ABSTRACT
Numerous studies reported that developmental dyslexia in alphabetic languages was associated with a wide range of sensorimotor deficits, including balance, motor skill and time estimation, explained by skill automatization deficit hypothesis. Neural correlates of skill automatization deficit point to cerebellar dysfunction. Recently, a behavioral study revealed an implicit motor learning deficit in Chinese children with developmental dyslexia in their left hands, indicating left cerebellar dysfunction. Using functional magnetic resonance imaging (fMRI), our study examined the brain activation during implicit motor learning in 9 Chinese dyslexic and 12 age-matched children. Dyslexic children showed abnormal activations in the left cerebellum, left middle/medial temporal lobe and right thalamus compared with age-matched children during implicit motor learning. These findings provide evidence of cerebellar abnormality in Chinese dyslexic people. Furthermore, dysfunction of the left cerebellum in Chinese dyslexia is inconsistent with the right cerebellum abnormalities that were reported by studies on alphabetic-language dyslexia, suggesting that neurobiological abnormalities of impaired reading are probably language specific.
Subject(s)
Asian People , Cerebellar Diseases/diagnosis , Dyslexia/diagnosis , Magnetic Resonance Imaging , Reading , Asian People/ethnology , Cerebellar Diseases/ethnology , Cerebellar Diseases/physiopathology , Child , Dyslexia/ethnology , Dyslexia/physiopathology , Female , Humans , Magnetic Resonance Imaging/methods , Male , Photic Stimulation/methods , Psychomotor Performance/physiology , Reaction Time/physiologyABSTRACT
Independent component analysis with Infomax algorithm can separate functional magnetic resonance imaging (fMRI) data into independent spatial components (brain activation maps) and their associated time courses. In the current study, we propose a variant of the logistic transfer function in Infomax, referred to as a-logistic Infomax, and a postprocessing procedure to combine a consistently task-related (CTR) component with transiently task-related (TTR) components for a better definition of brain functional localization. This a-logistic Infomax introduced parameter a into the standard logistic transfer function of conventional Infomax algorithm. For postprocessing method, we suggest the use of a stepwise linear regression of CTR and TTR components to fit reference function and then to sum up with different weights only those with significant contributions to the reference function in order to obtain a task component activation map. The effectiveness of both approaches on separating components and functional localization was evaluated with simulated and real fMRI data.
