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Wang L, Ji Y, Ding H, Tian Q, Fan K, Shi D, Yu C, Qin W. Abnormal cerebral blood flow in patients with Leber's hereditary optic neuropathy. Brain Imaging Behav 2023; 17:471-480. [PMID: 37368154 DOI: 10.1007/s11682-023-00775-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2023] [Indexed: 06/28/2023]
Abstract
PURPOSE The study aimed to unravel abnormal cerebral blood flow (CBF) in patients with Leber's hereditary optic neuropathy (LHON) using arterial spin labeling (ASL) and to investigate the associations among disrupted CBF, disease duration, and neuro-ophthalmological impairment. METHODS ASL perfusion imaging data was collected from 20 patients with acute LHON, 29 patients with chronic LHON, and 37 healthy controls. We used a one-way analysis of covariance to test the intergroup differences in CBF. Linear and nonlinear curve fit models were applied to explore the associations among CBF, disease duration, and neuro-ophthalmological metrics. RESULTS Brain regions differed in LHON patients, including the left sensorimotor and bilateral visual areas (p < 0.05, cluster-wise family-wise error correction). Acute and chronic LHON patients demonstrated lower CBF in bilateral calcarine than the healthy controls. Chronic LHON had lower CBF in the left middle frontal gyrus and sensorimotor cortex, and temporal-partial junction than the healthy controls and acute LHON. A significant logarithmic negative correlation was shown between CBF of left middle frontal gyrus and disease duration. A significant linear positive correlation was found between retinal nerve fiber layer thickness and CBF in left middle frontal gyrus, and negative correlations between loss of variance and CBF in left middle frontal gyrus and sensorimotor cortex (p < 0.05, Bonferroni correction). CONCLUSION LHON patients exhibited reduced CBF in the visual pathway, sensorimotor and higher-tier cognitive areas. Disease duration and neuro-ophthalmological impairments can influence the metabolism of non-visual areas.
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Affiliation(s)
- Ling Wang
- Department of Medical Imaging, Henan Provincial People's Hospital, Zhengzhou, 450003, China
| | - Yi Ji
- Department of Radiology & Tianjin Key Lab of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, China
| | - Hao Ding
- Department of Radiology & Tianjin Key Lab of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, China
- School of Medical Imaging, Tianjin Medical University, Tianjin, 300070, China
| | - Qin Tian
- Department of Medical Imaging, Henan Provincial People's Hospital, Zhengzhou, 450003, China
| | - Ke Fan
- Henan Eye Institute, Henan Eye Hospital, Zhengzhou University People's Hospital, Henan Provincial People's Hospital, Zhengzhou, 450003, China
| | - Dapeng Shi
- Department of Medical Imaging, Henan Provincial People's Hospital, Zhengzhou, 450003, China.
- Department of Medical Imaging, Henan Provincial People's Hospital, Sanquan College of Xinxiang Medical University, Weiwu Road No. 7, Jinshui District, ZhengZhou, Henan Province, China.
| | - Chunshui Yu
- Department of Radiology & Tianjin Key Lab of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, China.
- Department of Radiology, Tianjin Medical University General Hospital, Anshan Road No. 154, Heping District, Tianjin, 300052, China.
| | - Wen Qin
- Department of Radiology & Tianjin Key Lab of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, 300052, China.
- Department of Radiology, Tianjin Medical University General Hospital, Anshan Road No. 154, Heping District, Tianjin, 300052, China.
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Ji Y, Wang L, Ding H, Tian Q, Fan K, Shi D, Yu C, Qin W. Aberrant neurovascular coupling in Leber's hereditary optic neuropathy: Evidence from a multi-model MRI analysis. Front Neurosci 2023; 16:1050772. [PMID: 36703998 PMCID: PMC9871937 DOI: 10.3389/fnins.2022.1050772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 12/22/2022] [Indexed: 01/12/2023] Open
Abstract
The study aimed to investigate the neurovascular coupling abnormalities in Leber's hereditary optic neuropathy (LHON) and their associations with clinical manifestations. Twenty qualified acute Leber's hereditary optic neuropathy (A-LHON, disease duration ≤ 1 year), 29 chronic Leber's hereditary optic neuropathy (C-LHON, disease duration > 1 year), as well as 37 healthy controls (HCs) were recruited. The neurovascular coupling strength was quantified as the ratio between regional homogeneity (ReHo), which represents intrinsic neuronal activity and relative cerebral blood flow (CBF), representing microcirculatory blood supply. A one-way analysis of variance was used to compare intergroup differences in ReHo/CBF ratio with gender and age as co-variables. Pearson's Correlation was used to clarify the association between ReHo, CBF, and neurovascular coupling strength. Furthermore, we applied linear and exponential non-linear regression models to explore the associations among ReHo/CBF, disease duration, and neuro-ophthalmological metrics. Compared with HCs, A_LHON, and C_LHON patients demonstrated a higher ReHo/CBF ratio than the HCs in the bilateral primary visual cortex (B_CAL), which was accompanied by reduced CBF while preserved ReHo. Besides, only C_LHON had a higher ReHo/CBF ratio and reduced CBF in the left middle temporal gyrus (L_MTG) and left sensorimotor cortex (L_SMC) than the HCs, which was accompanied by increased ReHo in L_MTG (p < 1.85e-3, Bonferroni correction). A-LHON and C-LHON showed a negative Pearson correlation between ReHo/CBF ratio and CBF in B_CAL, L_SMC, and L_MTG. Only C_LHON showed a weak positive correlation between ReHo/CBF ratio and ReHo in L_SMC and L_MTG (p < 0.05, uncorrected). Finally, disease duration was positively correlated with ReHo/CBF ratio of L_SMC (Exponential: Radj2 = 0.23, p = 8.66e-4, Bonferroni correction). No statistical correlation was found between ReHo/CBF ratio and neuro-ophthalmological metrics (p > 0.05, Bonferroni correction). Brain neurovascular "dyscoupling" within and outside the visual system might be an important neurological mechanism of LHON.
