Advancements in Retina Stimulation Enable Visualization of a New Human-Perceived Color

Researchers from the University of California, Berkeley, in collaboration with colleagues at the University of Washington, have pioneered a groundbreaking method to stimulate the retina, allowing individuals to perceive a color previously unseen by humans. Published in Science Advances, this innovative approach involves precisely targeting specific photoreceptors within the eye.

The human retina contains two primary types of photoreceptors: rods, which facilitate vision in low-light environments, and cones, responsible for color perception. Cones are further categorized based on their sensitivity to different wavelengths of light into long, medium, and short wavelength cones (L, M, and S). Prior research indicated that there is some overlap in the wavelengths processed by these cones. The research team hypothesized that stimulating only one type, particularly the M cones, could induce unique visual experiences.

Using adaptive optics optical coherence tomography, the scientists mapped individual M photoreceptors within volunteers’ retinas, creating personalized retinal profiles. Participants then focused on a specific target while a laser was directed at these M cells, activating them selectively. This technique was dubbed "Oz," a nod to the Wizard of Oz stories.

As a result of this targeted stimulation, participants— including some of the researchers—reported seeing a distinctive new color, which they named "olo." Most described olo as a vivid, highly saturated blue-green hue. To demonstrate this effect, the researchers added the olo color into photographs and videos, offering a novel visual experience.

The implications of this research are profound. Not only does it open pathways for understanding human color perception, but it also holds potential for developing treatments for color vision deficiencies, such as color blindness. Furthermore, the technique could simulate the perception of a fourth type of cone, similar to what is observed in tetrachromacy, potentially expanding our understanding of human visual capabilities.

This breakthrough offers exciting prospects for both scientific exploration and clinical applications, revealing new dimensions of how we see and interpret the world around us.