scholarly journals Structural changes to primary visual cortex in the congenital absence of cone input in achromatopsia

2021 ◽  
Author(s):  
Barbara Molz ◽  
Anne Herbik ◽  
Heidi A. Baseler ◽  
Pieter B. de Best ◽  
Richard Vernon ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
Structural Changes ◽  
Vision Loss ◽  
Time Window ◽  
Negative Impact ◽  
Congenital Absence ◽  
Grey Matter Volume ◽  
Multi Centre Study

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. Our findings indicate that there may be an optimum time window for gene therapy to counteract developmental cortical changes related to the absence of sensory input.

scholarly journals Structural changes to primary visual cortex in the congenital absence of cone input in achromatopsia

2021 ◽  
pp. 102925
Author(s):  
Barbara Molz ◽  
Anne Herbik ◽  
Heidi A. Baseler ◽  
Pieter B. de Best ◽  
Richard Vernon ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Structural Changes ◽  
Congenital Absence

scholarly journals Relationship Between the Visual Evoked Potential and Structure in the Primary Visual Cortex in Healthy Individuals and in Patients with Severe Mental Disorders

2021 ◽  
Author(s):  
Nora Berz Slapø ◽  
Kjetil Jørgensen ◽  
Torbjørn Elvsåshagen ◽  
Stener Nerland ◽  
Daniel Roelfs ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Mental Disorders ◽  
Structure Function ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
Visual Evoked Potential ◽  
Evoked Potential ◽  
Healthy Individuals ◽  
Severe Mental Disorders ◽  
Function Relationship

Abstract Schizophrenia (SCZ) spectrum and bipolar disorder (BD) are severe mental disorders with unknown pathophysiology. Altered visual evoked potential (VEP), an electroencephalogram signal reflecting function in the primary visual cortex (V1), abnormal visual processing and visual hallucinations reported in these patients, all point towards V1 dysfunction. While the mechanisms contributing to V1 dysfunction remain unknown, structural alterations are possible candidates. Lack of insight into neural substrates of structure and functional in V1 has limited our ability to determine implications of altered V1 function. While combining VEP and magnetic resonance imaging has increased our understanding of the structure-function relationship in V1 in healthy individuals, no previous study has examined the same structure-function relationship in patients with SCZ spectrum and BD. Here, we aimed to confirm previous findings of a selective positive correlation between the amplitude of the P100 component of the VEP and V1 surface area (SA) in 307 healthy individuals and to examine whether this relationship was altered in patients with SCZ spectrum (n=30) and BD (n=45). The correlation between the P100 amplitude and the total, (r=0.16, p=0.006), right (r=0.14, p=0.013) and left V1 surface area (r=0.13, p=0.02) was significant in healthy individuals, but not in patients. The current results support previous findings of a selective relationship between P100 amplitude and V1 surface area in healthy individuals and suggests that other factors than V1 surface area or thickness explain V1 dysfunction reported in these patients.

scholarly journals The Effect of Onset Age of Visual Deprivation on Visual Cortex Surface Area Across-Species

2018 ◽  
Vol 29 (10) ◽  
pp. 4321-4333 ◽  
Author(s):  
Adrian K Andelin ◽  
Jaime F Olavarria ◽  
Ione Fine ◽  
Erin N Taber ◽  
Daniel Schwartz ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
Final Analysis ◽  
Published Data ◽  
Brain Anatomy ◽  
Event Time ◽  
Longitudinal Measurements ◽  
Area Expansion ◽  
Reduced Surface

