Thalamus (non primate)
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GraySubject = | GrayPage = | Image = ThalamicNuclei.png | Caption = Thalamic nuclei:
MNG = Midline nuclear group
AN = Anterior nuclear group
MD = Medial dorsal nucleus
VNG = Ventral nuclear group
VA = Ventral anterior nucleus
VL = Ventral lateral nucleus
VPL = Ventral posterolateral nucleus
VPM = Ventral posteromedial nucleus
LNG = Lateral nuclear group
PUL = Pulvinar
MTh = Metathalamus
LG = Lateral geniculate nucleus
MG = Medial geniculate nucleus
| Image2 = |
Development
The mid-diencephalic territory is composed of the prethalamus (previously also known as ventral thalamus), the zona limitans intrathalamica (ZLI) and the thalamus (dorsal thalamus; Kuhlenbeck, 1930; Shimamura et al., 1995). From a comparative perspective the electrophysiology of thalamic neuron has been concerved over vertebrate evolution, as has been their relation to wakefullness and sleep (Llinas and Steriade 2006). Morphologically, the ZLI is a transverse boundary located between the prethalamus and the functional distinct thalamus. Besides its morphological characteristics, it bears the hallmarks of a signalling centre. Fate mapping experiments in chick have shown that the ZLI is cell lineage restricted at its boundaries and therefore can be termed a true developmental compartment in the forebrain (Zeltser et al., 2001). Besides morphological characteristics, the ZLI is the only structure in the alar plate of the neural tube that expresses signaling molecule Sonic-hedgehog (Shh; Figdor and Stern, 1993; Puelles and Rubenstein, 1993). In mouse, the function of Shh signaling at the ZLI has not been addressed directly due to a complete absence of the diencephalon in Shh mutants (Ishibashi and McMahon, 2000). Studies in chick have shown that Shh is both necessary and sufficient for thalamic gene induction in vitro Hashimoto-Torri et al., (2003), whereas Kiecker and Lumsden, (2004) have shown that Shh signaling from the ZLI is required for both prethalamic expression of Dlx2 and thalamic expression of Gbx2 and Sox14 in vivo. In zebrafish, the structure corresponding to the Hh expression has been termed as mid-diencephalic boundary (MDB; Macdonald et al., 1994, Scholpp et al., 2006) but subsequently referred to as ZLI (Barth and Wilson; 1995), in keeping with pre-existing terminology for other vertebrates. In zebrafish, it was shown that the expression of two shh genes, shh-a and shh-b (formerly described as twhh) mark the ZLI territory, and that ZLI development is accompanied by expression anteriorly of dlx2, a marker of the prethalamus, and posteriorly of dbx1a, a marker of the thalamus (Scholpp et al., 2006). Shh signaling is sufficient for the molecular differentiation of both the prethalamus and the thalamus but is not required for their maintenance and Shh signaling from the ZLI/alar plate is sufficient for the maturation of prethalamic and thalamic territory while ventral Shh signals are dispensable.
- a Kuhlenbeck, H. (1937). The ontogenetic development of diencephalic centres in the bird's brain (chick) and comparison with the reptilian and mammalian diencephalon. J. Comp. Neurol. 66
- a Llinas R and Steriade M. (2006). Bursting of thalamic neurons and states of vigilance. J. Neurophysiol 95:3297-3308.
- a Shimamura, K., Hartigan, D. J., Martinez, S., Puelles, L. and Rubenstein, J. L. (1995). Longitudinal organization of the anterior neural plate and neural tube. Development 121,3923 -3933.
- a Zeltser, L. M., Larsen, C. W. and Lumsden, A. (2001). A new developmental compartment in the forebrain regulated by Lunatic fringe. Nat. Neurosci. 4, 683-684.
- a Puelles, L. and Rubenstein, J. L. (2003). Forebrain gene expression domains and the evolving prosomeric model. Trends Neurosci. 26,469 -476.
- a Ishibashi, M. and McMahon, A. P. (2002). A sonic hedgehog-dependent signalling relay regulates growth of diencephalic and mesencephalic primordia in the early mouse embryo. Development 129,4807 -4819.
- a Kiecker, C. and Lumsden, A. (2004). Hedgehog signalling from the ZLI regulates diencephalic regional identity. Nat. Neurosci. 7,1242 -1249.
- a Scholpp S, Wolf O, Brand M, Lumsden A. Hedgehog signalling from the zona limitans intrathalamica orchestrates patterning of the zebrafish diencephalon'. Development. 2006 Mar;133(5):855-64[2]
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
