Neural signature of delayed fear generalization under stress

Abstract

Because threatening stimuli rarely occur in the exact same form across situations, the generalization of fear to stimuli resembling the stimulus initially associated with danger promotes the effective avoidance of threat. Research over the past decade suggested that this process of fear generalization

Rethinking avoidance

“…The enhancing effect of acute stress on the generalization of fear (i.e., US expectancies) described in Chapter 3 align well with previous studies that observed an acute stress or cortisol effect on fear generalization in humans (e.g., and animals (e.g., Bender et al, 2018;Kaouane et al, 2012;Kolodziejczyk & Fendt, 2020;Lesuis et al, 2021;Liu et al, 2019;Ren et al, 2022;Zhu et al, 2018). However, a recent study failed to find an effect of acute stress on fear generalization in healthy individuals (Kausche, Zerbes, Kampermann, Büchel, et al, 2021). Similar to the paradigm in Chapter 3 and the study by , participants in that study underwent a fear acquisition procedure on Day 1 and a stress induction (i.e., Trier Social Stress Test, TSST) or no-stress-control task and fear generalization test on Day 2 (Kausche, Zerbes, Kampermann, Büchel, et al, 2021).…”

“…However, a recent study failed to find an effect of acute stress on fear generalization in healthy individuals (Kausche, Zerbes, Kampermann, Büchel, et al, 2021). Similar to the paradigm in Chapter 3 and the study by , participants in that study underwent a fear acquisition procedure on Day 1 and a stress induction (i.e., Trier Social Stress Test, TSST) or no-stress-control task and fear generalization test on Day 2 (Kausche, Zerbes, Kampermann, Büchel, et al, 2021). Acute stress did not modulate fear generalization, neither on a behavioral nor on a neural level.…”

“…Most human studies investigated fear generalization on the same day as fear acquisition took place (e.g., Kaczkurkin et al, 2017;Lis et al, 2020;. However, given that the overgeneralization of fear in anxiety(-related) disorders (e.g., PTSD) often develops over time after the experience of a threatening event, more recent studies attempted to mimic this time course by investigating fear generalization after a delay (e.g., Andreatta et al, 2020;Kausche, Zerbes, Kampermann, Büchel, et al, 2021;Kausche, Zerbes, et al, 2021a. For example, Kausche, Zerbes, Kampermann, Büchel, et al (2021) found enhanced fear generalization to GSs after a 24h delay in contrast to an immediate test of fear generalization, but the fear memory for the original CS+ was not affected by the delay.…”

“…However, given that the overgeneralization of fear in anxiety(-related) disorders (e.g., PTSD) often develops over time after the experience of a threatening event, more recent studies attempted to mimic this time course by investigating fear generalization after a delay (e.g., Andreatta et al, 2020;Kausche, Zerbes, Kampermann, Büchel, et al, 2021;Kausche, Zerbes, et al, 2021a. For example, Kausche, Zerbes, Kampermann, Büchel, et al (2021) found enhanced fear generalization to GSs after a 24h delay in contrast to an immediate test of fear generalization, but the fear memory for the original CS+ was not affected by the delay. In contrast, Dunsmoor and colleagues (2017) found that the proportion of participants who correctly identified the CS+ was lower after a 24h delay in comparison to an immediate fear generalization test, which raises the question whether it is fear generalization per se or memory recall that is affected by time.…”

“…Stress (i.e., both early and late stress effects) had no impact on fear generalization tested 24 hours later. Similar to other human studies investigating the effect of stress on fear generalization Kausche, Zerbes, Kampermann, Büchel, et al, 2021;Kausche, Zerbes, et al, 2021a, our stress manipulation occurred 24h after fear acquisition and immediately before a fear generalization test. It should be noted that the results of the animal studies and human studies are difficult to compare, because stress seems to affect distinct processes.…”