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  • 1
    Electronic Resource
    Electronic Resource
    Neuroanatomical correlates of the near response: voluntary modulation of accommodation/vergence in the human visual system (2000)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 12 (2000), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: This study identifies brain regions participating in the execution of eye movements for voluntary positive accommodation (VPA) during open-loop vergence conditions. Neuronal activity was estimated by measurement of changes in regional cerebral blood flow (rCBF) with positron emission tomography and 15O-water. Thirteen naive volunteers viewed a checkerboard pattern with their dominant right eye, while a lens interrupted the line of gaze during alternate 1.5 s intervals. Three counterbalanced tasks required central fixation and viewing of a stationary checkerboard pattern: (i) through a 0.0 diopter (D) lens; (ii) through a −5.0-D lens while avoiding volitional accommodation and permitting blur; and (iii) through a −5.0-D lens while maintaining maximal focus. The latter required large-amplitude, high-frequency VPA. As an additional control, seven of the subjects viewed passively a digitally blurred checkerboard through a 0.0-D lens as above. Optometric measurements confirmed normal visual acuity and ability to perform the focusing task (VPA). Large-amplitude saccadic eye movements, verified absent by electro-oculography, were inhibited by central fixation. Image averaging across subjects demonstrated multifocal changes in rCBF during VPA: striate and extrastriate visual cortices; superior temporal cortices; and cerebellar cortex and vermis. Decreases in rCBF occurred in the lateral intraparietal area, prefrontal and frontal and/or supplementary eye fields. Analysis of regions of interest in the visual cortex showed systematic and appropriate task dependence of rCBF. Activations may reflect sensorimotor processing along the reflex arc of the accommodation system, while deactivations may indicate inhibition of systems participating in visual search.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2000.00962.x
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  • 2
    Electronic Resource
    Electronic Resource
    Functional neuroanatomy of the human near/far response to blur cues: eye-lens accommodation/vergence to point targets varying in depth (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 20 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this study was to identify the networks involved in the regulation of visual accommodation/vergence by contrasting the cortical functions subservient to eye-lens accommodation with those evoked by foveal fixation. Neural activity was assessed in normal volunteers by changes in rCBF measured with PET. Thirteen right-handed subjects participated in three monocular tasks: (i) resting with eyes closed; (ii) sustained foveal fixation upon a LED at 1.2 m (0.83 D); and (iii) accommodating alternately on a near (24 cm, 4.16 D) vs. a far (3.0 m, 0.33 D) LED alternately illuminated in sequential 2 s epochs. The contrast between the conditions of near/far accommodation and of constant foveal fixation revealed activation in cerebellar hemispheres and vermis; middle and inferior temporal cortex (BA 20, 21, 37); striate cortex and associative visual areas (BA 17/18). Comparison of the condition of constant fixation with the condition of resting with closed eyes indicated activation of cerebellar hemispheres and vermis; visual cortices (BA 17/18); a right hemisphere dominant network encompassing prefrontal (BA 6, 9, 47), superior parietal (BA 7), and superior temporal (BA 40) cortices; and bilateral thalamus. The contrast between the conditions of near/far accommodation with closed-eye rest reflected an incremental summation of the activations found in the previous comparisons (i.e. activations associated with constant fixation). Neural circuits activated selectively during the near/far response to blur cues over those during constant visual fixation, occupy posterior structures that include occipital visual regions, cerebellar hemispheres and vermis, and temporal cortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.2004.03743.x
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  • 3
    Electronic Resource
    Electronic Resource
    Tactile motion activates the human middle temporal/V5 (MT/V5) complex (2002)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 16 (2002), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The human middle temporal/V5 complex (hMT/V5) plays a central role in the perception of visual motion. This region is considered a unimodal visual area with little direct involvement of other sensory modalities. The current study uses H215O PET to test whether tactile motion influences the activity of hMT/V5. Regional cerebral blood flow (rCBF) within hMT/V5 was estimated in eight subjects in separate tactile motion and visual motion conditions, each contrasted with a resting, control. The tactile motion condition involved a brush stroked proximal-to-distal along the volar forearm and palm, while the subject attended to the stimulus with closed eyes. The visual motion condition consisted of low contrast, grey-scale rings radiating at 15°/s from a central point, upon which the subject was instructed to fixate. The location of hMT/V5 was defined for each subject separately as the local maximum of rCBF change during the visual motion condition (vs. control). The average change in rCBF within spherical regions of interest at each peak revealed significant bilateral activation of hMT/V5 in the tactile motion condition contrasted with a second, independent set of control scans. Additionally, a single subject received a sufficient number of scans to perform a pixel-wise, within-subject analysis. His functional images were coregistered to his anatomical MRI. In this subject, tactile motion produced a significant increase in rCBF that directly overlapped a region activated by visual motion at the posterior continuance of the inferior temporal sulcus, consistent with the known location of hMT/V5. These results suggest involvement of the hMT/V5 complex in tactile motion processing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.2002.02139.x
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  • 4
    Electronic Resource
    Electronic Resource
    Localization of a human system for sustained attention by positron emission tomography (1991)
    [s.l.] : Nature Publishing Group
    Nature 349 (1991), S. 61-64 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Vigilance tasks require subjects to focus and sustain their attention to subtle sensory signals within a given modality, to minimize distractibility to irrelevant internal as well as external information, and to maintain adequate alertness for the duration of the study session. Participants report ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/349061a0
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  • 5
    Electronic Resource
    Electronic Resource
    Gamma actin, spectrin, and intermediate filament proteins colocalize with vinculin at costameres, myofibril-to-sarcolemma attachment sites (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 449-462 
    Details
    ISSN: 0886-1544
    Keywords: myofibril to sarcolemma attachment ; costamere ; spectrin ; actin ; intermediate filaments ; vinculin ; fibronectin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Localization of vinculin at the sarcolemma of striated muscle fibers defines an orthogonal lattice. The costameres of the lattice are the riblike bands of vinculin that run perpendicular to the long axis of the fiber, repeat in register with I bands of the subjacent myofibrils, and seem to couple the myofibril to the sarcolemma [Pardo et al 1982, 1983a]. The colocalization studies presented in this paper show that gamma actin, spectrin, and intermediate filament antigens are additional components of this lattice of costameres. In addition, the results show that gamma actin and spectrin are also components of the internal network of collars, first visualized with antibody to desmin [Granger and Lazarides, 1978], that connects the myofibrils to each other at the level of the Z line.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030513
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