Figure 7.

Role of bulbar cholinergic receptors in acquisition of novel odor discrimination problems depends on perceptual similarity of odors. Ai, Average performance (±SEM) as a function of test session for rats performing the acquisition task using dissimilar odor sets (n = 9). Note the high performance in MLA-infused rats. Aii, Average performance (±SEM) as a function of test session for rats performing the acquisition task using similar odor sets (n = 4). Note the low performance in MLA-infused rats. B, PI for each of the drug treatment groups plotted separately for dissimilar and similar odor sets. *p < 0.005, **p < 0.001. C, Simulated cortical PI for networks trained with bulbar input under the four experimental conditions for odor inputs with low (dissimilar) and high (similar) overlap. Similar to behavioral results, the effect of turning off nicotinic receptors depends on odor set similarity, such that the cortical network exhibits poorer discrimination of similar odors following removal of bulbar nicotinic receptors.