Blue dots control, testing strength of synapse. Stimulate perforant fibres every 5min, then record from principle cell. See strength stays same so sees test stimulus doesn"t change synapse strength, so get baseline: during test stimulation, test epsp not enough to open ampar. Red dots are stimulated pathway, trying to induce plasticity at arrows: tetanic stimuli (15/s for 10 sec) to pp at arrows. Ltp: specific to input stimulated, need for learning & memory. There are other types of long-term plasticity but ltp & ltd are the 2 most studied. Need to lay down long term memories. Act pots down bundle of axons (perforant fibre pathway) onto. Pathways w bundles of axons, cell bodies in thal dendrities of principle neurons in dentate gyrus. Release glutamate ampa & nmda (excitatory synapses) Summate at cell bodies in dentate. Axons synapse onto dendrites in principal cells in ca3. Excitatory synapses, if enough then generate act pot to schaffer.