Abstract # 150:

Scheduled for Friday, June 22, 2007 05:00 PM-07:00 PM: Session 14 (South Main Hall) Poster Presentation

Cerebellar Asymmetry and Handedness in Chimpanzees (Pan troglodytes) and Capuchins (Cebus apella)

K. A. Phillips1 and W. D. Hopkins2,3
1Hiram College, Departments of Psychology and Biology, 11715 Garfield Rd., Hiram, OH 44234-0067, USA, 2Yerkes National Primate Research Center, 3Agnes Scott College
     The cerebellum plays an important role in coordinating motor actions and processing cognitive information via indirect projections to cortical motor areas and prefrontal cortex. Previous findings demonstrated an association between handedness and asymmetries in the dorsal portion of the precentral gyrus in chimpanzees and capuchins. Therefore, we hypothesized associations between handedness and cerebellar asymmetry would also be present in both species. Structural MR brain images and behavioral data on a coordinated bimanual task were obtained from 16 chimpanzees and 11 capuchins. Cerebellar measurements were taken from anterior and posterior subregions. Capuchins were more lateralized on the tube task than chimpanzees [t(25)=3.59, p<0.001]. Chimpanzees showed a rightward bias for the posterior cerebellum [t(15)=2.73, p<0.05] but no asymmetry for the anterior cerebellum [t(15)=1.31, p>0.05]. Capuchin anterior cerebellum showed leftward asymmetry [t(10)=-2.82, p<0.05], but the posterior cerebellum did not [t(10)=0.00, p >0.05]. A significant interaction was found between species and handedness [F(1,23)=27.84, p<0.001]. Right-handed capuchins showed the most pronounced leftward cerebellar asymmetry compared to non-right-handed capuchins [F(2,35)=17.54, p<0.01]. Right- and non-right-handed chimpanzees did not differ significantly in cerebellar asymmetry. Although incongruent with our hypotheses, our results indicate that cerebellar asymmetry is associated with handedness in capuchins but not in chimpanzees.