Bruce A. Berkowitz

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PURPOSE To test the hypothesis that high-resolution (23.4 microm intraretinal resolution) manganese-enhanced magnetic resonance imaging (MEMRI) can be used to noninvasively and simultaneously record from distinct layers of the rat retina cellular demand for ions associated with functional adaptation. METHODS In control rats, high-resolution images were(More)
MRI has recently been used for noninvasive examination of retinal structure and function in rats and cats. However, the advantages of quantitative high-resolution MRI of retina from mice have not yet been explored. In the present study, T(1) and T(2) relaxation time constants and the directional apparent diffusion coefficient (ADC) in the retina of C57/BL6(More)
PURPOSE To test the hypothesis that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) provides a useful in vivo measure of passive blood retinal barrier permeability surface area product (BRB PS) in experimental diabetic retinopathy. METHODS BRB PS (cm(3)/min) was measured using DCE-MRI and Gd-DTPA (MW 590 Da) in urethane-anesthetized control(More)
Cortical responses to visual stimulation have been studied extensively in the rodent, but often require post-stimulation ex vivo examination of the tissue. Here, we test the hypothesis that visual stimulus-dependent cortical activity from awake and free-moving rats can be encoded following systemically administered MnCl(2), and activity subsequently readout(More)
PURPOSE To test the hypothesis that the extent of outer retina uptake of manganese, measured noninvasively with manganese-enhanced MRI (MEMRI), is a quantitative biomarker of photoreceptor ion channel regulation by visual cycle activity. METHODS Four groups of animals were studied: control rats adapted to three different background light intensities,(More)
Manganese-enhanced MRI (MEMRI) is a powerful non-invasive approach for objectively measuring either retina or binocular visual brain activity in vivo. In this study, we investigated the sensitivity of MEMRI to monocular stimulation using a new protocol for providing within-subject functional comparisons in the retina and brain in the same scanning session.(More)
PURPOSE Ectopic expression of light-sensitive proteins, such as channelrhodopsin-2, represent a novel approach for restoring light-detection capabilities to degenerated retina. A noninvasive method that can detect light-mediated activities of such light-sensitive proteins in the retina in vivo would be important for correlating expression patterns and(More)
PURPOSE To test the hypothesis that in young, functionally blind mice, light-dependent intraretinal ion regulation occurs via melanopsin. METHODS Postnatal day (P) 7 wild type (WT, C57Bl/6) and melanopsin knockout (KO, opn4-/-, B6129) mice were light or dark adapted. Awake and freely moving animals were injected intraperitoneally (ip) with MnCl(2). Four(More)
PURPOSE To test the hypothesis that intraretinal calcium channels participate in retinal morbidity in a variable oxygen (VO) model of retinopathy of prematurity. METHODS In control and VO Long Evans (LE) rats, either untreated or treated with voltage- or ligand-gated calcium channel antagonists, we measured retinal neovascular (NV) incidence and severity(More)
PURPOSE To test the hypothesis that manganese-enhanced magnetic resonance imaging (MEMRI) is a sensitive approach for measuring of age-related ocular changes in experimental pigmentary glaucoma. METHODS Four groups of light-adapted mice were studied using MEMRI: young (2-3 months), C57BL/6 (negative controls), and DBA/2J mice and aged (10-11 months)(More)