Extracellular Recordings of Synaptic Plasticity and Network Oscillations in Hippocampal Slices

Activity-dependent strengthening and weakening of synaptic weights, manifested as long-term potentiation (LTP) and depression (LTD), are two major mechanisms that are thought to be involved in creating memory traces in the brain. Oscillations of neuronal activity, especially in the θ (4–12 Hz), γ (30–100 Hz), and “ripple” (130–200 Hz) frequency bands, are also fundamental phenomena that are believed to contribute to learning and memory. However, the interplay between oscillations and plasticity is still not understood. These brain phenomena are rarely considered together when synaptic plasticity is studied. In this chapter, we summarize the existing knowledge in the field, describe protocols that can be used to induce LTP in seven major excitatory synaptic pathways in hippocampal slices, and introduce a procedure to investigate synaptic plasticity and induce high-frequency oscillations under one experimental paradigm.