Last year, we published our study “Principles of connectivity among morphologically defined cell types in adult neocortex” in Science. The paper generated quite a bit of attention – and now a technical comment, which was recently published in Science. In their comment, Barth et al. criticize our study as (i) overstating the completeness of our study; (ii) reporting a potentially biased connectivity matrix due to technical limitations of our brain-slicing and multipatching methods; and (iii) simply renaming previously identified interneuron types.
Details of our reply to their criticism can be found in the published version. In particular, we addressed their point about potential biases in the connectivity matrix due to slice cutting quantitatively. Assuming that the neuron are approximately rotationally symmetric, we computed the amount of overlap of their dendritic and axonal fields potentially cut away by the slicing (because this is were connections between the two can happen). A similar method had been used before by Levy and Reyes. The analysis clearly shows that the correction factor that needs to be applied does not strongly depend on the cell type pair, suggesting that the connectivity matrix may need to be scaled, but is unlikely to be distorted.
In the course of preparing the reply, we also submitted all fully reconstructed neurons from that study (n=298) to neuromorpho.org, where they will be available shortly.