There’s the AMGEN scholars program, which has research sites at many prestigious school. Harvard SROH and SHURP, UPenn SUIP, Cornell MBG-REU, etc. Especially since he’s a minority, I encourage him to look into those. He can apply throug the Leadership Alliance to 3 research sites with one application, Harvard and UPenn’s program are part of that, but there’s also many more! You can also apply to UPenn separately. In these, you get matched with a faculty mentor when admitted according to your research interests, so I assume it’ll be someone in Neuro.
I have been admitted to most of those and am currently getting a PhD, so feel free to ask any questions 
Ps: For a PhD program, no one really cares about your extracurriculars for admissions, they care about your ability to conduct good research. So, doing school and research alone would make him a very impressive “one trick pony” in the eyes of an adcom. Trying to impress by doing many different things at the same time is more useful for medical school.