Reduced power and phase-locking values were accompanied by thalamus, putamen, and hippocampus atrophy in Parkinson's disease with mild cognitive impairment: an event-related oscillation study.

Parkinson's disease (PD) is a multifaceted neurodegenerative disorder accompanied by mild cognitive impairment (MCI) as a crucial nonmotor manifestation. Event-related oscillations (EROs) are suggested to reflect cognitive status associated with subcortical structures in neurodegenerative conditions. In this study, 36 individuals with PD-MCI and 32 PD-CN were compared with 60 healthy control (HC) participants using visual EROs by measures of event-related spectral perturbation and inter-trial coherence, along with subcortical gray matter volumes based on the FIRST algorithm. Cross-correlations among electrophysiological, neuropsychological, and structural parameters were investigated exploratively. Both PD-MCI and PD-CN patients had diminished delta and alpha phase-locking than HC, however, electrophysiological abnormalities were more pronounced in PD-MCI over frontal, central, parietal, and temporal locations in almost all frequency bands, accompanied by bilateral thalamus, hippocampus, and right putamen atrophy. PD-CN had lower hippocampal volumes than HC, without exhibiting any subcortical differences from PD-MCI. Lastly, EROs showed low-to-high correlations with structural and neuropsychological measures. These findings may highlight the complex interplay between electrophysiological, neuropsychological, and structural parameters in detected abnormalities of PD-CN and PD-MCI.

Immature event-related alpha dynamics in children compared with the young adults during inhibition shown by day-night stroop task.

Introduction: Inhibitory control develops gradually from infancy to childhood and improves further during adolescence as the brain matures. Related previous studies showed the indispensable role of task-related alpha power during inhibition both in children and young adults. Nonetheless, none of the studies have been able to investigate the direct differences in brain responses between children and young adults when confronted with a stimulus that should be inhibited. Because, unlike event-related designs, task-related designs involve continuous tasks over a certain period, which precludes the possibility of making such a comparison. Accordingly, by employing event-related design, the present study first time in the literature, aimed to analyze the event-related alpha phase locking and event-related alpha synchronization/ desynchronization to differentiate the inhibitory processes in children compared to young adults. Methods: Twenty children between the ages of 6 to 7 years and 20 healthy young adult subjects between the ages of 18 to 30 years were included in the study. Day-night Stroop task was applied to all subjects during 18-channel EEG recordings. Event-related time-frequency analysis was performed with the complex Morlet Wavelet Transform for the alpha frequency band (8-13 Hz). Event related spectral perturbation (ERSP) in three different time windows (0-200 ms, 200-400 ms, 400-600 ms) and Event-related phase locking in the early time window (0-400 ms) was calculated. Results: The children had increased alpha power in early and late time windows but decreased alpha phase locking in the early time windows compared to young adults. There were also topological differences between groups; while young adults had increased alpha phase-locking in frontal and parietal electrode sites, children had increased occipital alpha power and phase locking. Discussion: The shift in event-related alpha power observed from posterior to anterior regions with age may suggest a progressive maturation of the frontal areas involved in inhibitory processes from childhood to adulthood. The results of the present study showed that children and young adults had different EEG oscillatory dynamics during inhibitory processes at alpha frequency range.

Theta and alpha oscillatory responses differentiate between six-to seven-year-old children and adults during successful visual and auditory memory encoding.

The healthy maturation of the brain is one of the intriguing topics that need to be investigated to understand human brain and child development. The present study aimed to investigate the development of memory processes both for auditory and visual memory using electroencephalography (EEG)-Brain Dynamics methodologies. Sixteen healthy children between the ages of 6 and 7 years and eighteen healthy young adults (age: 21.32 ± 3.28 years) were included in the study. EEG was recorded from 18 channels during the visual and auditory memory paradigms. Two different subtests of the WISC-IV IQ test were applied to all children. Event-related theta (4-7 Hz), alpha (8-13 Hz) power and phase-locking were analyzed. The young adults had higher memory performance than the children for both auditory and visual paradigms. The children had increased theta phase-locking and left alpha power in response to the remembered objects in comparison to the forgotten objects. The young adults had higher theta and alpha phase-locking than the children over the frontal and central locations (p < 0.05), and the children had higher parietal-occipital alpha phase-locking than the young adults. There was an increase in alpha power in children, whereas young adults had decreased post-stimulus alpha power in response to memory paradigms. The present study showed that frontocentral theta and alpha phase-locking had an essential role in brain maturation and successful memory performance. Event-related theta and alpha responses could be one of the important indicators of the mature and healthy brain, and these responses could change depending on the maturation state and age.