Abstract
Prior research suggests the presence of higher order cortical chromatic channels that process colors along intermediate axes of color space, in addition to the LM and S opponent channels. The chromatic visual evoked potential (crVEP) has been used to study color processing in basic, clinical, and developmental studies. Although the resistance of the crVEP to attentional modulation suggests that the crVEP reflects relatively low level responses, the level at which the crVEP reflects chromatic processing is unknown. Chromatic adaptation studies have revealed evidence for contributions from selective cardinal mechanisms in the crVEP. However, evidence for contribution from the intermediate channels has been less compelling. In the present study we employed chromatic contrast adaptation to test for the presence of input from intermediate channels in the crVEP. Amplitude changes of the CIII-CII pre- and post-adaptation waveform components were measured. The data were fit to ellipses in a cone-based color space and analyzed for interactive adaptation effects on orthogonal axes. The results indicate substantial contribution from intermediately tuned channels to the crVEP. These data suggest that the crVEP can be used to objectively and noninvasively investigate spatial and temporal characteristics of these higher-order channels and the role they play in cortical color processing.
Meeting abstract presented at VSS 2012