Isolating the Contribution of the Koniocellular Visual Pathway in Aversive Learning in Human Visual Cortex

The present study examined the contribution of the koniocellular retino-geniculate visual pathway to the electrocortical amplification of threat cues in human visual cortex using an aversive conditioning task. The task involved tritan stimuli, which are thought to convey visual information through S-cone signals that project to regions along the koniocellular pathway (tritan condition) and achromatic stimuli that preferentially activate luminance channels (luminance condition). Steady-state visual evoked potential (ssVEPs) responses to the conditioned threat (CS+) and safety cues (CS-) in each condition were analyzed using a non-parametric Bayesian bootstrapped approach. Results showed that the tritan and luminance conditions exhibited greater ssVEP responses to the CS+ compared to the CS-stimuli in occipital sensors early into the trial (0 ms - 1000 ms; logBF10 > 2, decisive support). In addition to these early conditioning effects, a late conditioning effect was observed (1500 ms - 2500 ms) in the tritan condition that emerged in bilateral anterior sensors (logBF10 > 2). To further examine the tritan contribution to aversive learning, transitive Bayes factors were computed to compare the magnitude of the conditioning effects across conditions. Transitive Bayes factors showed that the early conditioning effect was larger in the luminance condition compared to the tritan condition (logBF10 > 2). Furthermore, the late conditioning effect remained larger in the tritan condition compared to the luminance condition (logBF10 > 2). Our findings suggest that both the koniocellular visual pathway and luminance channels play a role in the electrocortical amplification of threat signals in human visual cortex.