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Brian J. White, Susan E. Boehnke, Robert A. Marino, Laurent Itti, Douglas P. Munoz; Color Signals in the Primate Superior Colliculus. Journal of Vision 2008;8(17):5. doi: 10.1167/8.17.5.
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© ARVO (1962-2015); The Authors (2016-present)
Color is important for segmenting objects from backgrounds, which can in turn facilitate visual search in complex scenes. However, neural substrates that control overt visual orienting towards interesting objects (i.e., saccadic eye movements) are not believed to encode visual features such as color (Bichot, Schall, & Thompson, 1996; McPeek & Keller, 2002), despite direct projections from color-related areas to saccadic substrates such as the Superior Colliculus (SC)(Lock, Baizer, & Bender, 2003). Using a delayed saccade task, we measured the activity of visually responsive SC neurons (N=68) in two monkeys to stimuli derived from the DKL color space (Derrington, Krauskopf, & Lennie, 1984). We show the first evidence that neurons in the intermediate SC layers can respond to pure chromatic stimuli with the same magnitude as the best luminance stimulus (100% contrast). This activity is not adequately explained by residual luminance signals because 1) neurons with an equal or better color response showed significantly longer visual onset latencies (25–30ms), and 2) the luminance control-stimulus was more than 20cd/m2 different from the color stimuli. Furthermore, the color response was not seen for phasic-visual neurons obtained from the superficial SC layers. This implies that the color-related activity in the SC involves different pathways than luminance, and projects primarily to the intermediate SC layers. The delayed color response is also reflected by the longer saccadic reaction times previously reported for chromatic DKL stimuli (White, Kerzel, & Gegenfurtner, 2006). We conclude that this activity represents a true colour response only one stage from the brainstem premotor circuitry that drives the eyes.
BichotN. P.SchallJ. D.ThompsonK. G. (1996). Visual feature selectivity in frontal eye fields induced by experience in mature macaques. Nature, 381(6584), 697–699.
DerringtonA. M.KrauskopfJ.LennieP. (1984). Chromatic mechanisms in lateral geniculate nucleus of macaque. J Physiol, 357, 241–265.
LockT. M.BaizerJ. S.BenderD. B. (2003). Distribution of corticotectal cells in macaque. Exp Brain Res, 151(4), 455–470.
McPeekR. M.KellerE. L. (2002). Saccade target selection in the superior colliculus during a visual search task. J Neurophysiol, 88(4), 2019–2034.
WhiteB. J.KerzelD.GegenfurtnerK. R. (2006). Visually guided movements to color targets. Exp Brain Res, 175(1), 110–126.
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