Hello!
I'm an M.S. student looking to apply for Ph.D. programs in neuroscience. A lot of the schools I'm looking into asks for 3 academic recs and I'm having a bit of a struggle trying to figure out who to ask for the letters. I heard that for rec letters I should get them from PIs or lab supervisors in the research you're involved in, but I was wondering if I can also ask professors that you've had as well. Also, I recently became a co-author for a research paper for a lab I was involved in college. Would the schools mind if I ask someone from undergrad for rec letters?