Transcranial Doppler Assessment of Cerebral Flow Velocity at Rest and During Voluntary Movements in Young and Elderly Healthy Subjects

Abstract

Fifty-five healthy volunteers (thirty young and twenty-five elderly), all of them right-handed, were investigated by Transcranial Doppler monitoring mean flow velocity on the right and left middle cerebral artery at rest, during a motor task performed by the hand and in the following rest condition. In all cases the motor task induced an increase in bilateral mean flow velocity, but significantly greater on the opposite side middle cerebral artery in the task. The percentage increase in mean flow velocity compared to the rest condition observed during the motor task performed by the opposite side hand to the artery investigated was significantly greater in the young than the elderly. Moreover, in the young, this increase showed a slight prevalence during the left middle cerebral artery assessment relating to right hand preference. Furthermore, elderly subjects achieved the greatest mean flow velocity percentage increase compared to rest condition later than young subjects and returned to basal values more slowly.

Contributions to the Development of Objective Techniques for Presence Measurement in Virtual Environments by means of Brain Activity Analysis

“…It is important to note that the BFV absolute or relative variations that can be observed during cognitive tasks are studied in most functional TCD works. However, and although the high temporal resolution of TCD is one of the key advantages of this technique, the instantaneous temporal evolution of BFV signals in subjects performing cognitive tasks has only been analyzed in some of the functional studies [20], which have found a maximum peak in BFV between 4 [180] to 20 s [181] after the initiation of a cognitive task, with an average peak after 6-9 s [31,158,149].…”

“…Given that the user had to navigate and control a joystick in the environment (with right arm movements), the differences could have their origin in these motor tasks (as subjects are right-handed, they move the right arm to control the joystick and variations in BFV are generated in the left hemisphere) [160,178,158].…”

“…Orlandi and Murri [158] performed a study with fifty-five right-handed volunteers. BFV in right MCA (MCA-R) and left MCA (MCA-L) were investigated at rest (30 s), during a motor task performed by the hand (60 s), and in the following rest condition (30 s).…”

“…As long as the neurovascular coupling occurs a few seconds after the beginning of a mental task [31,180,158,149,181] and velocity remains relatively constant while the activity is maintained, only a section of the period (both in the free navigation condition and the automatic navigation condition) was included in the analysis. This procedure can contribute to avoid BFV variations caused by factors different to the VE exposure (for example, a possible fatigue effect).…”

“…In the previously described study from Orlandi and Murri [158], BFV percentage variations were analyzed. Temporal evolution was also studied, and it was found that elderly subjects achieved the maximum variations later than young subjects and returned to repose values more slowly.…”