Functional imaging of the retinal layers by laser scattering: an approach for study of spreading depression in intact tissue

A special optical approach for the study of spreading depression in isolated retina is presented in this article. The method allows to register the laser light scattered, in a dark field configuration, by each layer of the tissue producing a functional imaging during spreading depression. The layers can be seen maintaining the tissue intact without any histological cut. The method seems to be useful for the measurements of different variables, like extracellular potential, simultaneously with the functional image in a high spatial resolution. The positioning of the microelectrode tip is easily monitored. An image processing method was used to compact in a single image the information about the layers scattering and temporal evolution. The technique allows the visualization of the light scattered by the inner plexiform layer, which is the most prominent scatter layer, during spreading depression.