I did give a tour today to half of the interviewees, and one of them did mention that he was asked about the downregulation of NMDA receptors. Ouch.
For those who are apprehensive about upcoming interviews, I can assure you that most of the interviews here are NOT like that. I actually found it slightly humorous that it was the chair of the OMM department who asked the interviewee the above question. As others have said, questions like these are just posed to ruffle your feathers and see how you respond to being put on the spot/high pressure. Better to say "I don't know" than to fumble around for something you may end up regretting. I know the interview day is stressful enough as it is, but being prepped for these curveballs will make it a little easier on you.
So yes, there is a mix of stressful interviews and laid-back interviews- it's all luck of the draw, but be prepared for anything and everything. Be confident, be honest, and be enthusiastic, and you'll be fine. Remember, they've made it clear that they want you, and that interview is your one opportunity to sell yourself to them.
Good luck to all future interviewees, see you soon...