yaleuniversity:

Yale researchers used light to probe the actions of the neurotransmitter GABA on single synapses along the branches of a neuron.

This photo shows a mouse cortical neuron in red, with dendritic branches that are studded with synaptic spines. Surrounding the neuron are inhibitory axons or fibers (in blue) that are genetically engineered to release GABA when activated by light, a technique known as optogenetics. Learn more  →