seeing color my friend??
Friday, March 23rd, 2007The retinas of most non-primate mammals contain only two classes vision cells that support dual-colored vision. In human and other primates, a duplication occurred on the x-chromosome, allowing for trichromatic vision(!!!!)- and hello to RBG color.
Obviously, having the peripheral sensory perception such as being able to see tri-color goes hand-in-hand with having the proper neuronal circuitry (the wires) to interpret it. Interestingly, New World Monkeys do not have this x-chromosome duplication of the photoreceptors. They were able to see color vision via changes in their single gene. And something called an X-linked inactivation (similar mechanism that produces the Calico cat) could produce patches of color R, color B, and color G. So, scientists thought may be the hardware is in place long before we had the physical traits to see color. Nature is waiting for this one last step before committing to full color vision!
Recently, scientists at the Neuroscience research institute at UC, Santa Barbara and the Departments of Opthalmology, medicine, and genetics at Johns Hopkins University were able to insert a color rod receptor gene into mouse. Their initial result shows the mouse do seem to respond to color now!! They ask can the brain have enough plasticity (a fancy word for being flexible) in interpreting this new dimension of color discrimination?
It turns out that mouse with newly acquired skill have changed physiological behavior and were able to discriminate along the axis of this new color dimension. This means, these animals do have the neuronal capacity but not yet the proper physiological/genetic endowment. Imagine inserting a gene that allows the mouse to talk!! hehehe
Reference: Jacobs et al, Science 23 March 2007:Vol. 315. no. 5819, pp. 1723 - 1725
