Reticular activating system
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| Brain: Reticular activating system | ||
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| Deep dissection of brain-stem. Ventral view. (Reticular formation labeled near center.) | ||
| NeuroNames | ancil-231 | |
| Dorlands/Elsevier | s_33/12787787 | |
The reticular activating system (or ARAS, for Ascending Reticular Activating System) is the name given to the part of the brain (the reticular formation and its connections) believed to be the center of arousal and motivation in animals (including humans).
[edit] Functions
The activity of this system is crucial for maintaining the state of consciousness. It is situated at the core of the brain stem between the myelencephalon (medulla oblongata) and mesencephalon (midbrain).
It is involved with the circadian rhythm; damage can lead to permanent coma. It is thought to be the area affected by many psychotropic drugs. General anesthetics work through their effect on the reticular formation.
Fibers from the reticular formation are also vital in controlling respiration, cardiac rhythms, and other essential functions.
Although the functioning of this system is a prerequisite for consciousness to occur, it is generally assumed that this system's role is indirect and it does not, by itself, generate consciousness. Instead, its unique anatomical and physiological characteristics ensure that the thalamocortical system fire in such a way that is compatible with conscious experience.
[edit] Clinical significance
The reticular activating system has received attention from neuroscientists interested in various pathological conditions affecting behaviour, such as Alzheimer's Disease. More recently, results of research on the area has prompted extrapolations from the data into attention-deficit hyperactivity disorder (ADHD). The reticular activating system is believed to cause ADD and ADHD due to the imbalance of norepinephrine in the cells[citation needed].
