Photostimulation and Whole-Cell Patch Clamp Recordings of Neurons in Mouse Hippocampal Slices

Take an immobilized transfected mouse brain slice in an electrophysiology recording chamber perfused with oxygenated aCSF.

This slice contains thalamic neurons' axon terminals expressing light-sensitive ion channels fused to a fluorescent protein.

Visualize the fluorescent thalamic neuron axons and select a pyramidal neuron.

Advance a recording pipette containing an electrode in an intracellular solution toward the selected neuron with slight positive pressure.

The positive pressure creates a dimple on the neuronal membrane upon contact.

Release the pressure to form a high-resistance seal.

Set the membrane potential to a constant negative value.

Apply a negative pressure pulse to rupture the membrane, achieving a whole-cell configuration.

Illuminate the axon terminals, activating the light-sensitive channels and depolarizing the neuronal membranes, triggering action potentials.

Excitatory neurotransmitters are released, binding to receptors on the recorded neuron, causing cation influx.

Record the resulting excitatory post-synaptic currents, indicating a direct synaptic connection between the neurons.