LTP Saturation and Spatial Learning Disruption: Effects of Task Variables and Saturation Levels

synapses should impair spatial learning was reinvestigated in the light of a more specific consideration of the theory of Hebbian associative networks, which predicts a nonlinear relationship between LTP “saturation ” and memory impair-ment. This nonlinearity may explain the variable results of studies that have addressed the effects of LTP “saturation” on behavior. The extent of LTP “saturation ” in fascia dentata produced by the standard chronic LTP stimulation protocol was as-sessed both electrophysiologically and through the use of an anatomical marker (activation of the immediate-early gene zifZ66). Both methods point to the conclusion that the stan-dard protocols used to induce LTP do not “saturate ” the process at any dorsoventral level, and leave the ventral half of the hippocampus virtually unaffected. LTP-inducing, bi