Reading difficulty is associated with failure to lateralize temporooccipital function.
OBJECTIVE
Studies of focal epilepsy have revealed abnormalities of language organization; however, little attention has been paid to disorders of reading in this group. We hypothesized that language functional magnetic resonance imaging (fMRI) would reveal differences in language organization between focal epilepsy patients with and without reading difficulties.


METHODS
We conducted language fMRI studies of 10 focal epilepsy patients with reading difficulties, 34 focal epilepsy patients without reading difficulties, and 42 healthy controls.


RESULTS
We defined regions of interests on the basis of activation patterns on an orthographic lexical retrieval task. Comparison of activations within these ROIs on a second Noun-Verb task revealed epilepsy-related effects (relative to healthy controls: reduced activation in left inferior frontal cortex), as well as greater activation in the right temporooccipital cortex specific to the reading difficulty group.


CONCLUSIONS
These findings identify a focal epilepsy effect in the left frontal region (present in patients with and without reading difficulties), and a functional abnormality specific to the reading difficulty group localized to right temporooccipital cortex-a region implicated in lexicosemantic processing. Our observations suggest a failure of left hemisphere specialization among focal epilepsy patients with reading difficulties.
The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.|School of Psychological Sciences, University of Melbourne, Victoria, Australia.
Chris
C
Tailby
Department of Neuropsychology, Austin Health, Melbourne, Victoria, Australia.
David L
DL
Weintrob
School of Psychological Sciences, University of Melbourne, Victoria, Australia.|Department of Neuropsychology, Austin Health, Melbourne, Victoria, Australia.
Michael M
MM
Saling
The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.
Carly
C
Fitzgerald
The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia.|Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia.
Graeme D
GD
Jackson
D000328:Adult; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D004410:Dyslexia / Q000175:diagnosis / Q000503:physiopathology*; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D011939:Mental Recall / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000503:physiopathology*; D013702:Temporal Lobe / Q000503:physiopathology*
Dyslexia; Epilepsy; Functional magnetic resonance imaging; Reading disorder