Annual Meeting of the Society for Neuroscience edition:36 location:Atlanta, GA, U.S.A. date:October 14-18, 2006
While an increasing number of genetically manipulated mouse models of human disorders are produced, physiologically and behaviorally characterized, the degree to which cortical organization in mice compares with other species remains poorly known. Large behavioral and cognitive differences exist between mice and rats, but the structural basis of such variance is not fully understood. In the present study we show that the extent, location and delineation of prefrontal areas in mouse differs from that in rat based on the cyto- and chemoarchitectural characteristics of these regions in adult C57BL/6 mice. In each cortical area, we examined neurofilament protein immunoreactivity using monoclonal antibodies against nonphosphorylated epitopes on the high molecular weight subunits (Covance) and the low molecular weight subunits (Chemicon) of the neurofilament triplet protein. Neurochemical features permitted improved demarcation of the orbitofrontal cortex and its relationships to the anterior insular cortex and regions on the midline, compared to standard Nissl-based parcellations. We clarified the boundary of the dorsolateral orbital cortex with the ventral insula, the overall span of the dorsal and ventral insular domains, and revealed the existence of a hitherto unrecognized group of neurons at the posterior pole of the ventral orbital cortex that seemingly connects the anterior claustrum with the piriform cortex. We also used design-based stereologic approaches to provide a comprehensive quantitative database of the neuronal make-up of these fields. Such stereology-based chemoarchitectural parcellation can also be integrated with digital high-resolution magnetic resonance microscopy brain atlases, and be further used in combination with physiologic and behavioral data, compared to known patterns from other species, and serve as a normative dataset for quantitative studies of the effects of brain aging as well as neurodegenerative changes in mouse models.