Agradecimentos: We are grateful to Dr Hiss Martins-Ferreira for his constructive suggestions and enthusiastic encouragement, which made this work possible. We are also thankful to Dr Nada N. Boustany for her comments on the drafts of this manuscript. This project was supported by the following Brazilian government agencies: Conselho Nacional de Pesquisas—CNPq, Coordenação de Aperfeiçoamento de Pessoal de Ni'vel Superior-CAPES and Fundação de Amparo a Pesquisas do Estado de Minas Gerais-FAPEMIG Ver menos

Abstract: This paper presents a novel optical approach for the study of spreading depression in isolated retina. The method makes it possible to register the laser light scattered from each layer of the tissue, yielding a functional image of the retina during spreading depression. The tissue is kept intact, since histological cuts are not necessary. Measurements of other variables, such as extracellular potential, are also allowed by the described method. This is done simultaneously with the functional image in a high spatial resolution, with the positioning of the microelectrode tip being easily monitored. The information about temporal and spatial evolution of light was compacted in a single image. The image-processing technique used here enables the visualization of the light scattered by the inner plexiform layer (IPL), which is the most prominent scatter layer during spreading depression. The wavefront velocity and its increase as two wavefronts approach each other can then be determined, and it is also possible to observe the thickness variation of the tissue during the wave travel. The relationship between two peaks of light-scattering sequence during the phenomenon was studied at two wavelengths (632.8 and 543.5 nm). This relationship is shown to be dependent on the wavelength Ver menos