Anxiety and the visual brain
- Prof.dr.ir. M.J. (Matthias) Wieser
- Wednesday 7 June 2017
- Pieter de la Courtbuilding
2333 AK Leiden
Electrocortical facilitation of threat-predictive cues in early visual cortex
Sensory facilitation of cues that predict harm is a useful mechanism for the efficient detection of threat in the environment. In this talk, I report studies employing steady-state visual evoked potentials (ssVEPs), in which we examined sensory gain in early visual cortex in response to different sources of inherent or acquired threat.
Inherently threating faces enhanced sensory gain in high socially anxious individuals, only. Across aversive conditioning experiments, amplitudes of the face-evoked ssVEP revealed larger cortical mass activity in response to faces paired with aversive stimuli, indicating successful affective learning and concomitant short-term plasticity in visual cortex depending on the learning experience. Gaze cues seem to play a subordinate role in this type of fear acquisition, but may lead to different time courses in visuocortical learning, as single-trial analysis of ssVEP amplitudes revealed. Interestingly, the visual cortex seems not to track fear generalization in a linear manner but instead responses to the stimuli with greatest similarity to the threat-predictive cue were suppressed. In a modified NPU-threat paradigm, we observed that unpredictable threat is associated with sustained electrocortical amplification, whereas predictable threat leads to selective facilitation of threat-predictive cues.
Together, these results point at the preferential processing of both inherent and acquired threat in early visual cortex. The visual brain responses to inherent threat seem to depend on individual levels of social anxiety. The visual brain responses after aversive learning were persistently and selectively enhanced for only the threat stimulus. These changes support the hypothesis that short-term plasticity in primary visual cortex mediates the formation of perceptual biases to threat. The reported studies also nicely demonstrate the use of steady-state visual evoked potentials in tracking visual cortex plasticity in aversive learning and threat processing.