Frequency potentiation of a central cholinergic circuit.

We have used the cholinergic projection from the nucleus of the horizontal limb of the diagonal band (HDB) to the olfactory bulb as a model for studying the neurophysiology of cholinergic projections from the basal forebrain to cortical structures. Although single shocks to HDB have little effect upon function of the target structure, short periods of repetitive stimulation produce profound changes. These observations are discussed in terms of the known physiology of central cholinergic systems and the significance of cholinergic synaptic potentiation for Alzheimer's disease.