Roger's passing 10y ago was a loss not just for science but for society at large. Some of what plagues some fields today (the constant overselling and jockeying for attention) would likely be curtailed with just a few frank comments from him.

Roger, you are very much missed.

What fewer people knew about, however, was Roger's kindness and integrity. He never claimed more than he deserved, letting the science speak for itself, and giving credit wherever due. He'd give an honest opinion when asked, whether positive or negative, something I really valued.

Roger's contribution to GFP wasn't its discovery or its first demonstration outside jellyfish, but in understanding its chemistry, and then using that to engineer BFP, CFP, YFP, and a series of indicators, including the first FRET and single-FP calcium indicators.

Roger arguably deserved his own Nobel Prize earlier, for the invention of fluorescent calcium dyes such as Fura-2 (beginning as PhD student self-taught in organic synthesis), which are widely used as indicators of neuronal firing, myocyte contraction, and GPCR activation.

Roger was an interdisciplinary chemical biologist long before those terms existed. His BA was in chemistry & physics, and his PhD in physiology. He combined the deepest understanding of chemistry (since high school, below) with curiosity for the hardest biological questions.

Thanks too to @spencerlaveresmith.bsky.social, @michaelgoard.bsky.social, @andyalexander.bsky.social, Sung-Soo Kim, Mathieu Louis, and MCDB students for thought-provoking discussions. It's inspiring to see so many people advancing the frontiers of neuroscience with sharp ideas and smart execution.

That's exactly right, but if you want ms temporal resolution, well then you have to image at near kHz speeds

Which then means the quality of the optics and camera are more important now.

Oh not your review, which was really great (and thanks for citing us).

True at slower speeds GECIs have higher SNRs. The problem becomes when people assume SNR differences in the cell are proportional to molecular performance. It may be okay within a design (eg GCaMP3 vs 6) but not between designs.

It depends on how much you are willing to overexpress the GCaMP. Brinks and Cohen estimated the abundance difference as 100x. We find we can overexpress GCaMP to get 100x more per cell body, but then get into the realm of lower dF/F.

www.sciencedirect.com/science/arti...

In fact, I should point out that we recently worked with Promega to improve bioluminescent imaging in the brain further. We identified cephalofurimazine-9 (CFz9), a modification of the original CFz, as a substrate with higher sustainable brightness in the brain.
www.nature.com/articles/s41...

Our hope is to speed up biological and therapeutic discovery for all researchers by visualizing a wide variety of cells, pathogens, pathways etc, all noninvasively and using simple inexpensive equipment. So far the results are looking good!

The visit (at Promega that is) was especially illuminating and motivating. It was great to learn that the in vivo NanoLuc substrates we identified together with the Promega chemists are really catching on in the biomedical research community, especially for tumor and immune cell detection.

It's like saying fewer people have worked on engineering airplanes than cars, so there are fewer pilots than drivers — each part might be true, but the former didn't cause the latter. Rather it's an inherently harder problem where both engineering and usage require specialized and expensive methods.

In sum, the belief that GEVIs haven't been engineered as much as GECIs and thus voltage imaging is less commonly performed than calcium imaging links two true statements as cause-effect when they are more related as effect-effect: both are effects of the difficulty of working with voltage.

Eventually this will get cleared up, maybe after we get a chance to present our comparisons between GECIs and GEVIs at different rates. For now though just a reminder that simple explanations are not always 100% correct.

So it's no longer the case that GEVIs are lagging behind in molecular performance because of insufficient engineering. Rather GEVIs have a higher performance bar to clear and will always need better equipment. Still, GEVIs are already better for AP tracking if you can image fast.