Self-Organizing Circuit Assembly through Spatiotemporally Coordinated Neuronal Migration within Geometric Constraints

Neurons are dynamically coupled with each other through neurite-mediated adhesion during development. Understanding the collective behavior of neurons in circuits is important for understanding neural development. While a number of genetic and activity-dependent factors regulating neuronal migration have been discovered on single cell level, systematic study of collective neuronal migration has been lacking. Various biological systems are shown to be self-organized, and it is not known if neural circuit assembly is self-organized. Besides, many of the molecular factors take effect through spatial patterns, and coupled biological systems exhibit emergent property in response to geometric constraints. How geometric constraints of the patterns regulate neuronal migration and circuit assembly of neurons within the patterns remains unexplored.We established a two-dimensional model for studying collective neuronal migration of a circuit, with hippocampal neurons from embryonic rats on Matrigel-coated self-assembled monolayers (SAMs). When the neural circuit is subject to geometric constraints of a critical scale, we found that the collective behavior of neuronal migration is spatiotemporally coordinated. Neuronal somata that are evenly distributed upon adhesion tend to aggregate at the geometric center of the circuit, forming mono-clusters. Clustering formation is geometry-dependent, within a critical scale from 200 µm to approximately 500 µm. Finally, somata clustering is neuron-type specific, and glutamatergic and GABAergic neurons tend to aggregate homo-philically.We demonstrate self-organization of neural circuits in response to geometric constraints through spatiotemporally coordinated neuronal migration, possibly via mechanical coupling. We found that such collective neuronal migration leads to somata clustering, and mono-cluster appears when the geometric constraints fall within a critical scale. The discovery of geometry-dependent collective neuronal migration and the formation of somata clustering in vitro shed light on neural development in vivo

THE KABUKI (NIIKAWA-KUROKI) SYNDROME - FURTHER DELINEATION OF THE PHENOTYPE IN 29 NON-JAPANESE PATIENTS

The Kabuki (Niikawa-Kuroki) syndrome was reported in 1981 by Niikawa et al. [19] and Kuroki et al. [15] in a total of ten unrelated Japanese children with a characteristic array of multiple congenital anomalies and mental retardation. The syndrome is characterized by a distinct face, mild to moderate mental retardation, postnatal growth retardation, dermatoglyphic and skeletal abnormalities. In Japan, the syndrome appears to have an incidence of about 1:32 000 newborns. Outside of Japan, a growing number of patients have been recognized. Clinical data are presented on 29 Caucasian patients; the patients were diagnosed over a relatively short period of time, indicating that the incidence outside of Japan is probably not lower than in Japan, A literature review of 89 patients (60 Japanese and 29 non-Japanese) is given. In 66% of the non-Japanese patients serious neurological problems were present, most notably hypotonia and feeding problems (which were not only related to the cleft palate); this was not reported in the Japanese patients. Inheritance is not clear. Most patients are isolated, sex-ratio is equal. The syndrome can be recognized in patients with cleft (lip/)palate, with mild to moderate developmental delay and in young children with hypotonia and/or feeding problems. In counselling parents, the designation ''Kabuki'' syndrome seems to be more appropriate than ''Kabuki make-up'' syndrome