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The term neurovascular coupling denotes the relationship between neuronal activity and regional cerebral blood flow. A method that would enable analysis of neurovascular coupling in humans is still to be discovered. The aim of our study was to establish whether it is possible to analyze neurovascular coupling noninvasively by simultaneously measuring visual evoked potentials (VEP) and visually evoked cerebral blood flow responses (VEFR) by transcranial Doppler (TCD). The records were made from 30 healthy volunteers of both sexes aged 38.0±9.6 years. The mean arterial velocity in the left middle cerebral artery (vmMCA) and the mean arterial velocity in the right posterior cerebral artery (vmPCA) were monitored by using TCD. The VEPs were recorded from occipital leads. Neuronal activity was changed by changing visual contrast. The relationship between VEP and VEFR was tested using linear regression analysis. The VEFRs at 100% visual contrast were higher than those at 10% visual contrast (p<0.01) and the VEFRs at 10% visual contrast higher than those at 1% visual contrast (p<0.01). In addition, the VEPs at 100% visual contrast were higher than those at 10% visual contrast (p<0.01) and the VEPs at 10% visual contrast higher than those at 1% visual contrast (p<0.01). The relationship between the VEPs in the VEFR was moderate and significant (r=0.66; p<0.01).
It was concluded that simultaneous measuring of VEPs and VEFRs enable us to analyze neurovascular coupling in healthy subjects.