Headstage commutator requirements

[glopesdev]

The goal of this issue is to track design requirements for the headstage commutator, assuming we will need one for the dense neuropixel recordings. One possibility would be to use the VR movement sensor in Bonsai (optical flow or otherwise) to drive the ONIX coaxial commutator. The advantage would be to separate the commutation of neural data transmission and simplify the design of the remaining signals coming off the headstage. Another advantage could be to have independent points of failure that would allow e.g. recordings to keep going even in the failure of camera and other signals (or vice-versa).

[glopesdev]

@ederancz any thoughts on the above? We were wondering you might already have one of these ONIX coaxial commutators and they seem to integrate seamlessly with Bonsai judging from their docs: https://open-ephys.github.io/onix-docs/Software%20Guide/Bonsai%20Examples/Commutator.html

[ederancz]

@glopesdev you are suggesting separating the platform signals (optical sensors, pupil cameras, reward delivery, whatnot) from the neuropixels/ONIX signal? I see some advantages, but I still think it would be ideal to have everything through a single slipring. One disadvantage I see is the requirement to physically mount the commutator above the animal. I don't have the ONIX one delivered yet (should arrive fairly soon though).

In general, as there are many moving parts as you pointed out before, it would be very beneficial to have a high-level design document. That would allow us to only make concessions which need to be made and keep an eye on the overall goal.

[glopesdev]

@ederancz just to clarify, even in the case of a single slipring from below for all signals coming out of the platform, you would still want to use the ONIX commutator when using the ONIX system, right? (i.e. when running just behavior or imaging we wouldn't depend on the ONIX commutator, but when doing ephys recordings with ONIX you wouldn't need to go through the custom new commutator).

EDIT: the reason we are hesitant to go for this as a first choice is we know that their commutator was made specifically for their system as a custom design, and there might be specific requirements we are not familiar with yet which might make it hard to condense everything in a single commutator, but as you were also mentioning we will be putting all of these requirements in a design document soon.

[ederancz]

@glopesdev, I’m a bit confused, sorry. Originally I though to replace the ONIX commutator with the new slipring (so that it carries all signals from the platform) and will use it in all experiments (practically making the ONIX commutator surplus). To me the bottleneck seems to be the existence of the required slipring.

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On 18 Jul 2022, at 18:31, glopesdev @.***> wrote:

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[ederancz]

No available RF commutator compatible with all the other requirements (through-hole, USBs, power lines) exists.