i remember seeing research in which the disruption of rem sleep
completely prevented any learning in lab mice. a quick search in pubmed
yielded a couple of more recent abstracts.
1: Behav Brain Res 2000 Jul;112(1-2):159-63
Morning recall of verbal material depends on prior sleep organization.
Ficca G, Lombardo P, Rossi L, Salzarulo P
Department of Psychology, University of Florence,Via S. Niccolo 93 50125,
Firenze, Florence, Italy.
[Medline record in process]
Despite the evidence that sleep may facilitate memory, controversial findings
concern the role of sleep states (NREM, REM). We put forward the hypothesis that
sleep organization, i.e. the regular occurrence of NREM-REM cycles, more than
sleep states per se, may be crucial for the retention of verbal material
presented before sleep. An experiment was performed in which recall of verbal
material was requested of young subjects after three different kinds of night
sleep: undisturbed sleep, fragmented sleep without sleep cycles disorganization,
and fragmented sleep interrupted with sleep disorganization. Morning recall of
verbal material was impaired after the night with disturbed sleep cycles,
whereas it was not after the night with preserved sleep cycles; the amount of
REM was similar in both cases. We conclude that the recall of verbal material is
greatly affected by sleep cycle disorganization.
PMID: 10862947, UI: 20322994
1: Brain Res 2000 Feb 7;855(1):176-80
Experience-dependent phase-reversal of hippocampal neuron firing during REM
Poe GR, Nitz DA, McNaughton BL, Barnes CA
VCAPP Department, Washington State University, Wegner 205, Pullman, WA
The idea that sleep could serve a cognitive function has remained popular since
Freud stated that dreams were "not nonsense" but a time to sort out experiences
[S. Freud, Letter to Wilhelm Fliess, May 1897, in The Origins of Psychoanalysis
- Personal Letters of Sigmund Freud, M. Bonaparte, A. Freud, E. Kris (Eds.),
Translated by E. Mosbacher, J. Strachey, Basic Books and Imago Publishing,
1954]. Rapid eye movement (REM) sleep, which is associated with dream reports,
is now known to be is important for acquisition of some tasks [A. Karni, D.
Tanne, B.S. Rubenstein, J.J.M. Askenasy, D. Sagi, Dependence on REM sleep of
overnight improvement of a perceptual skill, Science 265 (1994) 679-682; C.
Smith, Sleep states and learning: a review of the animal literature, Biobehav.
Rev. 9 (1985) 157-168]; although why this is so remains obscure. It has been
proposed that memories may be consolidated during REM sleep or that forgetting
of unnecessary material occurs in this state [F. Crick, G. Mitchison, The
function of dream sleep, Nature 304 (1983) 111-114; D. Marr, Simple memory: a
theory for archicortex, Philos. Trans. R. Soc. B. 262 (1971) 23-81]. We studied
the firing of multiple single neurons in the hippocampus, a structure that is
important for episodic memory, during familiar and novel experiences and in
subsequent REM sleep. Cells active in familiar places during waking exhibited a
reversal of firing phase relative to local theta oscillations in REM sleep.
Because firing-phase can influence whether synapses are strengthened or weakened
[C. Holscher, R. Anwyl, M.J. Rowan, Stimulation on the positive phase of
hippocampal theta rhythm induces long-term potentiation that can be
depotentiated by stimulation on the negative phase in area CA1 in vivo, J.
Neurosci. 15 (1977) 6470-6477; P.T. Huerta, J.E. Lisman, Bidirectional synaptic
plasticity induced by a single burst during cholinergic theta oscillation in CA1
in vitro, Neuron 15 (1995) 1053-1063; C. Pavlides, Y.J. Greenstein, M. Grudman,
J. Winson, Long-term potentiation in the dentate gyrus is induced preferentially
on the positive phase of theta-rhythm, Brain Res. 439 (1988) 383-387] this
experience-dependent phase shift, which developed progressively over multiple
sessions in the environment, is consistent with the hypothesis that circuits may
be restructured during REM sleep by selectively strengthening recently acquired
memories and weakening older ones.
PMID: 10650147, UI: 20117498
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