Acute horizontal hippocampal slices were made from 2-4 months- and 12 months-old from APP−/− mice and their control littermates (APP+/−). Following euthanasia with isoflurane, 400 μm-thick hippocampal slices were cut with a vibroslicer (Campden Instruments, Leicester, UK). The brain slices were kept at room temperature for 1-2 hours before transfer to a recording chamber in artificial CSF (ACSF) containing (in mM) 125 NaCl, 2.4 KCl, 1.2 NaH2PO4, 1 CaCl2, 2 MgCl2, 25 NaHCO3, and 25 glucose. In the recording chamber, the slices were perfused with oxygenated ASCF containing 2 mM CaCl2 and 1 mM MgCl2. Extracellular recordings of excitatory postsynaptic potentials (fEPSPs) were obtained from the stratum radiatum in the CA1 area using microelectrodes filled with extracellular recording solution. A bipolar stimulating electrode was placed in the stratum radiatum for stimulation of the Schaffer collateral/commissural pathway. Basal synaptic transmission was assessed by comparing the input and output relationship of the fEPSPs recorded. For each animal, we measured the fiber volley amplitude and initial slope of the fEPSP responses to a range of stimulation from 100 to 900 μA, and the
