最新Nature 两篇华人科学家文章

　　

生物通报道：在昨天新鲜出炉的Nature杂志上发表了南极冰层与光遗传学（optogenetics）的相关研究成果，领导这两项研究的分别是中国冰川学家，中国北极考察队和中国第15次南极冰盖考察队科学家孙波教授与国际知名的神经学科学家蔡理慧（Li-Huei Tsai）。

在第一篇文章中，研究人员根据在两个季节中所进行的一项能够穿透冰层的雷达研究，完成了对Gamburtsev山系形态的详细勘查和分析。

南极冰层首次形成的方式（当时是距今大约3400万年前的一个全球气候迅速变化的时期）一直是一个有相当大猜测性的问题。来自几个方面的证据都表明，南极中部山系是最初冰层的所在地点，但关于当前冰层地貌的知识高度局限在冰层最初形成最可能发生的区域：位于当前冰层中心、沿冰川下的Gamburtsev山系的地方。

研究人员根据在两个季节中所进行的一项能够穿透冰层的雷达研究，完成了对Gamburtsev山系形态的详细勘查和分析。所获数据显示了一个最初被河流切割、然后又被冰的运动加深的山地景观。深至冰层下3000米的地貌像是经典高山峡谷地貌发生爆炸后的版本，似乎是在距今3400万年前形成的，当时的平均夏季气温约为3摄氏度。

第二篇文章中，研究人员利用一种新开发的技术：光遗传学（optogenetics）——结合遗传工程与光来操作个别神经细胞的活性，发现脑部如何产生γ波（gamma oscillations），并为它们在调控脑部功能中的角色提供新证据，这将有助于发展一系列脑相关失调的新疗法。

蔡立慧（Li-Huei Tsai）表示，“研究表明在罹患精神分裂症与其他精神病学与神经病学疾病的患者身上（被扰乱）会出现γ波，这种新工具给予我们很大的机会来探索这些信号通路的功能。”

原文摘要：

The Gamburtsev mountains and the origin and early evolution of the Antarctic Ice Sheet

Ice-sheet development in Antarctica was a result of significant and rapid global climate change about 34 million years ago1. Ice-sheet and climate modelling suggest reductions in atmospheric carbon dioxide (less than three times the pre-industrial level of 280 parts per million by volume) that, in conjunction with the development of the Antarctic Circumpolar Current, led to cooling and glaciation paced by changes in Earth's orbit2. Based on the present subglacial topography, numerical models point to ice-sheet genesis on mountain massifs of Antarctica, including the Gamburtsev mountains at Dome A, the centre of the present ice sheet2, 3. Our lack of knowledge of the present-day topography of the Gamburtsev mountains4 means, however, that the nature of early glaciation and subsequent development of a continental-sized ice sheet are uncertain. Here we present radar information about the base of the ice at Dome A, revealing classic Alpine topography with pre-existing river valleys overdeepened by valley glaciers formed when the mean summer surface temperature was around 3 °C. This landscape is likely to have developed during the initial phases of Antarctic glaciation. According to Antarctic climate history (estimated from offshore sediment records) the Gamburtsev mountains are probably older than 34 million years and were the main centre for ice-sheet growth. Moreover, the landscape has most probably been preserved beneath the present ice sheet for around 14 million years.

 

Driving fast-spiking cells induces gamma rhythm and controls sensory responses

Cortical gamma oscillations (20-80 Hz) predict increases in focused attention, and failure in gamma regulation is a hallmark of neurological and psychiatric disease. Current theory predicts that gamma oscillations are generated by synchronous activity of fast-spiking inhibitory interneurons, with the resulting rhythmic inhibition producing neural ensemble synchrony by generating a narrow window for effective excitation. We causally tested these hypotheses in barrel cortex in vivo by targeting optogenetic manipulation selectively to fast-spiking interneurons. Here we show that light-driven activation of fast-spiking interneurons at varied frequencies (8-200 Hz) selectively amplifies gamma oscillations. In contrast, pyramidal neuron activation amplifies only lower frequency oscillations, a cell-type-specific double dissociation. We found that the timing of a sensory input relative to a gamma cycle determined the amplitude and precision of evoked responses. Our data directly support the fast-spiking-gamma hypothesis and provide the first causal evidence that distinct network activity states can be induced in vivo by cell-type-specific activation.