I cannot fathom this leap

Okay, so here is my situation. I am an undergrad student attempting to complete my bachelors in computer engineering. Eventually, I want to have a job doing research into something with computational neuroscience. My dream job is a researcher for mental illness and learn about the brain through computational models and mathematics. My question is how do I get there?
Do I get a masters in CS and try to get a Ph D in Neuroscience? Do I try to just jump into a ph D? Does a masters in bioinformatics suffice? Also, how, in general, can I get a job as a pure academic researcher? I feel I cannot get into a good ph D program straight from undergrad because my GPA is a 2.6 and I have had to withdraw from university for extreme circumstances, but plan to get back to school this fall and do much better. Advice on how I can get from where I am to where I want to be?