Neural intersections of the phonological, visual magnocellular and motor/cerebellar systems in normal readers: Implications for imaging studies on dyslexia
Article first published online: 27 JUN 2012
Copyright © 2012 Wiley Periodicals, Inc.
Human Brain Mapping
Volume 34, Issue 10, pages 2669–2687, October 2013
How to Cite
Danelli, L., Berlingeri, M., Bottini, G., Ferri, F., Vacchi, L., Sberna, M. and Paulesu, E. (2013), Neural intersections of the phonological, visual magnocellular and motor/cerebellar systems in normal readers: Implications for imaging studies on dyslexia. Hum. Brain Mapp., 34: 2669–2687. doi: 10.1002/hbm.22098
- Issue published online: 12 SEP 2013
- Article first published online: 27 JUN 2012
- Manuscript Accepted: 15 MAR 2012
- Manuscript Revised: 14 MAR 2012
- Manuscript Received: 11 OCT 2011
- developmental dyslexia;
- occipitotemporal cortex;
We used fMRI to explore the extent of the anatomical overlap of three neural systems that the literature on developmental dyslexia associates with reading: the auditory phonological, the visual magnocellular, and the motor/cerebellar systems. Twenty-eight normal subjects performed four tasks during fMRI scans: word and pseudoword reading, auditory rhyming for letter names, visual motion perception, and a motor sequence learning task. We found that the left occipitotemporal cortex (OTC), which previous studies reported to be dysfunctional in dyslexia, can be fractionated into different functional areas: an anterior and lateral area that was activated by both reading and auditory rhyming tasks; a posterior area that was commonly activated by both the reading and the motion perception task and a medial/intermediate area, including the so-called Visual Word Form Area, which was specifically activated by the reading task. These results show that the left OTC is an area of segregated convergence of different functional systems. We compared our results with the hypoactivation pattern reported for reading in a previous cross-cultural PET study on 36 dyslexic subjects from three countries. The region of decreased activation in dyslexia overlapped with regions that are specific for reading and those activated during both the auditory rhyming task and the single word and pseudoword reading task described in the present fMRI study. No overlap was found with the activation patterns for the visual motion perception task or for the motor sequence learning task. These observations challenge current theories of dyslexia. Hum Brain Mapp 34:2669–2687, 2013. © 2012 Wiley Periodicals, Inc.