Electrode depth tracking during recording
The screws have a pitch of 250 micron/turn, however, the spring mechanism introduces a small >1 scaling factor to the actual travel, if you depend on ~10micron precision over long travel ranges, simply measure the actual tetrode depth during plating after a known number of turns relative to 0.
For the new shuttle drive see the paper for a travel distance estimate.
initial calibration:
During the implant, i usually keep the 2 corner tetrodes out by ~250um - i can then use pictures of these taken during insertion to register my guide tube array to pictures taken after the craniotomy in which i have scale bars - this way i know exactly where the drive went.
I lower the other trodes as soon as i can after the implant, we've waited as much a 4-5 days, but i think earlier is generally better, in semi-acute preps the dura/bone seems to grow back pretty fast.
If the surgery went well and the mouse is nesting the next day ill put the mouse in a head-post on a floating ball to avoid putting any torque on the implant and start lowering.
post implant calibration for brain swelling etc.:
Lower one or max. 2 trodes (if they're at opposite ends of the array) at a time to avoid bunching and waited >3hrs between lowering sessions to allow the brain to settle.
Lower one or max. 2 trodes (if they're at opposite ends of the array) at a time to avoid bunching and waited >3hrs between lowering sessions to allow the brain to settle.
Try to record data during these lowering sessions and actually look at it in simpleclust (or whatever spike sorting method you like) to check if i get units - L1 MUA can look surprisingly like units unless you look closely and sorting is the best way to know for sure when any given trode is in rather than just on the brain.