Brain volumetry from CT-scan endocasts of three neotropical carnivores.

Studies on brain anatomy can clarify specific evolutionary and behavioural aspects of wild animals. The rich diversity in a broad range of habitats makes carnivorans especially eligible for studying the relations between the brain form and behaviour, cognitive, sensorial and motor traits. This study compared the brain's contour and total and segmented brain volumetry in three species of neotropical carnivorans. CT images of 17 skulls of three species were acquired: Conepatus chinga (n = 6), Galictis cuja (n = 6) and Lontra longicaudis (n = 5). Three-dimensional endocasts allowed for estimating the brain's total and segmented volumes (olfactory bulb, rostral cerebrum, caudal cerebrum and cerebellum/brain stem). The average volume percentage of the segments was compared interspecifically and intraspecifically between the sexes. The otter has a notably more complex gyrification, typical for semiaquatic carnivorans. Proportionally, the olfactory bulb was significantly larger in hog-nosed skunks, possibly due to a better sense of smell for capturing insects. The proportional volumes of the rostral cerebrum, caudal cerebrum and cerebellum/brain stem segments did not differ between these species. Social behaviour traits and tactile, motor and balance skills were probably not sufficiently distinct to reflect differences in the brain segments analysed in these three species.