Automated Morphometry of the Visual Pathway in Primary Open-Angle Glaucoma

PURPOSE. To establish whether primary open-angle glaucoma (POAG) is associated with a change in volume of the visual pathway structures between the eyes and the visual cortex. METHODS. To answer this question, magnetic resonance imaging (MRI) was used in combination with automated segmentation and voxel-based morphometry (VBM). Eight patients with POAG and 12 age-matched control subjects participated in the study. Only POAG patients with bilateral glaucomatous visual field loss were admitted to the study. The scotoma in both eyes had to include the paracentral region and had to, at least partially, overlap. All participants underwent high-resolution, T(1)-weighted, 3-T MRI scanning[b]. Subsequently, VBM was used to determine the volume of the optic nerves, the optic chiasm, the optic tracts, the lateral geniculate nuclei (LGN), and the optic radiations. Analysis of covariance was used to compare these volumes in the POAG and control groups. The main outcome parameter of the measurement was the volume of visual pathway structures. RESULTS. Compared with the controls, subjects with glaucoma showed reduced volume (P <0.005) of all structures along the visual pathway, including the optic nerves, the optic chiasm, the optic tracts, the LGN, and the optic radiations. CONCLUSIONS. POAG adversely affects structures along the full visual pathway, from the optic nerve to the optic radiation. Moreover, MRI in combination with automated morphometry can be used to aid the detection and assessment of glaucomatous damage in the brain. (Invest Ophthalmol Vis Sci. 2011;52:2758-2766) DOI:10.1167/iovs.10-568

White matter alterations in glaucoma and monocular blindness differ outside the visual system

The degree to which glaucoma has effects in the brain beyond the eye and the visual pathways is unclear. To clarify this, we investigated white matter microstructure (WMM) in 37 tracts of patients with glaucoma, monocular blindness, and controls. We used brainlife.io for reproducibility. White matter tracts were subdivided into seven categories ranging from those primarily involved in vision (the visual white matter) to those primarily involved in cognition and motor control. In the vision tracts, WMM was decreased as measured by fractional anisotropy in both glaucoma and monocular blind subjects compared to controls, suggesting neurodegeneration due to reduced sensory inputs. A test-retest approach was used to validate these results. The pattern of results was different in monocular blind subjects, where WMM properties increased outside the visual white matter as compared to controls. This pattern of results suggests that whereas in the monocular blind loss of visual input might promote white matter reorganization outside of the early visual system, such reorganization might be reduced or absent in glaucoma. The results provide indirect evidence that in glaucoma unknown factors might limit the reorganization as seen in other patient groups following visual loss

Occipital Proton Magnetic Resonance Spectroscopy ((1)H-MRS) Reveals Normal Metabolite Concentrations in Retinal Visual Field Defects

BACKGROUND: Progressive visual field defects, such as age-related macular degeneration and glaucoma, prevent normal stimulation of visual cortex. We investigated whether in the case of visual field defects, concentrations of metabolites such as N-acetylaspartate (NAA), a marker for degenerative processes, are reduced in the occipital brain region. METHODOLOGY/PRINCIPAL FINDINGS: Participants known with glaucoma, age-related macular degeneration (the two leading causes of visual impairment in the developed world), and controls were examined by proton MR spectroscopic ((1)H-MRS) imaging. Absolute NAA, Creatine and Choline concentrations were derived from a single-voxel in the occipital region of each brain hemisphere. No significant differences in metabolites concentrations were found between the three groups. CONCLUSIONS/SIGNIFICANCE: We conclude that progressive retinal visual field defects do not affect metabolite concentration in visual brain areas suggesting that there is no ongoing occipital degeneration. We discuss the possibility that metabolite change is too slow to be detectable

Cómo Cultivar Valores Éticos a través de la Práctica del Yoga

The Humanistic Psychology movement has been from the beginning attentive and receptive to integrate eastern approaches that have contributed to enrich the psychotherapeutic and personal growth processes. Moreover, it has explicitly been opened to considering and cultivating ethical values and spirituality (Declaration at the European Congress in Geneva, 1981). Here, we demonstrate how a yoga practice can be a powerful tool to deeply connect with our ethical values, and therefore give us the opportunity to live more connected to our deep self and the world. In this paper, we present a yoga sequence (Boucard, 2015) designed to connect with the ethical values from the psychological perspective as introduced by Ramón Rosal (2003; 2012 and Rosal y Gimeno-Bayón (2011) using postures, breathing and meditations. The possibility to combine the eastern practice of yoga with the cultivation of western ethical values shows that both approaches have the same objective: to become aware of the fact that we are part of the world as well as the sense of responsibility that derives from it.Desde su nacimiento, el movimiento de la psicología humanista estuvo atento y receptivo a la integración de aportaciones orientales, las cuales han contribuido a enriquecer los procesos psicoterapéuticos y de crecimiento personal. Por otra parte, también mostró explícitamente su apertura a la reflexión y cultivo de los valores éticos y la espiritualidad (v. declaración del Congreso Europeo de Ginebra, 1981). En este trabajo, se muestra cómo una práctica de yoga puede convertirse en una herramienta para conectar con los valores éticos, los cuales nos incitan a relacionarnos con el mundo de una manera más profunda. Se expone aquí una secuencia de yoga creada por la autora (Boucard, 2015). La secuencia está especialmente diseñada para conectar a través de posturas, respiración y meditaciones con los valores éticos desde la Psicología, en la elaboración recogida por Ramón Rosal (2003; 2012) y Rosal y Gimeno-Bayón (2011). La posibilidad de combinar la práctica oriental del yoga con el cultivo de los valores éticos definidos bajo contexto occidental demuestra que ambos enfoques comparten el mismo objetivo: ser conciente de hacer parte del mundo y de la responsabilidad que se deriva de ello.

