The Experts below are selected from a list of 52086 Experts worldwide ranked by ideXlab platform
D. James Surmeier - One of the best experts on this subject based on the ideXlab platform.
-
Modulation of Striatal Projection Systems by Dopamine
Annual Review of Neuroscience, 2011Co-Authors: Charles R Gerfen, D. James SurmeierAbstract:The basal ganglia are a chain of subcortical nuclei that facilitate action selection. Two striatal Projection Systems--so-called direct and indirect pathways--form the functional backbone of the basal ganglia circuit. Twenty years ago, investigators proposed that the striatum's ability to use dopamine (DA) rise and fall to control action selection was due to the segregation of D(1) and D(2) DA receptors in direct- and indirect-pathway spiny Projection neurons. Although this hypothesis sparked a debate, the evidence that has accumulated since then clearly supports this model. Recent advances in the means of marking neural circuits with optical or molecular reporters have revealed a clear-cut dichotomy between these two cell types at the molecular, anatomical, and physiological levels. The contrast provided by these studies has provided new insights into how the striatum responds to fluctuations in DA signaling and how diseases that alter this signaling change striatal function.
Charles R Gerfen - One of the best experts on this subject based on the ideXlab platform.
-
Modulation of Striatal Projection Systems by Dopamine
Annual Review of Neuroscience, 2011Co-Authors: Charles R Gerfen, D. James SurmeierAbstract:The basal ganglia are a chain of subcortical nuclei that facilitate action selection. Two striatal Projection Systems--so-called direct and indirect pathways--form the functional backbone of the basal ganglia circuit. Twenty years ago, investigators proposed that the striatum's ability to use dopamine (DA) rise and fall to control action selection was due to the segregation of D(1) and D(2) DA receptors in direct- and indirect-pathway spiny Projection neurons. Although this hypothesis sparked a debate, the evidence that has accumulated since then clearly supports this model. Recent advances in the means of marking neural circuits with optical or molecular reporters have revealed a clear-cut dichotomy between these two cell types at the molecular, anatomical, and physiological levels. The contrast provided by these studies has provided new insights into how the striatum responds to fluctuations in DA signaling and how diseases that alter this signaling change striatal function.
Edward F Kelley - One of the best experts on this subject based on the ideXlab platform.
-
Stray light compensation in small area contrast measurements of Projection displays
electronic imaging, 2002Co-Authors: Paul A. Boynton, Edward F KelleyAbstract:The accurate measurement of small area-black levels is important in Projection display characterization. For example, techniques can be used to determine resolution of Projection Systems by measuring the contrast of alternating grille patterns or fully-modulated sine waves of various spatial frequencies. Unfortunately, the measurement of the contrast of these patterns may be influenced by stray light, either from ambient and reflected light in the environment, or from veiling glare scatter in the lens of the light-measuring device. Such stray-light corruption can lead to large errors in contrast determination, providing an inaccurate characterization of the projector. For large-area measurements, various techniques have been employed, including the use of frustums and masks, to minimize such unwanted effects and provide a more accurate measurement. With some modifications, these same tools may be used for small-area measurements with similar results. The design, construction, and implementation of these tools will be discussed. Results will be shown comparing small-area contrast measurements of Projection Systems, including resolution determination, with and without stray light compensation, for different measurement instrumentation.
-
Stray light compensation in small area contrast measurements of Projection displays | NIST
2002Co-Authors: Paul A. Boynton, Edward F KelleyAbstract:The accurate measurement of small area-black levels is important in Projection display characterization. For example, techniques can be used to determine resolution of Projection Systems by measuring the contrast of alternating grille patterns or fully-modulated sine waves of various spatial frequencies. Unfortunately, the measurement of the contrast of these patterns may be influenced by stray light, either from ambient and reflected light in the environment, or from veiling glare scatter in the lens of the light-measuring device. Such stray-light corruption can lead to large errors in contrast determination, providing an inaccurate characterization of the projector. For large-area measurements, various techniques have been employed, including the use of frustums and masks, to minimize such unwanted effects and provide a more accurate measurement. With some modifications, these same tools may be used for small-area measurements with similar results. The design, construction, and implementation of these tools will be discussed. Results will be shown comparing small-area contrast measurements of Projection Systems, including resolution determination, with and without stray light compensation, for different measurement instrumentation.
