31
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      Imaging Retinal Blood Flow with Laser Speckle Flowmetry

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Laser speckle flowmetry (LSF) was initially developed to measure blood flow in the retina. More recently, its primary application has been to image baseline blood flow and activity-dependent changes in blood flow in the brain. We now describe experiments in the rat retina in which LSF was used in conjunction with confocal microscopy to monitor light-evoked changes in blood flow in retinal vessels. This dual imaging technique permitted us to stimulate retinal photoreceptors and measure vessel diameter with confocal microscopy while simultaneously monitoring blood flow with LSF. We found that a flickering light dilated retinal arterioles and evoked increases in retinal blood velocity with similar time courses. In addition, focal light stimulation evoked local increases in blood velocity. The spatial distribution of these increases depended on the location of the stimulus relative to retinal arterioles and venules. The results suggest that capillaries are largely unresponsive to local neuronal activity and that hemodynamic responses are mediated primarily by arterioles. The use of LSF to image retinal blood flow holds promise in elucidating the mechanisms mediating functional hyperemia in the retina and in characterizing changes in blood flow that occur during retinal pathology.

          Related collections

          Most cited references31

          • Record: found
          • Abstract: found
          • Article: not found

          Glial regulation of the cerebral microvasculature.

          The brain is a heterogeneous organ with regionally varied and constantly changing energetic needs. Blood vessels in the brain are equipped with control mechanisms that match oxygen and glucose delivery through blood flow with the local metabolic demands that are imposed by neural activity. However, the cellular bases of this mechanism have remained elusive. A major advance has been the demonstration that astrocytes, cells with extensive contacts with both synapses and cerebral blood vessels, participate in the increases in flow evoked by synaptic activity. Their organization in nonoverlapping spatial domains indicates that they are uniquely positioned to shape the spatial distribution of the vascular responses that are evoked by neural activity. Astrocytic calcium is an important determinant of microvascular function and may regulate flow independently of synaptic activity. The involvement of astrocytes in neurovascular coupling has broad implications for the interpretation of functional imaging signals and for the understanding of brain diseases that are associated with neurovascular dysfunction.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Intrinsic brain activity triggers trigeminal meningeal afferents in a migraine model.

            Although the trigeminal nerve innervates the meninges and participates in the genesis of migraine headaches, triggering mechanisms remain controversial and poorly understood. Here we establish a link between migraine aura and headache by demonstrating that cortical spreading depression, implicated in migraine visual aura, activates trigeminovascular afferents and evokes a series of cortical meningeal and brainstem events consistent with the development of headache. Cortical spreading depression caused long-lasting blood-flow enhancement selectively within the middle meningeal artery dependent upon trigeminal and parasympathetic activation, and plasma protein leakage within the dura mater in part by a neurokinin-1-receptor mechanism. Our findings provide a neural mechanism by which extracerebral cephalic blood flow couples to brain events; this mechanism explains vasodilation during headache and links intense neurometabolic brain activity with the transmission of headache pain by the trigeminal nerve.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Dynamic imaging of cerebral blood flow using laser speckle.

              A method for dynamic, high-resolution cerebral blood flow (CBF) imaging is presented in this article. By illuminating the cortex with laser light and imaging the resulting speckle pattern, relative CBF images with tens of microns spatial and millisecond temporal resolution are obtained. The regional CBF changes measured with the speckle technique are validated through direct comparison with conventional laser-Doppler measurements. Using this method, dynamic images of the relative CBF changes during focal cerebral ischemia and cortical spreading depression were obtained along with electrophysiologic recordings. Upon middle cerebral artery (MCA) occlusion, the speckle technique yielded high-resolution images of the residual CBF gradient encompassing the ischemic core, penumbra, oligemic, and normally perfused tissues over a 6 x 4 mm cortical area. Successive speckle images demonstrated a further decrease in residual CBF indicating an expansion of the ischemic zone with finely delineated borders. Dynamic CBF images during cortical spreading depression revealed a 2 to 3 mm area of increased CBF (160% to 250%) that propagated with a velocity of 2 to 3 mm/min. This technique is easy to implement and can be used to monitor the spatial and temporal evolution of CBF changes with high resolution in studies of cerebral pathophysiology.
                Bookmark

                Author and article information

                Journal
                Front Neuroenergetics
                Front. Neuroenerg.
                Frontiers in Neuroenergetics
                Frontiers Research Foundation
                1662-6427
                01 April 2010
                15 September 2010
                2010
                : 2
                : 128
                Affiliations
                [1] 1simpleDepartment of Neuroscience, University of Minnesota Minneapolis, MN, USA
                Author notes

                Edited by: Anna Devor, University of California San Diego, USA

                Reviewed by: Gabriel A. Silva, University of California San Diego, USA; Chris Shaffer, Cornell University, USA

                *Correspondence: Eric A. Newman, Department of Neuroscience, University of Minnesota, 321 Church St. SE, Minneapolis, MN 55455, USA. e-mail: ean@ 123456umn.edu
                Article
                10.3389/fnene.2010.00128
                2950742
                20941368
                34eecfc4-ff33-4de1-beef-78112d449183
                Copyright © 2010 Srienc, Kurth-Nelson and Newman.

                This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.

                History
                : 03 March 2010
                : 06 August 2010
                Page count
                Figures: 6, Tables: 0, Equations: 2, References: 37, Pages: 10, Words: 7991
                Categories
                Neuroscience
                Original Research

                Neurosciences
                laser speckle flowmetry,arterioles,blood flow,capillaries,choroid,functional hyperemia,retina

                Comments

                Comment on this article