TY - JOUR
T1 - Brain mechanisms of recovery from pure alexia
T2 - A single case study with multiple longitudinal scans
AU - Cohen, Laurent
AU - Dehaene, Stanislas
AU - McCormick, Samantha
AU - Durant, Szonya
AU - Zanker, Johannes M
N1 - Output uploaded to RURR on 21/07/2016 - meeting OA criteria.
PY - 2016/7/13
Y1 - 2016/7/13
N2 - 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.
AB - 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.
U2 - 10.1016/j.neuropsychologia.2016.07.009
DO - 10.1016/j.neuropsychologia.2016.07.009
M3 - Article
C2 - 27422538
SN - 0028-3932
VL - 91
SP - 36
EP - 49
JO - NEUROPSYCHOLOGIA
JF - NEUROPSYCHOLOGIA
ER -