For instance, the mammalian brain has a six-layered structure, while the avian brains consist of compartmentalized nuclear slabs. These results indicate that species-specific microenvironments with distinct mechanical properties emerging during development might contribute to the formation of brain structures with unique morphology.Īlthough the vast majority of molecular machinery to generate neurons from progenitors are commonly conserved in amniotes ( Englund et al., 2005 Martínez-Cerdeño et al., 2016 Nomura et al., 2016 Turrero García et al., 2016 Yamashita et al., 2018), the alignment of neurons in matured brains exhibits remarkable diversity ( Medina and Abellán, 2009 Jarvis et al., 2013 Puelles et al., 2017 Cárdenas and Borrell, 2019 Pessoa et al., 2019). The embryonic chick and matured turtle pallia showed gradually increasing stiffness along the apico-basal tissue axis, the lowest region at the most apical region, while the ferret pallium exhibited a catenary pattern, that is, higher in the ventricular zone, the inner subventricular zone, and the cortical plate and the lowest in the outer subventricular zone. We found stage-dependent and species-specific stiffness in pallia among amniotes. We also measured brain stiffness in other amniotes (chick, turtle, and ferret) following glyoxal fixation. Based on this method, we found that the homologous brain regions between mice and songbirds exhibited different stiffness patterns. Notably, brain tissue fixed by glyoxal remained much softer than PFA-fixed brains, and it can maintain the relative stiffness profiles of various brain regions. A comparison of embryonic and juvenile mouse and songbird brain tissue revealed that glyoxal fixation can maintain brain structure as well as paraformaldehyde (PFA) fixation. For a systematic measurement of the brain stiffness of remotely maintained animals, we developed a novel strategy of tissue-stiffness measurement using glyoxal as a fixative combined with atomic force microscopy. To address this point, a comparative analysis of mechanical properties using several animals is required. However, little is known about the correlation between mechanical properties and species-specific brain structures. Recent studies have indicated that differences in the mechanical properties of tissue may result in the dynamic deformation of brain structure, such as folding. 3RIKEN Center for Biosystems Dynamics Research, Kobe, Japanīrain structures are diverse among species despite the essential molecular machinery of neurogenesis being common.2Developmental Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.1Korea Brain Research Institute, Daegu, South Korea.Haldipur.Misato Iwashita 1*, Tadashi Nomura 2, Taeko Suetsugu 3, Fumio Matsuzaki 3, Satoshi Kojima 1 and Yoichi Kosodo 1* Update: This article has been updated to reflect that the information was equally contributed by Dr. “We expect that this information will provide new insights into the underlying causes of human cerebellar neurodevelopmental disorders, including medulloblastoma, which we can leverage to provide better diagnostic information and perhaps eventual new therapies,” said Millen and Haldipur. ![]() As just an example of two cerebellum related disorders, the new research suggests that studies on these moving forward may not reveal the whole picture and may need to look elsewhere for answers. Dandy-Walker malformation affects the formation of the cerebellum and may result in problems with movement, coordination, intellect, mood, and other neurological functions. Medulloblastoma is a brain tumor that affects the cerebellum and is the most common type of malignant brain tumor found in children. “Our results indicate that we need to exercise caution when using animal models to study human brain development and disease.” Our data shows that we cannot truly model what we do not know,” explained Millen and Haldipur. While this is broadly true, the details are important. “We had previously developed our ideas based on mouse development thinking that mice approximated human development. According to Millen and Haldipur, the new work may specifically affect research on Dandy-walker malformation and cerebellar brain tumors (Medulloblastoma) and suggest that mice no longer serve as an accurate model for this research. Damage to the cerebellum, whether acquired at birth or obtained through a traumatic injury, can lead to slowed and uncoordinated movement and speech.
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