Clonal relationships impact neuronal tuning within a phylogenetically ancient vertebrate brain structure.
Bottom Line: To address this question, we examined the influence of lineage on the response properties of neurons within the optic tectum, a visual brain area found in all vertebrates.If lineage relationships do not influence the functional properties of tectal neurons, one prediction is that the RF positions of sister neurons should be no more (or less) similar to one another than those of neighboring control neurons.Our data reveal that the RF centers of sister neurons are significantly more similar than would be expected by chance.
Affiliation: Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.Show MeSH
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Mentions: To examine whether lineage-based rules contribute to functional circuit organization in the optic tectum, we developed a method for labeling a single neuronal clone per animal, which enabled us to definitively identify sister tectal neurons. All animal procedures were conducted in accordance with UK Home Office regulations. Individual tectal progenitor cells in the proliferative zone  of stage 44–47 Xenopus laevis tadpoles (7–16 days postfertilization) were targeted for single-cell electroporation with a dextran-conjugated red fluorescent dye (Figure 1A; Supplemental Experimental Procedures available online) . This dye does not leak out of cells and is only passed on to daughter cells [10, 11]. To ensure that a single neuronal clone was labeled, we conducted in vivo two-photon imaging at different time points. The first imaging was conducted 1–3 hr after electroporation to be certain that only one progenitor had taken up the dextran (Figure 1B). From a total of 438 animals in which we confirmed that a single progenitor cell was labeled, 103 contained two or more labeled sister neurons when the animal was reimaged 6–19 days later at stage 49 or 50 (Figure 1C).
Affiliation: Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.