The Journal of Neuroscience, April 15, 1999, 19(8):3094-3106
Selective Color Constancy Deficits after Circumscribed Unilateral
Brain Lesions
Lukas
Rüttiger1,
Doris I.
Braun2,
Karl R.
Gegenfurtner3,
Dirk
Petersen4,
Paul
Schönle5, and
Lindsay T.
Sharpe1
1 Forschungsstelle für Experimentelle
Ophthalmologie, Universitätsaugenklinik Tübingen, 72076 Tübingen, Germany, 2 Sektion Visuelle Sensorik,
Universitätsaugenklinik Tübingen, 72072 Tübingen,
Germany, 3 Max-Planck-Institut für Biologische
Kybernetik, 72076 Tübingen, Germany, 4 Medizinische
Universität, Abteilung Neuroradiologie, 23538 Lübeck, Germany, and 5 Neurologische
Rehabilitationsklinik Schmieder, 78473 Allensbach, Germany
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.
Key words:
color vision; color constancy; visual perception; patients; lesions; clinical
Copyright © 1999 Society for Neuroscience 0270-6474/99/1983094-13$05.00/0