Seconding this and disagreeing with others here. There's a lot of caveats to a double major and the risk is absolutely not worth the reward unless you are very very sure of yourself (I was).
I was a double major double minor with one of my majors being Computer Science. My ability to do that and graduate with a 4.0 was brought up at almost every single one of my interviews, even by the Dean of Admissions at Harvard. I was frequently asked how I balanced all of that work with great ECs. Not to mention, computer science skill is rather rare/unique in medicine, so having that major undoubtedly enhanced my application.
In your case, I don't think a double major would be worth it even if you are sure of yourself, as biology and neuroscience are very close fields, and it's unlikely it would be of any noteworthy achievement. Not to mention biology and neuroscience are probably the two popular majors for pre-meds, so no diversity there either.
@NY_Premed What were your three majors? You can be more generic if you think it might be too identifying. My major isn't actually CS, just very closely related.