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Affiliation(s)
- Yi Ji
- Tianjin Key Lab of Functional Imaging, Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Ling Wang
- Department of Medical Imaging, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Hao Ding
- Tianjin Key Lab of Functional Imaging, Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China,School of Medical Imaging, Tianjin Medical University, Tianjin, China
| | - Qin Tian
- Department of Medical Imaging, Henan Provincial People’s Hospital, Zhengzhou, China
| | - Ke Fan
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Zhengzhou, China
| | - Dapeng Shi
- Department of Medical Imaging, Henan Provincial People’s Hospital, Zhengzhou, China,*Correspondence: Dapeng Shi,
| | - Chunshui Yu
- Tianjin Key Lab of Functional Imaging, Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China,Chunshui Yu,
| | - Wen Qin
- Tianjin Key Lab of Functional Imaging, Department of Radiology, Tianjin Medical University General Hospital, Tianjin, China,Wen Qin,
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Duarte JV, Abreu R, Castelo-Branco M. A two-stage framework for neural processing of biological motion. Neuroimage 2022; 259:119403. [PMID: 35738331 DOI: 10.1016/j.neuroimage.2022.119403] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Revised: 05/18/2022] [Accepted: 06/19/2022] [Indexed: 11/26/2022] Open
Abstract
It remains to be understood how biological motion is hierarchically computed, from discrimination of local biological motion animacy to global dynamic body perception. Here, we addressed this functional separation of the correlates of the perception of local biological motion from perception of global motion of a body. We hypothesized that local biological motion processing can be isolated, by using a single dot motion perceptual decision paradigm featuring the biomechanical details of local realistic motion of a single joint. To ensure that we were indeed tackling processing of biological motion properties we used a discrimination instead of detection task. We discovered using representational similarity analysis that two key early dorsal and two ventral stream regions (visual motion selective hMT+ and V3A, extrastriate body area EBA and a region within fusiform gyrus FFG) showed robust and separable signals related to encoding of local biological motion and global motion-mediated shape. These signals reflected two independent processing stages, as revealed by representational similarity analysis and deconvolution of fMRI responses to each motion pattern. This study showed that higher level pSTS encodes both classes of biological motion in a similar way, revealing a higher-level integrative stage, reflecting scale independent biological motion perception. Our results reveal a two-stage framework for neural computation of biological motion, with an independent contribution of dorsal and ventral regions for the initial stage.
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Affiliation(s)
- João Valente Duarte
- Centre of Biomedical Imaging and Translational Research (CIBIT), Institute of Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Portugal
| | - Rodolfo Abreu
- Centre of Biomedical Imaging and Translational Research (CIBIT), Institute of Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Portugal
| | - Miguel Castelo-Branco
- Centre of Biomedical Imaging and Translational Research (CIBIT), Institute of Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Portugal; Faculty of Medicine, University of Coimbra, Portugal.
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Tian Q, Wang L, Zhang Y, Fan K, Liang M, Shi D, Qin W, Ding H. Brain Gray Matter Atrophy and Functional Connectivity Remodeling in Patients With Chronic LHON. Front Neurosci 2022; 16:885770. [PMID: 35645726 PMCID: PMC9135140 DOI: 10.3389/fnins.2022.885770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/19/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose The aim of this study was to investigate the brain gray matter volume (GMV) and spontaneous functional connectivity (FC) changes in patients with chronic Leber's hereditary optic neuropathy (LHON), and their relations with clinical measures. Methods A total of 32 patients with chronic LHON and matched sighted healthy controls (HC) underwent neuro-ophthalmologic examinations and multimodel magnetic resonance imaging (MRI) scans. Voxel-based morphometry (VBM) was used to detect the GMV differences between the LHON and HC. Furthermore, resting-state FC analysis using the VBM-identified clusters as seeds was carried out to detect potential functional reorganization in the LHON. Finally, the associations between the neuroimaging and clinical measures were performed. Results The average peripapillary retinal nerve fiber layer (RNFL) thickness of the chronic LHON was significantly thinner (T = −16.421, p < 0.001), and the mean defect of the visual field was significantly higher (T = 11.28, p < 0.001) than the HC. VBM analysis demonstrated a significantly lower GMV of bilateral calcarine gyri (CGs) in the LHON than in the HC (p < 0.05). Moreover, in comparison with the HC, the LHON had significantly lower FC between the centroid of the identified left CG and ipsilateral superior occipital gyrus (SOG) and higher FC between this cluster and the ipsilateral posterior cingulate gyrus (p < 0.05, corrected). Finally, the GMV of the left CG was negatively correlated with the LHON duration (r = −0.535, p = 0.002), and the FC between the left CG and the ipsilateral posterior cingulate gyrus of the LHON was negatively correlated with the average peripapillary RNFL thickness (r = −0.522, p = 0.003). Conclusion The atrophied primary visual cortex of the chronic LHON may be caused by transneuronal degeneration following the retinal damage. Moreover, our findings suggest that the functional organization of the atrophied primary visual cortex has been reshaped in the chronic LHON.
