| dc.description.abstract | The cortical visual system in rodents can be divided into primary visual cortex (V1), also called striate cortex, and surrounding secondary visual areas comprising V2, also known as extrastriate cortex. Though once thought to be a uniform strip surrounding V1, it is now known that extrastriate cortex is in fact a string of distinct visual areas that each receive distinct patterns of V1 afferents, exhibit unique functional properties and send projections to different cortical areas. It has been suggested that collections of extrastriate areas form functionally distinct pathway that, like primates and other mammals, can be divided into dorsal and ventral visual streams. One of the major components of the putative “dorsal pathway” in rodents is the connection from extrastriate areas to the frontal motor area M2, an area thought to link sensory cues with specific motor actions and higher behavioral functions. However, exactly where and to what extent different visual areas feed forward to frontal motor areas is not well understood. The aim of this thesis is therefore to describe where efferent projections from V1 co-localize with M2-projecting neurons over the entire posterior cortex, and specifically with respect to the posterior parietal cortex (PPC). This was done by injecting eight mice with anterograde 10 KD biotinylated dextran amine (BDA) tracer into V1 to visualize the locations of the higher visual areas, and retrograde recombinant adeno-associated virus (rAAV) into M2. Brains were cut in flattened tangential and coronal planes to visualize at the full extent of co-localization, and to identify which cortical layers show the most overlap. Extensive co-localization was found in several extrastriate areas, the most prominent being areas A, AM, PM, RL and AL. These findings are consistent with a functional “dorsal-ventral” division amongst extrastriate areas, and indicate that these areas may play important roles in producing visually guided actions. | |