Richard has addressed the ambiguity just in considering the motor
(efferent) aspects of vagal activity; but it has sensory (afferent)
aspects as well, making the phrase even more ambiguous. (n.b.: given
that its activities are not much like what we usually think of when we
say "motor" or "sensory", the alternative terms--with less "surplus
meaning" are preferrable)
I have not kept up with it, but I believe there is a considerable
literature on stimulation of the vagus and inhibition of seizure
activity; I do not understand it very well, and welcome comments from
someone who does--i.e., what is the exact mechanism of this action?
F. Frank LeFever, Ph.D.
New York Neuropsychology Group
In <email@example.com> rhall at uvi.edu (Richard Hall)
>>The vagus nerve sends projections to much of the body visceral organs.
>originates in the brain stem and is very important in the control of
>rate, gastric motility, digestive, and metabolic activities. When the
>vagus sends messages to the heart, the heart rate slows. When the
>sends messages to salivary glands, they secrete saliva. Vagal
>of the pupil causes the aperature to close (mydriasis.)
>>One common term used in conjunction with vagal function is vagal tone.
>Increased vagal tone results in a slower heart rate, salivary
>and pupillary constriction. Decreased vagal tone has the opposite
>It is possible to inhibit the actions of the vagus which would
>vagal tone, but that is probably not what is implied by vagal
>>You see vagal inhibition a potentially sloppy phrase. Vagal
>the heart slows the heart rate. Inhibition of the vagus accelerates
>>>At 7:47 PM +0100 4/11/99, Peter Moss wrote:
>>Hi, could anybody please give me a brief description of what this is?
>>Preferably in non-technical language,
>>Richard Hall, Associate Professor of
>Comparative Animal Physiology
>Division of Sciences and Mathematics
>University of the Virgin Islands
>St. Thomas, USVI 00802
>rhall at uvi.edu