Experience with GCaMP8m or GCaMP7f

[Alfredo Elhazaz]

Hello all,

We have been using the v3 miniscopes with GCaMP6s for a while in our lab with good results, but would like to upgrade soon to a newer sensors. We image mouse orbitofrontal cortex (deep, we use a 0.6mm relay lens) at 15 Hz.

Specially interested of people's experience with GCaMP8m, since i've read some reports of signal being too bright and adding a lot of background fluorescence. Has anyone found a virus/titer that works for them?

We're also interested in 7f, for those that have successfully used it, which construct and at which dilution did you use it?

Thanks!

Alfredo

[Roman Doronin]

We tried gcamp8f with hSyn promoter, and it was indeed creating a lot of background fluorescence, not possible to see individual cells, what was working is gcamp6f with Ef1a promoter. At the end it is unclear how much to the problem did the version of GCaMP contributed and how much - promoter (hSyn seem to label L5 more intensely than Ef1a, and their extensive dendritic arbors could contribute a lot to the background fluorescence)