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Affiliation(s)
- Qin Tian
- Department of Medical Imaging, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Ling Wang
- Department of Medical Imaging, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
| | - Yu Zhang
- Department of Radiology, Tianjin Medical University, Tianjin, China
- Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
| | - Ke Fan
- Henan Eye Institute, Henan Eye Hospital, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, China
| | - Meng Liang
- Department of Radiology, Tianjin Medical University, Tianjin, China
- Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- School of Medical Imaging, Tianjin Medical University, Tianjin, China
| | - Dapeng Shi
- Department of Medical Imaging, People's Hospital of Zhengzhou University, Henan Provincial People's Hospital, Zhengzhou, China
- *Correspondence: Dapeng Shi
| | - Wen Qin
- Department of Radiology, Tianjin Medical University, Tianjin, China
- Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- Wen Qin
| | - Hao Ding
- Department of Radiology, Tianjin Medical University, Tianjin, China
- Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin, China
- School of Medical Imaging, Tianjin Medical University, Tianjin, China
- Hao Ding
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Molz B, Herbik A, Baseler HA, de Best PB, Vernon RW, Raz N, Gouws AD, Ahmadi K, Lowndes R, McLean RJ, Gottlob I, Kohl S, Choritz L, Maguire J, Kanowski M, Käsmann-Kellner B, Wieland I, Banin E, Levin N, Hoffmann MB, Morland AB. Structural changes to primary visual cortex in the congenital absence of cone input in achromatopsia. Neuroimage Clin 2022; 33:102925. [PMID: 34959047 PMCID: PMC8718719 DOI: 10.1016/j.nicl.2021.102925] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 11/30/2022]
Abstract
Anatomy of primary visual cortex (V1) assessed with surface-based morphmetry in those with congenital achromatopsia (ACHM). Reduction in cortical surface area in foveal, parafoveal and paracentral representations of V1 in those with ACHM. In ACHM a localized thickening in the area of V1 that represents the region of retina occupied solely by cones. V1 changes in ACHM may limit its ability to take on normal properties if retinal function were to be restored. Early intervention, before the development plastic period is over, may offer better restoration of vision in ACHM.
Autosomal recessive Achromatopsia (ACHM) is a rare inherited disorder associated with dysfunctional cone photoreceptors resulting in a congenital absence of cone input to visual cortex. This might lead to distinct changes in cortical architecture with a negative impact on the success of gene augmentation therapies. To investigate the status of the visual cortex in these patients, we performed a multi-centre study focusing on the cortical structure of regions that normally receive predominantly cone input. Using high-resolution T1-weighted MRI scans and surface-based morphometry, we compared cortical thickness, surface area and grey matter volume in foveal, parafoveal and paracentral representations of primary visual cortex in 15 individuals with ACHM and 42 normally sighted, healthy controls (HC). In ACHM, surface area was reduced in all tested representations, while thickening of the cortex was found highly localized to the most central representation. These results were comparable to more widespread changes in brain structure reported in congenitally blind individuals, suggesting similar developmental processes, i.e., irrespective of the underlying cause and extent of vision loss. The cortical differences we report here could limit the success of treatment of ACHM in adulthood. Interventions earlier in life when cortical structure is not different from normal would likely offer better visual outcomes for those with ACHM.
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Affiliation(s)
- Barbara Molz
- Department of Psychology, University of York, Heslington, YO10 5DD York, United Kingdom; Language and Genetics Department, Max Planck Institute for Psycholinguistics, 6525 XD Nijmegen, Netherlands
| | - Anne Herbik
- Department of Ophthalmology, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Heidi A Baseler
- Department of Psychology, University of York, Heslington, YO10 5DD York, United Kingdom; Hull York Medical School, University of York, Heslington, YO10 5DD York, United Kingdom; York Biomedical Research Institute, University of York, Heslington, YO10 5DD York, United Kingdom
| | - Pieter B de Best
- MRI Unit, Department of Neurology, Hadassah Medical Center, 91120 Jerusalem, Israel
| | - Richard W Vernon
- Department of Psychology, University of York, Heslington, YO10 5DD York, United Kingdom
| | - Noa Raz
- MRI Unit, Department of Neurology, Hadassah Medical Center, 91120 Jerusalem, Israel
| | - Andre D Gouws
- York Neuroimaging Centre, Department of Psychology, University of York, YO10 5NY York, United Kingdom
| | - Khazar Ahmadi
- Department of Ophthalmology, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Rebecca Lowndes
- York Neuroimaging Centre, Department of Psychology, University of York, YO10 5NY York, United Kingdom
| | - Rebecca J McLean
- University of Leicester Ulverscroft Eye Unit, University of Leicester, Leicester Royal Infirmary, LE2 7LX Leicester, United Kingdom
| | - Irene Gottlob
- University of Leicester Ulverscroft Eye Unit, University of Leicester, Leicester Royal Infirmary, LE2 7LX Leicester, United Kingdom
| | - Susanne Kohl
- Molecular Genetics Laboratory, Institute for Ophthalmic Research, Centre for Ophthalmology, University Clinics Tübingen, 72076 Tübingen, Germany
| | - Lars Choritz
- Department of Ophthalmology, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - John Maguire
- School of Optometry and Vision Sciences, University of Bradford, BD7 1DP Bradford, United Kingdom
| | - Martin Kanowski
- Department of Neurology, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Barbara Käsmann-Kellner
- Department of Ophthalmology, Saarland University Hospital and Medical Faculty of the Saarland University, 66421 Homburg, Germany
| | - Ilse Wieland
- Department for Molecular Genetics, Institute for Human Genetics, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany
| | - Eyal Banin
- Degenerative Diseases of the Retina Unit, Department of Ophthalmology, Hadassah Medical Center, 91120 Jerusalem, Israel
| | - Netta Levin
- MRI Unit, Department of Neurology, Hadassah Medical Center, 91120 Jerusalem, Israel
| | - Michael B Hoffmann
- Department of Ophthalmology, University Hospital, Otto-von-Guericke University, 39120 Magdeburg, Germany; Center for Behavioral Brain Sciences, 39106 Magdeburg, Germany
| | - Antony B Morland
- Department of Psychology, University of York, Heslington, YO10 5DD York, United Kingdom; York Biomedical Research Institute, University of York, Heslington, YO10 5DD York, United Kingdom; York Neuroimaging Centre, Department of Psychology, University of York, YO10 5NY York, United Kingdom.
