Functional ultrasound reveals effects of MRI acoustic noise on brain function

Loud acoustic noise from the scanner during functional magnetic resonance imaging (fMRI) can affect functional connectivity (FC) observed in the resting state, but the exact effect of the MRI acoustic noise on resting state FC is not well understood. Functional ultrasound (fUS) is a neuroimaging method that visualizes brain activity based on relative cerebral blood volume (rCBV), a similar neurovascular coupling response to that measured by fMRI, but without the audible acoustic noise. In this study, we investigated the effects of different acoustic noise levels (silent, 80 dB, and 110 dB) on FC by measuring resting state fUS (rsfUS) in awake mice in an environment similar to fMRI measurement. Then, we compared the results to those of resting state fMRI (rsfMRI) conducted using an 11.7 Tesla scanner. RsfUS experiments revealed a significant reduction in FC between the retrosplenial dysgranular and auditory cortexes (0.56 ± 0.07 at silence vs 0.05 ± 0.05 at 110 dB, p=.01) and a significant increase in FC anticorrelation between the infralimbic and motor cortexes (−0.21 ± 0.08 at silence vs −0.47 ± 0.04 at 110 dB, p=.017) as acoustic noise increased from silence to 80 dB and 110 dB, with increased consistency of FC patterns between rsfUS and rsfMRI being found with the louder noise conditions. Event-related auditory stimulation experiments using fUS showed strong positive rCBV changes (16.5% ± 2.9% at 110 dB) in the auditory cortex, and negative rCBV changes (−6.7% ± 0.8% at 110 dB) in the motor cortex, both being constituents of the brain network that was altered by the presence of acoustic noise in the resting state experiments. Anticorrelation between constituent brain regions of the default mode network (such as the infralimbic cortex) and those of task-positive sensorimotor networks (such as the motor cortex) is known to be an important feature of brain network antagonism, and has been studied as a biological marker of brain disfunction and disease. This study suggests that attention should be paid to the acoustic noise level when using rsfMRI to evaluate the anticorrelation between the default mode network and task-positive sensorimotor network.journal articl

A pristine record of outer Solar System materials from asteroid Ryugu’s returned sample

Volatile and organic-rich C-type asteroids may have been one of the main sources of Earth’s water. Our best insight into their chemistry is currently provided by carbonaceous chondritic meteorites, but the meteorite record is biased: only the strongest types survive atmospheric entry and are then modified by interaction with the terrestrial environment. Here we present the results of a detailed bulk and microanalytical study of pristine Ryugu particles, brought to Earth by the Hayabusa2 spacecraft. Ryugu particles display a close compositional match with the chemically unfractionated, but aqueously altered, CI (Ivuna-type) chondrites, which are widely used as a proxy for the bulk Solar System composition. The sample shows an intricate spatial relationship between aliphatic-rich organics and phyllosilicates and indicates maximum temperatures of ~30 °C during aqueous alteration. We find that heavy hydrogen and nitrogen abundances are consistent with an outer Solar System origin. Ryugu particles are the most uncontaminated and unfractionated extraterrestrial materials studied so far, and provide the best available match to the bulk Solar System composition

A dehydrated space-weathered skin cloaking the hydrated interior of Ryugu

Without a protective atmosphere, space-exposed surfaces of airless Solar System bodies gradually experience an alteration in composition, structure and optical properties through a collective process called space weathering. The return of samples from near-Earth asteroid (162173) Ryugu by Hayabusa2 provides the first opportunity for laboratory study of space-weathering signatures on the most abundant type of inner solar system body: a C-type asteroid, composed of materials largely unchanged since the formation of the Solar System. Weathered Ryugu grains show areas of surface amorphization and partial melting of phyllosilicates, in which reduction from Fe3+ to Fe2+ and dehydration developed. Space weathering probably contributed to dehydration by dehydroxylation of Ryugu surface phyllosilicates that had already lost interlayer water molecules and to weakening of the 2.7 µm hydroxyl (–OH) band in reflectance spectra. For C-type asteroids in general, this indicates that a weak 2.7 µm band can signify space-weathering-induced surface dehydration, rather than bulk volatile loss

The human dimension of climate change research in Greenland: Towards a new form of knowledge generation

In the field of climate change research, social sciences have lagged behind natural sciences and have not yet mustered enough recognition from the public. Studies on the human dimension of climate change commonly use the concepts of ‘vulnerability’ and ‘resilience’. The ‘resilience’ approach investigates the capacity of a community that absorbs environmental disturbances, so as to retain essential social, cultural, and economic structures, while the ‘vulnerability’ approach seeks to identify factors that make the community in question vulnerable to ongoing or future climate change. The term ‘resilience’ tends to give an impression that a system may remain static, and because of this, I adopt the term ‘vulnerability’ in this essay. ‘Vulnerability’ does not mean that Arctic communities are always “vulnerable” to environmental changes but may be negatively impacted by the associated social and political changes. Accordingly, vulnerability means the social and political “characteristics” of the community that is experiencing the changes. This concept helps researchers direct their attention not only to environmental changes, but also to the societal situation of the community. In the second half of this essay, I exemplify how the vulnerability approach works, drawing data from my fieldwork conducted in Siorapaluk, in 2009. More local communities want scientific data in order to plan a course of action and to shape their political and economic policies in the rapidly changing environment. In future, it will be increasingly important for natural scientists to work closely with local communities, and this may lead to a new form of knowledge generation.気候変動といえば自然科学の分野が先行し，社会科学的調査の認知度は低い．社会科学の分野には， 「復元性（resilience）」と，「脆弱性（vulnerability）」に注目する手法がある．復元性とは，環境攪乱が おきても，社会，文化，経済構造を維持できる地域の包容力であり，脆弱性とは，調査地が現在また は未来の気候変動に対して，脆弱になる可能性である．「復元性」という言葉は，社会が変わらないと いう印象を与えるため，筆者は，脆弱性に注目した手法を本稿で解説する．脆弱性という言葉は，北 極圏に住んでいる人たちが，単に環境変化に「脆弱である」という意味ではなく，環境変化に伴って おきる社会的，経済的，政治的変化に対応できないために，脆弱になるということを意味している． つまり，「脆弱性」とは，変化にさらされている調査地の社会的，政治的「特徴」を表していると考え てよい．この概念は，環境変化だけでなく，調査地の社会状況をも考慮する必要性を喚起する．後半 では，筆者が2009 年に行ったシオガパルクでの現地調査を紹介し，気候変動の社会科学的な調査がど のように行われたか解説する．現在，多くの町や村では，将来の政治経済方針や事業方針を定めるの に有用な科学的データが必要とされている．今後，自然科学者はますます，調査地の社会と連携を図 る必要性が出てくるであろう．そしてそれは，新しい知識の形成に繋がるのである

How to Help Acehnese Helping Themselves? : A Note after a Visit with Kobe University Medical Team

On December 26, Aceh Province in Indonesia was hit by the worst earthquake and tsunami. A medical team from Kobe University Graduate School of Medicine visited two of the affected areas on the eastern coast of Aceh: Sigli and Lhokseumawe. This article provides a simple description of experience and assessment derived from the visit. The disaster has left Indonesia with complex problems, which will take a long time to overcome. A continuity of the aid and assistance from various resources is crucial to help Indonesia rebuilt the affected areas. These continuous efforts will provide great contribution for Acehnese people to recover and rebuild their life after tsunami