Neurochemical and connectional organization of the dorsal pulvinar complexin monkeys

To investigate the organization of the dorsal pulvinar complex, patterns of neurochemical staining were correlated with cortico-pulvinar connections i n macaques (Macaca mulatta). Three major neurochemical subdivisions of the dorsal pulvinar were identified by acetylcholinesterase (AChE) histochemist ry, as well as immunostaining for calbindin-D-28K and parvalbumin. The dors al lateral pulvinar nucleus (PLd) was defined on histochemical criteria as a distinct AChE- and parvalbumin-dense, calbindin-poor wedge that was found to continue caudally along the dorsolateral edge of the pulvinar to within I mm of its caudal pole. The ventromedial border of neurochemical PLd with the rest of the dorsal pulvinar, termed the medial pulvinar PM), was sharp ly de fined. Overall, PM was lighter than PLd for AChE and parvalbumin and displayed lateral (PM1) and medial (PMm) histochemical divisions. PMm conta ined a central "oval" (PMm-c) that stained darker for AChE and parvalbumin than the surrounding region. The neurochemically defined PLd was labeled by tracer injections in the inferior parietal lobule (IPL) and dorsolateral p refrontal cortex but not the superior temporal gyrus (STG). Label within PM I was found after prefrontal and IPL and, to a lesser extent, after STG inj ections. The PMm was labeled after injections of the IPL and STG, but only sparsely following prefrontal injections. The histochemically distinct subr egion or module of PMm, PMm-c, was labeled only by STG injections. Overlapp ing labeling was found in dorsal pulvinar divisions PMI and PLd following p aired IPL/prefrontal, but not IPL/STG or these particular STG/prefrontal, i njections. Thus, PLd may be a visuospatially related region whereas PM appe ars to contain several types of territories, some related to visual or audi tory inputs, and others that receive directly converging input from posteri or parietal and prefrontal cortex and may participate in a distributed cort ical network concerned with visuospatial functions. J. Comp. Neurol. 419:61 -86, 2000. (C) 2000 Wiley-Liss, Inc.