CORTICAL TYPE PREDICTS THE EXPRESSION OF GLUTAMATERGIC NEUROTRANSMISSION GENES IN THE HUMAN AND MACAQUE CEREBRAL CORTEX

The human cerebral cortex can be parcelled into cortical areas, according to particular physiological, clinico-pathological, and anatomical features. Alternatively, it can be parcelled into cortical types which are operationally defined along a gradient of laminar complexity. Cortical types are related to synaptic connectivity and are rooted in ontogeny and phylogeny; thus, they have more explanatory power than cortical areas and can be used as conceptual tools in the design of experiments to provide a meaningful biological context.
In the present study we analyze gene expression data in the human and macaque cerebral cortex using the conceptual tool of cortical type. For this purpose, expression data of genes related to GABAergic and glutamatergic transmission were obtained from single-cell genome wide databases of human and macaque cortex (BRAIN Initiative Cell Census Network, Allen Brain Institute). The data were curated and organized according to the cortical type of the analyzed areas. We found that the expression of genes related to glutamatergic transmission decrease from areas of simpler laminar complexity (allo- and mesocortex) to areas of higher laminar complexity (koniocortex). In the reverse direction, some genes related to GABAergic transmission decrease from koniocortex to allocortex. Our findings confirm that the concept of cortical type encompass features of cortical neurons at the level of synaptic circuits, cellular features, and gene expression.