Abstract # 36:

Scheduled for Saturday, September 17, 2011 01:40 PM-02:00 PM: Session 9 (Meeting Room 410) Oral Presentation


DEVELOPMENTAL CHANGES IN THE NEOCORTICAL MICROSTRUCTURE OF HUMANS AND CHIMPANZEES

C. Sherwood, T. Duka, D. Miller, C. Stimpson, A. Fobbs, D. Wildman and P. Hof
Mount Sinai School of Medicine, The George Washington University, Washington, DC 20052, USA
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     Human cognition arises through the interaction among species-specific neurodevelopmental processes, social learning, and experience. The extent to which neocortical development in humans unfolds differently from closely related primates, however, is not well understood. Previous research indicates that humans may be distinct from macaque monkeys in displaying delayed maturation of connectivity in higher-order association regions of the prefrontal cortex, allowing for a more extended period of plasticity in the acquisition of executive cognitive functions. We are currently examining developmental changes in the microstructure of the neocortex of common chimpanzees (n =14 from birth to sexual maturity; n = 4 adults) in comparison to humans. We have used multiple analytical approaches to characterize ontogenetic variation in the neuron/neuropil fraction, the distribution of myelinated axons, density of synapses, and the expression of synapse- and myelin-associated proteins across diverse regions of the neocortex. Our results show that chimpanzees display humanlike asynchrony of prefrontal cortex development in many indicators of synaptic connectivity and function. Quantification of axon length density reveals similar rates of myelination across cortical regions in both species until the age of weaning, after which the trajectory of myelination displays region- and species-specific patterns. These findings indicate that a slowly developing prefrontal cortex characterizes the evolutionary branch of African apes, including humans, and might be related to the enhancement of social learning capabilities.