We seek to renew our joint discovery and technology based bioengineering research partnership (BRP). Our program advances the use of amplified ultrashort laser pulses as a tool to manipulate living and histological tissue. This unique technology, pioneered by the BRP team, permits tissue to be cut on the micrometer scale by light-fueled plasma-meditated ablation. Cutting occurs without thermal damage and can be combined with spectroscopic feedback to identify and limit the region being perturbed. We advance this technology in new ways, including the use of temporal focusing for deep ablation, and apply it to three key test beds. The first is construction of the angiotome, i.e., a complete vectorized map of cortical vasculature;here we use plasma mediated ablation to automate a form of block-face imaging along with novel algorithms to filter and vectorize features in the data. The second is the study of neuronal viability in response to perturbations of subcortical blood flow;here we use plasma-mediated ablation to block flow in individual targeted microvessels that lie below the cortical surface. The third test bed is the automation of cranial and spinal surgery;we combine plasma-mediated ablation with laser-induced breakdown spectroscopy to cut bone yet avoid injury to soft tissue. These investigations are particularly relevant to diagnosing and understanding microinfarctions, i.e., damage to the brain as the result of damage to single cortical vessels, that accumulate with age and trauma.
These studies advance the use of light to image and manipulate the flow of blood in the brain. We make use of rats and mice as model systems for our experiments. The new capabilities from the proposed work hold two promises for advances in medicine: One is an understanding of micro- infarctions - lesions of individual blood vessels in cortex that lead to the death of brain cells- that accrue with age and trauma. The second is an understanding of the normal patterns of blood flow throughout the brain, which provide the basis for interpreting medical images of brain function.
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