Table 2.

Activation volume (in cm³) in response to the motor (FTAP), cognitive (DSST) and hypercapnia (BH) tasks in young and old subjects. Values from each subject were normalized to the average gray matter volume of the whole population scanned.

Subject	Young				old
	NC	FTAP	DSST	BH	NC	FTAP	DSST	BH
1	0.86	53.57	50.93	337.36	1.10	----	----	----
2	0.86	35.69	33.47	587.31	0.99	52.60	12.87	654.45
3	0.93	41.77	44.74	646.64	1.18	17.88	32.33	307.13
4	0.91	159.52	46.31	603.30	1.06	34.42	41.00	325.41
5	0.93	52.41	55.29	331.32	1.09	39.87	48.96	603.47
6	0.94	72.88	83.13	624.25	1.28	301.38	27.83	354.65
7	1.03	61.53	35.80	556.53	1.13	54.83	25.38	501.96
8	0.90	37.53	46.19	182.98	1.15	132.63	48.94	207.94
9	0.86	40.17	33.59	228.83	0.99	168.53	39.03	431.77
10	1.08	80.49	30.98	360.14	1.10	52.85	55.09	431.98
11	0.94	79.24	77.17	422.80	0.99	28.46	88.51	318.92
12	0.96	44.70	66.20	220.36	0.99	133.06	45.99	437.70
Mean	0.95	63.29	50.32	425.15	1.07	92.41	42.36	415.94
SD	0.06	34.23	17.29	171.59	0.09	81.50	18.77	126.82
CV	0.06	0.54*	0.34**	0.40§	0.08	0.88	0.44	0.30

NC- normalization constant

Significantly different compared to older,

^*P<0.03; Bartlett’s test of equality of variance.

No significant difference compared to older,

^**P< 0.6 and

^§P< 0.3; Bartlett’s test of equality of variance.