On Wed, 18 Oct 2000, Paul Leiberton wrote: > Are there increased levels of neurotransmitter production during > REM sleep? A question asked by one of my high school students? > The long-standing answer seems to be yes. The problem is that no one can decide what those neurotransmitters should be. I believe the originator of the first biochemical theory of sleep was the French neurophysiologist Michel Jouvet, whose classic papers (and much more) are available on-line at: http://sommeil.univ-lyon1.fr/index_e.html See, in particular, his non-technical paper "The States of Sleep", Scientific American, vol 216, 1967. He proposed there that REM sleep is caused by the release of noradrenalin from the locus coeruleus in the brainstem. Unfortunately, although he provided some impressive evidence in support of his hypothesis, there were enough negative findings to weaken acceptance of the theory. Hobson & McCarley ("The brain as a dream-state generator", American Journal of Psychiatry, 1977,v 134, 1335--) instead argued in an important paper that the REM-inducing chemical was acetylcholine from the pons, and the locus coeruleus actually turned REM off (just to show you how little people really knew). And even as we (metaphorically) speak, Mark Solms ("Dreaming and REM sleep are controlled by different brain mechanisms", in press, Behavioral and Brain Sciences, 23) has little to say about the proposal that acetylcholine is involved in REM sleep, but quite a bit about proposing that yet another neurochemical, dopamine, is responsible for dreaming, and the critical region is the forebrain, not the brainstem. This relates to one of my favourite themes in physiological psychology: that while most undergraduates are undoubtedly still being taught that REM sleep = dreaming, this has been known to be untrue for a long time. Solms is quite clear on this point. First he reviews the original Foulkes data showing that dreams can occur during NREM sleep. Then he points out that while there are a large number of human cases of brainstem damage eliminating REM sleep, there is no evidence that this impairs dreaming (but unfortunately, little evidence that dreaming continues, either). He also cites a substantial body of evidence that forebrain lesions impair dreaming without affecting REM sleep. He says: "These observations demonstrate conclusively that dreaming can be initiated by forebrain mechanisms (which are unrelated to REM sleep) and terminated by forebrain lesions (which spare the REM cycle"). And if that's not clear enough, he concludes: "Dreaming and REM sleep are in fact doubly dissociable states, they have different physiological mechanisms, and in all likelihood they serve different functional purposes...Progress in this area will now be hampered if we do not acknowledge our initial error." I acknowledge. While his paper isn't yet published, it's available in draft form at: http://www.cogsci.soton.ac.uk/bbs/Archive/bbs.solms.html Isn't the Internet wonderful? -Stephen ------------------------------------------------------------------------ Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy Check out TIPS listserv for teachers of psychology at: http://www.frostburg.edu/dept/psyc/southerly/tips/ ------------------------------------------------------------------------