Mindfulness is associated with intrinsic functional connectivity between default mode and salience networks

Mindfulness is attention to present moment experience without judgment. Mindfulness practice is associated with brain activity in areas overlapping with the default mode, salience, and central executive networks (DMN, SN, CEN). We hypothesized that intrinsic functional connectivity (iFC;i.e.,synchronized ongoing activity) across these networks is associated with mindfulness scores. After 2 weeks of daily 20 min attention to breath training, healthy participants were assessed by mindfulness questionnaires and resting-state functional MRI. Independent component analysis (ICA) of imaging data revealed networks of interest, whose activity time series defined inter-network intrinsic functional connectivity (inter-iFC) by temporal correlation. Inter-iFC between subnetworks of the DMN and SN and inter-iFC between subnetworks of the SN and left CEN at trend was correlated with mindfulness scores. Additional control analyses about visual networks' inter-iFC support the specificity of our findings. Results provide evidence that mindfulness is associated with iFC between DMN and SN. Data suggest that ongoing interactions among central intrinsic brain networks link with the ability to attend to current experience without judgment

Neurodegeneration beyond the primary visual pathways in a population with a high incidence of normal-pressure glaucoma

Purpose: Glaucoma is the most common age-related neurodegenerative eye disease in western society. It is an insidious disease that, when untreated or detected too late, leads inevitably to blindness. An outstanding issue is whether glaucoma should be considered exclusively an eye disease or also a brain disease. To further examine it, we used Diffusion Tensor Imaging (DTI) to study white matter integrity in a Japanese glaucoma population. This population has a very high incidence of normal-pressure glaucoma, in which optic nerve damage occurs in the absence of the elevated eye pressure that characterises the more common form of glaucoma. Methods: We performed DTI in 30 participants with normal-pressure glaucoma and 21 age-matched healthy controls. We used voxel-wise tract-based spatial statistics to compare fractional anisotropy and mean diffusivity of the white matter of the brain between patients and control group. Whole-brain and region of interest-based analyses served to find associations between diffusion indices and clinical measures of glaucomatous damage. Results: Fractional Anisotropy was significantly lower in glaucoma patients in a cluster in the right occipital lobe (p <0.05; family-wise error-corrected) comprising fibres of both the optic radiation and the forceps major. Additional analysis confirmed bilateral involvement of the optic radiations and forceps major and additionally revealed damage to the corpus callosum and parietal lobe (p <0.09; family-wise error-corrected). The region of interest-based analysis revealed a positive association between Fractional Anisotropy of the optic radiation and optic nerve damage. Conclusions: In this specific population, glaucoma is associated with lower Fractional Anisotropy in the optic radiations, forceps major and corpus callosum. We interpret these reductions as evidence for white matter degeneration in these loci. In particular, the degeneration of the corpus callosum suggests the presence of neurodegeneration of the brain beyond what can be explained on the basis of propagated retinal and pre-geniculate damage. We discuss how this finding links to the emerging view that a brain component that is independent from the eye damage plays a role in the aetiology of glaucoma

White-matter lesions drive deep gray-matter atrophy in early multiple sclerosis: support from structural MRI

Background: In MS, the relationship between lesions within cerebral white matter (WM) and atrophy within deep gray matter (GM) is unclear. Objective: To investigate the spatial relationship between WM lesions and deep GM atrophy. Methods: We performed a cross-sectional structural magnetic resonance imaging (MRI) study (3 Tesla) in 249 patients with clinically-isolated syndrome or relapsing-remitting MS (Expanded Disability Status Scale score: median, 1.0; range, 0-4) and in 49 healthy controls. Preprocessing of T1-weighted and fluid-attenuated T2-weighted images resulted in normalized GM images and WM lesion probability maps. We performed two voxel-wise analyses: 1. We localized GM atrophy and confirmed that it is most pronounced within deep GM; 2. We searched for a spatial relationship between WM lesions and deep GM atrophy; to this end we analyzed WM lesion probability maps by voxel-wise multiple regression, including four variables derived from maxima of regional deep GM atrophy (caudate and pulvinar, each left and right). Results: Atrophy of each deep GM region was explained by ipsilateral WM lesion probability, in the area most densely connected to the respective deep GM region. Conclusion: We demonstrated that WM lesions and deep GM atrophy are spatially related. Our results are best compatible with the hypothesis that WM lesions contribute to deep GM atrophy through axonal pathology

Example of PRESS box position and spectra.

<p><i>Left</i>: To delineate the single-voxel, an elongated PRESS box was located in each hemisphere (here shown only in the left hemisphere) along the calcarine sulcus as far to the back of the occipital pole and the midline of the brain as possible while avoiding the inclusion of fat and vasculature. <i>Right</i>: Example of spectra with Choline, Creatine and NAA peaks.</p

Metabolite concentrations.

<p>Averaged absolute concentrations (in nM) of each of the measured metabolites (NAA, Cr and Cho) for each group (controls, AMD and glaucoma). The ANOVA analysis between the three groups (AMD, glaucoma and controls) showed no significant differences for any of the three metabolites concentration.</p