Acetylcholine from the pontine tegmental nucleus and basal forebrain activates brain locations and brings about focus.

“Acetylcholine is a neurotransmitter that at the neuron to muscle connections, the so called neuromuscular junctions is involved in generating muscular contractions of all kinds for all movements. Acetylcholine is also released from two sites in the brain... neurons reside in an area or a structure that's called the pedunculopontine nucleus, the PPN and then there's a separate collection of neurons in the basal forebrain called unimaginatively nucleus basalis the nucleus at the base and they also hose the brain with acetylcholine, but in a much more specific way... those two sources of acetylcholine, collaborate to activate particular locations in the brain, and really bring about a tremendous degree of focus to whatever is happening at those particular synapses.”