Assessing the Dream-Lag Effect for REM and NREM Stage 2 Dreams

This study investigates evidence, from dream reports, for memory consolidation during sleep. It is well-known that events andmemories from waking life can be incorporated into dreams. These incorporations can be a literal replication of what occurredin waking life, or, more often, they can be partial or indirect. Two types of temporal relationship have been found tocharacterize the time of occurrence of a daytime event and the reappearance or incorporation of its features in a dream. Thesetemporal relationships are referred to as the day-residue or immediate incorporation effect, where there is the reappearance offeatures from events occurring on the immediately preceding day, and the dream-lag effect, where there is the reappearanceof features from events occurring 5–7 days prior to the dream. Previous work on the dream-lag effect has used spontaneoushome recalled dream reports, which can be from Rapid Eye Movement Sleep (REM) and from non-Rapid Eye Movement Sleep(NREM). This study addresses whether the dream-lag effect occurs only for REM sleep dreams, or for both REM and NREM stage2 (N2) dreams. 20 participants kept a daily diary for over a week before sleeping in the sleep laboratory for 2 nights. REM andN2 dreams collected in the laboratory were transcribed and each participant rated the level of correspondence between everydream report and every diary record. The dream-lag effect was found for REM but not N2 dreams. Further analysis indicatedthat this result was not due to N2 dream reports being shorter, in terms of number of words, than the REM dream reports.These results provide evidence for a 7-day sleep-dependent non-linear memory consolidation process that is specific to REMsleep, and accord with proposals for the importance of REM sleep to emotional memory consolidation

Acute Exposure to Terrestrial Trunked Radio (TETRA) has effects on the electroencephalogram and electrocardiogram, consistent with vagal nerve stimulation

BACKGROUND: Terrestrial Trunked Radio (TETRA) is a telecommunications system widely used by police and emergency services around the world. The Stewart Report on mobile telephony and health raised questions about possible health effects associated with TETRA signals. This study investigates possible effects of TETRA signals on the electroencephalogram and electrocardiogram in human volunteers. METHODS: Blinded randomized provocation study with a standardized TETRA signal or sham exposure. In the first of two experiments, police officers had a TETRA set placed first against the left temple and then the upper-left quadrant of the chest and the electroencephalogram was recorded during rest and active cognitive processing. In the second experiment, volunteers were subject to chest exposure of TETRA whilst their electroencephalogram and heart rate variability derived from the electrocardiogram were recorded. RESULTS: In the first experiment, we found that exposure to TETRA had consistent neurophysiological effects on the electroencephalogram, but only during chest exposure, in a pattern suggestive of vagal nerve stimulation. In the second experiment, we observed changes in heart rate variability during exposure to TETRA but the electroencephalogram effects were not replicated. CONCLUSIONS: Observed effects of exposure to TETRA signals on the electroencephalogram (first experiment) and electrocardiogram are consistent with vagal nerve stimulation in the chest by TETRA. However given the small effect on heart rate variability and the lack of consistency on the electroencephalogram, it seems unlikely that this will have a significant impact on health. Long-term monitoring of the health of the police force in relation to TETRA use is on-going

Characterization of dispersion in an alluvial aquifer by tracing techniques and stochastic modelling.

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ERP Shape repetition effects.

<p>(a) Grand average ERPs to new (blue line) versus change (black line) stimuli plotted between −100 and 500 msec, with respective topographies for the N1 at peak amplitude; (b) topography associated with the difference in mean amplitude for the new versus change contrast over the highlighted 40 msec epoch for the N1; (c) mean amplitudes across posterior electrode clusters during the N1 as a function of laterality and transformation.</p

Mean response times (msec) and percentage correct (%) for the coloured-object decision test; values in brackets represent standard error.

<p>Mean response times (msec) and percentage correct (%) for the coloured-object decision test; values in brackets represent standard error.</p

ERP Shape+colour repetition effects.

<p>(a) Grand average ERPs to same (red line) versus change (black line) stimuli plotted between −100 and 500 msec, with respective topographies for the P2 at peak amplitude; (b) topography associated with the difference in mean amplitude for the same versus change contrast over the highlighted 40 msec epoch for the P2; (c) mean amplitudes across posterior electrode clusters during the P2 as a function of laterality and transformation.</p

ERP Colour effects.

<p>Grand average ERPs to correctly (black line) and incorrectly (red line) coloured objects plotted between −100 and 800 msec with (a) topography associated with the peak amplitude for correctly versus incorrectly coloured objects for the P2; and (b) topography associated with the peak amplitude for correctly versus incorrectly coloured objects for the P3.</p