engleski

Transcranial Doppler measurements of middle cerebral artery blood flow velocity changes during mental activities

The method of transcranial Doppler sonography (TCD) was used in order to examine blood flow velocities in the middle cerebral artery (MCA) bilaterally, during selective stimulation of cognitive centres by specific groups of mental tasks. The study comprised homogene sample of 66 right-handed female subjects. The subjects performed four 90 s tasks and had five 42 s rest phases. Two verbal tasks were presumed to be processed predominantly by the left, while spatial and visual perception tasks by the right hemisphere. TCD monitoring was performed during rest and while performing cognitive tasks, alternatively. During cognitive stimulation, bilaterally increased blood flow velocities in middle cerebral artery were found. Statistically significant greater increase of blood flow velocities in the right MCA were found during stimulation of cortical centres in the right cerebral hemisphere. Vice versa, statistically significant greater increase of blood flow velocities in the left MCA were found during stimulation of cortical centres on the left, compared to the contralateral artery. The time course of blood flow velocitiy during cognitive activity showed initial increase to maximum at approximately 4-6.5 s, and a rapid decrease in velocity at approximately 14-25 s. A steady state was reached after approximately 25-40 s. Our results suggest that selective stimulation of cognitive centres causes hemispheric lateralization of blood flow velocities. The time course of blood flow velocity changes was similar regarding the task or the side we examined. This method thus enables selective detection of vasomotor reactivity. THIS INVESTIGATION HAS BEEN REWARDED AS AN OUTSTANDING PRESENTATION DURING THE 4 th INTERNATIONAL CONFERENCE ON STROKE AND 1 st CONFERENCE OF THE MEDITERRANEAN STROKE SOCIETY, in Marrakech, Morroco, March 4-7, 1998.

transcranial Doppler; cognitive activity

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