PubMed · 14923931
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J M PICKETT. 1952. Non-equipotential cortical function in maze learning.. https://pubmed.ncbi.nlm.nih.gov/14923931/
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DNA packaging into heterochromatin is a fundamental mechanism of transcriptional silencing, yet its role in regulating neural progenitor behavior during brain development remains poorly understood. Trimethylation of histone H3 lysine 9 (H3K9me3), catalyzed by the methyltransferases SETDB1, SUV39H1, and SUV39H2, is a defining feature of heterochromatin, but functional redundancy among these enzymes has obscured their developmental roles. Here, we generated a cortex-specific triple knockout mouse model lacking Setdb1, Suv39h1, and Suv39h2 to directly interrogate H3K9me3 function during corticogenesis. Combined loss of H3K9 methyltransferases caused genome-wide depletion of H3K9me3, disruption of neural progenitor cell-cycle progression, and impaired cortical neurogenesis, resulting in microcephaly. H3K9 methyltransferases preserve neural progenitor identity and function by silencing clustered protocadherins, meiosis-associated genes, and a cell-cycle restraint program through H3K9me3 deposition. Loss of H3K9me3 promoted local chromatin opening and increased transcription factor occupancy, enabling transposable elements to acquire cryptic enhancer activity and modulate proximal gene expression. Together, these findings establish H3K9me3 heterochromatin as an active regulator of neural progenitor dynamics and lineage fidelity, revealing a central epigenetic mechanism that restricts aberrant transcriptional programs to ensure cortical growth.
OBJECTS: A case of a Suriname female occipito-parietal to occipito-parieto-temporal craniopagus twins is described. The girls were transferred to the VU University Medical Center (VUmc) in Amsterdam, the Netherlands, for further diagnostics and to analyze whether surgical separation was feasible and ethically justifiable. The multifactorial aspects of different treatment options are discussed. METHODS: The twins underwent multiple investigations by a multidisciplinary team. Advanced imaging techniques with 3D-CT scan, MRI and MRA scans, image fusion techniques and, most importantly, cerebral angiography with balloon occlusion tests were performed. CONCLUSIONS: Because of a shared venous ring, with preferential drainage to the left child, and which endovascular balloon occlusion showed could not be separated, surgical separation of the twins with a fair chance of survival without additional neurological damage and with prospects of a good quality of life was regarded as impossible. In accordance with the parents' wishes, the twins were not separated and offered optimal integral conservative treatment.
Functional interaction between cortical areas may involve synchronization of activities, manifest as coherence between EEG signals. However, although EEG-EEG coherence changes when motor tasks are compared to each other or rest, there is little evidence that coherence is modulated within an action. To address this issue we used a bimanual drawer-opening task necessitating asymmetrical hand actions and comprising distinct movement phases. Pronounced modulations in EEG-EEG coherence in the beta band (>12-24 Hz) occurred with movement phase. Differences in coherence due to a switch in role of the hands were mainly observed in the alpha band (8-12 Hz). These findings suggest that inter-regional synchronization changes dynamically across task execution in line with behavioral performance.