tree shrews and rodents. Based on cumulative evidence, we provide insights into the possible evolution of the visual pulvinar complex, as well as the possible co-evolution of the inferior pulvinar nuclei and temporal cortical visual areas within the MT complex.

Architectonic characteristics of the visual thalamus and superior colliculus in titi monkeys

“…In the present study, we focus primarily on the inferior and lateral pulvinar divisions. The inferior and lateral divisions share strong connections with cortical visual structures, receive input from the superficial layers of the superior colliculus (PIp and PIcm), and also receive direct projections from the retina (PIm) (See Baldwin et al, ; Baldwin & Bourne ; Bridge et al, for review).…”

“…PIcl is often considered to be functionally associated with the lateral pulvinar, PL (Kaas & Lyon, ; Baldwin et al, ), but for historical consistency, PIcl is still considered to be within the inferior pulvinar. This subdivision is more clearly differentiated from PIcm by its relatively lighter VGLUT2 staining characteristics.…”

“…Vesicular glutamate transporter 2 (VGLUT2) is responsible for transferring glutamate into presynaptic vesicles of glutamatergic neurons across the central nervous system and has been associated with excitatory inputs from subcortical structures (i.e., Balaram, Takahata, & Kaas, ; Balaram, Hackett, & Kaas, ; Rovo, Ulbert, & Acsady, ). Importantly, tissue processed for VGLUT2 protein expression reveals specific subdivisions of the pulvinar that are not always apparent in other histological stains, such as calbindin (Baldwin, Balaram, & Kaas, ). The subcortical visual structures have not been studied using VGLUT2 immunohistological preparations in New World monkeys (except for the pulvinar in squirrel monkeys, Baldwin et al, ), but VGLUT2 has been used to study the superior colliculus, lateral geniculate nucleus, and pulvinar complex of galagos (Balaram et al, ; Baldwin et al, 2013), macaques (Balaram et al, ), as well as tree shrews and squirrels (Baldwin et al, ; Balaram et al, ).…”

“…Importantly, tissue processed for VGLUT2 protein expression reveals specific subdivisions of the pulvinar that are not always apparent in other histological stains, such as calbindin (Baldwin, Balaram, & Kaas, ). The subcortical visual structures have not been studied using VGLUT2 immunohistological preparations in New World monkeys (except for the pulvinar in squirrel monkeys, Baldwin et al, ), but VGLUT2 has been used to study the superior colliculus, lateral geniculate nucleus, and pulvinar complex of galagos (Balaram et al, ; Baldwin et al, 2013), macaques (Balaram et al, ), as well as tree shrews and squirrels (Baldwin et al, ; Balaram et al, ). These immunohistological stains were used in conjunction with more classical architectonic staining procedures such as cytochrome oxidase (CO), Nissl, and acetylcholinesterase (AChE), to reveal thalamic borders, the laminar organization of the superior colliculus and the lateral geniculate nucleus, as well as subdivisions of the pulvinar.…”

Interactive histogenesis of axonal strata and proliferative zones in the human fetal cerebral wall

“…In all “normal” term brains (Zagreb Neuroembryological Collection), we found strongly myelinated fiber bundles running along the VZ and SVZ, and also found that these myelinated tracts stop at the border of visual areas 17/18. This fiber system may represent a projection from the associative pulvinar nucleus, from the visual pulvinar (Kostović and Rakić 1984; Baldwin et al 2017) and primary visual projection from the lateral geniculate body (Polyak 1957). The other possibility is that the early myelinated fibers belong to geniculocortical projections, as proposed by other authors (Yakovlev and Lecours 1967).…”