Autonomic Nervous System
F. Frank LeFever
flefever at ix.netcom.com
Thu Oct 22 22:27:10 EST 1998
I meant, of course, sinus _arrythmia_, i.e. an interruption of the
normal heart rhythm! (it didn't sound right even as I wrote it, hence
my fudging it--"called the sinus rhythm, I believe" !)
In <70m2h7$6ne at dfw-ixnews3.ix.netcom.com> flefever at ix.netcom.com(F.
Frank LeFever) writes:
>In <firstname.lastname@example.org> rhall at uvi.edu (Richard
>- - - - - - - - - - - - - - - - -(snip) - - - - - - - - - - - - - -
> (He wrote an excellent correction of a prior post and extension of
> the discussion, which I'll snip most of, but recommend readers
> read his original post in its more readable format)
> Towards the end, he said the following (to which I'll add
>>-Consider heart rate. Vagal tone has immediate effect while elevated
>>sympathetic activity has long lasting effects primarily on cardiac
>>contractility. Indeed, studies of heart rate variability assume that
>>frequency variations reflect sympathetic activity while high
>>variations reflect parasympathetic activity.
>>- - - - - - - - -(snip)- - - - - - - - - - - - - - - - -
>>Comparative Animal Physiologist
>>Division of Sciences and Mathematics
>>University of the Virgin Islands
>>St. Thomas, USVI 00802
>>rhall at uvi.edu
>There are some interesting and useful consequences to this precise
>parasympathetic control of hear rate.
> For one example, the brief slowing coordinated to respiration
(called the sinus rhythm, I believe) has been used as an index of
cholinergic tone, in studies of head injury and a few other conditions.
> For another example, the cardiac deceleration response (part of
>Pavlov's orienting response) has been used to study perception in
human infant and other nonverbal animals: i.e., there is a very brief
slowing when the organism detects some stimulus change (e.g. a light
going on, OR going off; a tone abruptly changing in pitch or some other
quality, etc.). I used it in an attempt to determine whether comatose
patients (whose relatives are CONVINCED understand everything said to
them) can discriminate one word from another. First reported at
International Neuropsychological Association meeting, in Veldhoven,
June of 1986, I believe.
>Maybe I'll add a bit more: in contrast to GSR, which many US
>investigators used as a lazy man's index of an orienting reflex, the
>cardiac response can unambiguously differentiate an ORIENTING reflex
>from a DEFENSIVE reflex...
Some details in my chapter in "Windows on the Brain: Neuropsychology's
Technological Frontiers", NY Academy of Sciences Annals,1991, vol. 620.
>F. Frank LeFever, Ph.D.
>New York Neuropsychology Group
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