most successful surgery timeline and light entry during recordings

[Michael Graupner]

Hello,

We have run our first batch of animals with the miniscope (V4)  and saw some cells in only a few of them. There is much to improve in our procedure. For two aspects regarding surgery timeline and light entry during recordings, I would appreciate your input very much.

1. For half of the animals we performed virus injections and relay lens implantation during the same surgery and for the other half, the two surgeries were separated by two weeks. We noticed that both approaches are mentioned in various documentations. In your experience, which of the approaches led most reliably to good GCaMP expression and imaging quality?

2. We have the impression that light enters into the space between the minscope and the relay lens, which is surrounded by dental cement and topped with the baseplate. For an example, see this movie between time-points 00:01.5 and 00:02.0. This seems to happen in particular when the mouse lowers its head for grooming. Do you have an idea where the light might enter and how we can prevent  this from happening?

Thanks very much in advance.

Best regards,
Michael Graupner

[Daniel Aharoni]

Hi!

1. For half of the animals we performed virus injections and relay lens implantation during the same surgery and for the other half, the two surgeries were separated by two weeks. We noticed that both approaches are mentioned in various documentations. In your experience, which of the approaches led most reliably to good GCaMP expression and imaging quality?

• Generally, either approach should work pretty well. I know some people will always space out injection and GRIN lens surgery when needing to aspirate for the GRIN lens implant. If planning on doing injections and implants for a batch of animals, it is often easier/quicker to do all injections in one sitting and then come back to do all the surgeries.

2. We have the impression that light enters into the space between the minscope and the relay lens, which is surrounded by dental cement and topped with the baseplate. For an example, see this movie between time-points 00:01.5 and 00:02.0. This seems to happen in particular when the mouse lowers its head for grooming. Do you have an idea where the light might enter and how we can prevent  this from happening?

• Some people use black dental cement and others will paint the outside of the cement with black paint or nail polish.