| Why do we perceive a white object still as white in the reddish light at dusk? Because there is white balance, a mechanism of color constancy present in the eye that makes us interpret the color of an object independently of the spectral composition of the illumination. This mechanism originates in the first synapse of the retina, between the light-sensitive cone photoreceptors and the horizontal cells. The mechanism by which horizontal cells seem to communicate with cones is a rather unique one (ephaptic). My work in the Retinal Signal Processing Unit is to characterize this mechanism and to look at its modulation by neurotransmitters involved in light-dark adaptation. Horizontal cells are measured using intracellular sharp electrodes and cone photoreceptors are studied using patch-clamp measurements. Together, these measurements give a quantitative description of the communication between cones and horizontal cells. |
