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. Author manuscript; available in PMC: 2020 Nov 1.

Published in final edited form as: Psychopharmacology (Berl). 2019 Jun 13;236(11):3371–3382. doi: 10.1007/s00213-019-05297-x

Figure 1. — 1a: This figure displays the procedures completed at each visit in this within-subjects crossover design. Screening visit procedures included obtaining informed consent, preliminary eligibility determination, and shock sensitivity assessment. At study visit 1 we randomly assigned participants to drug administration order (between-subjects). All participants receive both prazosin and placebo (within-subjects), one at each study visit. Participants randomized to order A (n = 34) received 2mg prazosin at study visit 1 and placebo at study visit 2. Participants randomized to order B (n = 30) received placebo at study visit 1 and 2mg prazosin at study visit 2. At study visits 1 and 2 participants were orally administered a pill and completed the General Startle Reactivity Task (75 minutes post-dose) and NPU Task (90 minutes post-dose).

1b: In the NPU task, participants viewed a series of colored square “cues” displayed briefly on a computer screen. We presented cues in a blocked design with three conditions: No Shock (N), Predictable Shock (P), and Unpredictable Shock (U). The upper panel displays counterbalanced conditions both within- and between-subjects. Participants completed the same condition order at both study visits. The lower panel displays examples of each condition. All blocks included 6 cues presented sequentially for 5 seconds separated by a variable inter-trial interval (ITI; 14-20 seconds). In No Shock, we instruct participants that no electric shocks will be administered at any time. In Predictable Shock, we instructed participants that they would receive a shock at the end of every cue, but never during the ITI, so that the cue ‘predicted’ that the shock would occur in several seconds. In Unpredictable Shock, we instructed participants that they could receive a shock at any time, during both the cues and ITIs, so that the occurrence of the shock was unpredictable to the participant. We measured the eye-blink startle response elicited by “startle probes” (5ms acoustic white noise) presented binaurally over headphones. We calculated startle potentiation during cues separately in Predictable and Unpredictable Shock conditions as the differences between response to startle probes during the shock conditions and no-shock conditions (i.e., predictable startle potentiation = predictable cue – no shock cue). After the NPU task, participants retrospectively reported their subjective anxiety/fear during each condition cue. A figure legend is displayed in the left panel.

Figure 1b modified with permission from Schmitz & Grillon (2012). Used with permission of Springer Nature.

Figure 1. — 1a: This figure displays the procedures completed at each visit in this within-subjects crossover design. Screening visit procedures included obtaining informed consent, preliminary eligibility determination, and shock sensitivity assessment. At study visit 1 we randomly assigned participants to drug administration order (between-subjects). All participants receive both prazosin and placebo (within-subjects), one at each study visit. Participants randomized to order A (n = 34) received 2mg prazosin at study visit 1 and placebo at study visit 2. Participants randomized to order B (n = 30) received placebo at study visit 1 and 2mg prazosin at study visit 2. At study visits 1 and 2 participants were orally administered a pill and completed the General Startle Reactivity Task (75 minutes post-dose) and NPU Task (90 minutes post-dose).

1b: In the NPU task, participants viewed a series of colored square “cues” displayed briefly on a computer screen. We presented cues in a blocked design with three conditions: No Shock (N), Predictable Shock (P), and Unpredictable Shock (U). The upper panel displays counterbalanced conditions both within- and between-subjects. Participants completed the same condition order at both study visits. The lower panel displays examples of each condition. All blocks included 6 cues presented sequentially for 5 seconds separated by a variable inter-trial interval (ITI; 14-20 seconds). In No Shock, we instruct participants that no electric shocks will be administered at any time. In Predictable Shock, we instructed participants that they would receive a shock at the end of every cue, but never during the ITI, so that the cue ‘predicted’ that the shock would occur in several seconds. In Unpredictable Shock, we instructed participants that they could receive a shock at any time, during both the cues and ITIs, so that the occurrence of the shock was unpredictable to the participant. We measured the eye-blink startle response elicited by “startle probes” (5ms acoustic white noise) presented binaurally over headphones. We calculated startle potentiation during cues separately in Predictable and Unpredictable Shock conditions as the differences between response to startle probes during the shock conditions and no-shock conditions (i.e., predictable startle potentiation = predictable cue – no shock cue). After the NPU task, participants retrospectively reported their subjective anxiety/fear during each condition cue. A figure legend is displayed in the left panel.

Figure 1b modified with permission from Schmitz & Grillon (2012). Used with permission of Springer Nature.