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Chow-Wing-Bom HT, Callaghan MF, Wang J, Wei S, Dick F, Yu-Wai-Man P, Dekker TM. Neuroimaging in Leber Hereditary Optic Neuropathy: State-of-the-art and future prospects. Neuroimage Clin 2022; 36:103240. [PMID: 36510411 PMCID: PMC9668671 DOI: 10.1016/j.nicl.2022.103240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 06/14/2022] [Accepted: 10/17/2022] [Indexed: 11/05/2022]
Abstract
Leber Hereditary Optic Neuropathy (LHON) is an inherited mitochondrial retinal disease that causes the degeneration of retinal ganglion cells and leads to drastic loss of visual function. In the last decades, there has been a growing interest in using Magnetic Resonance Imaging (MRI) to better understand mechanisms of LHON beyond the retina. This is partially due to the emergence of gene-therapies for retinal diseases, and the accompanying expanded need for reliably quantifying and monitoring visual processing and treatment efficiency in patient populations. This paper aims to draw a current picture of key findings in this field so far, the challenges of using neuroimaging methods in patients with LHON, and important open questions that MRI can help address about LHON disease mechanisms and prognoses, including how downstream visual brain regions are affected by the disease and treatment and why, and how scope for neural plasticity in these pathways may limit or facilitate recovery.
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Affiliation(s)
- Hugo T Chow-Wing-Bom
- Institute of Ophthalmology, University College London (UCL), London, United Kingdom; Birkbeck/UCL Centre for NeuroImaging, London, United Kingdom.
| | - Martina F Callaghan
- Wellcome Centre for Human Neuroimaging, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - Junqing Wang
- Department of Ophthalmology, The Chinese People's Liberation Army General Hospital, The Chinese People's Liberation Army Medical School, Beijing, China
| | - Shihui Wei
- Department of Ophthalmology, The Chinese People's Liberation Army General Hospital, The Chinese People's Liberation Army Medical School, Beijing, China
| | - Frederic Dick
- Birkbeck/UCL Centre for NeuroImaging, London, United Kingdom; Department of Psychological Sciences, Birkbeck, University of London, United Kingdom; Department of Experimental Psychology, UCL, London, United Kingdom
| | - Patrick Yu-Wai-Man
- Institute of Ophthalmology, University College London (UCL), London, United Kingdom; John van Geest Centre for Brain Repair and MRC Mitochondrial Biology Unit, Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom; Cambridge Eye Unit, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, United Kingdom; Moorfields Eye Hospital NHS Foundation Trust, London, United Kingdom
| | - Tessa M Dekker
- Institute of Ophthalmology, University College London (UCL), London, United Kingdom; Birkbeck/UCL Centre for NeuroImaging, London, United Kingdom; Department of Experimental Psychology, UCL, London, United Kingdom
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Widespread Reductions of Spontaneous Neurophysiological Activity in Leber’s Disease—An Application of EEG Source Current Density Reconstruction. Brain Sci 2020; 10:brainsci10090622. [PMID: 32911650 PMCID: PMC7563180 DOI: 10.3390/brainsci10090622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 08/31/2020] [Accepted: 09/04/2020] [Indexed: 11/16/2022] Open
Abstract
Leber’s hereditary optic neuropathy (LHON) is a rare, maternally inherited genetic disease caused by a mutation of mitochondrial DNA. Classical descriptions have highlighted structural abnormalities in various parts of patients’ optic tracts; however, current studies have proved that changes also affect many cortical and subcortical structures, not only these belonging to the visual system. This study aimed at improving our understanding of neurophysiological impairments in LHON. First of all, we wanted to know if there were any differences between the health control and LHON subjects in the whole-brain source electroencephalography (EEG) analysis. Second, we wanted to investigate the associations between the observed results and some selected aspects of Leber’s disease’s clinical picture. To meet these goals, 20 LHON patients and 20 age-matched healthy control (HC) subjects were examined. To investigate the electrophysiological differences between the HC and LHON groups, a quantitative analysis of the whole-brain current source density was performed. The signal analysis method was based on scalp EEG data and an inverse solution method called low-resolution brain electromagnetic tomography (eLORETA). In comparison with the healthy subjects, LHON participants showed significantly decreased neuronal activity in the alpha and gamma bands; more specifically, in the alpha band, the decrease was mainly found in the occipital lobes and secondary visual cortex, whereas, in the gamma band, the reduced activity occurred in multiple cortical areas. Additionally, a correlation was found between the alpha band activity of the right secondary visual cortex and the averaged thickness of the right retinal nerve fiber layer in the LHON participants. Our study suggests that LHON is associated with widespread cortical de-activation, rather than simply abnormalities of structures constituting the visual system.
