Sleep Medicine Institute, Chaim Sheba Medical Center and Tel Aviv University, Israel;
NIMH, NIH, Bethesda, USA; and Dept. Of Neurobiology, Weitzmann Institute, Rehovot Israel.
rocesses at cellular and molecular levels are necessary in order to consolidate long-lasting visual memory. Our study suggests that this dynamic process also occurs during dreaming.
The acquisition of procedural visual knowledge was investigated in 6 adults (3 females, 3 males), aged 17-22. The differential effects of sleep-stage deprivation upon performance with regard to a novel stimulus configuration were compared with the performance of a control task. In subjects suffering from REM sleep deprivation the perceptual learning of a visual task (the discrimination of three line elements differing in orientation from a background texture of identical elements) was significantly poorer (F(1,12) = 37.009, p<0.001) than their performance, under the same conditions, of a previously learnt (control) task F(1,12) = 17.896, p = 0.001. This discrepancy suggests that REM deprivation affected the consolidation of the recent perceptual experience but not perceptual performance in itself, making it less likely that the effects observed were nonspecific consequences of disturbed sleep in general.
Against a background of increased metabolism and blood flow, muscarinic activity at cellular level during REM sleep seems to be a necessary condition for the evolution of experience-dependent plasticity within the adult sensory cortex, ensuring the visual memory consolidation process during paradoxical sleep (PS). The elegant suggestion that PS stages should be called "windows," because of the presence of consolidation processes, was validated. It is assumed that a precise repertoire of cellular and molecular mechanisms underlies visual motor skill consolidation during PS.
The study opens new horizons for understanding the disturbances in the acquisition of non-declarative skills that occur in Alzheimer's disease, Parkinson's disease, multi-infarct dementia and multi-system atrophy. These are under investigation in our Institute.
