Functional magnetic resonance imaging outcomes from a comprehensive magnetic resonance study of children with fetal alcohol spectrum disorders

Table 4 Comparison of performance and reaction time on the 2-back working memory tasks during the fMRI scan between the four study groups

		Group				ANOVA
Task and (condition)^a	Response	1. FAS/PFAS	2. SE/AE	3. ND/AE	4. Control	Overall	Post hoc	A priori contrast. Linear trend
		Number of responses	Number of responses	Number of responses	Number of responses	Overall	Post hoc	A priori contrast. Linear trend
		Mean (SD)	Mean (SD)	Mean (SD)	Mean (SD)	F (p)^e	Duncan^f	F (p)^g
		N = 13	N = 18	N = 16	N = 13	F (p)^e	Duncan^f	F (p)^g
2-back task
Control: 0-back	True-positive^b	13.2 (1.7)	13.6 (0.7)	13.3 (1.9)	14.0 (0.0)	1.0 (0.41)		1.6 (0.21)
	True-negative^b	25.6 (1.0)	25.6 (1.0)	25.7 (1.3)	26.0 (0.0)	0.6 (0.62)		1.2 (0.28)
	False-positive	0.3 (0.8)	0.4 (1.0)	0.3 (1.3)	0.0 (0.0)	0.6 (0.61)		0.9 (0.35)
	False-negative	0.8 (1.7)	0.4 (0.7)	0.7 (1.9)	0.0 (0.0)	1.0 (0.41)		1.6 (0.21)
	Reaction time (ms)^c	792.8 (112.9)	836.3 (154.3)	777.3 (90.1)	712.8 (116.0)	2.6 (0.06)		3.9 (0.051)
Activation: 2-back	True-positive^d	8.2 (2.5)	7.7 (3.0)	10.5 (1.9)	11.5 (1.1)	9.1 (0.000)	12, 34	19.5 (0.000)
	True-negative^d	24.5 (2.8)	25.7 (0.8)	25.6 (0.9)	26.4 (1.2)	3.5 (0.02)	1, 234	9.3 (0.004)
	False-positive	2.5 (2.8)	1.3 (0.8)	1.4 (0.9)	0.6 (1.2)	3.5 (0.02)	1, 234	9.3 (0.004)
	False-negative	4.6 (2.3)	5.3 (3.0)	2.5 (1.9)	1.5 (1.1)	9.2 (0.000)	12, 34	18.6 (0.000)
	Reaction time (ms)^c	886.4 (146.5)	970.1 (213.5)	839.3 (122.9)	783.8 (197.4)	3.2 (0.03)	123, 134	4.2 (0.046)

Among subjects with ≥65% correct true-positive and true-negative responses and able to lie still in the scanner
Duncan a multiple comparison range test; commas separate groups with homogeneous means at p < 0.05, F f statistic, ms milliseconds, p two-tailed p-value, SD standard deviation
^aIn the activation condition, subjects were instructed to respond if the stimulus was the same as the stimulus one slide back (1-back) or two slides back (2-back). In the control condition, subjects were instructed to respond if the stimulus was a man’s face
^bThere were 14 true-positive and 26 true-negative stimuli in the 0-back control condition
^cReaction time for true-positive and false-positive responses
^dThere were 12 true-positive and 28 true-negative stimuli in the N-back activation condition
^eNumerator degrees of freedom = 3; denominator df = total sample size minus 4
^fThe Duncan range test was presented only when the Overall F-test for the ANOVA was statistically significant (p < 0.05)
^gNumerator degrees of freedom = 1; denominator df = total sample size minus 4

ISSN: 1866-1955