Figure 2:

Cholinergic receptor distribution in lateral geniculate nucleus (LGN) and primary visual cortex (V1) in nonhuman primates (unless noted otherwise) separated by methodology. Size of symbol indicates relative density of the receptor. (A) Top panel: Muscarinic binding sites are present throughout LGN with higher binding in the lateral portion. Bottom panel: Nicotinic binding sites are denser in supra- and infragranular layers in V1 while muscarinic binding sites are fairly uniform across cortex with slight variations in the subdivisions of layer IV (cortex data from humans). (B) Top panel: mRNA copies of α2, α4, α5, and β2 are present in LGN. Localization by layers is unknown. Bottom panel: Distribution of mRNA for different muscarinic and nicotinic receptor subtypes in V1. β2 mRNA is remarkably dense in layer IV, while all other types tend to be most strongly expressed in the deeper layers, specifically layer VI. Note: data is derived from a study looking at the entire cortex, not just specifically V1. (C) Laminar patterns of mRNA copy detection and receptor protein expression are not perfectly matched, but receptor expression across laminae mimics in situ data from (B), particularly in layer IV (m2 was densest in layer IVa and IVc). m2 labeling also showed patches of intermittent light and dark staining in layers II and III overlapping with the CO-rich blobs (data not shown). Data adapted from Shaw & Cynader 1986 (A, top panel); Eickhoff et al 2007 (A, bottom panel); Han et al 2000 (B); and Tigges et al 1997, Disney et al 2006, 2007, and Disney & Aoki 2008 (C).