Sylvian fissure asymmetries in nonhuman primates revisited: A comparative MRI study

Magnetic resonance images (MRI) were collected in a sample of 28 apes, 16 O ld World monkeys and 8 New World monkeys. The length of the sylvian fissure (SF) and the superior temporal sulcus (STS) was traced in each hemisphere from three regions of the cerebral cortex, These three regions were labeled according to their position on the sagittal plane as lateral, medial and i nsular, It was hypothesized that the length and asymmetry of these fissures would be dependent on the region of measurement and that a leftward asymme try in the SF and STS would be more robust in the great ape sample than for the monkeys, The results indicated within the ape sample a population-leve l leftward asymmetry in the medial and insular regions of the SF, Within th e Old and New World monkey samples, the SF was leftward in the medial regio n at the population level, but not at the insular region, Additionally, the Old World monkeys exhibited a population-level rightward lateral SF and a rightward lateral STS, No other families exhibited population-level asymmet ries in the lateral region of the SF or in any region of the STS, These res ults are consistent with findings reported in apes and, to a lesser extent, monkeys, MRI has excellent potential for comparing neuroanatomy across tax onomic families that will help future investigations. Copyright (C) 2001 S. Karger AG. Basel.