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Sang Wook Hong, QIng Yu, Won Mok Shim; Attentional modulation of color representation in human lateral geniculate nucleus. Journal of Vision 2016;16(12):1147. doi: 10.1167/16.12.1147.
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Studies on the non-human primate visual system show a strict distinction between two cardinal chromatic channels, parvocelluar (L-M) and koniocellular (S-(L+M)), in neuronal responses of the lateral geniculate nucleus (LGN), which may result in a limited color representation at LGN level. Using functional Magnetic Resonance Imaging (fMRI) in conjunction with a forward encoding model (Brouwer & Heeger, 2009), we investigate first, whether both cardinal and inter-cardinal colors can be represented in the human LGN, and second, whether these color representations can be modulated by selective attention. On each block, observers viewed equi-luminant concentric ring patterns, composed of either one of four cardinal colors varying on only one channel or four inter-cardinal colors varying on both channels, and equal-energy-spectrum white, which drifted alternately in expanding and contracting directions. Observers performed either a central RSVP task (attention to fixation condition) or a color discrimination task (attention to color condition), which were alternated between blocks within each experimental run. Observers were instructed to report the target (letter 'J' or 'K') among other letters in the central RSVP task and to detect near-threshold level (measured for individual observers and for each color separately) changes in color in the color discrimination task. We found that attention can modulate the population-level color tuning responses to both cardinal and inter-cardinal colors. Our results demonstrate that both cardinal and inter-cardinal colors can be represented at the LGN level and that attentional feedback alters population-level responses to chromatic information in the LGN.
Meeting abstract presented at VSS 2016
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