TABLE 2.

Within- and between-group differences in MID activity.

	Chronic Pain				Control				Male		Female
	Male	Female			Male	Female			Patient vs. control		Patient vs. control
	(n = 17)	(n = 23)			(n = 20)	(n = 30)
	Mean (SD)	Mean (SD)	t	p	Mean (SD)	Mean (SD)	t	p	t	p	t	p
Reward
All vs. Neutral	1.28 (1.02)	1.47 (1.03)	0.6	0.58	2.68 (1.30)	1.69 (1.25)	2.7	0.01	3.6	0.001	0.7	0.49
Large vs. Neutral	1.95 (1.56)	1.88 (1.25)	0.1	0.89	4.13 (2.44)	2.12 (1.48)	3.3	0.002	3.2	0.003	0.6	0.54
Medium vs. Neutral	0.87 (1.13)	1.16 (1.13)	0.8	0.42	2.07 (1.05)	1.28 (1.44)	2.1	0.04	3.3	0.002	0.3	0.76
Small vs. Neutral	1.03 (0.77)	1.35 (1.35)	0.9	0.39	1.82 (0.90)	1.67 (1.35)	0.4	0.66	2.9	0.007	0.9	0.40
Loss
All vs. Neutral	0.91 (1.21)	1.16 (1.12)	0.7	0.5	1.75 (1.25)	1.08 (1.07)	2.0	0.05	2.1	0.05	0.2	0.80
Large vs. Neutral	1.58 (1.38)	1.56 (1.46)	0.03	0.98	2.78 (1.90)	1.53 (1.22)	2.6	0.02	2.2	0.04	0.09	0.93
Medium vs. Neutral	0.82 (1.44)	0.92 (1.27)	0.25	0.81	1.74 (1.62)	1.03 (1.19)	1.8	0.08	1.8	0.08	0.3	0.75
Small vs. Neutral	0.32 (1.25)	0.99 (1.15)	1.7	0.09	0.73 (1.39)	0.69 (1.42)	0.1	0.92	0.9	0.36	0.8	0.41
All incentives
All vs. Neutral	1.09 (1.10)	1.31 (0.98)	0.7	0.51	2.21 (1.23)	1.39 (1.09)	2.5	0.02	2.9	0.007	0.3	0.8
Large vs. Neutral	1.76 (1.38)	1.72 (1.22)	0.09	0.93	3.46 (2.09)	1.83 (1.25)	3.1	0.004	2.8	0.007	0.3	0.77
Medium vs. Neutral	0.84 (1.21)	1.05 (1.08)	0.5	0.59	1.91 (1.19)	1.16 (1.18)	2.2	0.03	2.7	0.01	0.4	0.73
Small vs. Neutral	0.68 (0.91)	1.17 (0.98)	1.6	0.11	1.28 (0.82)	1.18 (1.24)	0.3	0.76	2.1	0.05	0.03	0.98

Mean ± 1 SD of changes in ventral striatal BOLD signal contrast averaged across right and left hemispheres during anticipation of monetary incentives.

Reward, Trials of the monetary incentive delay task in which participants could earn or not earn money; Loss, Trials of the monetary incentive delay task in which participants could avoid losing or lose money; All incentives, All trials of the monetary incentive delay task in which an incentive was at stake.