Connectional and neurochemical subdivisions of the pulvinar in Cebus monkeys

Abstract

Based on cytoarchitectonic criteria, the primate pulvinar nucleus has been subdivided into medial (PM), lateral (PL), and inferior (PI) regions. However, these subdivisions show no correlation with those established by electrophysiological, immunocytochemical, or neuroanatomical tracer studies. In this work, we studied the connections of the pulvinar nucleus of Cebus monkey with visual areas V1, V2, V4, MT, and PO by means of retrograde fluorescent tracers injected into these areas. Based on the projection zones to cortical visual areas, the visual portion of the pulvinar of Cebus monkey was subdivided into three subregions: P1, P2, and P3, similar to those described in the macaque (Ungerleider et al., 1984). In Cebus, P1 includes the centrolateral portion of traditionally defined PI and adjacent portion of PL. P2 is located in the dorsal portion of PL and P3 includes the medial portion of PI and extends dorsally into adjacent PL and PM. In addition, we studied the histology of the pulvinar using multiple criteria, such as cytoarchitecture and myeloarchitecture; histochemistry for cytochrome oxidase, NADPH-diaphorase, and acetylcholinesterase; and immunocytochemistry for two calcium-binding proteins, calbindin and parvalbumin, and for a neurofilament recognized by the SMI-32 antibody. Some of these stains, mainly calbindin, showed additional subdivisions of the Cebus pulvinar, beyond the traditional PI, PL, and PM. Based on this immunohistochemical staining, the border of PI is moved dorsally above the brachium of the superior colliculus and PI can be subdivided in five regions (PI(P), PI(M), PI(C), PI(L), and PI(LS)). Regions P1, P2, and P3 defined based on efferent connections with cortical visual areas are not architectonically/neurochemically homogeneous. Rather they appear to consist of further chemoarchitectonic subdivisions. These distinct histochemical regions might be related to different functional modules of visual processing within one connectional area.

Pulvinar contributions to the dorsal and ventral streams of visual processing in primates

“…As some projections also came from PIcm, and PIp, there probably was some involvement of rostral V4. These findings are consistent with those of a number of studies describing the connections of caudal DL/V4 with the pulvinar (Lin and Kaas, 1980;Soares, et al, 2001;O'Brien, et al, 2002;Shipp, 2003). In contrast, injections in rostral DL (DLr or V4r) of the dorsal stream labeled neurons mainly in PIcm (Cusick et al, 1993;Gray et al, 1999).…”

A Dissociation of Motion and Spatial-Pattern Vision in the Avian Telencephalon: Implications for the Evolution of “Visual Streams”

“…Moreover, these projections are topographic. Soares et al (2001), in their Figure 9, in Cebus, identified areas P1, P2, and P3 that have differential projections to V1, V2, V4, and MT.…”

“…The homolog of nRT in mammals is those areas in the thalamus that receive input from the superior colliculus (i.e., tectum) and/or project to the telencephalon (Nauta and Karten, 1970;Karten, 1979;Karten and Shimizu, 1989;Husband and Shimizu, 2001). This includes the lateral posterior nucleus of the thalamus and the adjacent pulvinar in cats and squirrels (Robson and Hall, 1977;Chalupa et al, 1983;Kelly et al, 2003) and parts of the medial, lateral, and inferior pulvinar subdivisions in primates (Soares et al, 2001). As with the nRT, the pulvinar can be divided into various areas on the basis of cytoarchitecture, electrophysiology, connectivity, and immunohistochemistry (for review, see Soares et al, 2001, their Fig.…”

“…Most of the electrophysiological research on the mammalian pulvinar has examined motionsensitive cells (Chalupa et al, 1983;Bender, 1988;Casanova et al, 1989;Chalupa and Abramson, 1989;Merabet et al, 1998;Dumbrava et al, 2001), but neurons responsive to form and color have also been reported (Felsten et al, 1983;Benevento and Port, 1995). The cortical connections of the pulvinar are widespread and include areas 17, 18, and 19 in squirrels (Robson and Hall, 1977) and area MT, V1, V2, V4, IT, and parietal area 7 in various primates (Adams et al, 2000;Soares et al, 2001) (for review, see Robinson and McClurkin, 1989). Moreover, these projections are topographic.…”

Long‐range interneurons within the medial pulvinar nucleus of macaque monkeys

“…On the basis of neurochemical and connectional features, recent studies have demonstrated finer subdivisions within the classical boundaries of the inferior, lateral, and medial pulvinar thalamic nuclei (reviewed in Gutierrez et al, 2000;Soares et al, 2001;Stepniewska, 2004). The micro-organization within and between these zones, however, remains poorly understood, as does the degree of perceptual transmission vs. higher order integration of information through the thalamus (Chalupa, 1991;Benevento and Port, 1995;Guillery, 1995Guillery, , 2005Grieve et al, 2000;Casanova et al, 2001;Sherman andGuillery, 2001, 2004;Basso et al, 2005;Shaman, 2005).…”