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Jorge L, Canário N, Quental H, Bernardes R, Castelo-Branco M. Is the Retina a Mirror of the Aging Brain? Aging of Neural Retina Layers and Primary Visual Cortex Across the Lifespan. Front Aging Neurosci 2020; 11:360. [PMID: 31998115 PMCID: PMC6961569 DOI: 10.3389/fnagi.2019.00360] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 12/10/2019] [Indexed: 01/13/2023] Open
Abstract
How aging concomitantly modulates the structural integrity of the brain and retina in healthy individuals remains an outstanding question. Given the strong bottom-up retinocortical connectivity, it is important to study how these structures co-evolve during healthy aging in order to unravel mechanisms that may affect the physiological integrity of both structures. For the 56 participants in the study, primary visual cortex (BA17), as well as frontal, parietal and temporal regions thicknesses were measured in T1-weighted magnetic resonance imaging (MRI), and retinal macular thickness (10 neuroretinal layers) was measured by optical coherence tomography (OCT) imaging. We investigated the statistical association of these measures and their age dependence. We found an age-related decay of primary visual cortical thickness that was significantly correlated with a decrease in global and multiple layer retinal thicknesses. The atrophy of both structures might jointly account for the decline of various visual capacities that accompany the aging process. Furthermore, associations with other cortical regions suggest that retinal status may index cortical integrity in general.
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Affiliation(s)
- Lília Jorge
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Nádia Canário
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Hugo Quental
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal
| | - Rui Bernardes
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Miguel Castelo-Branco
- Coimbra Institute for Biomedical Imaging and Translational Research (CIBIT), University of Coimbra, Coimbra, Portugal.,Institute for Nuclear Sciences Applied to Health (ICNAS), University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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9
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Castaldi E, Cicchini GM, Falsini B, Binda P, Morrone MC. Residual Visual Responses in Patients With Retinitis Pigmentosa Revealed by Functional Magnetic Resonance Imaging. Transl Vis Sci Technol 2019; 8:44. [PMID: 31867144 PMCID: PMC6922275 DOI: 10.1167/tvst.8.6.44] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 09/24/2019] [Indexed: 01/20/2023] Open
Abstract
PURPOSE We evaluated the potential of magnetic resonance imaging in identifying signs of cortical visual processing with greater sensitivity than standard ophthalmological measures in patients with retinitis pigmentosa (RP) at advanced stages. METHODS Eight patients affected with RP with only bare light perception and weak or absent visual evoked potential (VEP) or electroretinogram (ERG) responses to flashes of light were tested. Visual impairment was evaluated by means of psychophysical testing, where patients were asked to discriminate the drifting direction of a contrast modulated grating. Patients underwent magnetic resonance imaging scanning, and the behavioral performance was correlated with both blood oxygenation level-dependent (BOLD) signal elicited by flashes of lights and cortical thickness measured in primary visual area. RESULTS Contrast sensitivity to drifting gratings of very low spatial and temporal frequency was greatly impaired, yet measurable in all patients. Weak luminance flashes elicited significant BOLD responses in the striate and extrastriate cortex, despite that the stimuli were not perceived during scanning. Importantly, patients with less severe impairment of contrast sensitivity showed stronger V1 BOLD responses. Striate cortical thickness did not correlate with visual sensitivity. CONCLUSIONS BOLD responses provide a sensitive and reliable index of visual sparing more than VEPs or ERGs, which are often absent in RP patients. The minimal residual vision can be assessed by optimal visual stimulation in two alternative forced choice discrimination tasks and by BOLD responses. Imaging techniques provide useful information to monitor progressive vision loss. TRANSLATIONAL RELEVANCE Functional magnetic resonance imaging might be a practical tool for assessing visual sparing, as it is more feasible and sensitive than psychophysical or ophthalmological testing.
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Affiliation(s)
- Elisa Castaldi
- Department of Neuroscience, Psychology, Pharmacology and Child Health, University of Florence, Florence, Italy
| | | | - Benedetto Falsini
- Department of Ophthalmology, Policlinico Gemelli, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Paola Binda
- Institute of Neuroscience CNR, Pisa, Italy
- Department of Translational Research and New technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Maria Concetta Morrone
- Department of Translational Research and New technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
- IRCCS Stella Maris, Calambrone, Pisa, Italy
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Enhanced Visual Attentional Modulation in Patients with Inherited Peripheral Retinal Degeneration in the Absence of Cortical Degeneration. Neural Plast 2019; 2019:8136354. [PMID: 31341470 PMCID: PMC6614956 DOI: 10.1155/2019/8136354] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Accepted: 06/11/2019] [Indexed: 12/20/2022] Open
Abstract
The role of attentional mechanisms in peripheral vision loss remains an outstanding question. Our study was aimed at determining the effect of genetically determined peripheral retinal dystrophy caused by Retinitis Pigmentosa (RP) on visual cortical function and tested the recruitment of attentional mechanisms using functional magnetic resonance imaging (fMRI). We included thirteen patients and twenty-two age- and gender-matched controls. We analyzed cortical responses under attentional demands and passive viewing conditions while presenting a visual stimulus covering the central and paracentral visual field. Brain activity was studied in visual areas V1, V2, and V3 as well as in cortical regions of interest corresponding to the preserved and the damaged visual field. The influence of visual field extent and age of disease onset were also investigated. Cortical thickness of visual areas was also measured. We found that cortical visual responses under attentional demands were increased in patients with larger degeneration of visual field, as demonstrated by significant interaction effects between group and task conditions. Moreover, activation during the task condition was increased for patients in two cortical regions of interest corresponding to the preserved and damaged visual field, specifically in patients with severe visual field loss. These findings were observed in the presence of preserved visual cortical structure. We conclude that RP patients have enhanced visual attention recruitment despite their retinal degeneration, while cortical structure and overall response levels remain intact. The unmasking of feedback signals from higher level visual regions involved in attentional processes may explain the increased cortical responses. These findings are relevant for the design of strategies for treating retinal diseases, based on attentional cuing.
