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: We then used two-photon calcium imaging to assess the response properties of clonally related neurons. We mapped spatial receptive fields (RFs) by simultaneously recording visually evoked calcium responses in both dextran-labeled and nonlabeled tectal neurons in the same animals (Figures 3A–3C; Supplemental Experimental Procedures) [14–16]. For clones to be included in the analysis, labeled neurons were required to exhibit robust spatially localized RFs, as determined statistically by fitting each RF with a 2D Gaussian function (Figures 3D and 3E; Supplemental Experimental Procedures). Clones in which only one neuron satisfied these criteria had to be excluded because sister comparisons were not possible. Under these criteria, we obtained a subset of animals with significant spatially selective responses in multiple dextran-labeled sister neurons and in a large fraction of nonlabeled neighboring neurons (11 labeled neurons, 531 nonlabeled neurons, four animals). Importantly, there was no significant difference between labeled and nonlabeled neurons in terms of their response amplitudes, the quality (R2) of the RF fits, or the eccentricity of their RF centers (Figure 3F).
Affiliation: Department of Pharmacology, University of Oxford, Oxford OX1 3QT, UK.