Study of functional magnetic resonance imaging (fMRI) in children and adolescents with specific learning disorder (dyslexia).

BACKGROUND

Dyslexia is a type of specific learning disability (SLD) which has neurobiological origin. It is characterized by difficulties with accurate and/or fluent word recognition and by poor spelling and decoding abilities. The impaired reading in dyslexia is associated with inability to process the sensory input that enters the nervous system. Functional magnetic resonance imaging (fMRI) has emerged as a potential source in understanding the neurobiology and to identify the brain basis of sensory stimuli processed in dyslexic patients.

METHODOLOGY

The present study was conducted to assess the difference in neural changes using fMRI in children and adolescents with SLD compared with normal children and also the correlation of clinical parameters with BOLD - fMRI changes. Sixteen children and adolescents diagnosed as dyslexia were assessed with All India Institute of Medical Sciences (AIIMS) SLD Battery, Mini-International Neuropsychiatric Interview for Children and Adolescents (MINI KID) and Aggregated Neurobehavioral Student Health and Educational Review (ANSER) system and compared with 15 controls matched with age and sex. Participants of both groups were asked to perform 3 tasks during the fMRI acquisition (phonological, picture-naming and semantic tasks).

RESULT

As compared to control group, the participants with dyslexia show phonological decoding problem. During picture task, the participants with dyslexia use more areas of brain involve in recalling the memory events while during semantic tasks processing the occipito-temporal (fusiform) gyrus was less activated when in contrast to control.

CONCLUSION

This study shows that participants with dyslexia fail to use normal brain regions specialized in language processing, but rather use different areas.