Neural correlates of the Bezold-Br'cke color shift
Our ability to see and recognize objects seems effortless, yet depends upon an elaborate neural circuitry that is poorly understood. We use the macaque monkey as a model system to investigate the neural mechanisms of vision because the monkey has highly developed visual abilities like humans. In monkeys, we can collect responses from neurons throughout the visual-processing pathway, allowing us to establish neural correlates of perceptual phenomena. To understand whether the specific computations neurons are performing are important to perception, we compare neural responses to perceptual judgments. In this study I explored the neural correlates of the Bezold-Br'cke hue shift, which describes the observations that the color associated with a particular wavelength changes depending on the intensity of the light. For example, lights that are blue at low luminance will appear greener at higher luminance. The Conway lab discovered clusters of neurons in macaque visual area V4 that show sharp color selectivity. In my project, I tested the extent to which these neurons shift their color preferences as the luminance of the stimuli is changed. To evaluate the extent to which these cells could support the Bezold- Br'cke perceptual phenomenon, I measured human color judgments in a color-matching task, using the same stimuli that were used to test the color properties of the macaque neurons. If the color cells in V4 are responsible for color perception, I predict that the shifts in their color tuning should be tightly correlated with perceptual judgments.