Transcranial Doppler assessment of cerebral flow velocity during cognitive tasks.

BACKGROUND AND PURPOSE: The purpose of this study was to assess the ability of transcranial Doppler ultrasonography to detect selective circulatory changes during cognitive activity. METHODS: We measured cerebral artery flow velocity in 21 normal volunteers by transcranial Doppler ultrasonography during rest followed by cerebral activation. Mean and peak systolic flow velocities of the anterior, middle, and posterior cerebral arteries were measured during the performance of a commercial video game. We also measured flow velocity of the anterior cerebral arteries in 18 subjects during a mental arithmetic task. Serial measurements of the right and left sides were made with a headband with two probes. RESULTS: We observed a global increase in the flow velocity above baseline measurements during task performance. During the video game, both middle cerebral arteries (t = 2.6, p = 0.02 for the left; t = 3.3, p = 0.004 for the right) and the left posterior cerebral artery (t = 2.2, p = 0.004) had selective increase in mean flow velocity compared with the ipsilateral anterior cerebral artery. This selective activation was most prominent in the right middle cerebral artery, which had a greater degree of activation than the right posterior cerebral artery (t = 2.8, p = 0.013). We did not observe a statistically significant difference between the right and left middle cerebral arteries, but there was a trend toward a greater activation on the right for both the mean velocity (t = 1.7, p = 0.098) and the peak velocity (t = 1.9, p = 0.079). CONCLUSIONS: Our preliminary investigation suggests that this noninvasive technique has the potential to correlate selective cerebral artery flow dynamics with cognitive activity.