Table 1A. The effect of preprocessing steps on spectral power of BOLD signals within regions of interest.

	Before	Low pass		Global		CSF		White matter		All
Regions of interest (ROIs)	Mean±s.d.	Mean±s.d.	P-value	Mean±s.d.	P-value	Mean±s.d.	P-value	Mean±s.d.	P-value	Mean±s.d.	P-value
Right isthums of cingulate cortex	6.52±3.83	6.44±3.79	0.001	2.25±1.40	0.001	5.08±2.75	0.079	3.19±1.35	0.004	1.99±1.00	0.001
Left isthums of cingulate cortex	5.28±3.14	5.22±3.09	0.007	2.10±1.32	0.001	4.08±2.29	0.080	2.69±1.29	0.004	1.86±1.01	0.001
Right hippocampus	1.45±1.01	1.43±1.00	<0.001	0.54±0.22	0.006	1.00±0.31	0.094	0.61±0.23	0.014	0.48±0.21	0.005
Left hippocampus	1.34±0.97	1.32±0.96	0.002	0.52±0.18	0.013	0.92±0.30	0.123	0.58±0.27	0.026	0.46±0.18	0.011
Right lateral occipital cortex	1.81±1.08	1.79±1.07	0.010	0.63±0.25	0.002	1.47±0.69	0.092	0.83±0.39	0.002	0.58±0.22	0.001
Left lateral occipital cortex	1.41±0.89	1.39±0.88	0.004	0.58±0.36	0.001	1.25±0.89	0.057	0.74±0.49	0.001	0.54±0.34	0.001

BOLD, blood oxgen level dependent; CSF, cerebrospinal fluid. Bold represents P<0.05 after Bonferroni correction. Values are mean±standard deviation. P-values represent the results of paired t-test compared with before preprocessing. The effects of each preprocessing step as well as all of the steps combined are presented. Spectral power was derived from 0.016 to 0.078 Hz. The unit of BOLD signal spectral power is arbitary.