TY - JOUR
T1 - A N400 ERP Study in letter recognition after passive tactile stimulation training in blind children and sighted controls
AU - Ortiz, Tomas
AU - Ortiz-Teran, Laura
AU - Turrero, Agustin
AU - Poch-Broto, Joaquin
AU - De Erausquin, Gabriel A.
N1 - Publisher Copyright:
© 2019 - IOS Press and the authors. All rights reserved.
PY - 2019
Y1 - 2019
N2 - Background: We previously demonstrated that using a sensory substitution device (SSD) for one week, tactile stimulation results in faster activation of lateral occipital complex in blind children than in seeing controls. Objective: We used long-term haptic tactile stimulation training with an SSD to test if it results in stable cross-modal reassignment of visual pathways after six months, to provide high level processing of tactile semantic content. Methods: We enrolled 12 blind and 12 sighted children. The SSD transforms images to a stimulation matrix in contact with the dominant hand. Subjects underwent twice-daily training sessions, 5 days/week for six months. Children were asked to describe line orientation, name letters, and read words. ERP sessions were performed at baseline and 6 months to analyze the N400 ERP component and reaction times (RT). N400 sources were estimated with Low Resolution Electromagnetic Tomography (LORETA). SPM8 was used to make population-level inferences. Results: We found no group differences in RTs, accuracy of identifications, N400 latencies or distributions with the line task at 1 week or at 6 months. RTs on the letter recognition task were also similar. After 6 months, behavioral training increased accurate letter identification in both seeing and blind children (Chi 2 = 11906.934, p = 0.000), but the increase was larger in blind children (Chi 2 = 8.272, p = 0.004). Behavioral training shifted peak N400 amplitude to left occipital and bilateral parietal cortices in blind children, but to left precentral and postcentral and bilateral occipital cortices in sighted controls. Conclusions: Blind children learn to recognize SSD-delivered letters better than seeing controls and had greater N400 amplitude in the occipital region. To the best of our knowledge, our results provide the first published example of standard letter recognition (not Braille) by children with blindness using a tactile delivery system.
AB - Background: We previously demonstrated that using a sensory substitution device (SSD) for one week, tactile stimulation results in faster activation of lateral occipital complex in blind children than in seeing controls. Objective: We used long-term haptic tactile stimulation training with an SSD to test if it results in stable cross-modal reassignment of visual pathways after six months, to provide high level processing of tactile semantic content. Methods: We enrolled 12 blind and 12 sighted children. The SSD transforms images to a stimulation matrix in contact with the dominant hand. Subjects underwent twice-daily training sessions, 5 days/week for six months. Children were asked to describe line orientation, name letters, and read words. ERP sessions were performed at baseline and 6 months to analyze the N400 ERP component and reaction times (RT). N400 sources were estimated with Low Resolution Electromagnetic Tomography (LORETA). SPM8 was used to make population-level inferences. Results: We found no group differences in RTs, accuracy of identifications, N400 latencies or distributions with the line task at 1 week or at 6 months. RTs on the letter recognition task were also similar. After 6 months, behavioral training increased accurate letter identification in both seeing and blind children (Chi 2 = 11906.934, p = 0.000), but the increase was larger in blind children (Chi 2 = 8.272, p = 0.004). Behavioral training shifted peak N400 amplitude to left occipital and bilateral parietal cortices in blind children, but to left precentral and postcentral and bilateral occipital cortices in sighted controls. Conclusions: Blind children learn to recognize SSD-delivered letters better than seeing controls and had greater N400 amplitude in the occipital region. To the best of our knowledge, our results provide the first published example of standard letter recognition (not Braille) by children with blindness using a tactile delivery system.
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U2 - 10.3233/RNN-180838
DO - 10.3233/RNN-180838
M3 - Article
C2 - 31227674
AN - SCOPUS:85067864825
SN - 0922-6028
VL - 37
SP - 197
EP - 206
JO - Restorative Neurology and Neuroscience
JF - Restorative Neurology and Neuroscience
IS - 3
ER -