Figure 6.

Activation of nicotinic cholinergic receptors sharpens MC tuning curves in the glomerular-layer model. A, Histograms of activity in all 25 glomeruli under control conditions, artificially arranged according to their levels of afferent activation for ease of visualization. Top, Steady-state OSN input levels; middle, odor-evoked spike rates in MCs; bottom, odor-coding spike rates in MCs (see Materials and Methods). B, As in A, but with nicotinic cholinergic neuromodulation active. C, Raster plot of MC spiking activity immediately before and after the onset of odor presentation, under control conditions. D, As in B, but with nicotinic cholinergic neuromodulation active. E, Simulated LFP (top) during odor presentation, with autocorrelation (middle) and power spectrum (bottom), under control conditions. F, As in E, but with nicotinic cholinergic neuromodulation active.