Abstract Blindness early in life induces permanent alterations in brain anatomy, including reduced surface area of primary visual cortex (V1). Bilateral enucleation early in development causes greater reductions in primary visual cortex surface area than at later times. However, the time at which cortical surface area expansion is no longer sensitive to enucleation is not clearly established, despite being an important milestone for cortical development. Using histological and MRI techniques, we investigated how reductions in the surface area of V1 depends on the timing of blindness onset in rats, ferrets and humans. To compare data across species, we translated ages of all species to a common neuro-developmental event-time (ET) scale. Consistently, blindness during early cortical expansion induced large (~40%) reductions in V1 surface area, in rats and ferrets, while blindness occurring later had diminishing effects. Longitudinal measurements on ferrets confirmed that early enucleation disrupted cortical expansion, rather than inducing enhanced pruning. We modeled the ET associated with the conclusion of the effect of blindness on surface area at maturity (ETc), relative to the normal conclusion of visual cortex surface area expansion, (ETdev). A final analysis combining our data with extant published data confirmed that ETc occurred well before ETdev.

scholarly journals Structural Differences Across Multiple Visual Cortical Regions in the Absence of Cone Function in Congenital Achromatopsia

2021 ◽  
Vol 15 ◽  
Author(s):  
Rebecca Lowndes ◽  
Barbara Molz ◽  
Lucy Warriner ◽  
Anne Herbik ◽  
Pieter B. de Best ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Surface Area ◽  
Grey Matter Volume ◽  
Cortical Surface ◽  
Colour Perception ◽  
Cortical Surface Area ◽  
Visual Areas ◽  
Cortical Regions ◽  
Visual Cortical ◽  
Cortical Morphology

Most individuals with congenital achromatopsia (ACHM) carry mutations that affect the retinal phototransduction pathway of cone photoreceptors, fundamental to both high acuity vision and colour perception. As the central fovea is occupied solely by cones, achromats have an absence of retinal input to the visual cortex and a small central area of blindness. Additionally, those with complete ACHM have no colour perception, and colour processing regions of the ventral cortex also lack typical chromatic signals from the cones. This study examined the cortical morphology (grey matter volume, cortical thickness, and cortical surface area) of multiple visual cortical regions in ACHM (n = 15) compared to normally sighted controls (n = 42) to determine the cortical changes that are associated with the retinal characteristics of ACHM. Surface-based morphometry was applied to T1-weighted MRI in atlas-defined early, ventral and dorsal visual regions of interest. Reduced grey matter volume in V1, V2, V3, and V4 was found in ACHM compared to controls, driven by a reduction in cortical surface area as there was no significant reduction in cortical thickness. Cortical surface area (but not thickness) was reduced in a wide range of areas (V1, V2, V3, TO1, V4, and LO1). Reduction in early visual areas with large foveal representations (V1, V2, and V3) suggests that the lack of foveal input to the visual cortex was a major driving factor in morphological changes in ACHM. However, the significant reduction in ventral area V4 coupled with the lack of difference in dorsal areas V3a and V3b suggest that deprivation of chromatic signals to visual cortex in ACHM may also contribute to changes in cortical morphology. This research shows that the congenital lack of cone input to the visual cortex can lead to widespread structural changes across multiple visual areas.

scholarly journals Anatomical changes to primary visual cortex in the congenital absence of cone input

2021 ◽  
Vol 21 (9) ◽  
pp. 2362
Author(s):  
Barbara Molz ◽  
Anne Herbik ◽  
Heidi Baseler ◽  
Pieter B. de Best ◽  
Richard Vernon ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
Congenital Absence ◽  
Anatomical Changes

Age-Related Structural Changes in Primary Visual Cortex Cells of Rats under High-Intensity Light Exposure

2018 ◽  
Vol 8 (4) ◽  
pp. 298-301 ◽  
Author(s):  
Yu. O. Sverdeva ◽  
Ye. Yu. Varakuta ◽  
A. A. Zhdankina ◽  
A. V. Potapov ◽  
A. V. Gerasimov ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Primary Visual Cortex ◽  
High Intensity ◽  
Structural Changes ◽  
Light Exposure ◽  
Age Related ◽  
High Intensity Light

Childhood adversity and cortical thickness and surface area in a population at familial high risk of schizophrenia

