Ah man, what a pity. That VR rig is awesome, but it doesn't really seem to me they are planning to continue these experiments, or do they?
Even if you're sort of like an alien abducting them for experiments.... if you offered me a sugar drip to play doom in VR, I'd be there
I know rats aren't long-lived, but I would be interested to know how they determined the rats 'aged out'.
Could also be a complete failure they spent considerable effort in with zero results, and are hand waving and constructing a way to quit while claiming success.
I could see the rats not really connecting things and just puttering around. It's a pretty involved setup and I poor uptake on the part of the rats would be a steep disappointment.