Abstract
Neurons in the visual cortex sharpen their orientation tuning as humans learn aversive contingencies. A stimulus orientation (CS+) that reliably predicts an aversive noise (unconditioned stimulus: US) is selectively enhanced in lower-tier visual cortex, while similar unpaired orientations (CS−) are inhibited. Here, we examine in male volunteers how sharpened visual processing is affected by fear extinction learning (where no US is presented), and how fear and extinction memory undergo consolidation one day after the original learning episode. Using steady-state visually evoked potentials from electroencephalography in a fear generalization task, we found that extinction learning prompted rapid changes in orientation tuning: Both conditioned visuocortical and skin conductance responses to the CS+ were strongly reduced. Next-day re-testing (delayed recall) revealed a brief but precise return-of-tuning to the CS+ in visual cortex accompanied by a brief, more generalized return-of-fear in skin conductance. Explorative analyses also showed persistent tuning to the threat cue in higher visual areas, 24 h after successful extinction, outlasting peripheral responding. Together, experience-based changes in the sensitivity of visual neurons show response patterns consistent with memory consolidation and spontaneous recovery, the hallmarks of long-term neural plasticity.
Highlights
In the present study, we tested the alternative hypotheses that visuocortical responses will show extinction recall or spontaneous recovery after a consolidation period
We explored how occipital cortex activity is shaped by fear acquisition and extinction across the two experimental days
We found a significant effect of learning phase (F(1.7,30.2) = 4.756, p = 0.021, part. η2 = 0.209, N = 19), due to higher occipital state visually evoked potentials (ssVEP) power during acquisition (Fig. 2A)
Summary
We tested the alternative hypotheses that visuocortical responses will show extinction recall or spontaneous recovery after a consolidation period. To validate the extent to which learning took place, we assessed conditioned skin conductance responses (SCR, an indicator of sympathetic nervous system activity), subjective ratings of CS valence and arousal (evaluative learning), and collected US expectancy ratings (contingency knowledge). For those responses, we expected to see a gradual decrease in responding with decreasing similarity to the CS+, i.e. stimulus generalization[25,39,40] instead of lateral inhibition
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.