2015 ◽  
Vol 46 (4) ◽  
pp. 891-896 ◽  
Author(s):  
V. Barker ◽  
C. Bois ◽  
E. C. Johnstone ◽  
D. G. C. Owens ◽  
H. C. Whalley ◽  
...  
Keyword(s):  
High Risk ◽  
Surface Area ◽  
Cortical Thickness ◽  
Structural Changes ◽  
Childhood Adversity ◽  
Grey Matter Volume ◽  
Cortical Surface ◽  
Cortical Surface Area ◽  
Structural Abnormalities ◽  
Familial High Risk

BackgroundThere is now a well-established link between childhood adversity (CA) and schizophrenia. Similar structural abnormalities to those found in schizophrenia including alterations in grey-matter volume have also been shown in those who experience CA.MethodWe examined whether global estimates of cortical thickness or surface area were altered in those familial high-risk subjects who had been referred to a social worker or the Children's Panel compared to those who had not.ResultsWe found that the cortical surface area of those who were referred to the Children's Panel was significantly smaller than those who had not been referred, but cortical thickness was not significantly altered. There was also an effect of social work referral on cortical surface area but not on thickness.ConclusionsCortical surface area increases post-natally more than cortical thickness. Our findings suggest that CA can influence structural changes in the brain and it is likely to have a greater impact on cortical surface area than on cortical thickness.

scholarly journals STRUCTURAL CHANGES IN MICROCIRCULATORY VESSELS AND THEIR SURROUNDINGS IN THE PRIMARY VISUAL CORTEX OF 3- AND 18-MONTH-OLD RATS WITH RETINAL PHOTODAMAGE AND STRUCTURAL CHANGE CORRECTION

2020 ◽  
pp. 123-133
Author(s):  
Yu.O. Bakhareva ◽  
E.Yu. Varakuta ◽  
S.V. Logvinov ◽  
A.V. Potapov ◽  
A.A. Zhdankina ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
High Intensity ◽  
Light Exposure ◽  
Capillary Density ◽  
Male Rats ◽  
Capillary Surface ◽  
Glia Cells ◽  
Old Rats

Morphofunctional changes in microvasculature play an important role in the nerve cell plasticity, the ability to change their functional state under the influence of various factors. The aim of the research was to study the morphology of the microvasculature vessels, surrounding neurons and glia cells in the primary visual cortex of 3- and 18-month-old rats in norm and under stress caused by high-intensity twenty-four-hour light exposure, as well as under correction. Materials and Methods. The experiments were carried out on 60 Wistar male rats, aged 3- and 18-months. The authors used light and electron microscopy, and morphometry to evaluate: capillary surface area and density, surface area of altered vessels (due to stasis, sludge of formed elements and thrombosis) and unchanged ones, as well as the morphology of the surrounding cells. The Kruskal-Wallis test was used for multiple comparisons within age groups, while Mann-Whitney test was used for pair comparison. Results. The authors observed different capillary reactions to light exposure in 3- and 18-month-old rats. It resulted in an increase of capillary density in 3-month-old rats and in a decrease of capillary density in 18-month-old rats (p≤0.05). Destructive changes in neurons and glia cells were more evident in 18-month-old rats. P-tyrosol administration in 3- and 18-month-old rats with light exposure led to an increase in capillary density (p≤0.05). Under correction, young rats also demonstrated an increase in the capillary surface area, and the number of glia cells and capillaries by 1 neuron (p≤0.05). Conclusion Thus, p-tyrosol improved microvascularization in the primary visual cortex under high-intensity long-term light exposure. Keywords: microcirculation, p-tyrosol, stress, primary visual cortex. Морфофункциональные изменения микроциркуляторного русла играют важную роль в пластичности нервных клеток, их способности менять свое функциональное состояние при воздействии различных факторов. Целью исследования являлось изучение морфологии сосудов микроциркуляторного русла и окружающих их нейронов и глиоцитов в первичной зрительной коре 3- и 18-месячных крыс в норме и при стрессе, вызванном высокоинтенсивным круглосуточным световым воздействием, а также в условиях коррекции. Материалы и методы. Эксперименты выполнены на 60 крысах-самцах линии «Вистар». Возраст – 3 и 18 мес. Методами световой и электронной микроскопии, морфометрии оценивали удельную площадь и численную плотность капилляров, удельную площадь измененных (со стазом, сладжем форменных элементов и тромбозом) и неизмененных сосудов, а также морфологию клеток, их окружающих. Для множественных сравнений внутри возрастных групп использовали критерий Крускала–Уоллиса, для парных – Манна–Уитни. Результаты. У 3- и 18-месячных крыс обнаружена различная реакция капилляров на световое воздействие, что выражалось в увеличении численной плотности капилляров у 3-месячных крыс и снижении – у 18-месячных (р≤0,05). Деструктивные изменения нейронов и глиоцитов более выражены у 18-месячных крыс. Коррекция п-тирозолом у 3- и 18-месячных крыс со световым воздействием приводила к увеличению численной плотности капилляров (р≤0,05). У молодых крыс при коррекции также отмечалось увеличение удельной площади капилляров, количества глиоцитов и капилляров на 1 нейрон (р≤0,05). Заключение. Применение п-тирозола улучшало состояние микроваскуляризации в первичной зрительной коре в условиях высокоинтенсивного длительного светового воздействия. Ключевые слова: микроциркуляция, п-тирозол, стресс, первичная зрительная кора.

