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Keith Brewster, Jon Smirl, Karen Bourns, Francisco Colino, Phil Ainslie, Gord Binsted; Effects of Visual Deprivation on Regional Cerebral Blood Flow Velocity and Neurovascular Coupling. Journal of Vision 2011;11(11):1019. doi: 10.1167/11.11.1019.
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Recently, short-term visual deprivation has been shown to affect a variety of non-visual processes and regional cortical activity (Sathian & Zangaladze, 2001). Surprisingly, very little is known about how such visual deprivation impacts regional cerebral blood flow velocity (CBFv) or its adaptation with the underlying neuronal activity (i.e., neurovascular coupling). The current study sought to investigate the effects of short-term (two-hour) visual deprivation on regional CBFv and neurovascular coupling. CBFv (transcranial Doppler ultrasound) was measured concurrently in the posterior cerebral artery (PCA) and the middle cerebral artery (MCA). Neurovascular coupling was assessed using established methods, consisting of two minutes of baseline (eyes closed and reading), five cycles of 40 seconds reading - 20 seconds eyes-closed (primary protocol), and five cycles of 40 seconds eyes-moving - 20 seconds eyes-closed (secondary protocol). Neurovascular coupling, using both protocols, was collected before and following a two-hour visual deprivation (black out) protocol whilst both regional CBFv and secondary neurovascular coupling protocol was measured at thirty-minute intervals throughout deprivation. Baseline measures indicated mean MCAv decreased 7.36% as a function of visual deprivation while PCAv showed the reciprocal effect, increasing 8.2% with differences arising via systolic peaks on both arteries. The primary (reading/closed) neurovascular-coupling protocol revealed post-deprivation decreases in MCAv of 9.32% while the secondary (moving/closed) protocol also decreased MCAv 12.5% as a function of deprivation. In addition, the secondary (moving/closed) protocol elicited systematic decreases in both systolic and diastolic peaks of PCAv across the 30, 60, and 90-minute intervals of visual deprivation. Short-term visual deprivation has been shown to differentially affect regional CBFv. Moreover, variations in blood flow provide further insight regarding visual processing, attenuation, and neurovascular coupling.
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