It's about both, actually. The experimenters added or modified a 'pain vector' in the model, and that's how they're 'making it suffer' .

Whether that's 'real suffering' or merely a convincing simulation is a job for the philosophers.

(I do have my own opinion, mind, and it's not what you might expect O:-) But the Overton window isn't there. A lot of people don't realize these vectors exist at all yet.)

Edit: On rereading, it might seem like I'm dodging the question. I'm really just trying to stick to my core points: A) the vectors exist B) they have a causal role in behavior, irrespective of the moral patienthood question.