ELECTROPHYSIOLOGICAL MARKERS OF MIDDLE CEREBRAL ARTERY BLOOD FLOW VELOCITY IN HEALTHY SUBJECTS

Aim: to determine electrophysiological markers of middle cerebral artery blood flow velocity (BFV). Patients and methods: transcranial Doppler registration of middle cerebral artery BFV and direct current (DC) potentials recording from surface of head were performed in 30 healthy volunteers. Analysis of correlation between the BFV and DC potentials was used. Results: significant correlation between BFV and DC potential characteristics was observed. The highest correlation was found between BFV in middle cerebral artery and the difference of DC potentials between central and temporal areas of head (r =0,55; p =0,003). These areas coincide with the location of middle cerebral artery and the correlation observed may be connected with streaming potential generated by the blood flow in middle cerebral artery. If electrode placement did not coincide with blood current, DC potentials and BFV were not correlated. Conclusions: it is assumed that electrical field created BFV in middle cerebral artery may contribute to the generation of DC potentials registered from the head.

TWO PATTERNS ОF CT-BRAIN PERFUSION AND DC-POTENTIALS ОF THE BRAIN EVOKED COGNITIVE TASK IN DISCIRCULATORY ENCEPHALOPATHY PATIENTS

In patients with discirculatory encephalopathy the influence of verbal fluency test on the characteristics of cerebral perfusion, DC-potentials of the brain, as well as on blood pressure and heart rate was investigated. Two patterns of responses to the verbal fluency test were observed. The first one is the process of generalized activation, manifested by the reduction of the TTP (time to peak) parameters of brain perfusion, the rise of the DC-potentials in all areas of brain and the modulation of blood pressure and heart rate. The second process, directly connected with cognitive processing, was manifested by the shifts of local characteristics of brain perfusion and DC-potentials in the frontal, temporal and central cortex, especially in the left hemisphere. Correlations were found between the characteristics of cerebral perfusion and DC-potentials on the one hand and the number of words during the verbal fluency test performance on the other hand.