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Long M, Wang L, Tian Q, Ding H, Qin W, Shi D, Yu C. Brain white matter changes in asymptomatic carriers of Leber’s hereditary optic neuropathy. J Neurol 2019; 266:1474-1480. [DOI: 10.1007/s00415-019-09284-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 03/13/2019] [Accepted: 03/15/2019] [Indexed: 10/27/2022]
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12
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Mitochondrial pathophysiology beyond the retinal ganglion cell: occipital GABA is decreased in autosomal dominant optic neuropathy. Graefes Arch Clin Exp Ophthalmol 2018; 256:2341-2348. [PMID: 30324419 PMCID: PMC6224020 DOI: 10.1007/s00417-018-4153-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 07/05/2018] [Accepted: 09/24/2018] [Indexed: 01/05/2023] Open
Abstract
PURPOSE It has remained a mystery why some genetic mitochondrial disorders affect predominantly specific cell types such as the retinal ganglion cell. This is particularly intriguing concerning retinal and cortical function since they are tightly linked in health and disease. Autosomal dominant optic neuropathy (ADOA) is a mitochondrial disease that affects the ganglion cell. However, it is unknown whether alterations are also present in the visual cortex, namely in excitation/inhibition balance. METHODS In this study, we performed in vivo structural and biochemical proton magnetic resonance imaging in 14 ADOA and 11 age-matched control participants focusing on the visual cortex, with the aim of establishing whether in this genetically determined disease an independent cortical neurochemical phenotype could be established irrespective of a putative structural phenotype. Cortical thickness of anatomically defined visual areas was estimated, and a voxel-based morphometry approach was used to assess occipital volumetric changes in ADOA. Neurochemical measurements were focused on γ-aminobutyric acid (GABA) and glutamate, as indicators of the local excitatory/inhibitory balance. RESULTS We found evidence for reduced visual cortical GABA and preserved glutamate concentrations in the absence of cortical or subcortical atrophy. These changes in GABA levels were explained by neither structural nor functional measures of visual loss, suggesting a developmental origin. CONCLUSIONS These results suggest that mitochondrial disorders that were previously believed to only affect retinal function may also affect cortical physiology, especially the GABAergic system, suggesting reduced brain inhibition vs. excitation. This GABA phenotype, independent of sensory loss or cortical atrophy and in the presence of preserved glutamate levels, suggests a neurochemical developmental change at the cortical level, leading to a pathophysiological excitation/inhibition imbalance.
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Dynamic response to initial stage blindness in visual system development. Clin Sci (Lond) 2017; 131:1515-1527. [DOI: 10.1042/cs20170234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Revised: 05/09/2017] [Accepted: 05/24/2017] [Indexed: 11/17/2022]
Abstract
Sensitive periods and experience-dependent plasticity have become core issues in visual system development. Converging evidence indicates that visual experience is an indispensable factor in establishing mature visual system circuitry during sensitive periods and the visual system exhibits substantial plasticity while facing deprivation. The mechanisms that underlie the environmental regulation of visual system development and plasticity are of great interest but need further exploration. Here, we investigated a unique sample of human infants who experienced initial stage blindness (beginning at birth and lasting for 2–8 months) before the removal of bilateral cataracts. Retinal thickness (RT), axial length (AL), refractive status, visual grating acuity and genetic integrity were recorded during the preoperative period or at surgery and then during follow-up. The results showed that the development of the retina is malleable and associated with external environmental influences. Our work supported that the retina might play critical roles in the development of the experience-dependent visual system and its malleability might partly contribute to the sensitive period plasticity.
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Combes RD, Shah AB. The use of in vivo, ex vivo, in vitro, computational models and volunteer studies in vision research and therapy, and their contribution to the Three Rs. Altern Lab Anim 2017; 44:187-238. [PMID: 27494623 DOI: 10.1177/026119291604400302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Much is known about mammalian vision, and considerable progress has been achieved in treating many vision disorders, especially those due to changes in the eye, by using various therapeutic methods, including stem cell and gene therapy. While cells and tissues from the main parts of the eye and the visual cortex (VC) can be maintained in culture, and many computer models exist, the current non-animal approaches are severely limiting in the study of visual perception and retinotopic imaging. Some of the early studies with cats and non-human primates (NHPs) are controversial for animal welfare reasons and are of questionable clinical relevance, particularly with respect to the treatment of amblyopia. More recently, the UK Home Office records have shown that attention is now more focused on rodents, especially the mouse. This is likely to be due to the perceived need for genetically-altered animals, rather than to knowledge of the similarities and differences of vision in cats, NHPs and rodents, and the fact that the same techniques can be used for all of the species. We discuss the advantages and limitations of animal and non-animal methods for vision research, and assess their relative contributions to basic knowledge and clinical practice, as well as outlining the opportunities they offer for implementing the principles of the Three Rs (Replacement, Reduction and Refinement).
