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Neuropsychologia. 2016 Oct;91:36-49. doi: 10.1016/j.neuropsychologia.2016.07.009. Epub 2016 Jul 13.

Brain mechanisms of recovery from pure alexia: A single case study with multiple longitudinal scans.

Author information

1
Inserm, U 1127, F-75013 Paris, France; Sorbonne Universités, UPMC University, Paris 06, UMR S 1127, F-75013 Paris, France; AP-HP, Hôpital de la Pitié Salpêtrière, Department of Neurology, F-75013 Paris, France; CNRS, UMR 7225, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France. Electronic address: laurent.cohen@aphp.fr.
2
Collège de France, Place Marcelin Berthelot, 75005 Paris, France; Cognitive Neuroimaging Unit, CEA DSV/I2BM, INSERM, Université Paris-Sud, Université Paris-Saclay, NeuroSpin Center, 91191 Gif/Yvette, France.
3
Department of Psychology, Royal Holloway, University of London, Egham TW20 0EX, UK; Department of Psychology, University of Roehampton, Whitelands College, Holybourne Avenue, London SW15 4JD, UK.
4
Department of Psychology, Royal Holloway, University of London, Egham TW20 0EX, UK.

Abstract

Pure alexia is an acquired reading disorder, typically due to a left occipito-temporal lesion affecting the Visual Word Form Area (VWFA). It is unclear whether the VWFA acts as a unique bottleneck for reading, or whether alternative routes are available for recovery. Here, we address this issue through the single-case longitudinal study of a neuroscientist who experienced pure alexia and participated in 17 behavioral, 9 anatomical, and 9 fMRI assessment sessions over a period of two years. The origin of the impairment was assigned to a small left fusiform lesion, accompanied by a loss of VWFA responsivity and by the degeneracy of the associated white matter pathways. fMRI experiments allowed us to image longitudinally the visual perception of words, as compared to other classes of stimuli, as well as the mechanisms of letter-by-letter reading. The progressive improvement of reading was not associated with the re-emergence of a new area selective to words, but with increasing responses in spared occipital cortex posterior to the lesion and in contralateral right occipital cortex. Those regions showed a non-specific increase of activations over time and an increase in functional correlation with distant language areas. Those results confirm the existence of an alternative occipital route for reading, bypassing the VWFA, but they also point to its key limitation: the patient remained a slow letter-by-letter reader, thus supporting the critical importance of the VWFA for the efficient parallel recognition of written words.

KEYWORDS:

Alexia; Language; Reading; Vision; fMRI

[Indexed for MEDLINE]

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