Development

Bounded Excitement

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Science  18 Dec 2009:
Vol. 326, Issue 5960, pp. 1590
DOI: 10.1126/science.326.5960.1590-c

Glutamatergic neurons (red) in the caudal thalamus.

CREDIT: SCHOLPP ET AL., PROC. NATL. ACAD. SCI. U.S.A. 106, 19895 (2009)

Brain development is characterized by shifting patterns of gene expression and by gradients of cell differentiation. Scholpp et al. have analyzed the zebrafish thalamus to understand how one such gradient defines neuronal phenotype. Proteins of the Hes/Her family repress transcription of their target genes, which in some cases keeps a neural progenitor cell in its precursor state. Initially, her6 is expressed throughout the developing thalamic region. Cells in the rostral thalamus, which maintain her6 expression longer, normally develop into inhibitory GABAergic neurons, whereas cells in the caudal thalamus, from which her6 expression recedes earlier, begin to express neurog1 and develop into excitatory glutamatergic neurons. Overly persistent expression of her6 in the caudal thalamus suppresses neurog1 and induces those cells to develop into GABAergic neurons. Thus, the shifting pattern of her6 expression defines separate identities for these two thalamic regions.

Proc. Natl. Acad. Sci. U.S.A.106, 19895 (2009).

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