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L. Forest Gruss, Andreas Keil; Visuocortical changes during discriminant aversive conditioning: Effects of inter-individual differences in contingency awareness and autonomic engagement. Journal of Vision 2015;15(12):1343. doi: 10.1167/15.12.1343.
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© ARVO (1962-2015); The Authors (2016-present)
Contingency learning of a noxious stimulus can be systematically studied in humans using classical fear conditioning. Conditioning studies utilizing the steady state visually evoked potential (ssVEP) have shown CS discrimination to occur as far downstream as lower-tier visual cortex, but the temporal evolution and inter-individual differences contributing to this process remain unclear. We implemented an uninstructed, differential fear-conditioning paradigm in which two orientations of a rapidly phase-reversing Gabor grating served as the conditioned stimuli (CS), only one of which (CS+) was ever paired with a 96db white noise (US, unconditioned stimulus). After a brief habituation phase, participants (n=20) were informed that a loud noise would occur at the end of some trials and were asked after every trial to indicate the likelihood of hearing the loud noise when viewing a specific Gabor grating. Acquisition consisted of an initial 100% CS+/US contingency followed by partial pairing (66%) and one re-exposure trial presented halfway through extinction. Preliminary results indicate that one group of participants (n=11) demonstrated rapid and sustained CS discrimination in their contingency ratings lasting throughout extinction, whereas the other group (n=9) showed gradual or no discrimination during acquisition. In terms of ssVEP data, observers with rapid and sustained discrimination learning demonstrated strong selective amplification of the CS+ grating, which habituated late in acquisition. By contrast, observers with little behavioral discrimination displayed later and smaller discrimination effects at the level of visual cortex. This suggests that behavioral responses to the conditioning regime are reflected in temporal dynamics of visual electrocortical facilitation.
Meeting abstract presented at VSS 2015
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