Neurons process luminance and color signals in ways that are still not fully understood. The first steps in the sensation of luminance and red-green chromaticity is the absorption of light by two classes of cone photoreceptors at the back of the eye: the long (L-) and medium (M-) wavelength-sensitive cones.
We seek to understand how signals from these two cone types are combined in the visual cortex (area V1). We record from individual V1 neurons while stimulating targeted regions of their receptive fields with uniformly colored flashes that modulate varying combinations of L- and M-cone ratios to varying degrees. Neuronal responses to these stimuli are then fit with mathematical models to find concise, accurate descriptions of cone signal combinations.