1. Harsha Radhakrishnan

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    1. Mentioned In 20 Articles

    2. Noninvasive, in vivo imaging of subcortical mouse brain regions with 1.7  μm optical coherence tomography

      Noninvasive, in vivo imaging of subcortical mouse brain regions with 1.7  μm optical coherence tomography
      A spectral/Fourier domain optical coherence tomography (OCT) intravital microscope using a supercontinuum light source at 1.7 m was developed to study subcortical structures noninvasively in the living mouse brain. The benefits of 1.7 m for deep tissue brain imaging are demonstrated by quantitatively comparing OCT signal attenuation characteristics of cortical tissue across visible and near-infrared wavelengths. Imaging of hippocampal tissue architecture and white matter microvasculature are demonstrated ...
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    3. Mapping the 3D Connectivity of the Rat Inner Retinal Vascular Network Using OCT Angiography

      Mapping the 3D Connectivity of the Rat Inner Retinal Vascular Network Using OCT Angiography
      Purpose : The purpose of this study is to demonstrate three-dimensional (3D) graphing based on optical coherence tomography (OCT) angiography for characterization of the inner retinal vascular architecture and determination of its topologic principles. Methods : Rat eyes ( N = 3) were imaged with a 1300-nm spectral/Fourier domain OCT microscope. A topologic model of the inner retinal vascular network was obtained from OCT angiography data using a combination of automated and manually-guided ...
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    4. Micro-heterogeneity of flow in a mouse model of chronic cerebral hypoperfusion revealed by longitudinal Doppler optical coherence tomography and angiography

      Micro-heterogeneity of flow in a mouse model of chronic cerebral hypoperfusion revealed by longitudinal Doppler optical coherence tomography and angiography
      Although microvascular dysfunction accompanies cognitive decline in aging, vascular dementia, and Alzheimers disease, tools to study microvasculature longitudinally in vivo are lacking. Here, we use Doppler optical coherence tomography (OCT) and angiography for noninvasive, longitudinal imaging of mice with chronic cerebral hypoperfusion for up to 1 month. In particular, we optimized the OCT angiography method to selectively image red blood cell (RBC)-perfused capillaries, leading to a novel way of ...
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    5. Feature Of The Week 9/14/14: UC Davis Investigates Brain Imaging with Optical Coherence Tomography

      Feature Of The Week 9/14/14: UC Davis Investigates Brain Imaging with Optical Coherence Tomography
      One of the nine high priority research areas in the recent BRAIN Initiative (executive summary available at HERE ) is to Delineate mechanisms underlying human brain imaging technologies. While empowering tools such as two-photon microscopy, used in conjunction with dyes and indicators, can image cellular and vascular activity, even measuring activity in all cells and vessels comprising a single voxel in a functional magnetic resonance imaging (fMRI) scanner remains a daunting ...
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    6. Optical Coherence Tomography angiography reveals laminar microvascular hemodynamics in the rat somatosensory cortex during activation

      Optical Coherence Tomography angiography reveals laminar microvascular hemodynamics in the rat somatosensory cortex during activation
      The BOLD (blood-oxygen-level dependent) fMRI (functional Magnetic Resonance Imaging) signal is shaped, in part, by changes in red blood cell (RBC) content and flow across vascular compartments over time. These complex dynamics have been challenging to characterize directly due to a lack of appropriate imaging modalities. In this study, making use of infrared light scattering from RBCs, depth-resolved Optical Coherence Tomography (OCT) angiography was applied to image laminar functional hyperemia ...
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    7. Feature Of The Week 10/20/13: Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke

      Feature Of The Week 10/20/13: Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke
      To better understand pathophysiology during brain injuries such as stroke, we combined a number of OCT imaging techniques. Namely, we employed Doppler methods to map blood flow, angiography methods to measure capillary-level perfusion and vessel diameter, and scattering quantification methods to determine cell viability. This multi-parametric approach was used to perform imaging in the acute and recovery stages in experimental ischemic stroke, with the goal of determining the fate of ...
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    8. Volumetric imaging and quantification of cytoarchitecture and myeloarchitecture with intrinsic scattering contrast

      Volumetric imaging and quantification of cytoarchitecture and myeloarchitecture with intrinsic scattering contrast
      We present volumetric imaging and computational techniques to quantify neuronal and myelin architecture with intrinsic scattering contrast. Using spectral / Fourier domain Optical Coherence Microscopy (OCM) and software focus-tracking we validate imaging of neuronal cytoarchitecture and demonstrate quantification in the rodent cortex in vivo . Additionally, by ex vivo imaging in conjunction with optical clearing techniques, we demonstrate that intrinsic scattering contrast is preserved in the brain, even after sacrifice and fixation ...
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    9. Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation

      Multiparametric optical coherence tomography imaging of the inner retinal hemodynamic response to visual stimulation
      The hemodynamic response to neuronal activation is a well-studied phenomenon in the brain, due to the prevalence of functional magnetic resonance imaging. The retina represents an optically accessible platform for studying lamina-specific neurovascular coupling in the central nervous system; however, due to methodological limitations, this has been challenging to date. We demonstrate techniques for the imaging of visual stimulus-evoked hyperemia in the rat inner retina using Doppler optical coherence tomography ...
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    10. Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke

      Multiparametric, Longitudinal Optical Coherence Tomography Imaging Reveals Acute Injury and Chronic Recovery in Experimental Ischemic Stroke
      Progress in experimental stroke and translational medicine could be accelerated by high-resolution in vivo imaging of disease progression in the mouse cortex. Here, we introduce optical microscopic methods that monitor brain injury progression using intrinsic optical scattering properties of cortical tissue. A multi-parametric Optical Coherence Tomography (OCT) platform for longitudinal imaging of ischemic stroke in mice, through thinned-skull, reinforced cranial window surgical preparations, is described. In the acute stages, the ...
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    11. Compartment-resolved imaging of cortical functional hyperemia with OCT angiography

      Compartment-resolved imaging of cortical functional hyperemia with OCT angiography
      Optical Coherence Tomography (OCT) angiography was applied to image functional hyperemia in different vascular compartments in the rat somatosensory cortex. Dynamic backscattering changes, indicative of changes in dynamic red blood cell (dRBC) content, were used to monitor the hemodynamic response. Three-dimensional movies depicting the microvascular response to neuronal activation were created for the first time. An increase in the attenuation coefficient during activation was identified, and a simple normalization procedure ...
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    12. Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography

      Quantitative imaging of cerebral blood flow velocity and intracellular motility using dynamic light scattering–optical coherence tomography
      This paper describes a novel optical method for label-free quantitative imaging of cerebral blood flow (CBF) and intracellular motility (IM) in the rodent cerebral cortex. This method is based on a technique that integrates dynamic light scattering (DLS) and optical coherence tomography (OCT), named DLSOCT. The technique measures both the axial and transverse velocities of CBF, whereas conventional Doppler OCT measures only the axial one. In addition, the technique produces ...
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  2. About Harsha Radhakrishnan

    Harsha Radhakrishnan is an Assistant Specialist at University of California at Davis.