Differential Effects of Neonatal Testosterone Treatment on Aggression in Two Selection Lines of Mice

Selection lines of mice, artificially selected for aggression based upon the attack latency score (ALS), were used. In order to determine the relative contribution of neonatal testosterone (T) in the development of aggression, we vary the plasma-T level in males of both selection lines on the day of birth. At 14 weeks the ALS was measured. Neonatal T treatment results in a reduction of aggression in the long attack latency (LAL) line, whereas aggressive behaviour of the short attack latency (SAL) line is not affected. Both selection lines show reduction in testicular weight, although the total amount of T-producing Leydig cells was not affected. Neonatal T may cause a permanent reduction in aggressive behaviour in the LAL line only, probably due to differential appearance of critical periods. It is suggested that the difference in aggressive behaviour between SAL and LAL selection lines is due to a prenatally determined difference in neonatal T sensitivity of the brain.

USCT data challenge 2019

Recent years have witnessed the active development of scanning systems and reconstructionalgorithms for ultrasound computed tomography (USCT) with applications to breast imagingfor early cancer detection. Despite these advances in hardware and software development,we encounter the need for reference data to develop, test and compare different imagingmethods. With the goals of encouraging scientific exchange and collaborations, providingbenchmarks of reconstruction algorithms, and standardizing USCT data formats, we havereleased open-source data sets of simulated waveforms that mimic measurements of a USCTscanning aperture using numerical breast phantoms. This is part of ongoing efforts centeredaround the USCT platform for data exchange and collaboration

Deforming the metric of cognitive maps distorts memory

Entorhinal grid cells, characterized by spatially periodic activity patterns, are thought to provide a universal spatial metric. However, grid cell firing-patterns are distorted in highly polarized environments such as trapezoids. Additionally, the functional role of grid cells in guiding behavior remains elusive. Here, we leverage immersive virtual reality using a novel motion platform to test the impact of environmental geometry on spatial memory in participants navigating a trapezoid arena. Object position memory in the trapezoid was degraded compared to a square control environment. Consistent with grid pattern distortions in rodents, this effect was more pronounced in the narrow than the broad part of the trapezoid. Remarkably, even outside of the encoding environment, these distortions persistently affected both navigated and judged distance estimates of never experienced paths between remembered positions and reconstructed memory maps. These distorted memory maps in turn explained behavior better than objective maps. Our findings demonstrate that environmental geometry interacts with human spatial memory similarly to how it affects rodent grid cells − thus strengthening the putative link between grid cells and behavior as well as cognitive functions beyond navigation

Food web stability and weighted connectance:the complexity-stability debate revisited

How the complexity of food webs relates to stability has been a subject of many studies. Often, unweighted connectance is used to express complexity. Unweighted connectance is measured as the proportion of realized links in the network. Weighted connectance, on the other hand, takes link weights (fluxes or feeding rates) into account and captures the shape of the flux distribution. Here, we used weighted connectance to revisit the relation between complexity and stability. We used 15 real soil food webs and determined the feeding rates and the interaction strength matrices. We calculated both versions of connectance, and related these structural properties to food web stability. We also determined the skewness of both flux and interaction strength distributions with the Gini coefficient. We found no relation between unweighted connectance and food web stability, but weighted connectance was positively correlated with stability. This finding challenges the notion that complexity may constrain stability, and supports the ‘complexity begets stability’ notion. The positive correlation between weighted connectance and stability implies that the more evenly flux rates were distributed over links, the more stable the webs were. This was confirmed by the Gini coefficients of both fluxes and interaction strengths. However, the most even distributions of this dataset still were strongly skewed towards small fluxes or weak interaction strengths. Thus, incorporating these distribution with many weak links via weighted instead of unweighted food web measures can shed new light on classical theories