Carol DeVolder said, in response to the query concerning why eye movements aren't paralyzed during REM sleep:
"Motor signals for eye movements are carried via the 3rd, 4th, and 6th cranial nerves and don't pass through the reticular formation." The question reminded me of the historically important study of Bremer (1937). Working with the cat, he reported on a preparation he called the "cerveau isole" [isolated forebrain] in which the brain was divided in two through the brainstem. Bremer showed using the newly-invented EEG that only slow- wave electrical activity was present in the upper part of the brain, and there were no eye movements. Eye movements should have been possible because they are controlled by nerves exiting the brain above the level of the cut, namely the oculomotor (III) and trochlear (IV) nerves. As Carol noted, this is why eye movements are still possible during brainstem-initiated paralysis of REM sleep. Bremer assumed incorrectly that the failure of wakefulness in the cerveau isole preparation was due to the loss of sensory input to the brain. A modern interpretation is that it disconnected the reticular formation from the upper brain. See http://tinyurl.com/yjjdzon for a discussion by Panksepp of this work. Also, http://tinyurl.com/ygf5zge on p. 3 (Fig. 1.2) shows the actual illustrations published by Bremer. On 23 Feb 2010 at 18:49, Serafin, John wrote: > And while I'm at it, I'll add my own question to this topic, which I've never > come up with a good answer to. > Some species sleep standing up. Why don't they flop over and fall down when > they enter REM? The answer, I believe, is that they do. If I correctly recall an old paper I have somewhere in my files on comparative aspects of animal sleep, ungulates such as horses and cows spend a lot of time sleeping standing up, but they do enter REM sleep for short periods. When they do, they lie down. Stephen ----------------------------------------------------------------- Stephen L. Black, Ph.D. Professor of Psychology, Emeritus Bishop's University e-mail: sbl...@ubishops.ca 2600 College St. Sherbrooke QC J1M 1Z7 Canada ----------------------------------------------------------------------- --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=826 or send a blank email to leave-826-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