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Affiliation(s)
| | - Atul B Shah
- Ophthalmic Surgeon, National Eye Registry Ltd, Leicester, UK
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15
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Ferreira S, Pereira AC, Quendera B, Reis A, Silva ED, Castelo-Branco M. Primary visual cortical remapping in patients with inherited peripheral retinal degeneration. NEUROIMAGE-CLINICAL 2016; 13:428-438. [PMID: 28116235 PMCID: PMC5233796 DOI: 10.1016/j.nicl.2016.12.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2016] [Revised: 11/10/2016] [Accepted: 12/14/2016] [Indexed: 12/17/2022]
Abstract
Human studies addressing the long-term effects of peripheral retinal degeneration on visual cortical function and structure are scarce. Here we investigated this question in patients with Retinitis Pigmentosa (RP), a genetic condition leading to peripheral visual degeneration. We acquired functional and anatomical magnetic resonance data from thirteen patients with different levels of visual loss and twenty-two healthy participants to study primary (V1) visual cortical retinotopic remapping and cortical thickness. We identified systematic visual field remapping in the absence of structural changes in the primary visual cortex of RP patients. Remapping consisted in a retinotopic eccentricity shift of central retinal inputs to more peripheral locations in V1. Importantly, this was associated with changes in visual experience, as assessed by the extent of the visual loss, with more constricted visual fields resulting in larger remapping. This pattern of remapping is consistent with expansion or shifting of neuronal receptive fields into the cortical regions with reduced retinal input. These data provide evidence for functional changes in V1 that are dependent on the magnitude of peripheral visual loss in RP, which may be explained by rapid cortical adaptation mechanisms or long-term cortical reorganization. This study highlights the importance of analyzing the retinal determinants of brain functional and structural alterations for future visual restoration approaches.
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Key Words
- FPZ, Function Projection Zone
- Functional magnetic resonance imaging (fMRI)
- Human
- LE, Left Eye
- LH, Left Hemisphere
- LPZ, Lesion Projection Zone
- MRI, Magnetic Resonance Imaging
- Plasticity
- Primary visual cortex
- RE, Right Eye
- RH, Right Hemisphere
- RNFL, Retinal Nerve Fiber Layer
- RP, Retinitis Pigmentosa
- Reorganization
- Retinitis pigmentosa
- Retinotopy
- fMRI, functional Magnetic Resonance Imaging
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Affiliation(s)
- Sónia Ferreira
- Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Andreia Carvalho Pereira
- Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Bruno Quendera
- Institute of Nuclear Sciences Applied to Health (ICNAS), Brain Imaging Network of Portugal, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Aldina Reis
- Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; Ophthalmology Unit, Centro Hospitalar e Universitário de Coimbra (CHUC), 3000-075 Coimbra, Portugal
| | - Eduardo Duarte Silva
- Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal
| | - Miguel Castelo-Branco
- Visual Neuroscience Laboratory, Institute for Biomedical Imaging and Life Sciences (CNC.IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; Institute of Nuclear Sciences Applied to Health (ICNAS), Brain Imaging Network of Portugal, University of Coimbra, 3000-548 Coimbra, Portugal
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16
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Aguirre GK, Datta R, Benson NC, Prasad S, Jacobson SG, Cideciyan AV, Bridge H, Watkins KE, Butt OH, Dain AS, Brandes L, Gennatas ED. Patterns of Individual Variation in Visual Pathway Structure and Function in the Sighted and Blind. PLoS One 2016; 11:e0164677. [PMID: 27812129 PMCID: PMC5094697 DOI: 10.1371/journal.pone.0164677] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/28/2016] [Indexed: 11/18/2022] Open
Abstract
Many structural and functional brain alterations accompany blindness, with substantial individual variation in these effects. In normally sighted people, there is correlated individual variation in some visual pathway structures. Here we examined if the changes in brain anatomy produced by blindness alter the patterns of anatomical variation found in the sighted. We derived eight measures of central visual pathway anatomy from a structural image of the brain from 59 sighted and 53 blind people. These measures showed highly significant differences in mean size between the sighted and blind cohorts. When we examined the measurements across individuals within each group we found three clusters of correlated variation, with V1 surface area and pericalcarine volume linked, and independent of the thickness of V1 cortex. These two clusters were in turn relatively independent of the volumes of the optic chiasm and lateral geniculate nucleus. This same pattern of variation in visual pathway anatomy was found in the sighted and the blind. Anatomical changes within these clusters were graded by the timing of onset of blindness, with those subjects with a post-natal onset of blindness having alterations in brain anatomy that were intermediate to those seen in the sighted and congenitally blind. Many of the blind and sighted subjects also contributed functional MRI measures of cross-modal responses within visual cortex, and a diffusion tensor imaging measure of fractional anisotropy within the optic radiations and the splenium of the corpus callosum. We again found group differences between the blind and sighted in these measures. The previously identified clusters of anatomical variation were also found to be differentially related to these additional measures: across subjects, V1 cortical thickness was related to cross-modal activation, and the volume of the optic chiasm and lateral geniculate was related to fractional anisotropy in the visual pathway. Our findings show that several of the structural and functional effects of blindness may be reduced to a smaller set of dimensions. It also seems that the changes in the brain that accompany blindness are on a continuum with normal variation found in the sighted.
