Reticular activating system

Reticular activating system

Infobox Brain
Name = Reticular activating system
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Caption = Deep dissection of brain-stem. Ventral view. (Reticular formation labeled near center.)

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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 mammals (including humans).


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. The reticular activating system controls our sexual patterns.

Clinical significance

The reticular activating system (RAS) 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 Fact|date=April 2008.

Another way to look at the RAS is to consider why you can sleep at night through all of the normal sounds of your house, but wake up to the sound of the ruffling pajamas of your child as they walk into your bedroom. This is a function of the RAS. It filters out all of the things you know are normal stimuli and activates when something new or different occurs.

External links

* [] at Stanford University
* [ Diagram] at Rutgers-Camden
* []

Wikimedia Foundation. 2010.

Look at other dictionaries:

  • reticular activating system — n a part of the reticular formation that extends from the brain stem to the midbrain and thalamus with connections distributed throughout the cerebral cortex and that controls the degree of activity of the central nervous system (as in… …   Medical dictionary

  • reticular activating system — noun the network in the reticular formation that serves an alerting or arousal function • Syn: ↑RAS • Hypernyms: ↑neural network, ↑neural net • Part Holonyms: ↑reticular formation, ↑RF …   Useful english dictionary

  • reticular activating system — the system of nerve pathways in the brain concerned with the level of consciousness from the states of sleep, drowsiness, and relaxation to full alertness and attention. The system integrates information from all of the senses and from the… …   Medical dictionary

  • reticular activating system — the system of nerve pathways in the brain concerned with the level of consciousness – from the states of sleep, drowsiness, and relaxation to full alertness and attention. The system integrates information from all of the senses and from the… …   The new mediacal dictionary

  • Ретикулярная активирующая система (reticular activating system) — Ретикулярная формация (РФ) простирается от каудального отдела продолговатого мозга до рострального отдела промежуточного мозга. Ее нейроны образуют сетчатую структуру ствола мозга, в ячейках к рой закреплены группы специфических ядер, снабжающих… …   Психологическая энциклопедия

  • Формация Ретикулярная, Система Ретикулярная Активирующая (Reticular Activating System) — совокупность нейронов и соединяющих их нервных волокон, расположенных в стволе мозга и образующих сеть. Ретикулярная формация связана со всеми органами чувств, двигательными и чувствительными областями коры большого мозга, таламусом и… …   Медицинские термины

  • Reticular formation — Brain: reticular formation Coronal section of the pons, at its upper part. (Formatio reticularis labeled at left.) …   Wikipedia

  • reticular formation — (also reticular activating system) noun Anatomy a diffuse network of nerve pathways in the brainstem connecting the spinal cord, cerebrum, and cerebellum …   English new terms dictionary

  • reticular formation — noun a complex neural network in the central core of the brainstem; monitors the state of the body and functions in such processes as arousal and sleep and attention and muscle tone • Syn: ↑RF • Hypernyms: ↑neural network, ↑neural net • Part… …   Useful english dictionary

  • system — 1. [TA] A consistent and complex whole made up of correlated and semiindependent parts. A complex of functionally related anatomic structures. 2. The entire organism seen as a complex organization of parts. 3. Any complex of structures… …   Medical dictionary

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