Pure alexia as a disconnection syndrome: New diffusion imaging evidence for an old concept

Epelbaum, Stéphane; Pinel, Philippe; Gaillard, R.; Delmaire, Christine; Perrin, M.; Dupont, Sophie; Dehaene, Stanislas; Cohen, Laurent

doi:10.1016/j.cortex.2008.05.003

Cited by 268 publications

(187 citation statements)

References 68 publications

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“…The latter usually involve damage to a single and long-distance fiber tract and a single clinical manifestation. [21][22][23] Conversely, our findings tie together diverse functional domains and involve fiber tracts connecting different regions within a single lobe instead of long-distance connections between, for instance, the parietal and the frontal lobe (see Fig 5). As many lesions involve damage to white matter, our findings hence suggest that the impact of disconnection on clinical deficit might still be largely underestimated.…”

Section: Discussionmentioning

confidence: 99%

A disconnection account of Gerstmann syndrome: Functional neuroanatomy evidence

Rusconi

Pinel

Eger

et al. 2009

Annals of Neurology

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Objective: To examine the functional neuroanatomy that could account for pure Gerstmann syndrome, which is the selective association of acalculia, finger agnosia, left-right disorientation, and agraphia. Methods: We used structural and functional neuroimaging at high spatial resolution in healthy subjects to seek a shared cortical substrate of the Grundstörung posited by Gerstmann, ie, a common functional denominator accounting for this clinical tetrad. We construed a functional activation paradigm that mirrors each of the four clinical deficits in Gerstmann syndrome and determined cortical activation patterns. We then applied fiber tracking to diffusion tensor images and used cortical activation foci in the four functional domains as seed regions. Results: None of the subjects showed parietal overlap of cortical activation patterns from the four cognitive domains. In every subject, however, the parietal activation patterns across all four domains consistently connected to a small region of subcortical parietal white matter at a location that is congruent with the lesion in a well-documented case of pure Gerstmann syndrome. Interpretation: Our functional neuroimaging findings are not in agreement with Gerstmann's postulate of damage to a common cognitive function underpinning clinical semiology. Our evidence from intact functional neuroanatomy suggests that pure forms of Gerstmann's tetrad do not arise from lesion to a shared cortical substrate but from intraparietal disconnection after damage to a focal region of subcortical white matter.

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Section: Discussionmentioning

confidence: 99%

A disconnection account of Gerstmann syndrome: Functional neuroanatomy evidence

Rusconi

Pinel

Eger

et al. 2009

Annals of Neurology

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“…On approaching the anterior temporal lobe, the fibres of the inferior fronto-occipital fasciculus gather together and enter the external capsule dorsally to the fibres of the uncinate fasciculus. The functions of the inferior fronto-occipital fasciculus are poorly understood, although it is possible that it is involved in reading, 42,44 attention 44 and vis ual processing. 40,46 The thalamic radiations are 2-way fibre connections between the thalamus and cerebral cortex, grouped into 4 (an terior, superior, posterior and inferior) fan-like radiations from the thalamus to most regions of the cortex, forming a major part of the internal capsule and corona radiata.…”

Section: Discussionmentioning

confidence: 99%

Is depression a disconnection syndrome? Meta- analysis of diffusion tensor imaging studies in patients with MDD

Liao

Huang

et al. 2013

J Psychiatry Neurosci

399

269

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“…Two case studies support this hypothesis. When damage to the arcuate fasciculus occurs at birth, normal reading skills can develop (15); when damage to the arcuate fasciculus occurs later, for example after reading instruction has begun, it can result in severe reading impairment (9). These cases suggest that learning depends on the circuits' current state and capacity for plasticity.…”

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confidence: 99%

“…Diffusion measurements of the white-matter pathways (3, 5-7) and neurological case studies (8,9) suggest that in typical development and education both the left hemisphere arcuate fasciculus and inferior longitudinal fasciculus (ILF) carry signals important for reading. Studies in adults, adolescents, and schoolage children have reported differences between good and poor readers in white-matter volume and diffusion properties in the vicinity of these pathways (10)(11)(12)(13)(14).…”

mentioning

confidence: 99%

Development of white matter and reading skills

Yeatman

Dougherty

Ben-Shachar

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

303

356

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White matter tissue properties are highly correlated with reading proficiency; we would like to have a model that relates the dynamics of an individual's white matter development to their acquisition of skilled reading. The development of cerebral white matter involves multiple biological processes, and the balance between these processes differs between individuals. Cross-sectional measures of white matter mask the interplay between these processes and their connection to an individual's cognitive development. Hence, we performed a longitudinal study to measure white-matter development (diffusion-weighted imaging) and reading development (behavioral testing) in individual children (age 7-15 y). The pattern of white-matter development differed significantly among children. In the left arcuate and left inferior longitudinal fasciculus, children with above-average reading skills initially had low fractional anisotropy (FA) that increased over the 3-y period, whereas children with belowaverage reading skills had higher initial FA that declined over time. We describe a dual-process model of white matter development comprising biological processes with opposing effects on FA, such as axonal myelination and pruning, to explain the pattern of results.R eading requires efficient communication within a network of visual, auditory, and language-processing regions that are separated by many centimeters. Hence, the white-matter fascicles that connect these regions are critical for proficient reading (1). Only in the last decade has it become possible to study the microstructural properties of the white matter in the living human brain, and only in recent years has there been an opportunity to trace the developmental progression of these fascicles systematically. During this decade it has been shown that learning to read is associated with corresponding changes in sensory and language circuits in the brain (2-5).Diffusion measurements of the white-matter pathways (3, 5-7) and neurological case studies (8, 9) suggest that in typical development and education both the left hemisphere arcuate fasciculus and inferior longitudinal fasciculus (ILF) carry signals important for reading. Studies in adults, adolescents, and schoolage children have reported differences between good and poor readers in white-matter volume and diffusion properties in the vicinity of these pathways (10-14). One possibility is that these differences are present from an early age, remain constant through development, and constrain children's aptitude for reading. An alternative possibility is that there is an interaction between the biological development and timing of instruction. Two case studies support this hypothesis. When damage to the arcuate fasciculus occurs at birth, normal reading skills can develop (15); when damage to the arcuate fasciculus occurs later, for example after reading instruction has begun, it can result in severe reading impairment (9). These cases suggest that learning depends on the circuits' current state and capacity for plasti...

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Pure alexia as a disconnection syndrome: New diffusion imaging evidence for an old concept

Cited by 268 publications

References 68 publications

A disconnection account of Gerstmann syndrome: Functional neuroanatomy evidence

A disconnection account of Gerstmann syndrome: Functional neuroanatomy evidence

Is depression a disconnection syndrome? Meta- analysis of diffusion tensor imaging studies in patients with MDD

Development of white matter and reading skills

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