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.