Bright waves in hippocampus calcium imaging

Huixin Lin

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Apr 26, 2022, 9:31:23 AM4/26/22

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Hello,

Has anyone ever seen such moving bright waves before while doing calcium imaging in mouse dCA1 region? I'd like to know the cause of these signals and how to avoid them.Thanks!

The GCaMP virus used was AAV2/9-hSyn-GCaMP6m-WPRE-pA (titer: 2.2E+12), and the video was taken 5 weeks after virus injection and lens implantation surgery using V4. And the 0.85mm-GRIN lens was purchased from Grintech.

CA1_gcamp6m.gif

Huixin Lin

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Apr 26, 2022, 10:41:35 PM4/26/22

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I used two-photon imaging to see more details but still have no clue... seems like virus issues?

CA1gcamp6m_2photon.gif

dsp

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Apr 27, 2022, 8:34:58 AM4/27/22

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Seems a bit epileptiform. The big waves that can come from spreading depression usually move slower, and activity "reset" is not as fast.

best, Darcy

On Tue, Apr 26, 2022, 22:41 Huixin Lin <huixin...@gmail.com> wrote:

I used two-photon imaging to see more details but still have no clue... seems like virus issues?

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Nat Kinsky

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Apr 27, 2022, 12:29:54 PM4/27/22

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I have seen these in the past in a subset of animals with AAV9-syn-GCaMP6f. Once they started, they generally grew in intensity and duration over the following days/weeks. The general consensus I got from talking to others was that they were pathological, but like yours they seemed to occur at much slower timescales than I've seen in the literature for waves generated in both epileptiform mice (https://www.nature.com/articles/s41598-018-19925-7) and non-epileptiform mice (https://www.eneuro.org/content/4/5/ENEURO.0207-17.2017, also transgenic in this paper).

We saw a lot more of these mice early on when we used higher titers of virus (1e13) and a lot less when we dialed it back to 2-5e12, so it could be viral related, but we never definitely figured out the root cause.

Nat

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