TABLE 1.

Regional comparison of average VMHC between the first normocapnia (NC1) and hypercapnia

Region		NC1	HC	P value NC1 versus HC	% of significantly decreased in each region
Anatomical subdivisions	Deep GM	0.47 ± 0.08	0.38 ± 0.09	0.006*	19.80%
	Frontal lobe	0.50 ± 0.09	0.40 ± 0.11	0.0007*	14.74%
	Parietal lobe	0.67 ± 0.13	0.58 ± 0.15	0.001*	13.28%
	Whole brain GM	0.56 ± 0.08	0.48 ± 0.10	0.002*	12.00%
	temporal lobe	0.39 ± 0.06	0.32 ± 0.09	0.0003*	7.41%
	Occipital lobe	0.75 ± 0.12	0.73 ± 0.15	0.3	0%
Functional network subdivisions	Ventral attention	0.52 ± 0.11	0.38 ± 0.12	<0.0001*	33.70%
	Somatomotor	0.61 ± 0.19	0.45 ± 0.21	<0.0001*	33.39%
	Default	0.56 ± 0.07	0.47 ± 0.11	0.002*	9.27%
	Frontoparietal	0.46 ± 0.10	0.38 ± 0.10	0.007*	4.58%
	Dorsal attention	0.57 ± 0.14	0.51 ± 0.15	0.03*	4.01%
	Limbic	0.25 ± 0.06	0.22 ± 0.09	0.05	1.62%
	Visual	0.7 ± 0.11	0.67 ± 0.13	0.2	0%
Functional hierarchical subdivisions	Primary SM	0.68 ± 0.14	0.54 ± 0.16	0.0001*	33.97%
	Paralimbic	0.49 ± 0.06	0.39 ± 0.08	<0.0001*	18.14%
	Unimodal	0.60 ± 0.09	0.51 ± 0.13	0.001*	12.56%
	Subcortical	0.57 ± 0.09	0.52 ± 0.08	0.1	10.24%
	Heteromodal	0.56 ± 0.09	0.46 ± 0.12	0.002*	9.13%
	Limbic	0.45 ± 0.08	0.40 ± 0.06	0.1	7.20%

Note: Average voxel based VMHC values within the listed regions were compared between the fist normocapnic (NC1) and the HC scan using a paired t-test (FDR corrected P < 0.05). Statistically significant comparisons are marked by *. Comparing the first and second normocapnic scans, no regions showed a significant difference in VMHC. Additionally, the percent of each region is indicated, which shows a significant decrease as a result of the voxel based group analysis (corrected P < 0.05 considered significant).