RESUMEN
Blood flow velocity changes induced by the focal brain activation can be assessed by using Transcranial Doppler sonography (TCD). To explore the hemispheric dominant hemodynamic effect by performing calculation, we applied TCD technique to detect cerebral blood velocity asymmetry. METHODS Twenty healthy right-handed subjects were tested. We measured mean flow velocities (MFV) in the middle and posterior cerebral arteries (MCA, PCA). Photic stimulation was given separately as a control task for calculation. RESULTS While the photic stimulation increased the blood velocity only in PCAs, performing calculation increased the velocity in MCAs. Right-left difference was noted by performing calculation with greater increase in left MCA (right: 8.8 %; left: 21.2 %). CONCLUSION Application of TCD enabled us to measure the hemodynamic changes supporting the left hemispheric dominance of calculation task. Futhermore, increase in non-dominant right hemisphere suggests the functional interaction of cerebral activity.