A framework for embracing variation and diversity in minicolumn structure

The minicolumn has been defined as the smallest functional unit of thecortex with the widely-held view that there is a conservation of structure for this cortical processing unit. However, comparative data reveal significant differences among species in both the structure and composition of minicolumns. Here we review the available data on interspecific variation in minicolumn widths and the evidence in favor of phylogenetic variation in GABAergic interneurons, known to be a key component of the cortical microcircuit. Using data collated from the literature, we highlight the importance of variation in cortical column structure and build a framework towards further evolutionary explanations of minicolumndiversity. Although our preliminary analysis indicates that minicolumn widthincreases with increasing brain mass among anthropoid primates, this relationship is not constant when applied to other taxonomic orders. These findings highlight the need for further comparative analyses of minicolumn structure and their ecological, behavioral, and cognitive correlates.