Molecular Mechanisms of Thalamocortical Axon Targeting

  1. Gregory Bock Organizer and
  2. Jamie Goode
  1. Nobuhiko Yamamoto,
  2. Takuro Maruyama,
  3. Naofumi Uesaka,
  4. Yasufumi Hayano,
  5. Makoto Takemoto and
  6. Akito Yamada

Published Online: 1 FEB 2008

DOI: 10.1002/9780470994030.ch14

Cortical Development: Genes and Genetic Abnormalities: Novartis Foundation Symposium 288

Cortical Development: Genes and Genetic Abnormalities: Novartis Foundation Symposium 288

How to Cite

Yamamoto, N., Maruyama, T., Uesaka, N., Hayano, Y., Takemoto, M. and Yamada, A. (2008) Molecular Mechanisms of Thalamocortical Axon Targeting, in Cortical Development: Genes and Genetic Abnormalities: Novartis Foundation Symposium 288 (eds G. Bock and J. Goode), John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9780470994030.ch14

Author Information

  1. Neuroscience Laboratories, Graduate School of Frontier Biosciences, Osaka University, Yamadaoka 1-3, Suita, Osaka 565-0871, Japan

Publication History

  1. Published Online: 1 FEB 2008
  2. Published Print: 11 JAN 2008

Book Series:

  1. Novartis Foundation Symposia

Book Series Editors:

  1. Novartis Foundation

ISBN Information

Print ISBN: 9780470060926

Online ISBN: 9780470994030

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Keywords:

  • extracellular and cell surface molecules role;
  • thalamic and cortical cells;
  • lamina-specific cortical connectivity;
  • time-lapse imaging, electrophysiological analysis and pharmacological manipulations;
  • homophilic binding protein;
  • sensory thalamic regions;
  • PCR-based amplification and fragmentation;
  • Stem cell factor (Scf);
  • axon growth promoting activity;
  • laminin-coated region

Summary

The thalamocortical (TC) projection in the mammalian brain is a well characterized system in terms of laminar specificity of neocortical circuits. To understand the mechanisms that underlie lamina-specific TC axon targeting, we studied the role of extracellular and cell surface molecules that are expressed in the upper layers of the developing cortex in in vitro culture techniques. The results demonstrated that multiple upper layer molecules co-operated to produce stop behaviour of TC axons in the target layer. Activity dependency of TC axon branching was also investigated in organotypic co-cultures of the thalamus and cortex. TC axon branches were formed dynamically by addition and elimination during the second week in vitro, when spontaneous firing increased in thalamic and cortical cells. Pharmacological blockade of firing or synaptic activity reduced the remodelling process, in particular branch addition, in the target layer. Together, these findings suggest that TC axon targeting mechanisms involve the regulation with multiple lamina-specific molecules and modification of the molecular mechanisms via neural activity.