Table III.

Measured values within visual cortex (VC) for younger (n = 10) and older subjects (n = 10) for a positive BOLD activated ROI (mean ± standard error)

	Number of voxels	Fractional change in CBF with hypercapnia (%)	BOLD changes with hypercapnia (%)	Cerebral reactivity to CO2 (CRC)	Fractional change in CBF with activation (%)	BOLD changes with activation (%)	Baseline CBF (mL/100 mL/min)
Younger (21‐ to 35‐years‐old)	610 ± 62	40.9 ± 7.8	2.08 ± 0.33	7.9 ± 1.2	33.5 ± 3.9	1.12 ± 0.08	54.2 ± 10.0
Older (45‐ to 60‐years‐old)	554 ± 54	*75.2 ± 14.8	2.47 ± 0.46	8.4 ± 1.3	35.6 ± 5.3	0.97 ± 0.07	*37.3 ± 5.2

^* P < 0.04.