Virtual Reality Integration with Bpod

maristanye

Hi Josh,

I'm setting up a new head-fixed mouse experiment with a running wheel coupled to a rotary encoder, and I'd like to integrate a virtual reality corridor that updates based on the animal's movement. The rest of the behavior (reward, odors, LEDs, speakers) will be controlled by Bpod as usual.

My current plan is to use the Rotary Encoder Module v2, with the CAT5e connection to the state machine for threshold events (reward delivery etc.) and the USB connection to stream position data to a VR engine for rendering. I've been looking at ViRMEn (Tank Lab) since I work primarily in MATLAB, and my idea is to run two MATLAB instances — one for the Bpod protocol and one for ViRMEn — communicating via TCP/IP on localhost, as you suggested in a previous thread.

A few questions I'd appreciate your input on:

Do you have a recommendation for the most appropriate VR software to pair with Bpod? Is ViRMEn good option, or are there better alternatives?
Is running Bpod and the VR engine on the same PC a reasonable approach, or would you recommend a dedicated second PC for the VR? My setup will be a simple 1D linear corridor — nothing graphically demanding.
Any general tips or pitfalls to watch out for when integrating VR with Bpod? For instance, is there anything tricky about running the USB position stream and the CAT5e threshold events simultaneously?

Thanks for the support!
Eduardo Maristany

Josh

Thanks for writing in

Unfortunately I'm not up to date on the latest VR packages. ViRMEn is the one I've heard most about. I'm not sure what its specs are, but with a good multi-core processor I'd imagine the MATLAB processes for the two instances will be on separate cores, so there should not be much interference in theory.
The rotary encoder is where you may run into issues. If you're initializing it in the the ViRMEn, you could initialize the RotaryEncoderModule class and use it to set thresholds, but the data wouldn't automatically propagate to ViRMEn. You can set the userCallbackFcn property of a RotaryEncoderModule object to call other MATLAB functions each time new data arrives from the encoder, so that may be one path to integration - though you'd probably have more latency than if you used ViRMEn's internal interface.

If you're not restricted to MATLAB, BonVision is a good option.

TCP/IP on localhost shouldn't be much of an issue. Bpod_Gen2 includes TCPCom, a class that wraps PsychToolbox's Pnet interface and should do most of what you need. I haven't updated it to use MATLAB's newer tcpclient and tcpserver interfaces, but it's on my ToDo list. If you don't have PsychToolbox you may be able to identify the relevant functions and plug them in to TCPCom, or build your own code using these built-in classes.

Please let me know if you run into any issues setting this up, I'd be glad to assist!

Josh