Abstract # 3123 Event # 212:

Scheduled for Monday, September 19, 2011 09:30 AM-09:45 AM: Session 27 (Meeting Room 410) Oral Presentation


CORTICAL ASYMMETRIES DETECTED IN SPECIES-SPECIFIC SULCI IN CHIMPANZEES BUT NOT MACAQUES

S. L. Bogart1,2, A. Bennett3, P. Pierre3 and W. D. Hopkins1,2
1Yerkes National Primate Research Center, Division of Developmental and Cognitive Neuroscience, Atlanta, Georgia 30322, USA, 2Department of Psychology and Neuroscience, Agnes Scott College, Decatur, Georgia 30030, 3Department of Physiology and Pharmacology and Department of Pediatrics, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157
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     The debate over population-level cortical asymmetries in human and nonhuman primates is hampered by the lack of consistent methods within and between species. Here, we used a novel software program that allows for measurements of cortical sulci in primates. We implemented BrainVISA on magnetic resonance images (MRI) collected from 88 chimpanzees (Pan troglodytes) along with 37 macaques, including 21 Rhesus (Macaca mulatta) and 16 Bonnet (Macaca radiate) monkeys. From the MRIs, 3-D cortical fold graphs of the left and right cerebral hemispheres were derived for each subject. We quantified 11 prominent sulci of the chimpanzee brain and five for the macaque, from which we obtained several different measures and hemispheric grey and white matter volumes. In macaques, no significant interhemispheric differences were found for the five sulci quantified. In contrast, most (10/11) chimpanzee sulci indicated significant differences. Greater left hemisphere measures were revealed in four sulci surface areas (sylvian t=-2.94, p=0.04; FO t=-2.42, p=0.02; SPC t=-3.39, p=0.001; IP t=-2.15, p=0.03) and six sulci maximum depths (sylvian t=-2.17, p=0.03; FO t=-3.31, p=0.001; PCI t=-2.13, p=0.04, IFS t=-2.22, p=0.03; Lunate t=-2.38, p=0.02; IP t=-4.01, p>0.001). Additionally, chimpanzees have significantly more white matter in the left compared to right hemisphere (t=-2.85, p=0.005). Chimpanzees exhibit population-level leftward asymmetry in cortical organization suggesting significant changes in the evolution of cortical asymmetries in nonhuman primates, particularly after Ape-Old World monkey divergence.