Cerebral Blood Flow Velocity Increases during Mental Arithmetic in Humans: Comparison between the Right and Left Hemispheres

Kaoru Ikeda, Akiko Oba, Yuko Okuda and Yasuaki Kawai

Second Department of Physiology, Faculty of Medicine, Tottori University, Yonago 683, Japan

Effects of neuronal activation by mental arithmetic on cerebral blood flow (CBF) velocity were examined in the middle cerebral artery (MCA) of humans, and the change in CBF velocity was compared between the right and left hemispheres using transcranial Doppler ultrasonography. The CBF velocity at rest in an upright sitting posture was 69.2 ± 2.7 cm/s and 66.4 ± 3.7 cm/s in the right and left MCAs, respectively. There was no significant right-left difference in CBF velocity. During 3 min of mental arithmetic, the CBF velocity increased in both right and left MCAs, and returned toward the baseline value during 3 min of the recovery period. Percent increase in the CBF velocity due to mental arithmetic was 8.2 ± 2.3% and 9.0 ± 1.6% in the right and left MCAs, respectively. The difference in percent change of CBF velocity between the 2 sides was statistically not significant. These results suggest that mental arithmetic increases the CBF velocity by increasing the neuronal activity. The extent of increased metabolic rate due to the calculation seems to be not so different between the right and left hemispheres.

Key words: cerebral blood flow; dominant hemisphere; mental arithmetic; middle cerebral artery; transcranial Doppler

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