Laser Doppler imaging of activation-flow coupling in the rat somatosensorycortex

Activation-how coupling (AFC) provides a physiological basis for mapping ce rebral activation using cerebral blood how (CBF) as a surrogate marker for neuronal function. Laser Doppler offers a minimally invasive approach for m easuring changes in cerebral blood flow but the spatial resolution of this technique is limited by the number of individual probes that can be used. R ecently, laser Doppler imaging (LDI) scanners, which use computer-driven op tics to scan and measure LD changes in two dimensions, have successfully me asured how changes in the exposed cortex of animals. Here we demonstrate th e use of an LDI device through a thinned shall to determine the spatiotempo ral characteristics of AFC in alpha-chloralose anesthetized rats in respons e to electrical forepaw stimulation. The spatial and temporal characteristi cs of the AFC response measured by LDI are in agreement with prior results obtained using a single LD probe. These results suggest a promising role fo r LDI in the characterization of the spatiotemporal characteristics of AFC in animal models and possibly for intraoperative monitoring in the human br ain. (C) 1999 Academic Press.