Recording CA3-CA1 Synaptic Responses in a Rat Hippocampal Slice

Place a rat hippocampal slice in an electrophysiology setup.

Position the stimulating electrodes in the stratum radiatum layer of the hippocampal CA1 region, which receives axonal projections from the CA3 neurons.

Place a recording electrode near the CA1 apical dendrites.

Position another recording electrode in the stratum pyramidale layer.

Upon stimulation, the CA3 axonal projections depolarize and generate action potentials, releasing excitatory neurotransmitters.

These neurotransmitters bind to postsynaptic CA1 apical dendrites, inducing a positive ion influx and membrane depolarization, termed excitatory postsynaptic potential, or EPSP.

The recording electrode measures summed EPSPs from the apical dendrites — the field EPSP or fEPSP. Once stable fEPSP signals are obtained, lower the electrodes and pause briefly.

Apply a range of stimulation intensities to determine the input-output relationship with the fEPSP slope, then select and apply a specific intensity based on the slope.

The second recording electrode measures the combined action potentials from CA1 neuronal cell bodies, generating population spikes.