Time-locked association between rapid cerebral blood flow modulation and attentional performance

Objective The study investigated relationships between rapid cerebral hemodynamic modulation and attentional performance. Based on former results on complex cognitive functioning, a specific association between the first seconds of the hemodynamic response and performance was hypothesized. Methods Using transcranial Doppler sonography, blood flow velocities in the middle cerebral arteries of both hemispheres were recorded in 48 healthy subjects. The applied task comprised motor reactions on a visual stimulus which was preceded by an acoustic warning signal (interstimulus interval 5 s). Task-induced hemodynamic changes were assessed second-by-second, and related to reaction time using analysis of variance and linear regression. Results A right dominant blood flow response was observed. Flow velocity increase in the middle fraction of the interstimulus interval, i.e. seconds 2 and 3 after the cuing signal, significantly correlated with reaction time. This was not the case for the very early and late components of the response. Conclusions The results suggest a time-locked association between cerebral blood flow increase and attentional performance. This is in accordance with neurophysiological studies that revealed the closest relationship between brain perfusion and cortical activity during a similar time window. Significance The study supports the assumption of a specific, relatively early time interval in which relationships between cerebral blood flow and behavior become apparent