The contribution of the koniocellular visual pathway to aversive learning in human visual cortex.

The present study examined the extent to which koniocellular inputs to the visual cortex are sensitive to aversive conditioning, as indexed by electrocortical activation modulated by conditioned threat. A simple differential aversive conditioning task was used to evoke visuocortical activation in response to conditioned threat (CS+) and safety (CS-) cues in each condition (tritan and luminance). The tritanopic technique was used to convey cues to S-cones that transmit color-opponent signals to regions along the koniocellular visual pathway (tritan condition). In addition, a luminance condition was included to examine visuocortical activation in response to achromatic cues that preferentially activate luminance channels (luminance condition). Steady-state visual evoked potential (ssVEP) responses to conditioned threat and safety cues were analyzed in each condition (luminance and tritan) using a nonparametric Bayesian bootstrap approach. Results showed decisive evidence (logarithmic Bayes factors, logBF10 > 2) of aversive learning in the tritan and luminance conditions, indicated by increased ssVEP envelope amplitudes in response to the CS+ compared to the CS- stimuli in occipital sensors. To further examine the koniocellular involvement in aversive learning, transitive Bayes factors were computed to compare the relative magnitude of the conditioning effects across conditions. Although transitive Bayesian comparisons showed decisive evidence indicating the magnitude of the luminance conditioning effect was larger than the tritan conditioning effect, differences in adaptation across conditions warrant further investigation. Importantly, the present study demonstrated that both koniocellular and luminance channel inputs were modulated by aversive conditioning in the human visual cortex.