Synapses in cerebellum, coloured transmission electron micrograph (TEM). Synapses in nerve tissue are the junctions between nerve cells. They contain mitochondria (green) and neurotransmitter chemicals contained in vesicles (round). When a nerve impulse (electrical signal) reaches a synapse, it triggers the release of the neurotransmitters which cross the junction, bind to receptors on the post-synaptic nerve cell, and trigger a new nerve impulse to continue the signal transmission. The cerebellum, at the rear and base of the brain, is a region that plays an important role in motor control.