Table 1.
Experimental design overview of studies investigating associations between brain morphology and associative processes during fear acquisition training and extinction in human participants.
| References | N | Segmenta-tion approach | RIR (%) | Extinction | # of Acq trials for CS+/CS− | # of Ext trials for CS+/CS− | Outcome measures | Tested associations with | SCR quanti-fication via | SCR scoring criteria; CS duration | Covariates | ||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| SCR | Fear rating | CSdiff | CS+ | CS− | CSavg | ||||||||||
| Abend et al., 201917 | 250 | Freesurfer | 80 | Immediate | 10/10 | 8/8 | ✓ | ✓ | ✗ | ✗ | ✗ | ✓ | TTP | 0–5 s post CS onset; 7 s CS | Age, anxiety |
| Abend et al., 202022 | 351 | Freesurfer | 80 | N/A | 10/10 | 8/8 | ✓ | ✓ | ✗ | ✓a | ✗ | ✗ | TTP | 1–5 s post CS onset; 7 s CS | Age, anxiety |
| Cacciaglia et al., 201314 | 52 | Manual | 50 | Immediate | 36/36 | 18/18 |
✓ ✓ |
✓ | ✓ | ✓ | ✓ | ✗ | TTP | 1–9 s post CS onset; 6 s CS | Age, gender, anxiety, education |
| Ehlers et al. (current study) | 107 | Freesurfer | 100 | Delayed | 14/14 | 14/14 | ✓ | ✓ | ✓ | ✓ | ✓ | ✗ | TTP | 0.9–3.5 s post CS onset; 6 s CS | TIV, sex |
| Hartley et al., 201120 | 18 | Freesurfer | 17 | N/A | 21/15; | N/A | ✓ | ✗ | ✓ | ✗ | ✗ | ✗ | TTP | 0.5–4.5 s post CS onset; 4 s CS | Sex, anxiety |
| 12 | Freesurfer | 35 | Immediate | 23/15 | 15/15 | ✓ | ✗ | ✓ | ✗ | ✗ | ✗ | TTP | 0.5–4.5 s post CS onset; 4 s CS | Sex, anxiety | |
| Milad et al., 200524 | 14 | Freesurfer | 100 | Immediate | 5/5 | 10/10 | ✓ | ✗ | ✓ | ✓ | ✓ | ✗ | b.c. | Max (12 s post CS onset)-mean (2 s pre CS onset); 12 s CS | N/A |
| Milad et al., 200721 | 14 | Freesurfer | 100 | Immediate | 5/5 | 10/10 | ✓ | ✗ | ✓ | ✗ | ✗ | ✗ | b.c. | Max (12 s post CS onset)-mean (2 s pre CS onset); 12 s CS | N/A |
| Rauch et al., 200525 | 14 | Freesurfer | 100 | Immediate | 5/5 | 10/10 | ✓ | ✗ | ✗ | ✓ | ✗ | ✗ | b.c. | Max (12 s post CS onset)-mean (2 s pre CS onset); 12 s CS | Sex, extraversion, neuroticism |
| Winkelmann et al., 201516 | 68; 53 | Freesurfer | 50 | Immediate | 36/36 | 18/18 | ✓ | ✓ | ✓ | ✗ | ✗ | ✗ | Ledalab | Sum (SCRs 1–7 s post CS onset); 6 s CS | TIV, age, gender |
Two studies (Abend et al. 2019, Abend et al. 2020) that did not investigate associative processes during fear acquisition training but average responding to the CS+ and CS− across experimental phases are included for completeness.
None of the studies explicitly instructed the participants with regard to the CS/US contingencies, Abend et al. (2019) and Hartley et al. (2011), however, informed participants about the fact that association can be learning during the experiment.
RIR reinforcement rate, N/A information not available, CSdiff differential SCR [(CS+) – (CS−)], CSavg SCR averaged across the CS+ and CS− as well as across fear acquisition and extinction training, TTP trough to peak, b.c. baseline correction, TIV total intracranial volume.
aIn Abend et al. (2020) computational modeling of SCR to the CS+ was used to predict SCR over the course of learning and assess learning rate during acquisition and extinction.