The neural correlates of dreaming.

Consciousness never fades during waking. However, when awakened from sleep, we sometimes recall dreams and sometimes recall no experiences. Traditionally, dreaming has been identified with rapid eye-movement (REM) sleep, characterized by wake-like, globally 'activated', high-frequency electroencephalographic activity. However, dreaming also occurs in non-REM (NREM) sleep, characterized by prominent low-frequency activity. This challenges our understanding of the neural correlates of conscious experiences in sleep. Using high-density electroencephalography, we contrasted the presence and absence of dreaming in NREM and REM sleep. In both NREM and REM sleep, reports of dream experience were associated with local decreases in low-frequency activity in posterior cortical regions. High-frequency activity in these regions correlated with specific dream contents. Monitoring this posterior 'hot zone' in real time predicted whether an individual reported dreaming or the absence of dream experiences during NREM sleep, suggesting that it may constitute a core correlate of conscious experiences in sleep

Climate change and human occupation in the Southern Arabian lowlands during the last deglaciation and the Holocene

Paleohydrological and archaeological evidence from the Southern and South-Eastern Arabian Peninsula reveal strong relations between phases of human settlements and climate change linked to the Indian monsoon system. During the early to mid-Holocene, large fresh-water lakes extended in the lowland deserts of Ramlat as-Sab'atayn (Yemen) and Wahiba Sands (Oman), which were very similar to those occurring in the North, in the Rub' al-Khali (Saudi Arabia), at that time. Many archaeological sites, characterized by scattered stone artefacts, ostrich-eggshells and bones around hearths, are related to this lacustrine phase, which culminated around 10 000-8000 cal yr B.P. in the lowland deserts before the lakes progressively dried up. The last record of fresh-water bodies' extensions date back 7300 cal yr B.P. at Shabwa (Yemen) and 7500 cal yr B.P. at al-Haid (Oman). Then, fresh-water was probably available only from seasonal run-off from adjacent highlands, where paleolakes persisted into the late Holocene. Dry climate conditions in the inland desert of Yemen during the late Holocene coincide with a phase of intensive human inhabitation as testified by development of irrigation in the piedmontane areas, numerous necropolises of built collective burials and houses

Diversity Analysis of Dairy and Nondairy Lactococcus lactis Isolates, Using a Novel Multilocus Sequence Analysis Scheme and (GTG)5-PCR Fingerprinting▿

The diversity of a collection of 102 lactococcus isolates including 91 Lactococcus lactis isolates of dairy and nondairy origin was explored using partial small subunit rRNA gene sequence analysis and limited phenotypic analyses. A subset of 89 strains of L. lactis subsp. cremoris and L. lactis subsp. lactis isolates was further analyzed by (GTG)5-PCR fingerprinting and a novel multilocus sequence analysis (MLSA) scheme. Two major genomic lineages within L. lactis were found. The L. lactis subsp. cremoris type-strain-like genotype lineage included both L. lactis subsp. cremoris and L. lactis subsp. lactis isolates. The other major lineage, with a L. lactis subsp. lactis type-strain-like genotype, comprised L. lactis subsp. lactis isolates only. A novel third genomic lineage represented two L. lactis subsp. lactis isolates of nondairy origin. The genomic lineages deviate from the subspecific classification of L. lactis that is based on a few phenotypic traits only. MLSA of six partial genes (atpA, encoding ATP synthase alpha subunit; pheS, encoding phenylalanine tRNA synthetase; rpoA, encoding RNA polymerase alpha chain; bcaT, encoding branched chain amino acid aminotransferase; pepN, encoding aminopeptidase N; and pepX, encoding X-prolyl dipeptidyl peptidase) revealed 363 polymorphic sites (total length, 1,970 bases) among 89 L. lactis subsp. cremoris and L. lactis subsp. lactis isolates with unique sequence types for most isolates. This allowed high-resolution cluster analysis in which dairy isolates form subclusters of limited diversity within the genomic lineages. The pheS DNA sequence analysis yielded two genetic groups dissimilar to the other genotyping analysis-based lineages, indicating a disparate acquisition route for this gene