Frontiers in Psychology
People who often recall their dreams respond more strongly to their name
Dreaming remains one of the great mysteries of human cognition. It is still not fully known when dreams occur, and which mechanisms in the brain produce them. A major difficulty for studying dreams is that they leave only a fleeting memory upon awakening.
Perrine Ruby and colleagues from the Lyon Neuroscience Research Center chose a new approach to investigate dreaming. They recorded brain activity of two groups of participants: high dream recallers who recall dreams nearly every day and low dream recallers who recall a dream once or twice a month. Brain activity (electroencephalogram) was recorded while they were hearing first names before and during sleep.
From the analysis of oscillatory brain signals, high and low dream recallers were found to differentially process first names during wakefulness, suggesting different functional organization of the brain in the two groups. Moreover, high dream recallers showed more intra-sleep wakefulness than low dream recallers.
Together with previous findings, these results suggest a greater brain reactivity in high than in low dream recallers which would facilitate awakenings during sleep and therefore dream memorisation
Dr Perrine Ruby
Lyon Neuroscience Research Center
CNRS and University of Lyon, France
Article title: Alpha reactivity to first names differs in subjects with high and low dream recall frequency
Journal: Frontiers in Psychology
Frontiers in Plant Science
Plants modify soil to maximize water uptake by their youngest roots
Roots of lupine plants exude a gel that facilitates water uptake from the deeper, wetter soil layers, while preventing water loss from older roots closer to the surface, a newstudy reports. Plants can respond to water shortage by reducing transpiration or by growing deeper roots, but also by modifying the soil. For example, roots exude mucilage, a gel that increases the water holding capacity ("wettability") of the soil. However, when roots have taken up most available water, the mucilage dries out, making the contact zone between roots and soil ("the rhizosphere") water-repellent precisely when water is needed most. But Andrea Carminati here shows that this decrease in wettability with increasing root age is actually an adaptive strategy. Studying the rhizosphere of lupine with neutron radiography (a technique similar to X-rays), he found that only the mucilage around upper, older roots becomes water repellent, while fresh mucilage ensures that the tips of younger, deeper roots always remain wet. Carminati concludes that the resulting isolation of older roots from the dry top soil increases the flow of water into the youngest roots.
Prof Andrea Carminati
Department of Crop Sciences
Georg-August University of Gttingen, Germany
Color images (obtained through neutron radiography) available upon request.
Journal : Frontiers in Plant Science
Article title : Rhizosphere wettability decreases with root age: A problem or a strategy to increase water uptake of young roots?
Frontiers in Plant Science
Plants respond similarly to the underground presence of competitors and parasites
When plant roots detect the presence of roots of other species, they respond in an adaptive manner: by growing away from the competing roots and increasing the expression of 14 genes implicated in the response against pathogens, according to a study. Christoph Schmid and colleagues grew the model plant Arabidopsis thaliana with or without a mild competitor, the mouse-ear hawkweed Hieracium pilosella, and measured changes in the level of expression of approximately 22000 A. thaliana genes. Its genetic response to the competitor's presence was in part similar to the response to the presence of plants from its own species. But surprisingly, the presence of H. pilosella also induced a genetic response in A. thaliana similar to its typical response to parasites (e.g. the oocmycote Phytophthora, which causes blight and root rot) and other forms of biological stress. Schmid and colleagues conclude that biological stress reactions are induced by foreign organisms in general, including the roots of competing plants.
Dr Maik Bartelheimer
Institute of Botany
University of Regensburg, Germany
Journal: Frontiers in Plant Science
Article title: Belowground neighbor perception in Arabidopsis thaliana studied by transcriptome analysis: roots of Hieracium pilosella cause biotic stress
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