Sparse optical microstimulation in barrel cortex drives learned behaviour in freely moving mice

Electrical microstimulation can establish causal links between the activity of groups of neurons and perceptual and cognitive functions. However, the number and identities of neurons microstimulated, as well as the number of action potentials evoked, are difficult to ascertain. To address these issues we introduced the light-gated algal channel channelrhodopsin-2 (ChR2) specifically into a small fraction of layer 2/3 neurons of the mouse primary somatosensory cortex. ChR2 photostimulation in vivo reliably generated stimulus-locked action potentials at frequencies up to 50 Hz. Here we show that naive mice readily learned to detect brief trains of action potentials (five light pulses, 1 ms, 20 Hz). After training, mice could detect a photostimulus firing a single action potential in approximately 300 neurons. Even fewer neurons (approximately 60) were required for longer stimuli (five action potentials, 250 ms). Our results show that perceptual decisions and learning can be driven by extremely brief epochs of cortical activity in a sparse subset of supragranular cortical pyramidal neurons.     

Stress changes from the 2008 Wenchuan earthquake and increased hazard in the Sichuan basin

On 12 May 2008, the devastating magnitude 7.9 (Wenchuan) earthquake struck the eastern edge of the Tibetan plateau, collapsing buildings and killing thousands in major cities aligned along the western Sichuan basin in China. After such a large-magnitude earthquake, rearrangement of stresses in the crust commonly leads to subsequent damaging earthquakes. The mainshock of the 12 May earthquake ruptured with as much as 9 m of slip along the boundary between the Longmen Shan and Sichuan basin, and demonstrated the complex strike-slip and thrust motion that characterizes the region. The Sichuan basin and surroundings are also crossed by other active strike-slip and thrust faults. Here we present calculations of the coseismic stress changes that resulted from the 12 May event using models of those faults, and show that many indicate significant stress increases. Rapid mapping of such stress changes can help to locate fault sections with relatively higher odds of producing large aftershocks.     

The mental wealth of nations

Countries must learn how to capitalize on their citizens' cognitive resources if they are to prosper, both economically and socially. Early interventions will be key.     

Jovian-like aurorae on Saturn

Planetary aurorae are formed by energetic charged particles streaming along the planet's magnetic field lines into the upper atmosphere from the surrounding space environment. Earth's main auroral oval is formed through interactions with the solar wind, whereas that at Jupiter is formed through interactions with plasma from the moon Io inside its magnetic field (although other processes form aurorae at both planets). At Saturn, only the main auroral oval has previously been observed and there remains much debate over its origin. Here we report the discovery of a secondary oval at Saturn that is approximately 25 per cent as bright as the main oval, and we show this to be caused by interaction with the middle magnetosphere around the planet. This is a weak equivalent of Jupiter's main oval, its relative dimness being due to the lack of as large a source of ions as Jupiter's volcanic moon Io. This result suggests that differences seen in the auroral emissions from Saturn and Jupiter are due to scaling differences in the conditions at each of these two planets, whereas the underlying formation processes are the same.     

Seeking Allies: Modelling How Listeners Choose Their Musical Friends

In this paper we describe in some detail a formal computer model of inferential discourse based on a belief system. The key issue is that a logical model in a computer, based on rational sets, can usefully model a human situation based on irrational sets. The background of this work is explained elsewhere, as is the issue of rational and irrational sets (Billinge and Addis, in: Magnani and Dossena (eds.), Computing, philosophy and cognition, 2004; Stepney et al., Journey: Non-classical philosophy—socially sensitive computing in journeys non-classical computation: A grand challenge for computing research, 2004). The model is based on the Belief System (Addis and Gooding, Proceedings of the AISB’99 Symposium on Scientific Creativity, 1999) and it provides a mechanism for choosing queries based on a range of belief. We explain how it provides a way to update the belief based on query results, thus modelling others’ experience by inference. We also demonstrate that for the same internal experience, different models can be built for different actors.

结合功能测试与模拟驾驶的老年人驾驶适性评估

为应对老年驾驶人驾驶能力下降带来的交通安全问题并降低与其相关的事故风险,建立了可有效替代道路驾驶测试的老年人驾驶适性评估方法.对92名老年驾驶人进行了功能测试、模拟驾驶测试与道路驾驶测试,通过独立样本T检验与分层逐步Logistic回归确定评价指标体系,分别建立并比选了决策树、随机森林和支持向量机3种评估模型.结果表明,以对比敏感度、功能性伸展、交通标志理解以及合流变道距离等作为评价指标的支持向量机模型对驾驶适性的评估效果最好,准确率高达84.6％.该方法可以有效替代道路测试评估老年人的驾驶适性,能为其停止驾驶、调整驾驶行为、训练提升驾驶能力、使用辅助驾驶技术等提供参考.     

The effects of vitamin A nutritional status on glutathione levels and microsomal lipid peroxidation in rat lung

In vitamin A-deficient rats, the glutathione level in lung was diminished and microsomal lipid peroxidation much increased. In vitamin A-loaded animals, however, both were depressed below control. Thus vitamin A protection against lipid peroxidation is independent of glutathione.