11 research outputs found
Electrophysiological Characterization of GFP-Expressing Cell Populations in the Intact Retina
Studying the physiological properties and synaptic connections of specific neurons in the intact tissue is a challenge for those cells that lack conspicuous morphological features or show a low population density. This applies particularly to retinal amacrine cells, an exceptionally multiform class of interneurons that comprise roughly 30 subtypes in mammals1. Though being a crucial part of the visual processing by shaping the retinal output2, most of these subtypes have not been studied up to now in a functional context because encountering these cells with a recording electrode is a rare event
3D Winding Number: Theory and Application to Medical Imaging
We develop a new formulation, mathematically elegant, to detect critical points of 3D scalar images. It is based on a topological number, which is the generalization to three dimensions of the 2D winding number. We illustrate our method by considering three different biomedical applications, namely, detection and counting of ovarian follicles and neuronal cells and estimation of cardiac motion from tagged MR images. Qualitative and quantitative evaluation emphasizes the reliability of the results
Modulation of coupling between retinal horizontal cells by retinoic acid and endogenous dopamine
The regulation of electrical coupling between retinal neurons appears to be an important component of the neuronal mechanism of light adaptation, which enables the retina to operate efficiently over a broad range of light intensities. The information about the ambient light conditions has to be transmitted to the neuronal network of the retina and previous evidence has indicated that dopamine is an important neurochemical signal. In addition, recent studies suggest that another important chemical signal is retinoic acid, which is a light-correlated byproduct of the phototransduction cycle. This review summarizes the latest findings about the effects of dopamine and retinoic acid on gap junctional coupling in the retinas of mouse, rabbit and fish. (C) 2000 Elsevier Science B.V. All rights reserved