Quantitative analysis of gyrification of cerebral cortex in dogs.

The degree of gyrification of the cerebral cortex was studied in a population of various breeds of dogs. The aim of the study was to demonstrate whether or not variations in brain weight, body size or body weight affect gyrification within a species. Results suggest that in spite of significant correlations between all these parameters the degree of gyrification is essentially determined by the size of the brain. This parameter shows neither sex-dependence nor asymmetry between the two hemispheres. The examination of frontal serial sections through dogs' brains has also revealed that in agreement with data on the primate brain the association cortical regions show an extraordinarily high gyrification. Accordingly, gyification is dependent from the overall growth of the brain in particular from that of the association areas growing most intensively in mammals. Measurement of the gyrification index is therefore, thought to be a suitable method to express in quantitative terms developmental trends of cortical organization.