Genetic correlates of the development of theta event related oscillations in adolescents and young adults.

The developmental trajectories of theta band (4-7Hz) event-related oscillations (EROs), a key neurophysiological constituent of the P3 response, were assessed in 2170 adolescents and young adults ages 12 to 25. The theta EROs occurring in the P3 response, important indicators of neurocognitive function, were elicited during the evaluation of task-relevant target stimuli in visual and auditory oddball tasks. Associations between the theta EROs and genotypic variants of 4 KCNJ6 single nucleotide polymorphisms (SNPs) were found to vary with age, sex, scalp location, and task modality. Three of the four KCNJ6 SNPs studied here were found to be significantly associated with the same theta EROs in adults in a previous family genome wide association study. Since measures of the P3 response have been found to be a useful endophenotypes for the study of a number of clinical and behavioral disorders, studies of genetic effects on its development in adolescents and young adults may illuminate neurophysiological factors contributing to the onset of these conditions.

Gender modulates the development of theta event related oscillations in adolescents and young adults.

The developmental trajectories of theta band (4-7 Hz) event-related oscillations (EROs), a key neurophysiological constituent of the P3 response, were assessed in 2170 adolescents and young adults ages 12 to 25. The theta EROs occurring in the P3 response, important indicators of neurocognitive function, were elicited during the evaluation of task-relevant target stimuli in visual and auditory oddball tasks. These tasks call upon attentional and working memory resources. Large differences in developmental rates between males and females were found; scalp location and task modality (visual or auditory) differences within males and females were small compared to gender differences. Trajectories of interregional and intermodal correlations between ERO power values exhibited increases with age in both genders, but showed a divergence in development between auditory and visual systems during ages 16 to 21. These results are consistent with previous electrophysiological and imaging studies and provide additional temporal detail about the development of neurophysiological indices of cognitive activity. Since measures of the P3 response has been found to be a useful endophenotypes for the study of a number of clinical and behavioral disorders, studies of its development in adolescents and young adults may illuminate neurophysiological factors contributing to the onset of these conditions.

Evoked gamma band response in male adolescent subjects at high risk for alcoholism during a visual oddball task.

This study investigates early evoked gamma band activity in male adolescent subjects at high risk for alcoholism (HR; n=68) and normal controls (LR; n=27) during a visual oddball task. A time-frequency representation method was applied to EEG data in order to obtain stimulus related early evoked (phase-locked) gamma band activity (29-45 Hz) and was analyzed within a 0-150 ms time window range. Significant reduction of the early evoked gamma band response in the frontal and parietal regions during target stimulus processing was observed in HR subjects compared to LR subjects. Additionally, the HR group showed less differentiation between target and non-target stimuli in both frontal and parietal regions compared to the LR group, indicating difficulty in early stimulus processing, probably due to a dysfunctional frontoparietal attentional network. The results indicate that the deficient early evoked gamma band response may precede the development of alcoholism and could be a potential endophenotypic marker of alcoholism risk.

Alcohol-related ERP changes recorded from different modalities: a topographic analysis.

BACKGROUND: There is controversy in the literature regarding the relationship between event-related-potential (ERP) abnormalities in abstinent alcoholics and stimulus-processing modality (i.e., visual versus auditory). The first purpose of this study was to address questions about whether ERP abnormalities observed in alcoholics are modality specific. The second purpose was to employ current source density (CSD) analyses to investigate topographic differences between alcoholics and controls within each modality. METHODS: Data were collected from 30 sober male alcoholics and 39 normal males in a typical auditory oddball task and in a visual oddball paradigm with novel stimuli, with an extensive set of 61 scalp electrodes. Visual and quantitative assessment of CSD maps as well as analyses of variances on both raw and normalized ERP data were performed. RESULTS: Positive findings were limited to the N1 and P3 components. The visual N1 amplitude was significantly smaller in alcoholics than in controls at the parietal region; no significant group differences in N1 were found in the auditory modality. Alcoholics had widespread reductions in P3 amplitudes in both modalities compared with controls, although in the frontal region this effect was partially due to the influence of age. These P3 reductions in alcoholics were statistically more pronounced in the posterior compared with the anterior regions regardless of modality. Topographically, sources in CSD maps were weaker in alcoholics than in controls; in the frontal and central regions, the weakness was more pronounced in the auditory modality but, in parietal and occipital regions, it was more pronounced in the visual modality. CONCLUSIONS: The results suggest that, in abstinent alcoholics, abnormalities in auditory ERPs may be localized to more anterior sources, while abnormalities in visual ERPs may be localized to more posterior sources. ERP topographic features are more sensitive than amplitude measurements in assessing alcoholic-related modality effects.