Receptor density pattern confirms and enhances the anatomic-functional features of the macaque superior parietal lobule areas

Abstract

The macaque monkey superior parietal lobule (SPL) is part of a neuronal network involved in the integration of information from visual and somatosensory cortical areas for execution of reaching and grasping movements. We applied quantitative in vitro receptor autoradiography to analyse the distribution patterns of 15 different receptors for glutamate, GABA, acetylcholine, serotonin, dopamine, and adenosine in the SPL of three adult male Macaca fascicularis monkeys. For each area, mean (averaged over all cortical layers) receptor densities were visualized as a receptor fingerprint of that area. Multivariate analyses were conducted to detect clusters of areas according to the degree of (dis)similarity of their receptor organization. Differences in regional and laminar receptor distributions confirm the location and extent of areas V6, V6Av, V6Ad, PEc, PEci, and PGm as found in cytoarchitectonic and functional studies, but also enable the definition of three subdivisions within area PE. Receptor densities are higher in supra- than in infragranular layers, with the exception of kainate, M2, and adenosine receptors. Glutamate and GABAergic receptors are the most expressed in all areas analysed. Hierarchical cluster analyses demonstrate that SPL areas are organized in two groups, an organization that corresponds to the visual or sensory-motor characteristics of those areas. Finally, based on present results and in the framework of our current understanding of the structural and functional organization of the primate SPL, we propose a novel pattern of homologies between human and macaque SPL areas.

A dopamine gradient controls access to distributed working memory in monkey cortex

“…Receptor density at the synapse is the functionally important quantity, and is directly measured here. The map of D1 receptor density here greatly expands previous descriptions of D1 receptor densities (Goldman-Rakic et al 1990;Impieri et al 2019;Lidow et al 1991;Niu et al 2020;Richfield et al 1989). We show that D1 receptor density increases along the cortical hierarchy, peaking in prefrontal and posterior parietal cortex.…”

“…Collection of this data is underway and will be made available in future studies. With the exception of the receptor densities in the superior parietal lobe (Impieri et al 2019) and intraparietal sulcus (Niu et al 2020), all D1 receptor densities are reported for the first time in this study.…”

“…All anatomical data was mapped to the appropriate parcellations on the Yerkes19 surface. For the present study, we mapped all data to the 40 area Lyon subgraph Markov et al 2014b, as the areas in this parcellation were generally larger than those in the Jülich macaque atlas (Impieri et al, 2019;Niu et al, 2020;Rapan et al, In Prep;Niu et al, In prep; this paper) and the Queensland (spine count) injection sites (Elston 2007), and closer to standard areal descriptions than the Vanderbilt (neuronal density) (Collins et al 2010) sections.…”

“…The receptor densities were quantified in 109 cortical regions defined by cyto-and receptor-architecture. The delineation of cortical region borders in the superior parietal lobe is described in (Impieri et al 2019). with areas in the Jülich macaque atlas.…”

“…Dopamine modulates neural activity through its receptors, of which the D1 receptor is the most common in cortex. The density of D1 receptors is known only for small sections of monkey cortex (Goldman-Rakic et al 1990;Impieri et al 2019;Lidow et al 1991;Niu et al 2020;Richfield et al 1989). A detailed map of the density of D1 receptors across cortex would clarify the degree to which dopamine's influence on cortical processing is restricted to specific sections of cortex, or distributed throughout cortical systems.…”