Rod-Cone Interaction in the mesopic

LUIS ISSOLIO; PABLO BARRIONUEVO; JUAN ANTONIO APARICIO; BEATRIZ MATEZANZ; ISABEL ARRANZ; SANTIAGO MAR; ELISA COLOMBO

Huerta Grande

Congreso; Segunda Reunión Conjunta de Neurociencias; 2010

Rod-cone interactions are a fundamental operation in visual processing under mesopic light levels. They can be observed when the stimulation of cones surrounding a test reduces the sensitivity of the rods sensing that test, or from the temporal point of view, acting to decrease the temporal bandwidth of the visual system. We present results obtained in two different kinds of psychophysical experiments made in the mesopic range evidencing these interactions. In one of them, the effect of a glare source was measured (10 degree to the visual axis) upon the brightness of a foveal test. The results showed a brightness reduction of the test due to the glare, but also they evidence that brightness reductión is stronger when the background luminance decreases. In the second experiment the sensitivity of the retina was studied when there are a sudden changes in adaptation. In this case the results showed a loss of sensitivity when moving from a steady dark adaptation condition to a transient mesopic condition. It also became clear that the speed of adaptation is greatest in an area of the retina between 6 and 9 degrees of eccentricity. Both sets of results show the phenomenon of rod-cone interaction and can be interpreted in terms of the cellular pathways that were proposed for this operation such as gap junctions and AII cells.