Short-Term Environmental Enrichment Rescues Adult Neurogenesis and Memory Deficits in APPSw,Ind Transgenic Mice

Epidemiological studies indicate that intellectual activity prevents or delays the onset of Alzheimer's disease (AD). Similarly, cognitive stimulation using environmental enrichment (EE), which increases adult neurogenesis and functional integration of newborn neurons into neural circuits of the hippocampus, protects against memory decline in transgenic mouse models of AD, but the mechanisms involved are poorly understood. To study the therapeutic benefits of cognitive stimulation in AD we examined the effects of EE in hippocampal neurogenesis and memory in a transgenic mouse model of AD expressing the human mutant β-amyloid (Aβ) precursor protein (APPSw,Ind). By using molecular markers of new generated neurons (bromodeoxiuridine, NeuN and doublecortin), we found reduced neurogenesis and decreased dendritic length and projections of doublecortin-expressing cells of the dentate gyrus in young APPSw,Ind transgenic mice. Moreover, we detected a lower number of mature neurons (NeuN positive) in the granular cell layer and a reduced volume of the dentate gyrus that could be due to a sustained decrease in the incorporation of new generated neurons. We found that short-term EE for 7 weeks efficiently ameliorates early hippocampal-dependent spatial learning and memory deficits in APPSw,Ind transgenic mice. The cognitive benefits of enrichment in APPSw,Ind transgenic mice were associated with increased number, dendritic length and projections to the CA3 region of the most mature adult newborn neurons. By contrast, Aβ levels and the total number of neurons in the dentate gyrus were unchanged by EE in APPSw,Ind mice. These results suggest that promoting the survival and maturation of adult generated newborn neurons in the hippocampus may contribute to cognitive benefits in AD mouse models

New MLD gratings adapted for tiling in petawatt-class lasers

Laser-induced damage threshold of gratings remains the main limiting factor towards generating higher-energy compressed pulses (terawatt and petawatt). HORIBA Jobin Yvon has first developed the manufacturing of large gold coated gratings, dimensions up to half a meter. Then we have developed large multilayer dielectric (MLD) gratings for working at 1.053 microns with 2 to 3 times higher damage threshold than gold coated gratings for ps pulses, and higher efficiency (up to 96% averaged over the full aperture). In addition these large MLD gratings are optimised for mosaic (tiling) configurations, in which the total useful grating length may reach 1 meter or more

Seasonal variability of bull and tiger shark presence on the west coast of Reunion Island, western Indian Ocean

A fisheries-independent survey using longlines and drumlines, and an acoustic telemetry study, revealed that bull sharks Carcharhinus leucas and tiger sharks Galeocerdo cuvier occur throughout the year off the west coast of Reunion Island. The research, which commenced in 2011, was conducted in response to an increase in the rate of shark attacks. Juvenile, subadult and young adult tiger sharks of 111-390 cm total length (TL) were caught in all months except July; the sex ratio was 1:1 (M:F; n = 61). All bull sharks taken, except one (183 cm TL), were mature (205-329 cm TL), with a sex ratio of 0.7:1 (M:F; n = 54), and catches occurred throughout the year except in May and August, with the highest CPUE in September. Presence/absence of a total of 46 tagged tiger sharks and 36 tagged bull sharks was monitored by means of 42 acoustic receivers distributed along the west coast of the island. Tagged tiger sharks were detected in all months, with seasonal variation between sexes. Detections of males remained low throughout the year but with a peak in winter, whereas detections of females were low in May and August only and peaked in summer. Tagged bull sharks of both sexes were more abundant in winter than in summer, with females present year round. The reasons for the apparent differences in seasonality found in longline and drumline catches compared to acoustic monitoring are discussed

Cell Class-Dependent Intracortical Connectivity and Output Dynamics of Layer 6 Projection Neurons of the Rat Primary Visual Cortex

Neocortical information processing is powerfully influenced by the activity of layer 6 projection neurons through control of local intracortical and subcortical circuitry. Morphologically distinct classes of layer 6 projection neuron have been identified in the mammalian visual cortex, which exhibit contrasting receptive field properties, but little information is available on their functional specificity. To address this we combined anatomical tracing techniques with high-resolution patch-clamp recording to identify morphological and functional distinct classes of layer 6 projection neurons in the rat primary visual cortex, which innervated separable subcortical territories. Multisite whole-cell recordings in brain slices revealed that corticoclaustral and corticothalamic layer 6 projection neurons exhibited similar somatically recorded electrophysiological properties. These classes of layer 6 projection neurons were sparsely and reciprocally synaptically interconnected, but could be differentiated by cell-class, but not target-cell-dependent rules of use-dependent depression and facilitation of unitary excitatory synaptic output. Corticoclaustral and corticothalamic layer 6 projection neurons were differentially innervated by columnar excitatory circuitry, with corticoclaustral, but not corticothalamic, neurons powerfully driven by layer 4 pyramidal neurons, and long-range pathways conveyed in neocortical layer 1. Our results therefore reveal projection target-specific, functionally distinct, streams of layer 6 output in the rodent neocortex

Synthetic aperture compression scheme for multi-petawatt high energy laser

An original synthetic aperture compressor scheme is proposed for multi-kilojoule petawatt beam. This scheme uses two compressor stages with multi-dielectric gratings allowing suppressing the mosaic of gratings. The main technical issues are detailed

Chronic exposure to haloperidol and olanzapine leads to common and divergent shape changes in the rat hippocampus in the absence of grey-matter volume loss

One of the most consistently reported brain abnormalities in schizophrenia (SCZ) is decreased volume and shape deformation of the hippocampus. However, the potential contribution of chronic antipsychotic medication exposure to these phenomena remains unclear. We examined the effect of chronic exposure (8 weeks) to clinically relevant doses of either haloperidol (HAL) or olanzapine (OLZ) on adult rat hippocampal volume and shape using ex vivo structural MRI with the brain retained inside the cranium to prevent distortions due to dissection, followed by tensor-based morphometry (TBM) and elastic surface-based shape deformation analysis. The volume of the hippocampus was also measured post-mortem from brain tissue sections in each group. Chronic exposure to either HAL or OLZ had no effect on the volume of the hippocampus, even at exploratory thresholds, which was confirmed post-mortem. In contrast, shape deformation analysis revealed that chronic HAL and OLZ exposure lead to both common and divergent shape deformations (q = 0.05, FDR-corrected) in the rat hippocampus. In particular, in the dorsal hippocampus, HAL exposure led to inward shape deformation, whereas OLZ exposure led to outward shape deformation. Interestingly, outward shape deformations that were common to both drugs occurred in the ventral hippocampus. These effects remained significant after controlling for hippocampal volume suggesting true shape changes. Chronic exposure to either HAL or OLZ leads to both common and divergent effects on rat hippocampal shape in the absence of volume change. The implications of these findings for the clinic are discussed