Sharleen T. Sakai - US grants

Results from a number of studies have suggested that the frontal agranular cortex plays a unique role in the complex sequencing of movements in primates. Furthermore, it is thought that area 6 is involved in the prehensile use of limbs. The overall objective of this proposal it to determine the anatomical and functional relationships of area 6 subdivisions in two behaviorally distinct carnivores, the dog and raccoon. The raccoon is noted for the manipulative capabilities of its forepaws while the dog uses its distal limbs primarily in locomotion. Both autoradiography and horseradish peroxidase techniques will be employed to determine the efferent and efferent connectivity of area 6. Additionally, the double fluorescent tracing technique and the autoradiographic tritiated wheat germ agglutinin technique in combination with horseradish peroxidase technique wil be used to determine the extent of collateralized thalamocortical projections of area 6.

central neural pathway /tract; model design /development

The goal of this project is to identify factors that contribute to the evolution of large brains. The idea that the evolution of large brains is the result of selection pressures derived from living in complex social or physical environments is tested in carnivore member species. Here, the social brain hypothesis which proposes that the cognitive abilities resulting from social living are related to the evolution of large brains including the expansion of the frontal lobes is evaluated. In addition, other factors such as home range size, tree dwelling and food seeking styles are assessed. A primary goal of this project is to analyze carnivore skulls using computed tomography (CT) to create endocasts (a virtual brain). The analysis will evaluate the relationship between brain size including regional volumes and various measures of social, behavioral and environmental complexity both across and within species in 4 carnivore families. This data set is unique as most studies examine only a few species and often report on a small sample size of each species. These studies will identify the factors that contribute to the evolution of large brains in carnivores. By understanding the evolution of the brain, we might better understand how the human brain works and determine whether brains of particular non-human animals might serve as useful models for studies of the human brain.
This project will also provide neuroscience training opportunities for undergraduate and graduate students. The project will yield a unique brain data set including both a range of rarely studied species and a large sample size of selected species. Importantly, these data have significant potential to influence the field as a resource for other researchers interested in utilizing this carnivore brain data set in developing new ideas of brain evolution and function. The brain volume data will ultimately be accessible through an arrangement with the Comparative Mammalian Brain Collection Website (www.brainmuseum.org).