Morphological changes in the pons and cerebellum during the first two weeks in term infants with pontine and cerebellar injury and profound neonatal asphyxia

Background The morphological changes in the pons and cerebellum of neonates experiencing profound asphyxia in the early period of life remain to be clarified. Purpose To assess the changes in the size of the pons and cerebellum during the first two weeks of life in term neonates with pontine and cerebellar injury caused by hypoxic-ischemic encephalopathy in comparison with a control group. Material and Methods Two groups were investigated: a group with pontine/cerebellar injury (PCI) (n = 10) demonstrated by magnetic resonance imaging (MRI) diffusion-weighted imaging; and a control group without PCI – focal-multifocal white matter injury and a normal pattern (n = 24). The anteroposterior diameter (APD) and height of the pons and cerebellar vermis, and the transverse width of the cerebellum were measured twice in the first and second weeks of life. Differences between the groups were analyzed statistically using paired and unpaired Student’s t-test at a significance level of P < 0.05. Results In the PCI group, the pontine APD and cerebellar vermian height were significantly decreased in the second week. An increase of pons and cerebellar size was evident during the first two weeks of life in the control groups. Conclusion Infants with PCI and profound asphyxia show rapid decreases in pontine APD and cerebellar vermian height within the first two weeks of life.

Relationship Between Early Functional and Structural Brain Developments and Brain Injury in Preterm Infants

Background Recent studies explored the relationship between early brain function and brain morphology, based on the hypothesis that increased brain activity can positively affect structural brain development and that excitatory neuronal activity stimulates myelination. Objective To investigate the relationship between maturational features from early and serial aEEGs after premature birth and MRI metrics characterizing structural brain development and injury, measured around 30weeks postmenstrual age (PMA) and at term. Moreover, we aimed to verify whether previously developed maturational EEG features are related with PMA. Design/Methods One hundred six extremely preterm infants received bedside aEEGs during the first 72h and weekly until week 5. 3T-MRIs were performed at 30weeks PMA and at term. Specific features were extracted to assess EEG maturation: (1) the spectral content, (2) the continuity [percentage of spontaneous activity transients (SAT%) and the interburst interval (IBI)], and (3) the complexity. Automatic MRI segmentation to assess volumes and MRI score was performed. The relationship between the maturational EEG features and MRI measures was investigated. Results Both SAT% and EEG complexity were correlated with PMA. IBI was inversely associated with PMA. Complexity features had a positive correlation with the cerebellar size at 30weeks, while event-based measures were related to the cerebellar size at term. Cerebellar width, cortical grey matter, and total brain volume at term were inversely correlated with the relative power in the higher frequency bands. Conclusions The continuity and complexity of the EEG steadily increase with increasing postnatal age. Increasing complexity and event-based features are associated with cerebellar size, a structure with enormous development during preterm life. Brain activity is important for later structural brain development.

Cerebellar granuloprival and trans-synaptic degeneration in a Chihuahua

An unusual form of cerebellocortical degeneration called cerebellar granuloprival degeneration was diagnosed in a four-month-old Chihuahua. The dog had a two-week history of progressive signs of cerebellar dysfunction, including a wide-based stance, intention tremors and bilateral absence of menace response without visual impairment. On MRI of the encephalon, a reduction in cerebellar size was detected. On histopathological examination, depletion of the cerebellar granule cell layer was observed, in addition to neuronal degeneration in the vestibular nuclei, reticular formation, red nucleus and internal laminae of the parietal and temporal cortices. A diagnosis of cerebellar granuloprival degeneration with trans-synaptic degeneration was made. To the authors’ knowledge, this is the first case report of cerebellar granuloprival degeneration in a Chihuahua and the first report of cerebellar granuloprival degeneration with trans-synaptic degeneration in a dog.

Amot regulates neuronal dendritic tree through Yap1

ABSTRACTThe Amot-Yap1 complex plays a major role in the regulation of cell contact inhibition, cellular polarity and growth. However, the function of Angiomotin (Amot) and Hippo pathway transcription co-activator Yap1 in the central nervous system remains unclear. In this study, we demonstrate that Amot is a critical mediator of dendritic morphogenesis in cultured hippocampal cells and Purkinje cells in the brain. Amot function in developing hippocampal neurons depends on interactions with Yap1, which is also indispensable for dendrite growth and arborization in vitro. Conditional deletion of Amot or Yap1 in neurons leads to impaired morphogenesis of Purkinje cell dendritic trees, decreased cerebellar size, and causes defects in locomotor coordination of mutant animals. Thus, our studies identified Amot and Yap1 as novel regulators of dendritic tree morphogenesis.

A cerebellar substrate for cognition evolved multiple times independently in mammals

Given that complex behavior evolved multiple times independently in different lineages, a crucial question is whether these independent evolutionary events coincided with modifications to common neural systems. To test this question in mammals, we investigate the lateral cerebellum, a neurobiological system that is novel to mammals, and is associated with higher cognitive functions. We map the evolutionary diversification of the mammalian cerebellum and find that relative volumetric changes of the lateral cerebellar hemispheres (independent of cerebellar size) are correlated with measures of domain-general cognition in primates, and are characterized by a combination of parallel and convergent shifts towards similar levels of expansion in distantly related mammalian lineages. Results suggest that multiple independent evolutionary occurrences of increased behavioral complexity in mammals may at least partly be explained by selection on a common neural system, the cerebellum, which may have been subject to multiple independent neurodevelopmental remodeling events during mammalian evolution.