THE LATERAL AND MEDIAL COMPARTMENTS OF THE OLFACTORY TUBERCLE AND THEIR RELATION TO OLFACTORY-RELATED INPUT AS DETERMINED BY ARTIFICIAL NEURAL-NETWORK ANALYSIS

The current literature indicates that olfactory bulbar input projects throughout layer IA of the entire olfactory tubercle, with apparently more fibers in the lateral part than in the medial part of the tubercl e. In addition, olfactory cortical association fibers project to layer s IB, II, and III in all regions of the tubercle. This study exploited the phenomenon of transsynaptic transfer of WGA-HRP after injection i nto the olfactory bulb of rats to explore the degree of olfactory-rela ted input to the tubercle. A computerized image analysis system was em ployed to quantify the amount of tracer transferred to layer II neuron s of the tubercle. Qualitative analysis of the data indicates that the lateral tubercle consists of areas that receive little olfactory-rela ted input. Nonparametric statistical tests and a novel application of artificial neural networks indicate regionally heterogeneous labeling across the tubercle and broad connections between homologous regions o f the bulb and tubercle. These results have implications for understan ding how olfactory sensory information is integrated into limbic-motor circuits by the olfactory tubercle.