PT  - JOURNAL ARTICLE
AU  - Jose L. Cantero
AU  - Mercedes Atienza
AU  - Rosa M. Salas
AU  - Elena Dominguez-Marin
TI  - Effects of Prolonged Waking-Auditory Stimulation on Electroencephalogram Synchronization and Cortical Coherence during Subsequent Slow-Wave Sleep
AID  - 10.1523/JNEUROSCI.22-11-04702.2002
DP  - 2002 Jun 01
TA  - The Journal of Neuroscience
PG  - 4702--4708
VI  - 22
IP  - 11
4099  - http://www.jneurosci.org/content/22/11/4702.short
4100  - http://www.jneurosci.org/content/22/11/4702.full
SO  - J. Neurosci.2002 Jun 01; 22
AB  - Evidence suggests that sleep homeostasis is not only dependent on duration of previous wakefulness but also on experience- and/or use-dependent processes. Such homeostatic mechanisms are reflected by selective increases in the duration of a sleep stage, modifications to electrophysiological–metabolic brain patterns in specific sleep states, and/or reactivation to neuronal ensembles in subsequent sleep periods. Use-dependent sleep changes, apparently different from those changes caused by memory consolidation processes, are thought to reflect neuronal restoration processes after the sustained exposure to stimulation during the preceding wakefulness. In the present study, we investigated changes in the brain electrical activity pattern during human sleep after 6 hr of continuous auditory stimulation during previous wakefulness. Poststimulation nights showed a widespread increase of spectral power within the α (8–12 Hz) and sleep spindle (12–15 Hz) frequency range during slow-wave sleep (SWS) compared with the baseline night. This effect was mainly attributable to an enhanced EEG amplitude rather than an increase of oscillations, except for temporal (within α and sleep spindles) and parietal regions (within sleep spindles) in which both parameters contributed equally to the increase of spectral energy. Power increments were accompanied by a strengthening of the coherence between fronto-temporal cortical regions within a broad frequency range during SWS but to the detriment of the coherence between temporal and parieto-occipital areas, suggesting underlying compensatory mechanisms between temporal and other cortical regions. In both cases, coherence was built up progressively across the night, although no changes were observed within each SWS period. No electrophysiological changes were found in rapid eye movement sleep.These results point to SWS as a critical brain period for correcting the cortical synaptic imbalance produced by the predominant use of specific neuronal populations during the preceding wakefulness, as well as for synaptic reorganization after prolonged exposure to a novel sensory experience.