The primate pulvinar is connected with several visual areas and is implicated in visual attention and in control of eye movements. Traditionally, the pulvinar has been divided into three broad zones: medial (PM), lateral (PL), and inferior pulvinar (PI). This division was based on cytoarchitecture and the location of prominent fiber bundles and did not correlate to connectional data. Recent studies using various modern neurochemical methods suggest a pattern of organization more consistent with the topography of connections with different visual areas. In monkeys, the ventral pulvinar, consisting of traditional PI and the ventral portion of traditional PL, constitutes a histochemically distinct area termed the inferior pulvinar (PI) complex. The PI complex in monkeys consists of 5, separate zones: the posterior, medial, central, lateral, and the lateral-shell (PIP, PIM, PIC, PIL, and PI L-S) subdivisions, each distinguished by several neurochemical stains There is evidence that the visual system is not spared in neurodegenerative diseases such as Alzheimer's Disease (AD). While AD usually affects memory and attention early in the course of the disease, studies have shown that AD can also affect the visual cortex and visual pathways, including subcortical visual centers. Disruption of functions mediated by the pulvinar may contribute to visual deficits seen in patients with AD. The goal of this study was to investigate the neurochemical organization of the pulvinar and to understand it's role in visuospatial function of non-human primates and humans with or without Alzheimer's Disease, and how certain symptoms of Alzheimer's disease can be related to pathology within this structure We obtained postmortem chimpanzee (Pan troglodytes; n = 8) brains and human brains with no known neurological pathology (n = 5), and brains of patients clinically diagnosed with AD (n = 9). Using cytochrome oxidase (CO) and acetylcholinesterase (AChE) histochemistry, and immunocytochemistry for calbindin D28k, we were able to identify 5 histochernical zones in the chimpanzee PI complex, and 4 zones in the human PI complex. Thioflavin S histochemistry was employed to identify amyloid plaque distribution. Dense plaques were irregularly distributed across the PI complex with a slight trend for PIC having the greatest accumulation