Guidance of Thalamocortical Innervation

  1. Gregory R. Bock Organizer and
  2. Gail Cardew
  1. Zoltán Molnár Bursar and
  2. Colin Blakemore

Published Online: 28 SEP 2007

DOI: 10.1002/9780470514795.ch7

Ciba Foundation Symposium 193 - Development of the Cerebral Cortex

Ciba Foundation Symposium 193 - Development of the Cerebral Cortex

How to Cite

Molnár, Z. and Blakemore, C. (2007) Guidance of Thalamocortical Innervation, in Ciba Foundation Symposium 193 - Development of the Cerebral Cortex (eds G. R. Bock and G. Cardew), John Wiley & Sons, Ltd., Chichester, UK. doi: 10.1002/9780470514795.ch7

Author Information

  1. Department of Physiology, University of Oxford, South Parks Road, Oxford OX1 3PT, UK

Publication History

  1. Published Online: 28 SEP 2007

ISBN Information

Print ISBN: 9780471957058

Online ISBN: 9780470514795

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Keywords:

  • thalamocortical innervation;
  • termination;
  • reeler mutant mouse;
  • temporal sequences;
  • chemospecificity

Summary

We propose that a sequence of individually simple mechanisms influences the pattern of thalamocortical innervation, which itself contributes to the determination of regional differentiation of the neocortex. In co-culture, the cortex appears to exert a remote growth-promoting influence on thalamic axons from E15, becomes growth-permissive to axon invasion at about E20 and expresses a stop signal, causing termination in layer IV, from P2–3. This cascade of cortical signals may determine the timing of events in vivo. However, any part of the thalamus will innervate any region of the developing cortex in culture, without obvious preference, suggesting that the topographic distribution of thalamic fibres in vivo does not depend on regional chemospecificity. The initial extension of axons from the cortical preplate and the thalamus starts at about E14, and the topography of both may be influenced by their temporal sequences of outgrowth (chronotopy). The axon arrays meet in the basal telencephalon, after which the preplate scaffold may guide thalamic axons and ensure both their ‘capture’ within the subplate layer and theestablishment of the waiting period. The unusual pattern of innervation in the Reeler mutant mouse supports the hypothesis that thalamic axons grow over preplate fibres to find the waiting compartment.