Table 1.

Summary of ΔCMR_O2/CMR_O2, Δν/ν, and ΔS/S in the contralateral cerebral cortex

	ΔCMRO2/CMRO2	Δν/ν	ΔS/S
Stimulation increment (from baseline I)	0.40  ± 0.13	0.29  ± 0.13	0.02  ± 0.01
Baseline decrement (from baseline I to baseline II)	−0.32  ± 0.08	−0.29  ± 0.11	−0.03  ± 0.01
Stimulation increment (from baseline II)	1.02  ± 0.22	1.04  ± 0.32	0.05  ± 0.02

^*ΔCMR_O2/CMR_O2 was averaged across all rats (n = 6) from 2 × 2 voxels in contralateral forepaw region (9). ΔCMR_O2/CMR_O2 was calculated from ΔCBF/CBF − {(ΔS/S)/Á + ΔCBV/CBV}(1 + ΔCBF/CBF), where Á has been determined (8). Although absolute values of CMR_O2 were not measured directly, the use of the data obtained in the baseline of condition I allowed all increments and decrements in activity to be normalized to that baseline value (Fig. 2, Table 2).

^† Δν/ν was averaged across all rats (n = 36) from all extracellular recordings in the contralateral side (9). Δν/ν was measured at a depth of layer 4 where ≈60% of the data showed an increase, ≈10% of the data showed a decrease, and ≈30% of the data showed no change (9). The absolute values of ν for the two baseline conditions were significantly different (9.5 ± 2.4 and 6.7 ± 1.8 Hz; P < 0.01), whereas the two stimulation conditions were approximately similar (12.3 ± 4.0 and 13.7 ± 3.2 Hz; P > 0.25). Because absolute values of ν were measured in all conditions, the relative changes were directly obtained from comparison of ν values obtained in the different conditions (Fig. 2, Table 2).

^‡ ΔS/S measured from spin-echo (echo time = 40 ms) contrast (13) with sequentially sampled echo-planar data (14). ΔS/S was averaged across all rats (n = 6) from the same 2 × 2 voxels for the ΔCMR_O2/CMR_O2 values shown.