We're implanting electrodes in cortex, with a ground screw centered over the cerebellum. The protocol we inherited says to check the resistance of the ground screw, to ensure it's properly positioned. It says the resistance should be 300 kOhms from the ground screw to the tail, but we can't find any evidence for this in the literature. Do others do this check, and if so, what are your measurements?
It's certainly the case that a high resistance ground will cause noisy recordings. However, I suspect that doing that measurement (ground pin to tail) would be a pretty silly way to measure your "ground resistance", as nearly all of that resistance is due to the resistance of the skin, and would be far more sensitive to "is the tail a little wet/what is the ambient humidity" than "is my ground good".
That said, if you get 1 resistance of >1 Meg, then you're ground is probably bad. That is to say, that measurement will tell you if your ground isn't working, but it wont tell you if it is average, good or great.
I'm confident there is lots of literature showing the importances of low ground resistance, not that I can find any with a trivial search (the Axon Guide talks about the importance of having a low resistance ground, but not in terms of noise).
300 kOhms to ground screw(s) is ok. If you use a thicker wire you should get a lower impedance, reducing noise level
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