usually the popup would read “Patient Preop” and “Patient Postop” if available.
I guess since you’re using a dataset with no postop-data, could be that Lead-DBS currently is buggy and doesn’t show the option to visualize the preop data at all.
Bigbrain is a histological dataset by the group of Katrin Amunts.
I don’t know any freely available datasets with postop data. I wish these were available, but I fear they aren’t.
Maybe Lead-DBS isn’t the optimal tool for what you are doing?