For instance, the brain stem, just above the spinal cord, houses the neural barometer that senses our relation to the environment, and raises or lowers our energy arousal and attention according to how vigilant we need to be. But each aspect of attention has its own distinct circuitry. For more detail on the basics, see Michael Posner and Steven Petersen, “The Attention System of the Human Brain,” Annual Review of Neuroscience 13 (1990): 25–42.
— Focus: The Hidden Driver of Excellence (Daniel Goleman), Loc. 3506–9