Disorders of Neuronal Migration

Abstract

Neuronal migration constitutes one of the major processes by which the central nervous system takes shape. Detailed knowledge about this important process now exists for different brain regions in rodent and monkey models as well as in the human. In the human, distinct genetic, chromosomal and environmental causes are known that affect neuronal migration, often in a morphologically distinct pattern, but the underlying pathological mechanisms are largely unknown. This review is intended to integrate our basic knowledge of the field with the accumulated intelligence on a large number of disorders and syndromes that represent the human part of the story. RESUME: Pertubations de la migration neuronale La migration neuronale constitue un des processus les plus importants par lequel le systeme nerveux central est fa?onne. Nous possedons actuellement des connaissances d^taillees sur ce processus important dans diffeYentes regions du cerveau de modeles animaux (rongeurs et singes) ainsi que chez l'humain. Chez I'humain, des causes g6netiques, chromosomiques et environnementales distinctes sont connues comme affectant la migration neuronale, donnant lieu a des patterns morphologiques souvent distincts; les m6canismes pathologiques sous-jacents sont pour la plupart inconnus. Dans la presente revue, nous d6sirons int6grer nos connaissances de base dans ce domaine avec les donnees accumulSes au sujet d'un grand nombre d'affections et de syndromes representant leur contrepartie chez l'humain.

Prenatal exposure to ultrasound waves impacts neuronal migration in mice

“…Although we have not as yet generated behavioral data, previous studies in rodents and primates indicate that prenatal exposure to USW may affect higher brain function of the offspring (26,27). Furthermore, there are numerous human neuropsychiatric disorders that are thought to be the result of misplacement of cells as a consequence of abnormal neuronal migration (e.g., 8,10,12,[22][23][24]. Therefore, our results in pregnant mice support the recommendations by the Food and Drug Administration that warn against the use of medically nonindicated or commercial prenatal ultrasound videos (44).…”

“…Cortical neurons acquire appropriate positions by migration from the site of their origin in the proliferative zones lining the cerebral ventricle, according to a precise schedule (2,3) and along well defined pathways (4)(5)(6). When the rate of neuronal migration and the sequence of arrival are altered because of genetic and͞or environmental factors, various consequences, including abnormal behavior, have been observed (7)(8)(9)(10)(11)(12)(13). In terms of orientation and directionality of movement, neuronal migration to the cerebral cortex can be classified into radial (proceeding radially from the ventricular to the pial surface) (5,14) and tangential (running parallel to the brain surface) (15)(16)(17).…”

“…Neuronal migration involves translocation of the nucleus and the surrounding cytoplasm with the leading process, which requires rearrangement of the cytoskeleton (20,21). As a consequence of these complex cellular and molecular interactions, the process of neuronal migration is highly sensitive to a variety of biological, physical, and chemical agents, as well as to specific genetic mutations (7)(8)(9)(10)(11)(12)(13). For example, repeated exposure of the rodent and primate fetal brain to environmental agents, such as alcohol (9), drugs (22), neurotrophic viruses (23), and ionizing irradiation (24,25), causes misplacement of neurons and behavioral deficits.…”

Correlation of EEG, neuroimaging and histopathology in an epilepsy patient with diffuse cortical dysplasia

“…Clinical features of them were also different between the patients. Some classifications of cortical dysplasia were proposed as based on the findings of neuroimaging and/or histological characteristics [1,2,3,6,11,16]. However, it may be difficult to classify into one of subtypes in these patients.…”

“…However, it may be difficult to classify into one of subtypes in these patients. Etiologically, it has been known that cortical dysplasia is caused by disorder of neuronal proliferation and/or migration [3,4,6,10,14,15,17], whereas polymicrogyria can occur from cortical damage such as cerebral ischemia in early postnatal period [16]. As microdysgenesis, which is identified only as microscopically abnormal structures of cortex, can not find in MR images, it seems to be better that cortical dysplasia is classified histopathologically.…”