Implant Wiring - BrendonWatsonLab/Digital-Homecage GitHub Wiki

Implant Wiring

Using 15 tetrodes, 4 accessory wires, 1 64 channel EIB board, and 1 head cap, you can wire a full implant

How to make an accessory wire
- Cut 4 cm of Phoenix red wire (31 AWG)
- Strip ⅛ cm from one end and ½ cm from the other
- Add small amount of solder on the stripped ends for rigidity
- Bend the longer end into a loop and solder the connection
Solder wires to underside of board (side without the black connector) such that the wire points down out from the board
- Solder a wire to the R and G board positions, and marked in the diagram
- Solder a wire to the A and D positions of channel 13
- Ensure that you mark/differentiate the wires in some way such that when you are surgerizing the animal, you can determine which is which

Each of the 4 ends of the split side of the tetrode must be wired into the same channel
Thread each end into the hole, inserting the wire as deep as possible such that you are minimizing the length above the insertion that the tetrode is split
After the 4 ends are threaded, pin each connection with a gold pin, gently pressing down on the top to make sure it is secure
- If you press too hard, or slip when pressing down, you run the risk of breaking a tetrode and losing a connection
Continue this process along all 15 channels until wiring process is complete
Notes:
- Eventually, you must use the green overcoat pen to insulate each tetrode connection to the EIB. This process is most easily done in parts (a few tetrodes at a time) because it will be easier to access the board and properly coat the connections when there are less tetrodes in the way
- If you are using a bilateral headcap, then you must separate the tetrodes for channels 5-12 from channels 1-4 and 13-16. For a standard Watson Lab Bilateral Implant, channels 5-12 will end up on the left side of the mouse/implant, and the other channels will end up on the right. You can determine right and left once you properly orient the headcap, which should have the accessory wire output facing towards you, where right and left and from your perspective

Begin by ensuring that the tetrodes and accessory wires are in the correct outgoing positions
- All accessory wires should exit the headcap through the accessory output hole
- For a bilateral implant, ensure that all tetrodes are exiting through the proper exit tunnel. This is crucial
With the underside of the EIB facing upwards, slowly lower the headcap onto the EIB
- Ensure that tetrodes aren’t getting scrunched inside the implant as you lower; don’t pull too firmly on each tetrode, but you will likely have to raise and lower the headcap in stages to make sure of there is no scrunching
Once the headcap is fully in place (the EIB board should sit nicely in the cap, with the rim of the cap spaced equally around the outer edge of the EIB Board) you can start fixing the EIB and headcap together
- Apply and cure a small layer of Diafil (UV cure composite) to the circumference around the edge of the EIB and inside edge of the implant
- Once that is cured and the EIB/headcap assembly is stable, carefully trim the protruding tetrode ends close to the base
- Apply and cure a small layer of Diafil to each pin connection, making sure that the composite isn’t too thick and won’t inhibit the the Hirose Low Profile Headstage from connecting with the EIB
- Once the last layer of Diafil is cured, trim any remaining protruding tetrode ends
Double check that the headstage connects with the assembled headcap

Extruding tetrode bundles must be glued to keep rigid
- Use a small amount of acetone or saliva (lick your finger) to bundle the extruding tetrode ends together carefully
- Drip a small amount of Krazy Glue from the top of the tetrode, letting it drip down the tetrode, drying as it goes
- If bubbles or clumps appear to form, use a small toothpick or piece of wire to break them and let the glue continue dripping
Cut dried tetrode bundles to appropriate length for the region you're recording