Abstract # 40:

Scheduled for Saturday, September 17, 2011 03:00 PM-03:20 PM: Session 9 (Meeting Room 410) Oral Presentation


NEURAL CORRELATES OF ORO-FACIAL MOTOR CONTROL IN CHIMPANZEES: IMPLICATIONS FOR THE ORIGINS OF SPEECH

W. Hopkins1,2, S. Bogart1,2, J. Mangin3 and S. Schapiro4
1Yerkes National Primate Res. Ctr., Division of Psychobiology, Atlanta, GA 30329, USA, 2Agnes Scott College, Decatur, GA 30030, 3LNAO, Neurospin, I2BM, CEA, Gif-sur-Yvette, France, 4Department of Veterinary Sciences, The University of Texas M. D. Anderson Cancer Center, Bastrop, Texas 78602
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     Recent studies have shown that captive chimpanzees have voluntary control over a class of learned sounds referred to as “attention-getting” (AG) vocalizations. There are considerable individual differences in the use of AG sounds with some apes reliably producing these sounds (Voc+) and some not (Voc-). Here, we examined whether Voc+ and Voc- chimpanzees differ in cortical organization within the frontal lobe. Magnetic resonance images were obtained from 88 chimpanzees and, from these scans, we obtained measures of surface area, sulcus depth and grey matter thickness from 5 frontal lobe sulci including the central, fronto-orbital, precentral inferior, inferior frontal and superior precentral. Statistical analyses of the five frontal lobe sulci indicated that Voc+ chimpanzees had significantly larger surface areas F(1, 84) = 6.12, p < 0.02, greater mean sulci depth F(1, 84) = 6.426, p < 0.02, and thicker grey matter F(1, 84) = 11.693, p < 0.003 than the Voc- apes. Voc+ chimpanzees also showed significantly greater leftward asymmetries for all five sulci in mean depth F(1, 84) = 7.959 , p < 0.01 and greater rightward asymmetries in grey matter thickness F(1, 84) = 7.123, p < 0.01 compared to Voc- apes. The results reported here are consistent with the theory that Broca’s area was involved in oro-facial motor control linked to communicative gestures and sounds in the common ancestor of humans and chimpanzees.