Preprint reviews by Stephen D Van Hooser

Lateral geniculate neurons show robust ocular dominance plasticity

Juliane Jaepel, Mark Huebener, Tobias Bonhoeffer, Tobias Rose

Review posted on 11th January 2017

Suggestion: plot Fig 2f on a log-log-scale, or somehow allow us to see the more numerous points in the middle of the graph.

Question: what are the typical "error bars" around the points in Fig. 2f. For example, if you calculated these responses by bootstrapping across trials, would the error bars be tight or large? That is, I am asking, are the points that greatly deviate from 0 on the Y axis "real", or are those values derived from noise? How many neurons exhibit an amplitude change that is significant, by such a "within bouton" analysis? (Right now I'm looking at Fig 2F, wondering if I believe that the changes from 0 on the y axis are "real".)

Question: how certain can you be that the signal reflects individual boutons and is not occasionally contaminated by nearby boutons. If this situation occurred, it could produce the data that is observed as an artifact, without an actual "conversion" of an LGN cell.

Question: is it certain the calcium activity in the bouton reflects only the presynaptic signals? If you patched a cortical neuron and fired it, is truly no signal observed in the presynaptic boutons? (One might imagine responses derived via presynaptic NMDA receptors, etc.)

Juliane, Mark, and Tobiases: Interesting work! I am new to this, and I hope my "single issue posting" of questions and suggestions is acceptable. Best wishes, Steve

Suggestion: Put data in Fig 2F on a log-log scale, so we can see the more numerous points near the origin?

Question: what are the "error bars" around the individual points in Fig. 2F. For example, if one used bootstrap (across trials) to create a distribution of the likely change in response to contra or ipsi eye for each cell, we could see if the values were noisy or robust. Right now, as I look at Fig. 2F, I can't decide whether the points that deviate from 0 on the Y axis are "real" or just "noisy". Similarly, if you did the bootstrap, how many cells exhibit "significant" deviations from 0 on the Y axis, vs. those that exhibit significant deviations from 0 on the X axis?

Question: is it possible that there is contamination of the signal from nearby boutons, that would give the appearance of binocular changes when really they are monocular?

Question: is it for certain that the bouton responses are purely presynaptic? One might imagine that there could be presynaptic NMDA receptors that might show responses that are actually derived from activity in the post-synaptic cell. A control: patching a nearby cortical cell, and demonstrating that nearby boutons do not exhibit responses when the cortical cell is activated at similar firing rates as it is during in vivo visual stimulation.

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