Medial Orbitofrontal De-Activation During Tonic Cold Pain Stimulation: A fMRI Study Examining the Opponent-Process Theory

Figures & data

Table 1 Characteristics of Participants

Characteristics	Statistics
Age (mean±SEM)	25±1.1246
Sex (NF, %)
Male	11 (42)
Female	15 (58)
Ethnicity (N,%)
Caucasian	14 (54)
Afro-American	4 (15)
Asian	8 (31)
Level of education (%)
College degree	58
Bachelor’s degree	31
Graduate studies	11
Employment status (%)
Employed	35
No income	19
Loan or bursary	23
Others (ie, independent worker, welfare)	23
Psychological symptoms (mean±SEM)
BDI-II	5.35 ± 0.08
STAI-S	45.54 ± 0.26
SHPS	50 ± 0.12
BPI
Pain severity	1.69 ± 0.77
Pain interference	1.55 ± 0.49

Abbreviations: BDI-II, Beck Depression Inventory-II; BPI, Brief Pain Inventory; SEM, standard of the mean; SHPS, Snaith–Hamilton Pleasure Scale; STAI-S, State and Trait Anxiety Inventory-State subscale.

Figure 1 Experimental design. Each run lasted 3 minutes and was comprised of four 45 second blocks (2 experimental conditions and 2 rest periods). There was a 10-minute interval between each run to insure that no pain sensitization occurred. The order of the administration of each stimulus in each run was counterbalanced between each participant in a pseudo-randomized manner.

Abbreviation: fMRI, functional magnetic resonance imagining.

Table 2 Brain Regions (De-)activated During the Modified Cold Pressor Test

Contrast	Brain Region	L/R	BA	MNI			Voxel Size	t-value	p value of Cluster
				x	y	z
Pain>ctl
	Insula	L	13	−34	6	10	6349	8.89	<0.001
	Putamen			−24	4	10		8.09	<0.001
	Caudate nucleus	L		−18	−26	22		7.28	<0.001
	Thalamus	L/R		−6	−26	12	-	7.49
	Insula	L/R		−30	−26	16	-	6.93
	Precuneus	L		−6	−42	64	1504	5.54	<0.001
	Paracentral lobule	L		−4	−28	72	-	4.57
	Middle frontal gyrus	L		−30	40	22	122	4.7	<0.001
	Lingual gyrus	R		18	−78	10	272	4.47	<0.001
Ctl>pain
	Medial orbital	R	11	6	24	−12	129	4.38	<0.001

Abbreviations: L, left; R, right; BA, Brodmann area; MNI, Montreal Neurologic Institute.

Figure 2 Brain regions (de-)activated during the modified cold pressor test. Two contrasts were analysed: [Pain >Control] and [Control>Pain]. (A) Activations; [Pain>Control] contrast. (B) De-activations; [Control>Pain] contrast.

Abbreviations: a, L-caudate nucleus; b, L/R-thalamus; c, L-paracentral lobule; d, L/R-insula; e, L-precuneus; f, L-putamen; g, L-middle frontal gyrus; h, R-medial orbital.

Figure 3 Mean beta. Three mean beta values were extracted for the right medial orbital frontal gyrus in the control>pain contrast. The average beta value for the contrast control>pain was 0.35 ± 0.09, the average beta value for this contrast during painful stimulation was −0.41 ± 0.11 and during the administration of the control stimulus was −0.16 ± 0.09. These negative values show de-activation in the right medial orbital during both the pain and the control stimuli. However, the de-activation was greater during painful stimulation.

Abbreviations: L, left; ctl, control.

Figure 4 (A) Correlation between the mean beta values of the insula and the mean pain intensity ratings taken during the administration of the modified CPT. This figure illustrates a significative positive correlation between the mean beta values of the insula and the mean pain intensity rating during the administration of both CPT. (B) Correlation between the mean beta values of the precuneus and the mean pain intensity ratings taken during the administration of the modified CPT. This figure illustrates a significative positive correlation between the mean beta values of the precuneus and the mean pain intensity rating during the administration of both CPT.

Abbreviation: CPT, cold pressor test.

Figure 5 (A) Correlation between the beta values of the precuneus with the BPI questionnaire (pain interference subscale). This figure illustrates a positive significant correlation between the precuneus during a painful stimulation and the pain interference subscale of the BPI questionnaire. (B) Correlation between the beta values of the medial orbital frontal gyrus with the BPI questionnaire (pain interference subscale). This figure illustrates a negative significant correlation between the medial orbital frontal gyrus during painful stimulation and the pain interference subscale of the BPI questionnaire.

Abbreviation: BPI, Brief Pain Inventory.