Color Compensation in Anomalous Trichromats Assessed with fMRI

A quadratic model captures the human V1 response to variations in chromatic direction and contrast

“…We do not, however, have any particular reason to think that the chromatic tuning and contrast response functions we measured would have been substantially different in the context of different attentional task difficulty. In this regard, we note that Tregillus et al, 2021 measured contrast response functions for L-M and S-(L+M) color directions within V1 under two different attentional tasks and found no significant effect of task on the two contrast response functions.…”

“…One possible cortical mechanism that could compensate for the reduced L-M signal-to-noise ratio with eccentricity as predicted by random wiring models is supra-threshold compensation for reduced signals. Mechanisms of this sort have been postulated in the domain of contrast perception ( Georgeson and Sullivan, 1975 ) and anomalous trichromatic vision ( Boehm et al, 2014 ; Tregillus et al, 2021 ). Another possibility is a differential change in stimulus integration area across chromatic directions and with eccentricity.…”

An image reconstruction framework for characterizing initial visual encoding

“…Although our analysis does underestimate the amount of total noise in the visual system (i.e. we only consider noise at cone excitations, but see Ala-Laurila et al, 2011 for a detailed treatment of noise in the retina), this nonetheless suggests that a downstream circuit that properly compensates for the shift in cone spectral sensitivity can, in principle, maintain relatively normal color perception in the low noise regime ( Tregillus et al, 2021 ). This may potentially be related to some reports of less than expected difference in color perception between anomalous trichromats and color normal observers ( Bosten, 2019 ; Lindsey et al, 2020 ).…”

An image reconstruction framework for characterizing initial visual encoding

“…As SNR drops, this becomes less feasible. Although our analysis does underestimate the amount of noise in the visual system (i.e., we only consider noise at cone excitations, but see Ala-Laurila et al 2011 for a detailed treatment of noise in the retinal circuit), this nonetheless suggests that a downstream circuit that properly compensates for the shift in cone spectral sensitivity can, in principle, maintain relatively normal color perception in the low noise regime (Tregillus et al 2021). This may potentially be related to some reports of less than expected difference in color perception between anomalous trichromats and color normal observers (Bosten 2019; Lindsey, Hutchinson, and Brown 2020).…”