Analyse du comportement alimentaire du poisson cavernicole aveugle Anoptichthys Gen. et d\u27hybrides F\u3csub\u3e1\u3c/sub\u3e (Astyanax x Anoptichthys) et F\u3csub\u3e2\u3c/sub\u3e

The feeding behaviour of the blind cave fish Anoptichthys is characterised by two phases, an initial short chemioreceptic one and second one in which the fish explores the bottom systematically for a longer period. The whole process last approximately 30 seconds, both in adults as in youngsters

Matching extendability in Cartesian products of cycles

In a bipartite graph G, a set (Formula presented) is deficient if |N(S)| \u3c |S|. A matching M with vertex set U is k-suitable if G − U has no deficient set of size less than k. Define the extremal function fk (G) to be the largest integer r such that every k-suitable matching in G with at most r edges extends to a perfect matching. Let G(2m)d be the d-fold Cartesian product of the cycle C2m,wherem ≥ 2. We extend results of Vandenbussche and West by showing that for any integers k and d such that (Formula presented), except when m =2 and d =1

Vandenbussche E: Optotype and grating visual acuity in patients with ocular and cerebral visual impairment. Invest Ophthalmol Vis Sci 2004

PURPOSE. To investigate the discrepancy between grating and optotype visual acuity in children with visual impairment due to brain and/or ocular abnormalities. METHODS. Better eye acuity at 114 cm was studied in 81 patients (ages, 5-24 years) attending special schools for the visually handicapped. Fourteen patients had a brain abnormality, 48 had an ocular disorder, and 19 had both. Three acuity tasks were administered: detecting gratings in one of two positions, discriminating the orientation of single gratings, and discriminating the orientation of uncrowded Landolt-C optotypes. The three paradigms were similar in stimulus contrast, luminance, presentation mode, and psychophysical procedure. RESULTS. Overall, grating acuity was better than optotype acuity, and the disparity increased with poorer optotype acuity. The largest discrepancies occurred in patients with brain abnormality, but disparities were also large in patients with optic nerve disorder. In patients with ocular and brain abnormality, grating acuities were only mildly better and not different from patients with only ocular abnormality. Grating orientation and grating detection tasks yielded similar thresholds, except in patients with cerebral visual impairment and with optic nerve disorder, whose grating detection acuity was better than grating orientation acuity. CONCLUSIONS. Grating-to-optotype acuity superiority is typically large in visual disorders involving the brain. The closely matched test paradigms point to stimulus characteristics as the explanation. However, because the discrepancy decreased with grating orientation acuity instead of grating detection acuity, the complexity of the response required also plays a role. (Invest Ophthalmol Vis Sci

Sampling extracellular aspartate, glutamate and gamma-aminobutyric acid in striate cortex of awake cat by in vivo microdialysis: surgical and methodological aspects

A method which permits repeated microdialysis in the cortical layers of area 17 of the awake cat is described. Under visual control through a surgical microscope and using a stereotactic instrument, four probe guides are permanently implanted in area 17 of one hemisphere of the anesthetized animal and two fixation bars an mounted on the skull to allow fixation of the cat in a stereotactic frame. The implantation of four probe guides in the same hemisphere allows simultaneous sampling from different cortical regions serving different parts of the visual field. A removable transparent cover protects the probe guides. After recovery from surgery the awake cats are trained to adapt to a fixation of 5 h in a stereotaxic apparatus. Once adapted to that situation, the cats are ready for microdialysis experiments without anesthesia. The day of the experiment, the awake animal was fixed in the stereotactic frame and the probes inserted into the guides. To test the validity of the method, the basal efflux and the depolarization efflux, triggered by the addition of 65 mM K+ to the artificial cerebrospinal fluid, of the amino acids aspartate, glutamate and gamma-aminobutyric acid are measured by two HPLC-electrochemical detection methods. The exact localization of the probes and the reaction of the surrounding tissue is studied using immunocytochemistry for glutamate and glial fibrilary acidic protein. Our neurochemical and morphological results suggest the feasibility of multiple and repeated probe insertions for microdialysis experiments in the cerebral cortex of awake and behaving cat. This method provides a new tool to investigate the cortical plasticity. (C) 2000 Elsevier Science B.V. All rights reserved.status: publishe

In vivo microdialysis in the visual cortex of awake cat I: Surgery, animal training and sampling

Sampling and monitoring release of excitatory and inhibitory amino acids in the striate cortex of mammals will provide important information for visual system research. A method allowing repeated microdialysis in the cortical layers of area 17 of the awake cat is described, Under visual control through a surgical microscope and using a stereotactic instrument, four probe guides are permanently implanted in area 17 of one hemisphere of the anesthetized animal and two fixation bars are mounted on the skull to allow fixation of the cat in a stereotactic frame. The implantation of four probe guides in the same hemisphere allows simultaneous sampling from different cortical regions subserving different parts of the visual field, A removable transparent cover protects the probe guides. After recovery from surgery the awake cats are trained to adapt to a fixation in a stereotaxic apparatus. Once adapted to that situation, the cats are used for 5 h in vivo microdialysis experiments without anesthesia. (C) 2001 Elsevier Science B.V. All rights reserved.status: publishe

Analysis of extracellular gamma-aminobutyric acid, glutamate and aspartate in cat visual cortex by in vivo microdialysis and capillary electrophoresis-laser induced fluorescence detection

To investigate the influence of a partial sensory deprivation on the extracellular concentration of amino acid neurotransmitters in cat visual cortex, a capillary electrophoresis method was developed for the quantification of gamma -aminobutyric acid (GABA), glutamate (Glu) and aspartate (Asp) in in vivo microdialysis samples of cat brain. Microdialysis samples from different regions of area 17 were obtained every 15-min using CMA 12 2-mm probes perfused with synthetic cerebrospinal fluid and derivatized using fluorescein isothiocyanate (FITC). Laser-induced fluorescence (LIF) detection was employed. Good selectivity was obtained with a berate buffer (20 mM, pH 10.25). The whole procedure, including the washing step takes only 15 min. The conditions fur derivatization and separation were optimized. The parameters for validation such as linearity, precision and detection limit are also reported. The results are consistent with those of HPLC but, as the sample volumes needed are only 1-5 nl, a much better time resolution can be obtained. (C) 2001 Elsevier Science B.V. All rights reserved.status: publishe

Using Strand Committees to Build Faculty Support for Departmental Change

In this article, the authors propose a department-level curricular committee structure, called Strand Committees, as a mechanism to facilitate oversight and enact significant change to policies and practices in specific courses. The primary goal of the Strand Committees is improving both student success and instruction while upholding a high degree of shared governance. The focus of this paper is based around three recommendations encapsulating the philosophy of Strand Committees: increasing faculty buy-in for change efforts; capitalizing on the enthusiasm of a few faculty members to serve as change agents; and structuring the committees so participation is open, voluntary, and there is continuity to the work. The authors present the history and context of Strand Committees at a large, recently consolidated public university, highlight examples of successful and beneficial changes resulting from this work, and discuss how Strand Committees may lead to supporting improvements in teaching and learning in undergraduate mathematics