AUTHOR=Džaja Domagoj , Hladnik Ana , Bičanić Ivana , Baković Marija , Petanjek Zdravko TITLE=Neocortical calretinin neurons in primates: increase in proportion and microcircuitry structure JOURNAL=Frontiers in Neuroanatomy VOLUME=8 YEAR=2014 URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2014.00103 DOI=10.3389/fnana.2014.00103 ISSN=1662-5129 ABSTRACT=

In this article we first point at the expansion of associative cortical areas in primates, as well as at the intrinsic changes in the structure of the cortical column. There is a huge increase in proportion of glutamatergic cortical projecting neurons located in the upper cortical layers (II/III). Inside this group, a novel class of associative neurons becomes recognized for its growing necessity in both inter-areal and intra-areal columnar integration. Equally important to the changes in glutamatergic population, we found that literature data suggest a 50% increase in the proportion of neocortical GABAergic neurons between primates and rodents. This seems to be a result of increase in proportion of calretinin interneurons in layers II/III, population which in associative areas represents 15% of all neurons forming those layers. Evaluating data about functional properties of their connectivity we hypothesize that such an increase in proportion of calretinin interneurons might lead to supra-linear growth in memory capacity of the associative neocortical network. An open question is whether there are some new calretinin interneuron subtypes, which might substantially change micro-circuitry structure of the primate cerebral cortex.