Visualization 2: Probing a synaptically connected neuronal microcircuit - excitatory neuron 1 stimulated.

Visualization 2 – Probing a synaptic microcircuit. Neurons from an E18 rat hippocampus were cultured for 14 days and imaged on Firefly-HR. After 7 days in culture, they were lentivirally transduced with optogenetic actuator CheRiff and voltage indicator QuasAr3. Patterned illumination was used to selectively excite the boxed neuron with a ramped stimulus. Magenta corresponds to depolarization and cyan corresponds to hyperpolarization. The stimulated neuron triggers an action potential in the inhibitory neuron on the lower left, which in turn induces inhibitory postsynaptic potentials (IPSP’s) in the two nearby cells. The movie, which was recorded at a 1 kHz frame rate, is played back at 1/50th of real time. The field of view is 210 μm high.