Lateralization of cerebral blood flow velocity changes during cognitive tasks - A simultaneous bilateral transcranial Doppler study

Background and Purpose-Transcranial Doppler ultrasonography (TCD) permits t he assessment of cognitively induced cerebral blood Row velocity (BFV) chan ges. We sought to investigate the lateralization of BFV acceleration induce d by a variety of cognitive tasks and to determine the influence of age, ge nder, IQ, and quality of the performance on the relative BFV changes. Methods-Simultaneous bilateral TCD monitoring of BFV in the middle cerebral arteries (MCAs) was performed in 90 normal right-handed volunteers during 13 verbal and visuospatial tasks and their preceding rest periods. Results-All tasks induced a significant bilateral BFV increase in the MCAs compared with the preceding rest periods. Five verbal tasks showed a signif icant left-hemispheric BFV acceleration. Linguistic tasks that required act ive or creative processing of the verbal stimuli, such as sentence construc tion or word fluency, elicited the most asymmetric response. Five visuospat ial tasks revealed a significant right-hemispheric BFV shift. Paradigms tha t combined visuospatial attention and visuomotor manipulation showed the mo st lateralized acceleration. Older volunteers (aged >50 years) showed highe r relative BFV changes, but lateralization was not influenced by age. Gende r, IQ, and performance quality did not reveal significant effects on BFV ch ange. Conclusions-Bilateral TCD is a noninvasive technique that has the potential to connect the particular change in Row pattern of the MCA distribution wi th selective cognitive activity and thus offers specific functional informa tion of scientific and clinical value.