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      Using magnetic resonance imaging to assess visual deficits: a review

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          Abstract

          Purpose

          Over the last two decades, magnetic resonance imaging ( MRI) has been widely used in neuroscience research to assess both structure and function in the brain in health and disease. With regard to vision research, prior to the advent of MRI, researchers relied on animal physiology and human post‐mortem work to assess the impact of eye disease on visual cortex and connecting structures. Using MRI, researchers can non‐invasively examine the effects of eye disease on the whole visual pathway, including the lateral geniculate nucleus, striate and extrastriate cortex. This review aims to summarise research using MRI to investigate structural, chemical and functional effects of eye diseases, including: macular degeneration, retinitis pigmentosa, glaucoma, albinism, and amblyopia.

          Recent Findings

          Structural MRI has demonstrated significant abnormalities within both grey and white matter densities across both visual and non‐visual areas. Functional MRI studies have also provided extensive evidence of functional changes throughout the whole of the visual pathway following visual loss, particularly in amblyopia. MR spectroscopy techniques have also revealed several abnormalities in metabolite concentrations in both glaucoma and age‐related macular degeneration. GABA‐edited MR spectroscopy on the other hand has identified possible evidence of plasticity within visual cortex.

          Summary

          Collectively, using MRI to investigate the effects on the visual pathway following disease and dysfunction has revealed a rich pattern of results allowing for better characterisation of disease. In the future MRI will likely play an important role in assessing the impact of eye disease on the visual pathway and how it progresses over time.

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          Most cited references157

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          Advances and Pitfalls in the Analysis and Interpretation of Resting-State FMRI Data

          The last 15 years have witnessed a steady increase in the number of resting-state functional neuroimaging studies. The connectivity patterns of multiple functional, distributed, large-scale networks of brain dynamics have been recognised for their potential as useful tools in the domain of systems and other neurosciences. The application of functional connectivity methods to areas such as cognitive psychology, clinical diagnosis and treatment progression has yielded promising preliminary results, but is yet to be fully realised. This is due, in part, to an array of methodological and interpretative issues that remain to be resolved. We here present a review of the methods most commonly applied in this rapidly advancing field, such as seed-based correlation analysis and independent component analysis, along with examples of their use at the individual subject and group analysis levels and a discussion of practical and theoretical issues arising from this data ‘explosion’. We describe the similarities and differences across these varied statistical approaches to processing resting-state functional magnetic resonance imaging signals, and conclude that further technical optimisation and experimental refinement is required in order to fully delineate and characterise the gross complexity of the human neural functional architecture.
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            Simultaneous in vivo spectral editing and water suppression.

            Water suppression is typically performed in vivo by exciting the longitudinal magnetization in combination with dephasing, or by using frequency-selective coherence generation. MEGA, a frequency-selective refocusing technique, can be placed into any pulse sequence element designed to generate a Hahn spin-echo or stimulated echo, to dephase transverse water coherences with minimal spectral distortions. Water suppression performance was verified in vivo using stimulated echo acquisition mode (STEAM) localization, which provided water suppression comparable with that achieved with four selective pulses in 3,1-DRYSTEAM. The advantage of the proposed method was exploited for editing J-coupled resonances. Using a double-banded pulse that selectively inverts a J-coupling partner and simultaneously suppresses water, efficient metabolite editing was achieved in the point resolved spectroscopy (PRESS) and STEAM sequences in which MEGA was incorporated. To illustrate the efficiency of the method, the detection of gamma-aminobutyric acid (GABA) was demonstrated, with minimal contributions from macromolecules and overlying singlet peaks at 4 T. The estimated occipital GABA concentration was consistent with previous reports, suggesting that editing for GABA is efficient when based on MEGA at high field strengths.
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              Vividness of Visual Imagery and Incidental Recall of Verbal Cues, When Phenomenological Availability Reflects Long-Term Memory Accessibility

              The relationship between vivid visual mental images and unexpected recall (incidental recall) was replicated, refined, and extended. In Experiment 1, participants were asked to generate mental images from imagery-evoking verbal cues (controlled on several verbal properties) and then, on a trial-by-trial basis, rate the vividness of their images; 30 min later, participants were surprised with a task requiring free recall of the cues. Higher vividness ratings predicted better incidental recall of the cues than individual differences (whose effect was modest). Distributional analysis of image latencies through ex-Gaussian modeling showed an inverse relation between vividness and latency. However, recall was unrelated to image latency. The follow-up Experiment 2 showed that the processes underlying trial-by-trial vividness ratings are unrelated to the Vividness of Visual Imagery Questionnaire (VVIQ), as further supported by a meta-analysis of a randomly selected sample of relevant literature. The present findings suggest that vividness may act as an index of availability of long-term sensory traces, playing a non-epiphenomenal role in facilitating the access of those memories.
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                Author and article information

                Journal
                Ophthalmic Physiol Opt
                Ophthalmic Physiol Opt
                10.1111/(ISSN)1475-1313
                OPO
                Ophthalmic & Physiological Optics
                John Wiley and Sons Inc. (Hoboken )
                0275-5408
                1475-1313
                25 April 2016
                May 2016
                : 36
                : 3 , Imaging the visual system: from the eye to the brain ( doiID: 10.1111/opo.2016.36.issue-3 )
                : 240-265
                Affiliations
                [ 1 ] Department of PsychologyUniversity of York YorkUK
                [ 2 ] Hull York Medical SchoolUniversity of York YorkUK
                Author notes
                [*] [* ] Correspondence: Antony B Morland

                E‐mail address: antony.morland@ 123456york.ac.uk

                Article
                OPO12293
                10.1111/opo.12293
                4855621
                27112223
                cfb0336f-2873-4a4d-b495-1b2bd7ff3c2a
                © 2016 The The Authors Ophthalmic and Physiological Optics published by John Wiley & Sons Ltd on behalf of College of Optometrists.

                This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

                History
                : 23 December 2015
                : 15 February 2016
                Page count
                Pages: 26
                Funding
                Funded by: Fight for Sight project
                Award ID: 1523/1524
                Funded by: Wellcome Trust
                Funded by: Medical Research Council
                Award ID: G0401339
                Categories
                Invited Review
                Invited Reviews
                Custom metadata
                2.0
                opo12293
                May 2016
                Converter:WILEY_ML3GV2_TO_NLMPMC version:4.9.1 mode:remove_FC converted:23.06.2016

                albinism,amblyopia,anophthalmia,functional magnetic resonance imaging,glaucoma,macular degeneration,magnetic resonance imaging,magnetic resonance spectroscopy,ophthalmology,visual deficit

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