Article Figures & Data
Figures
- Figure 1.
Experimental and control groups for each experimental paradigm (pain, Parkinson's disease, hormone secretion) used in the present study.
- Figure 2.
The effects of verbally induced expectations and pharmacological conditioning on pain tolerance. A, Natural history of tolerance to ischemic arm pain over 4 consecutive days. B, Verbal suggestion of analgesia (placebo) on day 2 induces an increase in tolerance. C, Suggestion of hyperalgesia (nocebo) on day 2 induces a decrease in tolerance. D, Suggestion of analgesia on day 4 after a 2 d preconditioning with ketorolac (ket) induces a larger increase in tolerance than verbal suggestion alone in B. E, The same ketorolac preconditioning is totally ineffective, however, if suggestion of hyperalgesia is given on day 4. Pla, Placebo; Noc, nocebo.
- Figure 3.
The effects of verbally induced expectations on motor performance in Parkinsonian patients with implanted stimulating electrodes in the subthalamic nuclei. After the stimulator (Stim) had been turned off several times, a sham turning off (nocebo) induces a velocity decrease (•). This decrease is completely blocked (○) by the opposite verbal instruction (placebo). The broken line represents the natural history.
- Figure 4.
Natural history of GH (A) and cortisol (B) plasma concentrations for 3 consecutive days. Note that the mean concentrations do not change either during an observation period of 90 min or over a period of 3 d.
- Figure 5.
Verbal suggestions of GH increase (A) and decrease (B) have no effect on GH plasma concentration. C, After 2 d of sumatriptan preconditioning, suggestion of GH increase (Placebo) mimics the effects of sumatriptan. D, This effect is not caused by the suggestion itself, however, because the same sumatriptan-like effect is present after the opposite verbal instruction. *p < 0.05; **p < 0.03; ***p < 0.01.
- Figure 6.
Verbal suggestions of cortisol decrease (A) and increase (B) have no effect on cortisol plasma concentration. C, After 2 d of sumatriptan preconditioning, suggestion of cortisol decrease (Placebo) mimics the effects of sumatriptan. D, This effect is not caused by the suggestion itself, however, because the same sumatriptan-like effect is present after the opposite verbal instruction. *p < 0.04; **p < 0.02; ***p < 0.01.
- Figure 7.
Model to explain the findings of the present study. During a placebo procedure, conscious physiological processes, such as pain and motor performance, are affected by verbally induced expectations, even though a conditioning procedure is performed. By contrast, unconscious physiological processes, such as hormone secretion, are totally unaffected by expectations, whereas they are influenced by placebos through unconscious conditioning mechanisms.
Tables
Group Sex (male/female) Age (years) Weight (kg) 1 7/7 45.1 ± 7.5 58.9 ± 11.1 2 6/6 46.9 ± 8.8 60.6 ± 10.5 3 5/7 45.8 ± 9.4 62.5 ± 9.7 4 5/6 44.1 ± 9.7 59.9 ± 10.3 5 6/5 46.4 ± 7.5 60.5 ± 9.8 - Table 2.
Characteristics of the patients and stimulation parameters of the subthalamic nuclei for optimal therapeutic effect
Left nucleus Right nucleus Patient Age (years) Sex History of Parkinson's disease (years) Time from surgery (months) Stage of disease before/after surgery Int (V) Freq (Hz) Width (μsec) Int (V) Freq (Hz) Width (μsec) 1 51 female 25 19 4.5/3 3.6 130 60 3.6 135 60 2 69 male 15 14 4/2 3.6 170 90 3.6 170 90 3 57 female 13 20 4/2 3.6 160 60 3.6 135 60 4 70 female 19 27 4/2.5 3.3 130 90 3.6 135 60 5 62 male 12 7 3/0.5 3.5 135 60 3.3 130 60 6 46 female 9 5 2.5/2 3.6 130 90 3.6 170 90 7 61 male 12 20 4/0.5 3.5 135 90 3.5 130 90 8 67 male 10 18 3/1.5 3.5 160 60 3.5 130 90 9 57 male 8 9 4/3 3.4 135 90 3.6 130 90 10 68 male 19 9 4.5/2.5 3.6 130 60 3.6 130 60 Intensity (Int) is expressed in volts (V), frequency (Freq) in Hertz, and pulse width in microseconds (μsec).
Group Sex (male/female) Age (years) Weight (kg) 1 8/7 47.4 ± 10.5 64.7 ± 12.5 2 5/4 49.3 ± 11.8 65.6 ± 11.7 3 5/6 49.1 ± 10.4 64.4 ± 12.6 4 5/4 50.1 ± 9.5 61.6 ± 12.9 5 5/6 48.7 ± 10.1 65.5 ± 11.4 6 4/5 47.0 ± 9.2 61.9 ± 12 7 5/5 49.0 ± 11.2 63.4 ± 13.1 8 5/5 50.8 ± 10.7 62.9 ± 12.4 9 5/6 48.4 ± 9.9 63.8 ± 11.8
