MICROSCOPY Vol.47▶No.3 2012

Live Imaging of Migration and Maturation of Corical Interneurons

Fujio Murakami

Abstract: Cerebral cortex in mammals is composed of excitatory projection neurons and inhibitory interneurons.  Due to their remarkable diversity, interneurons are thought to play important roles in emergence of higher brain functions. Thus, it is important to know how each interneuron subtypes is sorted into correct positions within the cerebral cortex. We addressed this issue by live imaging of interneurons utilizing glutamate decarboxylase (GAD) 67-GFP (green fluorescent protein) mice, in which GFP is specifically expressed by inhibitory interneurons, and in utero electroporation of appropriate constructs to the site of interneuron generation. We found that interneurons generated in the medial ganglionic eminence of the basal forebrain tangentially migrate to the cortex by way of the intermediate zone and the subventricular zones. These neurons then translocate to the marginal zone near the cortical surface, where they execute multidirectional tangential migration lasting for a few days.  Disruption of tangential migration of interneurons in the MZ altered the final distribution of interneurons subtypes, suggesting that this mode of migration play important roles for correct sorting of interneurons subtypes into appropriate regions within the cortex.

Key words: neocortex, neuronal migration, in utero electroporation, GFP