Anchoring your GRIN lens for hindbrain recordings

[Andrew Hardaway]

Greetings nerds, 

My lab has been working on an open source strategy to image neurons in the hindbrain. Anecdotal stories(and some published data) suggest that the hindbrain physically moves inside the skull which makes recording in freely behaving animals very difficult.  This is not easy, but we've been able to get some quality data from the nucleus of the solitary tract with stable fields of view using an "anchor disk" strategy combined with feeding small tungsten wires around the recording site. Schematized here:

Its still early days with this approach and the documentation associated with it, but I've decided to go ahead and put it out there to the community if anyone would like to try. We can potentially help iterate this together.

I'm attaching a few things to this message:

1) An stl file of the anchor disk to pair with a 500 uM diameter GRIN lens. Print at highest res with a resin printer and wash really well. Then use compressed air to make sure you open up the holes on the disks. This version has a sloped bottom to match the pitch of the occipital bone. If you want a flat version see below for CAD file.

2) Documentation that I've started on how to assemble the implant (substitute GRIN lens for optical fiber....same process)

3) A mounting jig to hold the lens and secure the anchor disk. You can put the disk on at different heights. The jig has slots for 0.5, 0.6, and 1 mm diameter lenses.

4)  A Holder you can print to grab the lip of the anchor disk during implantation. You just need an M1 screw and nut to pinch the holder together. Also, depending on the print, it's tight enough to where it will loosely hold and release enough for you to implant.

Finally, I created a public version of the cad files at Tinkercad which anyone can access 

here. It is public so I recommend you create a copy if you need to modify anything. I have a private version in case it gets messed up. This is an early release so I anticipate there will be questions or omissions of key use points. Feel free to email at andrewh...@uabmc.edu or reply here and I will do my best to answer. Thanks to Daniel and the UCLA miniscope team on creating this awesome community. Happy to pay it back a little for those brave souls who want to image in the hindbrain.

best,

Andrew

[Andrew Hardaway]

Sorry I had to break this up into two messages. Documentation attached here.