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Affiliation(s)
- Geoffrey K. Aguirre
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
- * E-mail:
| | - Ritobrato Datta
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Noah C. Benson
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Sashank Prasad
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Samuel G. Jacobson
- Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Artur V. Cideciyan
- Department of Ophthalmology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Holly Bridge
- FMRIB Centre, Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, United Kingdom
| | - Kate E. Watkins
- Department of Experimental Psychology, University of Oxford, Oxford, OX1 3UD, United Kingdom
| | - Omar H. Butt
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Aleksandra S. Dain
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Lauren Brandes
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Efstathios D. Gennatas
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
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Lemos J, Pereira D, Castelo-Branco M. Visual Cortex Plasticity Following Peripheral Damage To The Visual System: fMRI Evidence. Curr Neurol Neurosci Rep 2016; 16:89. [DOI: 10.1007/s11910-016-0691-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Nuclear expression of mitochondrial ND4 leads to the protein assembling in complex I and prevents optic atrophy and visual loss. MOLECULAR THERAPY-METHODS & CLINICAL DEVELOPMENT 2015; 2:15003. [PMID: 26029714 PMCID: PMC4444999 DOI: 10.1038/mtm.2015.3] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Revised: 01/05/2015] [Accepted: 01/09/2015] [Indexed: 12/13/2022]
Abstract
Leber hereditary optic neuropathy is due to mitochondrial DNA mutations; in ~70% of all cases, a point mutation in the mitochondrial NADH dehydrogenase subunit 4, ND4, gene leads to central vision loss. We optimized allotopic expression (nuclear transcription of a gene that is normally transcribed inside the mitochondria) aimed at designing a gene therapy for ND4; its coding sequence was associated with the cis-acting elements of the human COX10 mRNA to allow the efficient mitochondrial delivery of the protein. After ocular administration to adult rats of a recombinant adeno-associated viral vector containing the human ND4 gene, we demonstrated that: (i) the sustained expression of human ND4 did not lead to harmful effects, instead the human protein is efficiently imported inside the mitochondria and assembled in respiratory chain complex I; (ii) the presence of the human protein in the experimental model of Leber hereditary optic neuropathy significantly prevents retinal ganglion cell degeneration and preserves both complex I function in optic nerves and visual function. Hence, the use of optimized allotopic expression is relevant for treating mitochondrial disorders due to mutations in the organelle genome.
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Genetically induced impairment of retinal ganglion cells at the axonal level is linked to extrastriate cortical plasticity. Brain Struct Funct 2015; 221:1767-80. [PMID: 25680704 DOI: 10.1007/s00429-015-1002-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 02/04/2015] [Indexed: 10/24/2022]
Abstract
Leber hereditary optic neuropathy (LHON) is a maternally inherited mitochondrial disorder, which leads to initially silent visual loss due to retinal ganglion cell (RGC) degeneration. We aimed to establish a link between features of retinal progressive impairment and putative cortical changes in a cohort of 15 asymptomatic patients harboring the 11778G>A mutation with preserved visual acuity and normal ocular examination. To study plasticity evoked by clinically silent degeneration of RGC we only studied mutation carriers. We phenotyped pre-clinical silent degeneration from the psychophysical, neurophysiological and structural points of view to understand whether retinal measures could be related to cortical reorganization, using pattern electrophysiology, chromatic contrast sensitivity and high-resolution optical coherence tomography to measure macular, RGC nerve fiber layer as well as inner/outer retinal layer thickness. We then performed correlation analysis of these measures with cortical thickness estimates in functionally mapped retinotopic visual cortex. We found that compensatory cortical plasticity occurring in V2/V3 is predicted by the swelling (indicating deficits of axonal transport and intracellular edema) of the macular RGC axonal layer. Increased cortical thickness (CT) in V2 and V3 was observed in peripheral regions, like visual field loss, in these mutation carriers. CT was a very discriminative measure between carriers and controls, as revealed by ROC analysis. Importantly, the substantial cortical reorganization that occurs in the carrier state can be used to provide statistical discrimination between carriers and controls to a level that is similar to measures of retinal dysfunction. We conclude that peripheral cortical compensatory plasticity in early visual areas V2/V3 may be triggered by pathology in peripheral RGC axons in combination with potential developmental changes.
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20
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Mitochondrial dysfunction affecting visual pathways. Rev Neurol (Paris) 2014; 170:344-54. [DOI: 10.1016/j.neurol.2014.03.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 03/08/2014] [Accepted: 03/26/2014] [Indexed: 01/08/2023]
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Rosa AM, Silva MF, Ferreira S, Murta J, Castelo-Branco M. Plasticity in the human visual cortex: an ophthalmology-based perspective. BIOMED RESEARCH INTERNATIONAL 2013; 2013:568354. [PMID: 24205505 PMCID: PMC3800612 DOI: 10.1155/2013/568354] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/05/2013] [Accepted: 08/19/2013] [Indexed: 11/17/2022]
Abstract
Neuroplasticity refers to the ability of the brain to reorganize the function and structure of its connections in response to changes in the environment. Adult human visual cortex shows several manifestations of plasticity, such as perceptual learning and adaptation, working under the top-down influence of attention. Plasticity results from the interplay of several mechanisms, including the GABAergic system, epigenetic factors, mitochondrial activity, and structural remodeling of synaptic connectivity. There is also a downside of plasticity, that is, maladaptive plasticity, in which there are behavioral losses resulting from plasticity changes in the human brain. Understanding plasticity mechanisms could have major implications in the diagnosis and treatment of ocular diseases, such as retinal disorders, cataract and refractive surgery, amblyopia, and in the evaluation of surgical materials and techniques. Furthermore, eliciting plasticity could open new perspectives in the development of strategies that trigger plasticity for better medical and surgical outcomes.
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Affiliation(s)
- Andreia Martins Rosa
- Departamento de Oftalmologia, Centro Hospitalar e Universitário de Coimbra, 3000 Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Maria Fátima Silva
- Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Sónia Ferreira
- Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Joaquim Murta
- Departamento de Oftalmologia, Centro Hospitalar e Universitário de Coimbra, 3000 Coimbra, Portugal
- Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
- Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
| | - Miguel Castelo-Branco
- Visual Neuroscience Laboratory, IBILI, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3000-548 Coimbra, Portugal
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