Measurement Of The Prefrontal Cortex In Dyslexic Children By NIRS

Developmental dyslexia is a characterized by an unexpected difficulty in reading in children who otherwise possess the intelligence, motivation, and schooling considered necessary for accurate and fluent reading. Modern functional brain imaging technologies, such as fMRI and PET, had been used to study the brain activities of the children with dyslexia whose first language is English. The left prefrontal cortex and temporal cortex was associated with phonological processing. Recent research had indicated that impairing reading of Chinese children also had phonological processing deficits. In the functional brain imaging studies on children, the fMRI and PET had disadvantages respectively. A novel functional brain imaging technology was able to non-invasively detect the blood dynamical parameters of cerebral cortex in real time. Therefore, the cerebral cortex functional responses can be detected during cognitive task. This novel technology was functional Near-infrared imaging system.In this thesis, the basic principle of NIRS is introduced and a brain function imager of 16 channels based on continuous wave (CW) NIRS is presented, which has advantages of stabilization, portal and so no. The software of the system has the functions of sampling the data of light intensity; calculating and displaying the concentration changes of Hb, HbO2 and Tb; presenting the visual stimulates used by cognitive psychology research to subjects; recording the responses and response time of subjects during task. The software can accurately synchronize the presenting of stimulates and the sampling of data. It is important to analyzing experimentation's results.The NIRS was used to monitor the concentration changes of each hemoglobin species when Chinese children did the task of phonological processing and recognition test. During the phonological processing, the brain activities in dyslexia-reading children were significantly higher than normal-reading children in the left PFC. While in the phonological decoding task, the degree and the areas of the dyslexic prefrontal cortex activity are obviously less than the normal-children. The phenomena illuminated the deficits of reading for the dyslexic children was because of the dysfunction of their left prefrontal cortex. These experimental results presented a new evidence to indicate that there is abnormity of neural systems for dyslexic children during Chinese word reading.