Imagine zooming through an entire connectome as you see this beautiful set of synapses that have been rendered translucent so you can see vesicles full of neurotransmitters. Video by Daniel Berger of Seung Lab.
The video shows in gray a spiny apical dendrite of a Layer 6 pyramidal neuron in mouse somatosensory cortex, and in color several axons which make synapses onto spines of that dendrite.
At the synapse the axon forms an enlargement called a ’bouton’ which is filled with neurotransmitter-containing vesicles (yellow). When an electric signal (an ‘action potential’) arrives at the bouton, some of these vesicles will release their contents into the ‘synaptic cleft’ located between the axon and the spine head to send a chemical signal to the dendrite.