Distinct representations of subtraction and multiplication in the neural systems for numerosity and language

It has been proposed that recent cultural inventions such as symbolic arithmetic recycle evolutionary older neural mechanisms. A central assumption of this hypothesis is that the degree to which a preexisting mechanism is recycled depends on the degree of similarity between its initial function and the novel task. To test this assumption, we investigated whether the brain region involved in magnitude comparison in the intraparietal sulcus (IPS), localized by a numerosity comparison task, is recruited to a greater degree by arithmetic problems that involve number comparison (single-digit subtractions) than by problems that involve retrieving number facts from memory (single-digit multiplications). Our results confirmed that subtractions are associated with greater activity in the IPS than multiplications, whereas multiplications elicit greater activity than subtractions in regions involved in verbal processing including the middle temporal gyrus (MTG) and inferior frontal gyrus (IFG) that were localized by a phonological processing task. Pattern analyses further indicated that the neural mechanisms more active for subtraction than multiplication in the IPS overlap with those involved in numerosity comparison and that the strength of this overlap predicts interindividual performance in the subtraction task. These findings provide novel evidence that elementary arithmetic relies on the cooption of evolutionary older neural circuits.     

Interaction of Modeling and Experimental Approaches to Understanding Renal Salt and Water Balance

Understanding of renal function has profited greatly from quantitative and modeling approaches throughout this century. One of the most salient examples is the concentration and dilution of the urine—a fundamental characteristic of the mammalian kidney. Only in the last three decades have the necessary components of this and other renal mechanisms been confirmed at the molecular level, but there have also been surprises. For example, the high water permeability of the proximal tubule has been shown to be imparted by the water channel, aquaporin AQP1; however, genetic knockout of this water channel is at least partially compensated by intrarenal feedback mechanisms. Also, the critical role played by the fine regulation of Na⁺ reabsorption in the collecting duct for the maintenance of normal blood pressure presents challenges to our understanding of the integrated interaction among systems. As a first step in placing the kidney in the physiome paradigm, we need to integrate our currently restricted mathematical models, to develop accessible databases of critical parameter values together with indices of their degrees of reliability and variability, and to describe regulatory mechanisms and their interactions from the molecular to the interorgan level. However, even greater will be the challenge to anticipate, and hopefully predict, the subtle ways in which the organism typically adapts to aberrations in these normal functional parameters, but sometimes does not. © 2000 Biomedical Engineering Society. PAC00: 8716Uv, 8715Aa     

Strategy over operation: neural activation in subtraction and multiplication during fact retrieval and procedural strategy use in children

Arithmetic development is characterized by strategy shifts between procedural strategy use and fact retrieval. This study is the first to explicitly investigate children's neural activation associated with the use of these different strategies. Participants were 26 typically developing 4th graders (9‐ to 10‐year‐olds), who, in a behavioral session, were asked to verbally report on a trial‐by‐trial basis how they had solved 100 subtraction and multiplication items. These items were subsequently presented during functional magnetic resonance imaging. An event‐related design allowed us to analyze the brain responses during retrieval and procedural trials, based on the children's verbal reports. During procedural strategy use, and more specifically for the decomposition of operands strategy, activation increases were observed in the inferior and superior parietal lobes (intraparietal sulci), inferior to superior frontal gyri, bilateral areas in the occipital lobe, and insular cortex. For retrieval, in comparison to procedural strategy use, we observed increased activity in the bilateral angular and supramarginal gyri, left middle to inferior temporal gyrus, right superior temporal gyrus, and superior medial frontal gyrus. No neural differences were found between the two operations under study. These results are the first in children to provide direct evidence for alternate neural activation when different arithmetic strategies are used and further unravel that previously found effects of operation on brain activity reflect differences in arithmetic strategy use. Hum Brain Mapp 38:4657–4670, 2017. © 2017 Wiley Periodicals, Inc.     

三种缝线材料对人肺腺癌细胞A549增殖和细胞周期的影响

背景与目的细胞与生物医用材料之间的相互作用是影响其临床应用的重要因素之一,本研究旨在探讨三种缝线材料对人肺腺癌细胞A549增殖和细胞周期的影响。