What crowding can tell us about object representations

In crowding, perception of a target usually deteriorates when flanking elements are presented next to the target. Surprisingly, adding further flankers can lead to a release from crowding. In previous work we showed that, for example, vernier offset discrimination at 9� of eccentricity deteriorated when a vernier was embedded in a square. Adding further squares improved performance. The more squares presented, the better the performance, extending across 20� of the visual field. Here, we show that very similar results hold true for shapes other than squares, including unfamiliar, irregular shapes. Hence, uncrowding is not restricted to simple and familiar shapes. Our results provoke the question of whether any type of shape is represented at any location in the visual field. Moreover, small changes in the orientation of the flanking shapes led to strong increases in crowding strength. Hence, highly specific shape-specific interactions across large parts of the visual field determine vernier acuity

What crowding can tell us about object representations

Peer reviewedPublisher PD

Axonal regeneration is compromised in NFH-LacZ transgenic mice but not in NFH-GFP mice

To investigate neurofilament (NF) dynamics during the cytoskeleton reorganization in regenerating axons, and their electrophysiological and histological consequences, we used two transgenic lines of mice: neurofilament high (NFH)-LacZ and NFH-green fluorescent protein (GFP). In NFH-LacZ mice, NFs are retained in cell bodies and deficient in axons (Eyer and Peterson, 1994), while in NFH-GFP mice the fluorescent fusion protein is normally transported along axons (Letournel et al., 2006). Following a crush of the sciatic nerve, conduction recovery in NFH-GFP mice is similar to wild-type (wt) mice, but it is reduced in NFH-LacZ mice. Moreover, changes of axonal calibres following regeneration are similar between NFH-GFP and wt mice, but they are systematically reduced in NFH-LacZ mice. Finally, the axonal transport of NFH-GFP fusion protein and NFs is re-initiated after the crush as evidenced by the fluorescent and immunolabelling of axons distal from the crushed point, but NFs and the fusion protein are not transported along axons during regeneration in NFH-LacZ mice. Together, these results argue that the absence of axonal NFs in NFH-LacZ mice compromises the axonal regeneration, and that the NFH-GFP reporter fusion protein represents an efficient model to evaluate the NF dynamics during axonal regeneration

Eruptive Pyogenic Granulomas and Acne fulminans in Two Siblings Treated with Isotretinoin

We report the case of two siblings, one of whom presented isotretinoin-induced eruptive pyogenic granulomas in the course of severe acne, and the other developed isotretinoin-induced acne fulminans. A possible underlying common pathogenic process of these two side-effects of isotretinoin is discussed.</jats:p

Mise au point sur la prise en charge de la douleur chez les patients adultes atteints de déficience intellectuelle

Devant faire face quotidiennement aux problèmes de prescription chez les adultes présentant une déficience intellectuelle en contexte hospitalier et étant fréquemment confrontés à la question de la prescription d’un antalgique, nous avons mené une réflexion sur les spécificités à prendre en compte dans cette population sur la base des données de la littérature, de considérations pharmacologiques et de notre expérience clinique. Cette réflexion s’organise en trois étapes : sources de douleurs fréquentes dans cette population, méthodes d’évaluation de la douleur et spécificités pharmacologiques de cette population.</jats:p

Méthodes de Quasi Monte-Carlo pour l’évaluation de stratégies d’investissements

International audienc

Acetylcholine-induced endothelium-dependent contractions in the SHR aorta: the Janus face of prostacyclin

1. In the spontaneously hypertensive rat (SHR) and aging Wistar–Kyoto rats (WKY), acetylcholine releases an endothelium-derived contracting factor (EDCF) produced by endothelial cyclooxygenase-1, which stimulates thromboxane A(2) receptors (TP receptors) on vascular smooth muscle. The purpose of the present study was to identify this EDCF by measuring changes in isometric tension and the release of various prostaglandins by acetylcholine. 2. In isolated aortic rings of SHR, U 46619, prostaglandin (PG) H(2), PGF(2α), PGE(2), PGD(2), prostacyclin (PGI(2)) and 8-isoprostane, all activate TP receptors of the vascular smooth muscle to produce a contraction (U 46619≫8-isoprostane=PGF(2α)=PGH(2)>PGE(2)=PGD(2)>PGI(2)). The contractions produced by PGH(2) and PGI(2) were fast and transient, mimicking endothelium-dependent contractions. PGI(2) did not relax isolated aortic rings of WKY and SHR. 3. Acetylcholine evoked the endothelium-dependent release of thromboxane A(2), PGF(2α), PGE(2), PGI(2) and most likely PGH(2) (PGI(2)≫PGF(2α)⩾PGE(2)>TXA(2)>8-isoprostane, PGD(2)). Dazoxiben abolished the production of thromboxane A(2), but did not influence the endothelium-dependent contractions to acetylcholine. 4. The release of PGI(2) was significantly larger in the aorta of SHR than in WKY, and the former was more sensitive to the contractile effect of PGI(2) than the latter. The inhibition of PGI-synthase was associated with an increase in PGH(2) spillover and the enhancement of acetylcholine-induced endothelium-dependent contractions. 5. Thus, in the aorta of SHR and aging WKY, the endothelium-dependent contractions elicited by acetylcholine most likely involve the release of PGI(2) with a concomitant contribution of PGH(2)