The Reticular Activating System, and its Role in Attention Deficit Hyperactivity Disorder

In our last article about the neurology of ADHDinhibitory mechanisms of the brain. However, it is
we began to introduce the reader to the systemnot just activation levels of the Reticular
in the brain known as the Reticular ActivatingActivating System that are a problem with
System. The Reticular Activating System is theAttention Deficit Disordered individuals. It seems
"attention center" in the brain. It is the key tothat the same problems that cause the Reticular
"turning on your brain," and seems to be theActivating System to be under or over aroused
center of motivation. The Reticular Activatingalso restricts the development of neural
System is connected at its base to the spinalconnections and the required neural density
cord where it receives information projectedneeded to process incoming information. In other
directly from the ascending sensory tracts. Thewords, these are issues with the number of brain
brainstem reticular formation runs all the way upcells, the size of the brain cells, and the number of
to the mid-brain. As a result, the Reticularconnections between brain cells. It is not
Activating System is a very complex collection ofuncommon for one brain cell to have as many as
neurons that serve as a point of convergence for5,000 connections with other brain cells. Picture
signals from the external world and from interiorthe incoming information to be processed and
environment. In other words, it is the part oflearned as the volume of water coming out of
your brain where the world outside of you, andyour shower head. And picture the brain's ability
your thoughts and feelings from "inside" of you,to process this information as the drain and the
meet. This Reticular Activating System is verydrain pipe in the shower floor. If the pipe is
capable of generating dynamic effects on theclogged up, your shower will have problems
activity of the cortex, including the frontal lobes,draining. If the contractor originally installed a drain
and the motor activity centers of the brain. Itpipe that is too small, again your shower will have
plays a significant role in determining whether aproblems draining. In either case, you will either
person can learn and remember things well or not,have to reduce the amount of water coming out
on whether or not a person is impulsive orof the shower head, or you will have to let the
self-controlled, on whether or not a person hasshower back up and wait a while for the water to
high or low motor activity levels, and on whetherfinally drain out. Here's the connection... If the brain
or not a person is highly motivated or boreddoes not have enough neural connections, or lacks
easily. The Reticular Activating System is thethe neural density, to process the incoming
center of balance for the other systems involvedinformation, then it will be like a pipe that is too
in learning, self-control or inhibition, and motivation.small to handle a large volume of water. It will
When functioning normally, it provides the neuraltake in some, but the rest will be stopped and
connections that are needed for the processingwon't go down the pipe rapidly. Learning will take
and learning of information, and the ability to payplace, but the time that it takes to process the
attention to the correct task. But if the Reticularinformation will be slowed significantly. The impact
Activating System doesn't excite the neurons ofof this with an Attention Deficit Hyperactivity
the cortex as much as it ought to, then we seeDisorder child is best seen when the child is given
the results of an under-aroused cortex, such asa timed test, even with material that the child
difficulty learning, poor memory, little self-control,understands pretty well. The "timed" aspect of
and so on. In fact, if the Reticular Activatingthe test requires that the child have a "larger
System failed to activate the cortex at all onedrain pipe," as it were, to quickly process the
would see a lack of consciousness or even coma.problems on the test and recall the answer.
What would happen if the Reticular ActivatingHowever, with Attention Deficit Disorder - ADHD
System was too excited, and aroused the cortex- the "pipe" is often too small, and the results of
or other systems of the brain too much? Thenthe timed test will probably be very poor.
we would see individuals with excessive startleHowever, take away the timed element on the
responses, hyper-vigilance, touching everything,same test, and "allow the water to drain a the
talking too much, restless, and hyperactive. Soslower rate," and the child will often do well on the
the Reticular Activating System must betest. So the ADHD child, or adult, needs to
activated to normal levels for the rest of thedevelop a greater degree of neural density, and a
brain to function as it should.larger number of neural connections to process
What factors could cause the Reticular Activatinginformation faster and more efficiently. Now,
System to be either over-activated orplease do not think that this information to be
under-activated? According to Harvard Medicalprocessed is only what takes place in the
School, current research strongly suggests thatclassroom. The information to be processed
Attention Deficit Disorder is caused in part by aincludes information from the outside world,
deficiency of Norepinephrine in the ascendingincluding the touch of the clothes on his skin, the
reticular activating system, and it is thought thatbuzz of the lights overhead, the sound of the kids
the stimulant medications, such as Ritalin, increaseplaying outside, and the new information that the
the levels of Norepinephrine in that part of theteacher is lecturing on at the front of the
brain, as well as probably increasing dopamineclassroom. It also includes the information from
levels in the frontal lobes. This treatment strategyinside the head, the thoughts and feelings of the
works well for the inattentive under-aroused ADDADHD person. All of that must be sorted out and
kids, and somewhat well for the over-arousedfiltered, so that only the important information is
impulsive-hyperactive ADHD kids. However, forpaid attention to, and the unimportant information
the kids who have an over-aroused Reticularis ignored. Without proper filtering by the Reticular
Activating System to begin with, the use ofActivating System, the individual will be distracted
stimulants will often exacerbate the problems withby "noise," both from outside of him as well as
temper, sleep, and hyper-vigilance or anxiety. Forfrom inside of him. You can learn more about the
these individuals their physicians will oftenneurlogy of Attention Deficit Hyperactivity
prescribe a Norepinepherine antagonist such asDisorder by reading through the ADHD
Clonadine, or an antidepressant such as Prozac,Information Library.
which works to enhance the Serotonin driven