RT Journal Article
SR Electronic
T1 Selective Color Constancy Deficits after Circumscribed Unilateral Brain Lesions
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 3094
OP 3106
DO 10.1523/JNEUROSCI.19-08-03094.1999
VO 19
IS 8
A1 Lukas Rüttiger
A1 Doris I. Braun
A1 Karl R. Gegenfurtner
A1 Dirk Petersen
A1 Paul Schönle
A1 Lindsay T. Sharpe
YR 1999
UL http://www.jneurosci.org/content/19/8/3094.abstract
AB The color of an object, when part of a complex scene, is determined not only by its spectral reflectance but also by the colors of all other objects in the scene (von Helmholtz, 1886; Ives, 1912; Land, 1959). By taking global color information into account, the visual system is able to maintain constancy of the color appearance of the object, despite large variations in the light incident on the retina arising from changes in the spectral content of the illuminating light (Hurlbert, 1998; Maloney, 1999). The neural basis of this color constancy is, however, poorly understood. Although there seems to be a prominent role for retinal, cone-specific adaptation mechanisms (von Kries, 1902; Pöppel, 1986; Foster and Nascimento, 1994), the contribution of cortical mechanisms to color constancy is still unclear (Land et al., 1983; D’Zmura and Lennie, 1986). We examined the color perception of 27 patients with defined unilateral lesions mainly located in the parieto-temporo-occipital and fronto-parieto-temporal cortex. With a battery of clinical and specially designed color vision tests we tried to detect and differentiate between possible deficits in central color processing. Our results show that color constancy can be selectively impaired after circumscribed unilateral lesions in parieto-temporal cortex of the left or right hemisphere. Five of 27 patients exhibited significant deficits in a color constancy task, but all of the 5 performed well in color discrimination or higher-level visual tasks, such as the association of colors with familiar objects. These results indicate that the computations underlying color constancy are mediated by specialized cortical circuitry, which is independent of the neural substrate for color discrimination and for assigning colors to objects.