Figure 10.
Learning in the cortical network. Ai–Ci, Raster plots of Pyr cell firing before learning in response to a sample odor under the three modulatory conditions: (A) ACh ON, (B) ACh ON/Ni OFF, and (C) ACh ON, Mu OFF. Aii–Cii, Raster plots of Pyr cell firing after learning of the same odor. Note that Pyr cell firing is enhanced after learning with bulbar nicotinic receptors off, but not with muscarinic receptors off. Aiii–Ciii, Example activity of two Pyr cells in the network, one undergoing changes in response to learning and the other not. Aiv–Civ, Heat maps of synaptic weights in the model (100 × 100) before and after learning for each condition. The heat maps show synaptic weights between all pairs of Pyr cells before and after odor learning with warm colors indicating higher synaptic weights. D, Graph of average synaptic weights normalized relative to the highest weight reached during learning. E, Average change in Pyr cell firing rate during learning relative to the rate before learning under each condition.