Abstract
Reversal learning paradigms are commonly used to investigate cognitive and affective processes, including in neuropsychiatric conditions. The present study uses a novel aversive reversal learning paradigm to investigate visuocortical responses to threat stimuli, with prior research focusing on limbic and frontocortical regions. Participants (N = 44; 18-23 years) viewed flickering Gabor patches at different orientations, driving steady-state visual evoked responses (ssVEP) recorded with EEG. An aversive loud noise was used as the unconditioned stimulus, consistently paired with one orientation (the CS+) and never with the other (CS-). After the initial acquisition phase, the contingency between the conditioned and unconditioned stimuli was reversed. Test phases following initial acquisition and reversal examined frequency-tagged ssVEPs evoked by CS+ and CS-, as well as a neutral accompanying Gabor, allowing us to quantify competition effects as a function of learning. Participants were asked to rate each stimulus in terms of valence, arousal, and expectancy before, during, and after learning. Continuous EEG was recorded using a saline EEG system with 129 electrodes/sensors and artifact-free trials were analyzed in the frequency domain, using the Discrete Fourier Transform, after averaging trials by condition. Statistical analyses were conducted using Matlab. We compared the ssVEP amplitude at the tagging frequencies during the critical test phases, across the entire topography. As expected, the ssVEP evoked by the conditioned threat cue (CS+) was enhanced over posterior sites, compared to the CS-, after the initial acquisition phase. Importantly, this effect reversed after 60 trials of reversal learning, and increased in effect size: The new CS+ (the former CS-) prompted selectively heightened ssVEP signals compared to the new CS-. Findings support the notion that experience changes the amplitude of neural mass activity in human visual cortex. They also show that these changes are malleable, adapting and even reversing with environmental contingencies.