Targeted Occlusion to Surface and Deep Vessels in Neocortex Via Linear and Nonlinear Optical Absorption

We discuss two complementary methods for the study of cerebral blood flow and brain function in response to the occlusion of individual, targeted blood vessels. These bear on the study of microstroke and vascular dysfunction in cortex. One method makes use of linear optical absorption by a photosensitizer, transiently circulated in the blood stream, to induce an occlusion in a surface or near-surface vessel. The second method makes use of nonlinear optical interactions, without the need to introduce an exogenous absorber, to induce an occlusion in a subsurface microvessel. A feature of both methods is that the dynamics of blood flow and functional aspects of the vasculature and underlying neurons in the neighborhood of the occluded vessel may be monitored before, during, and after the occlusion. We present details of both methods and associated surgical procedures, along with example data from published studies.