Chapter 7 – Pharmacological fMRI 235 On average, participants reported that they believed the information they received during the study (M = 7.3, SD = 2.3), they were not concerned about what the researcher thought of them or changing their responses out of compliance (M = 0.6, SD = 1.1), they were focused on the heat stimuli (M = 8.2, SD = 1.2), and they noticed the increased pain association with the nocebo electrical stimuli (Mean = 9.2, SD = 1.2). We ran Pearson’s correlations between the magnitude of nocebo hyperalgesia and manipulation check exit questions and none of the responses to exit questions where significantly correlated with the magnitude of nocebo responses (all p > 0.05). Table 1. Descriptive statistics of demographics, temperatures used, pain ratings, questionnaires, and learning rates. Mean SD Min. Median Max. Age 22.9 3.3 18 22 35 Moderate pain used (°C) 46.78 0.56 45.00 46.9 48.00 High pain used (°C) 48.48 0.50 47.00 48.5 50.00 Warmth threshold (°C) 34.07 1.31 32.80 33.80 40.00 Pain threshold (°C) 44.47 2.56 34.80 45.10 47.20 Pre-conditioning pain difference 3.26 0.96 1.29 3.36 5.71 Baseline pain difference 2.40 1.33 -0.50 2.30 6.10 Acquisition pain difference 3.44 1.29 0.89 3.36 6.82 Extinction first trials pain difference * 1.77 1.47 -1.00 2.00 5.00 Extinction five trials pain difference * 1.14 1.05 -0.90 0.90 3.90 Extinction final trials pain difference * 0.73 0.63 -0.33 0.53 2.22 PCS score 25.12 6.82 13.00 24.00 45.00 BVS score 17.03 5.65 6.31 17.41 31.38 STAI state score 32.73 8.74 20.00 33.33 60.00 STAI trait score 37.46 7.385 25.00 37.00 58.00 Learning ± score total pre-DCS 5.59 1.49 2.00 5.75 8.00 Learning ± score total post-DCS 5.28 1.84 0.75 5.50 8.00 Learning ± change pre- to post-DCS -0.31 1.59 -4.00 -0.50 5.00 Note: All temperatures are reported in degrees Celsius. * Pain differences represent the mean NRS difference between nocebo/high pain trials minus control/moderate pain trials for each phase. In extinction, the first pair (evocation), first 5 pairs (evocation), and final 9 pairs of nocebo and control trials are reported. ± Learning was measured as a manipulation check with the Wechsler Memory Scale. PCS, Pain Catastrophizing Scale; BVS, Body Vigilance Scale; STAI, Spielberger State-Trait Anxiety Inventory; DCS, Dcycloserine.
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