entrainment (Some effects of the low frequency photic stimulation on limbic structures)

Igor Rubets ir at axess.com
Thu Oct 17 21:19:37 EST 1996


If it might be of any help to your discussion...

In our experiments with implanted electrodes (RPO, Hip, RF, CM Thal, Hpthl,
Am, LC, nucl. accumbens, cingulum, temp. cortex, occ. cortex, front.
cortex, and, occasionally, some other structures influencing the MFB
effects on the limbic system "behavior") we studied the effects of the low
frequency visual stimulation on the bioelectrical characteristics (EEG in
the "broad" sense) and on the behavior of the rats, guinea pigs and cats.
Animals were 4 - 10 days after implantation. Light flashes frequencies were
in the "high" delta - theta range (3 - 7 Hz). Main idea was somewhat off
the present discussion, though, I think, there is some relevant

We never registered any signs of the "slowing" of the EEG. There were some
behavioral changes with the increased amount of the periods of inactivity
corresponding the transient shifts of the electric activity of limbic
structures (and the limbic system as a whole) toward the "epileptization".
Besides, the photic stimulation affected the activity in the
"theta-producing loop" (Hip-LS-MS) to the degree when it took up to 2 or
even 3 full sleep cycles to restore all the spectral characteristics of the
original theta.

I'd be happy if this information could help you.

Since the general tendency of this newsgroup shifted to more
"philosophical" matters, feel free to contact me in person if you have any


Robert Arnott <R.H.Arnott at sheffield.ac.uk> wrote in article
<5457cd$27l at mserv1.dl.ac.uk>...
> >If you prime the nervous sytem with a harmonic stimulus of
> >say 4 hertz via sound, viberation, and flashing light,
> >would this reduce the need for anaesthetic chemicals because
> >it entrained the brain into a LOW conscious state?
> Dear Ron,
> I'm afraid I don't know.
> A researcher who worked in our lab a couple of years ago was also
> interested in measurement of human auditory evoked responses as a
> means for assessing anaesthetic depth in clinical practice.   In his
> initial experiments he blindfolded conscious subjects and administered
> clicks at 1 Hz binaurally.   When I acted as one of his subjects, I found
> the experience very soporific but I don't know whether this was related
> the stimulus or whether it was induced by sitting blindfolded in a nice
> warm room.   I actually suspect a bit of both but I don't know whether
> was reported by any of his other subjects.
> Unfortunately I am not sure that a phenomenon such as this would enable
> much reduction in administration dose of anaesthetics.   When we conduct
> our experiments in anaesthetised animals, delivery of a noxious stimulus
> (such as pinching the foot or increasing the amplitude and duration of
> electrical stimuli) causes quite marked changes in both the
> electrocorticogram (ECoG) and the stimulus-evoked response.   We see a
> reduction in latency and increase in amplitude of cortical mass evoked
> responses and a change in ECoG from high voltage low frequency (HVLF)
> activity to low voltage high frequency (LVHF) activity, both of these
> changes being associated with increased arousal (Angel, 1991).   I wonder
> whether the arousing effect of painful stimulation would completely
> overwhelm the possible soporific effect of low frequency auditory or
> stimulation.   Certainly it would be interesting to examine
> whether delivery of low frequency stimulation has a soporific effect.
> Sorry I can't be more helpful.
> Robert
> Reference:
> Angel, A. (1991):  Adventures in Anaesthesia.   Experimental Physiology.
> Vol. 76 pp. 1-38
> --+++++++++++++++++++++++++++++++++++++++++++++
> Robert Arnott,
> Centre for Research in Anaesthetic Mechanisms,
> Department of Biomedical Science,
> The University of Sheffield,
> S10 2TN
> England
> email   r.h.arnott at sheffield.ac.uk
> Telephone +44114 276 8555 ext. 4660
> Fax +44114 276 5413
> URL http://www.shef.ac.uk/uni/academic/A-C/amrc/
> ++++++++++++++++++++++++++++++++++++++++++++++

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