A rat cortical neuron expressing a calcium indicator (GCaMP6s) that flashes bright green during a burst of activity leading to calcium entering the cell. 10 minutes in, I add a drug called gabazine that blocks GABA receptors that usually inhibit neurons, and the neuron starts to 'flash' more!
Human Embryonic Kidney (HEK) Cells expressing fluorescent proteins. CaMKIIa is a protein that likes to bind to GluN2B in the brain when it is activated by calcium. When I add ionomycin, that allows calcium into cells, and you can actually see the CaMKII (blue) start to overlap more with GluN2B (purple) as it binds to it more and more.
The dendrites of a rat cortical neuron expressing a fluorescently-labeled protein (mVenus-CaMKIIa). When the neuron is 'stimulated' by glutamate, that CaMKII gets activated and concentrates into puncta at synapses - the connections between neurons.