engleski

Influence of cognitive stimulation on blood flow through the middle cerebral artery

The Transcranial Doppler Sonography (TCD) method was used in order to examine blood flow velocities in the middle cerebral artery (MCA), bilaterally, during selective stimulation of cognitive centers by specific groups of mental tasks. The study comprised a homogenous sample of 66 right-handed female subjects. The subjects performed four 90-second tasks and had five 42-second rest phases. Two verbal tasks were presumed predominantly by the left hemisphere and spatial and visual perception tasks by the right one. TCD monitoring was performed during rest and during the performance of cognitive tasks, in alternation. During cognitive stimulation, blood flow velocities in the middle cerebral artery were found to be bilaterally increased. A statistically significant greater increase in blood flow velocities through the right MCA was found during stimulation of cortical centers on the left side of the brain when compared to the contralateral artery. The time variation of blood flow velocity during a cognitive activity showed an initial increase to maximum after approximately 4-6.5 seconds and then a rapid decrease in velocity at approximately 14-25 seconds. A steady state was reached after approximately 25-40 seconds. Our results suggest that selective stimulation of cognitive centers causes hemispheric lateralisation of blood flow velocities. This method therefore enables a selective study of local vasomotor reactivity, which is an important contribution to the functional transcranial Doppler diagnosis.

cognition; cerebral arteries; ultrasonography Doppler transcranial; blood flow velocity

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