Train stimulation at 5 Hz in old animals.

A. There is a significant genotype difference in raw fEPSP amplitude in old animals upon 5(P<0.05). B. CA1 responses did not facilitate following pulse 1 in old 3xTgAD animals (data shown for CA1slm). Control [C] and 3xTgAD [D] representative responses for old animals. Note a lack of increase in response magnitude as the train progresses. 3xTgAD animal in [D] was the only old animal to show DG PS. Calibration 2 mV/10 ms. CSD analysis of pulses 10 and 20 in representative old control [E] and 3xTgAD [F] animals. CSD components are comparable to those seen in young mice at pulse 1 (Fig 6C & D; current sinks in blue, sources in red). A prolonged, facilitating afterpotential is clearly visible from 20 ms in the DG of both control and 3xTgAD animals (marked IAP).