Explanation: The Reticular activating system can be defined as the system in which is made from a set of nuclei that are interconnected which spreads throughout the brainstem.
This is not anatomically well defined because its network has been distributed into different parts of the brain.
One of the main function of this system is to decide whether the stimuli that is present in the environment is useful or useless. It ignores the useless repetitive stimuli and remains awake for the useful stimuli.
Example: A person who can sleep through the loud traffic in a large traffic but he awakes by the sound of the alarm.
-The light of dawn and the buzz of an alarm clock lead to wakefulness through the reticular activating system.
-The RAS is a network of neurons that are located in the brain stem, they project anteriorly to the hypothalamus to mediate behavior, as well as both posteriorly to the thalamus and directly to the cortex for the activation of awake, desynchronized cortical EEG patterns.
