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The question of whether dyslexic children have visual cognitive differences in terms of brain activity as compared to normal children remains unsolved. Here, we aimed to study the neuronal source activity during visual attentional processing reflected in the P300 Event-Related Potential (ERP) component, when being exposed to the different congruency of visual images on dyslexic children by utilizing an ERP. Twelve dyslexic and twelve non-dyslexic children in the range of age 8 to 11 years old took part in this study. They pressed button ‘1’ when they saw a congruence image of the animal in its natural habitat and button ‘2’ for incongruence animal images in non-natural habitat. The source localization of P300 was executed on the grand average waveform by utilising Standardised Low-Resolution Brain Electromagnetic Tomography (sLORETA) algorithm provided by Net Station software. The BA 19 of the left occipital lobe was the most activated during congruence and incongruence images in the dyslexic children. As for the control children, BA 18 and BA 17 of the occipital lobe were activated during congruence and incongruence images, respectively. In sum, there were no differences in source activity areas during both visual images in dyslexic children as compared to the control children, which brings us to a conclusion that the visual attentional activity in dyslexic children used the brain areas that are associated with visual characteristics rather than context differences. Keywords: Dyslexia; visual attention; event related potential; sLORETA; image congruency

Neuroplasticity has been subjected to a great deal of research in the last century. Recently, significant emphasis has been placed on the global effect of localized plastic changes throughout the central nervous system, and on how these changes integrate in a pathological context. The present study aimed to demonstrate the functional cortical reorganization before and after surgery using magnetoencephalography (MEG) in a participant with brain tumor. Results of Visual Evoked Magnetic Field (VEF) based on functional MEG study revealed significantly different of MEG N100 waveforms before and after surgery. Larger and additional new locations for visual activation areas after the surgery were found suggesting neuroplasticity. The present study highlight a physiological plasticity in a teenage brain and the alterations regarding neural plasticity and network remodeling described in pathological contexts in higher-order visual association areas.

The present study discussed functional reorganization and alteration in respond to the slow-growing tumour, hemangiopericytoma in the occipital cortex. Visual evoked field (VEF) and auditory evoked field (AEF) using magnetoencephalography (MEG) was used to evaluate the source localization and brain activity. Results of VEF source localization show a typical brain waves. Brain activity of the occipital lobe demonstrate low activation in the ipsilateral to the tumour. However, result shows the activation on the contralateral hemisphere was high and bigger in activation volume. AEF result shows an identical source localization and both side of the temporal lobe are activated. This result suggests that there is a positive plasticity in auditory cortex and slow-growing tumour can induce functional reorganization and alteration to the brain. DOI : http://dx.doi.org./10.17576/JSKM-2018-1602-11