Linking contrast sensitivity to cortical magnification in human primary visual cortex

2021 ◽  
Author(s):  
Marc M. Himmelberg ◽  
Jonathan Winawer ◽  
Marisa Carrasco
Keyword(s):  
Visual Cortex ◽  
Visual Perception ◽  
Contrast Sensitivity ◽  
Surface Area ◽  
Primary Visual Cortex ◽  
Fundamental Property ◽  
Polar Angle ◽  
Strongly Correlated ◽  
V1 Neurons ◽  
Cortical Magnification

ABSTRACTThe size and organization of primary visual cortex (V1) varies across individuals. Across neurotypical adults, V1 size varies more than twofold. Within individuals, surface area per unit of visual field – cortical magnification – varies with eccentricity and polar angle. Contrast sensitivity and cortical magnification covary with eccentricity, therefore it has been hypothesized that cortical magnification, specifically the number of activated V1 neurons, limits contrast sensitivity. Here, we quantify the relation between contrast sensitivity and V1 cortical magnification across observers and polar angle. We measured contrast sensitivity at four cardinal meridians in 29 observers. We then used fMRI to measure the size of V1 in the same observers, and the amount of surface area representing each of the four meridians (wedge-ROIs within 15° polar angle of the meridians, 1 to 8° eccentricity). We found that: First, an observer’s contrast sensitivity (averaged across polar angles) was predicted by the size of V1. Second, contrast sensitivity at each cardinal meridian was correlated with the surface area of the wedge-ROIs centered at the corresponding meridian. Third, increases in contrast sensitivity and cortical magnification at the horizontal compared to vertical meridian (horizontal-vertical anisotropy, ‘HVA’) were strongly correlated: a larger HVA in contrast sensitivity corresponded to a larger HVA in cortical magnification. These results reveal that contrast sensitivity and cortical magnification co-vary across observers and demonstrate a link between perceptual polar angle asymmetries and cortical anatomy. Broadly, the results show a link between visual perception and the idiosyncratic cortical organization of V1 in neurotypical observers.SIGNIFICANCE STATEMENTContrast sensitivity is a fundamental property of the human visual system, which indexes the limits of what one can detect or discriminate – the window of visibility. Contrast sensitivity varies with stimulus location on the retina and across observers. These variations are not well understood. Using psychophysics and magnetic resonance imaging, we tested the hypothesis that contrast sensitivity depends on the amount of responsive tissue in primary visual cortex (V1). Individuals with greater contrast sensitivity had a larger V1. Further, within observers, variation in contrast sensitivity across polar angle locations matched the variation in V1 surface area representing those locations. These findings demonstrate a tight link between visual perception and cortical anatomy, both within and among people.

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