Figure 8.

Axonal projection patterns of mitral and tufted cells in individual areas of the olfactory cortex. Total axon length (A), mean axon density (B), and axon filling rate (C) were plotted for TMT-responsive MCs (TMT-MC) (first column), 2MBA-responsive MCs (2MBA-MC) (second column), TMT-responsive TCs (TMT-TC) (third column), and 2MBA-responsive TCs (2MBA-TC) (fourth column). In this analysis, the OC was divided into seven areas consisting of the anterior olfactory nucleus (AON), tenia tecta (TT), olfactory tubercle (OT), anterior piriform cortex (APC), posterior piriform cortex (PPC), lateral entorhinal cortex (LEC), and olfactory amygdala region (AMYG) including the nucleus of the lateral olfactory tract (nLOT), anterior cortical amygdaloid nucleus (ACO), and posterolateral cortical amygdaloid nucleus (PLCO). The axon filling rate was computed to estimate the area that a given neuron occupied in individual areas of the OC (see Materials and Methods). Distribution patterns of axons differed across different areas (ANOVA, p < 0.001). Results from Tukey's post hoc HSD test (p < 0.05) were shown with a single asterisk. Significant differences from all the other areas are shown with triple asterisks. Double asterisks in the APC or PPC indicate significant difference from all the other areas except from the PPC or APC, respectively. For TMT-MC and 2MBA-MC, the APC had significantly more axonal projections compared with all other areas, and the PPC had more axonal projections compared with three of the other areas. Error bars indicate SEM. D, Cluster analysis of axonal projection patterns of individual MCs and TCs in the areas of the OC. The hierarchical tree grouped the 14 neurons into two clusters according to the similarity of their axonal projection patterns across the OC areas. These two clusters coincided with the MC and TC groups. The horizontal bar indicates 200 U in Euclidian distance.