Diagonal band stimulation increases piriform cortex neuronal excitability in vivo

THE effects of diagonal band (NDB) stimulation on the spontaneous discharge of pyramidal cells and evoked field potentials (FPs) in piriform cortex (P C) were investigated in vivo. NDB stimulation increased the spontaneous fir ing rate of PC cells, and increased the disynaptic excitatory (B1) and decr eased the disynaptic inhibitory (P2) FP components following lateral olfact ory tract (LOT) stimulation. NDB stimulation decreased the P2 component fol lowing activation of association fibers in caudal PC. NDB stimulation reduc ed the paired-pulse inhibition of the P2 component following LOT and caudal PC shocks. The effects of NDB stimulation were reversed by scopolamine, su ggesting the involvement of muscarinic receptors. These results suggest tha t activation of choline inputs to PC increases the excitability of pyramida l cells, probably by a disinhibitory mechanism. NeuroReport 10:2101-2105 (C ) 1999 Lippincott Williams & Wilkins.