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Cortical Visual Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
The prognosis for alexia depends on the cause. Global alexia can resolve into spelling dyslexia (279). Improvement may reflect reorganization of a word-processing network, with increased participation of the right fusiform region or left-sided regions around the visual word form area and the superior parietal lobule (306–308). Various approaches to rehabilitating alexia have been tried, though none have gained widespread acceptance (309, 310). These include highlighting the space between words or phrases (311, 312), oral articulation during reading (313), repetitive oral reading of text (311, 314), and finger tracing of letters (312, 315).
Cognition, Language and Intelligence
Published in Rolland S. Parker, Concussive Brain Trauma, 2016
Long axonal connections between regions may account for individual differences in cognitive skill and the development of such skills as reading. Genetic differences contributing to development involve genetic loading for white matter microstructure. There is a genetic role in developmental dyslexia. Reading involves development of cortical reorganization of functional cortical regions involved in an association between cortical regions supporting perception of visual words (orthographic) and spoken language (phonological). There are different influences upon task efficiency associated with performance and developmental levels. Age-related regions are left frontal and parietal cortices. Activity decreases with increasing age. Performance-related regions are bilateral extrastriate cortex and the left parietal-occipital-temporal (POT) junction. Reading skill (without age effects) is associated with activation of left ventral occipitotemporal regions. The visual word-form area appears associated with the left occipitotemporal region (midfusiform gyrus). Letter-sound integration involves heteromodal input (visual and auditory) for integration of orthographic and phonological processing in the left superior temporal cortex. Changes will differ between beginning readers and skilled readers (Schlaggar & McCandliss, 2007).
Diagnostic performance of a modified visual perception test
Published in Hearing, Balance and Communication, 2023
Mayada Elsherif, Mona Mourad, Nesrine Hamouda, Rania Abdou, Taima Salem
Our primary visual cortex has two major upward projections to the brain: both the dorsal and ventral pathway. The dorsal pathway receives input mainly from the magnocellular system which controls visual cues of attention and eye and limb movements. The slower ventral ‘what’ pathway projects to the visual word form area (VWFA), they travel ventrally beneath the occipito-temporal cortex. Its primary purpose is in recognizing objects’ colour, quality and shape [1]. Dorsal pathway projects to the middle temporal where the motion-sensitive area is represented, supramarginal and the cortical posterior parietal region. Reading responsible area is represented in the left hemispheric parietal area [2]. Those certain neurons are specialized in timing allowing the eye to move to land the letter on the part of retina with the highest visual acuity i.e. the fovea [3]. Because the ventral pathway comprising VWFA able to distinguish solitary letters nonetheless could not determine the precise location of them for example, the sequence of letters in a word is essential for reading, the fast dorsal pathway supramarginal and angular gyri resend signals to strait cortex and the VWFA indicating where should look so identifying the letter arrangement in a word [4].
Decoupling of the Occipitotemporal Cortex and the Brain’s Default-Mode Network in Dyslexia and a Role for the Cingulate Cortex in Good Readers: A Brain Imaging Study of Brazilian Children
Published in Developmental Neuropsychology, 2019
Augusto Buchweitz, Adriana Corrêa Costa, Rudineia Toazza, Ana Bassôa de Moraes, Valentina Metsavaht Cara, Nathália Bianchini Esper, Cristiano Aguzzoli, Bruna Gregolim, Luiz Fernando Dresch, Matheus Dorigatti Soldatelli, Jaderson Costa da Costa, Mirna Wetters Portuguez, Alexandre Rosa Franco
The present study shows evidence of disrupted connectivity between the visual word form area and the PCC in a resting-state paradigm (there was a negative correlation between VWFA and PCC function). For typical readers, in turn, there was a positive correlation between the two centers. The result converges with other resting-state studies that suggest that the coupling between occipitotemporal regions of the brain and the brain’s default mode network is disrupted in dyslexia. In a study of three dyslexic groups (no remediation, partial remediation, and full remediation), an increase in resting-state functional connectivity was identified between the visual word form area and medial prefrontal cortex in full remediation participants (Koyama et al., 2013). In another study, reading performance positively correlated with stronger connectivity between the visual word form area and anterior and posterior regions of the brain associated with phonological processing (Koyama et al., 2011). A study of correspondence between brain function in tasks and at rest showed the occipitotemporal region integrated a frontal-posterior network of brain regions that were strongly left-lateralized and associated with language paradigms (Smith et al., 2009). The present study corroborates the evidence that the coupling of the occipitotemporal region with other centers in the brain is associated with reading perfomance.
A case of aneurysmal subarchnoid haemorrhage and superficial siderosis complicated by prospagnosia, simultagnosia and alexia without agraphia
Published in British Journal of Neurosurgery, 2023
Mohammed Fadelalla, Avinash Kanodia, Mustafa Elsheikh, John Ellis, Vivien Smith, Kismet Hossain-Ibrahim
Alexia without agraphia, also known as ‘pure alexia’, ‘word blindness’ and ‘agnostic alexia, is known to be caused by lesions to the visual word form area in the left occipital lobe.5 In our case MRI ruled out any lesions in the fusiform gyri, occipital lobes and temporal lobes. The only prominent abnormality was widespread deposition of hemosiderin over the brain surfaces especially the corpus callosum and adjacent brain surfaces.