sLORETA Source Localization in Dyslexic Children during Different Congruency of Visual Images: P300 Component Analysis (Sumber aktiviti sLORETA dalam kalangan Kanak-kanak Disleksia dalam Stimulasi Imej Visual yang Berbeza Kesesuaian Konteks: Komponen P300 Analisis) / Jurnal Sains Kesihatan Malaysia

@#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.

Electroencephalographic Characteristics of Alcohol Dependent Patients: 3-Dimensional Source Localization

OBJECTIVES: The power spectral analysis of electroencephalogram has been widely used to reveal the pathophysiology of the alcoholic brain. However, the results were not consistent and the three dimensional study can be hardly found. The purpose of this study was to investigate characteristics of the three dimensional electroencephalographic (EEG) activity of alcohol dependent patients using standardized low resolution electromagnetic tomography (sLORETA). METHODS: The participants consisted of 30 alcohol dependent patients and 30 normal healthy controls. All the participants were males who had refrained from alcohol at least one month and were not taking any medications. Thirty two channel EEG data was collected in the resting state with eyes-closed condition during 30 seconds. The three dimensional data was compared between two groups using sLORETA for delta, theta, alpha, beta1, beta2, and beta3 frequency bands. RESULTS: sLORETA revealed significantly increased brain cortical activity in alpha, beta1, beta2, and beta3 bands each in alcohol dependent patients compared to normal controls. The voxels showing the maximum significance were in the left transverse temporal gyrus, left superior temporal gyrus, left anterior cingulate, and left fusiform gyrus in alpha, beta1, beta2, and beta3 bands respectively. CONCLUSIONS: These results suggest that chronic alcohol intake may cause neurophysiological changes in cerebral activity. Therefore, the measuring of EEG can be helpful in understanding the pathophysiology of cognitive impairements in alcohol dependence.

The Change of Cortical Activity Induced by Visual Disgust Stimulus / 수면정신생리

OBJECTIVES: There are a lot of studies that analyze the interaction between the emotion of disgust and the functional brain images using fMRI and PET. But studies using sLORETA (standardized low resolution brain electromagnetic tomography) almost do not exist. The aim of this research is to explore the relationship of the emotion of disgust and the cortical activation using sLORETA analysis. METHODS: Forty five healthy young adults (27.1+/-2.6 years) participated in the study. While they were watching 4 neutral images and 4 disgusting images associated with mutilation selected from the international affective picture system (IAPS), participants' EEGs were taken for 30 seconds per one picture. Through these obtained EEG data, sLORETA analysis was performed to compare EEGs associated with neutral and negative images. RESULTS: During looking for visual disgusting stimulus, all participants reported unpleasantness, arousal and stress. In sLORETA analysis, the decrease of current density in theta wave was shown at left frontal superior gyrus (BA10) and middle gyrus (BA10, 11). This voxel cluster consists of a total of 11 voxels and the threshold of t value indicating statistically significant decreases in the current density (p<0.05) was -1.984. There were no differences between male and female in the degree of being disgusted by the stimuli. CONCLUSION: This finding may suggest that the activation of dorsolateral prefrontal cortex might be associated with regulating disgust emotion.

Medial Temporal Activation in Mal de Debarquement Syndrome Revealed by Standardized Low-Resolution Brain Electromagnetic Tomography

BACKGROUND: Mal de debarquement (MdD) literally means "sickness of disembarkation", and refers to the illusion of movement perceived as an after-effect of traveling on a boat, train, or airplane. The pathophysiology of MdD is currently unknown. CASE REPORT: A 20-year-old man presented with dizziness and swaying sensation for 3 days after a boat trip. Compared with the follow-up EEG without symptoms, the EEG recorded while having MdD symptoms disclosed a significantly decreased alpha-band current source density at the precentral gyrus of the left frontal lobe and increased beta-2 activity at the parahippocampal gyrus of right mesial temporal region. CONCLUSIONS: Our results provide evidence of deranged cortical activity in MdD. To the best of our knowledge this is the first study to document cortical correlates of MdD using an EEG source-localization method.

Age Differences of Quantitative Electroencephalography and Current Source Density / 신경정신의학

OBJECTIVES: Age-related differences of the brain have been obtained by various methods. This study was aimed to explore the changes of quantitative electroencephalography (qEEG) and their source localization in normal aging. METHODS: Thirty-seven healthy young adults (mean age 35.22+/-13.62 years) and thirty-nine cognitively-healthy elderly subjects (mean age 72.95+/-5.73 years) participated in the study. Resting-state EEGs were recorded while subjects were in a relaxed state. Relative qEEG powers of five frequency bands were analyzed for eye closed conditions: delta (1-3 Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-25 Hz), and gamma (30-50 Hz). The standardized low resolution electromagnetic tomography (sLORETA) was used to identify the current source densities of each frequency band. RESULTS: The elderly group showed an increase of beta and gamma power while the reduction of delta, theta, and alpha power compared with the young group. Controlling education as a covariate, the beta power was positively correlated with age, while theta power was negatively correlated with age in all subjects. sLORETA revealed that elderly subjects had reduced current source density at the cingulate gyrus in the theta band, while increased current source densities at the frontal, parietal, insula, and limbic areas in the beta band compared with young adults. CONCLUSION: Our results suggested that qEEG could reflect normal aging. Cognitively healthy elderly subjects showed an increase of high-frequency power, while showing a reduction of low-frequency power. These functional implications were discussed.