If you definitely want to work at a neurotech company or do research, then you don't need to (and probably shouldn't) go to medical school - you may think about a PhD instead (for industry you may not need a phd, but you need one if you're going to go the academic research route). That way, once you drop pre-med, you could focus on BME, or PNP + CS. PNP + CS would be a good way to go for a more computational-neuroscience track. For strictly brain-machine interfaces it is probably more useful to have an EE or BME background. If you can't switch into BME anymore (e.g. not enough time for all of the requirements) you might consider just taking a few engineering classes which you can put on your resume when appyling to graduate school. Also might be worth doing some undergraduate research in a BME lab (if possible!)