Edward G. Jones - One of the best experts on this subject based on the ideXlab platform.
-
Vesicular glutamate transporters define two sets of glutamatergic afferents to the somatosensory thalamus and two thalamocortical Projections in the mouse.
The Journal of Comparative Neurology, 2008Co-Authors: Alessandro Graziano, Karl D Murray, Edward G. JonesAbstract:The ventral posterior nucleus of the thalamus (VP) receives two major sets of excitatory inputs, one from the ascending somatosensory pathways originating in the dorsal horn, dorsal column nuclei, and trigeminal nuclei, and the other originating from the cerebral cortex. Both Systems use glutamate as neurotransmitter, as do the thalamocortical axons relaying somatosensory information from the VP to the primary somatosensory cortex (SI). The synapses formed by these Projection Systems differ anatomically, physiologically, and in their capacity for short-term synaptic plasticity. Glutamate uptake into synaptic vesicles and its release at central synapses depend on two isoforms of vesicular glutamate transporters, VGluT1 and VGluT2. Despite ample evidence of their complementary distribution, some instances exist of co-localization in the same brain areas or at the same synapses. In the thalamus, the two transcripts coexist in cells of the VP and other nuclei but not in the posterior or intralaminar nuclei. We show that the two isoforms are completely segregated at VP synapses, despite their widespread expression throughout the dorsal and ventral thalamus. We present immunocytochemical, ultrastructural, gene expression, and connectional evidence that VGluT1 in the VP is only found at corticothalamic synapses, whereas VGluT2 is only found at terminals made by axons originating in the spinal cord and brainstem. By contrast, the two VGluT isoforms are co-localized in thalamocortical axon terminals targeting layer IV, but not in those targeting layer I, suggesting the presence of two distinct Projection Systems related to the core/matrix pattern of organization of thalamocortical connectivity described in other mammals. J. Comp. Neurol. 507:1258–1276, 2008. © 2008 Wiley-Liss, Inc.
Harald Ries - One of the best experts on this subject based on the ideXlab platform.
-
spectroscopic measurement of radiation of high pressure mercury discharge lamps
Journal of Applied Physics, 2005Co-Authors: Ling Fu, Ralf Leutz, Harald RiesAbstract:Compact size and high efficiency are important features for Projection Systems. As the most often used sources for Projection optics, short arc lamps are characterized by their impressive economy and the ability to produce extremely bright light from small dimensional sources. In this contribution the old principle of back reflection towards the sources is applied to a high-pressure mercury discharge lamp with a reflector to improve the radiance of the source by 35% at a certain reduced solid angle. Increasing the optical thickness of sources is equivalent to reducing the total phase space (etendue) of emitted radiation by the same factor, which is very useful for compacting sources. In addition, by comparing the forward radiation and the back-reflected radiation obtained from spectroscopic measurements, we calculate the absorptivity, emissivity, absorption, and emission coefficients of the plasma of the arc lamp based on Kirchhoff’s Law and Planck’s equation which is necessary for determining its temperature and pressure.Compact size and high efficiency are important features for Projection Systems. As the most often used sources for Projection optics, short arc lamps are characterized by their impressive economy and the ability to produce extremely bright light from small dimensional sources. In this contribution the old principle of back reflection towards the sources is applied to a high-pressure mercury discharge lamp with a reflector to improve the radiance of the source by 35% at a certain reduced solid angle. Increasing the optical thickness of sources is equivalent to reducing the total phase space (etendue) of emitted radiation by the same factor, which is very useful for compacting sources. In addition, by comparing the forward radiation and the back-reflected radiation obtained from spectroscopic measurements, we calculate the absorptivity, emissivity, absorption, and emission coefficients of the plasma of the arc lamp based on Kirchhoff’s Law and Planck’s equation which is necessary for determining its tempera...
