Rilling / Poster

FUNCTIONAL NEUROIMAGING OF LINGUISTIC PROCESSING IN CHIMPANZEES.

J. Rilling^3*, C. Kilts^2,3, S. Williams¹, J. Kelley¹, M. Beran¹, M. Giroux⁴, JM. Hoffman^2,4, S. Savage-Rumbaugh¹, and D. Rumbaugh¹.
¹Language Research Center, Georgia State University, ²Emory Center for PET, Dpts. of ³Psychiatry and ⁴Radiology, Emory Univ., Atlanta, GA, 30322.

     The objective of this study was to determine if humans and language competent chimpanzees recruit homologous neural substrates when processing linguistic stimuli. Following an intramuscular injection of 18F-FDG (10 mCi), two adult female chimpanzees ("Panzee" and "Lana") engaged in computerized speech and symbol comprehension tasks during the 40 minute period of glucose uptake into the brain. After the task, subjects were anesthetized with ketamine and 2% isoflurane and scanned in a Siemens 951 PET tomograph. Replicate scans were acquired from each chimp and both were also scanned following a sensorimotor control task. Two human subjects received H215O PET scans while performing the same tasks. Prior to statistical analyses, all scans were spatially registered to an anatomical MRI.
     In humans, the speech - control contrast revealed left lateralized activation in Heschel's gyrus, the planum polare, and frontal cortical areas (t>1.5). Homologous areas were not activated in the chimpanzee for the same contrast.; Panzee activated bilateral dorsomedial frontal cortex, cerebellum and thalamus. For the processing of symbolic lexigrams, the chimpanzees also exhibited different patterns of activation than humans. Despite good within-subject reproducibility, Panzee and Lana show different patterns of task-related activation that may reflect their differential rearing histories. Our results suggest that humans and language competent chimpanzees process language via different neural substrates. Supported by NICHD grant 06016 and Georgia State University College of Arts and Sciences.