Hi, You’ve asked a good question, which is great start for a scientist.
Your first step will be to choose between neuroscience or premed (or a double major) at a college with a solid undergraduate neuroscience program. Generally, you’d want to choose a college whose faculty have active research programs, and which offers a range of courses in neuroscience. Your interest in cell/molecular approaches will mean that you’ll benefit from biochemistry, cell biology and genetics. I’d also consider computational approaches, including bioinformatics, which will be a good skill to have in whichever career path you choose and would prepare you for an era of “precision medicine”.
Regarding your question about MD vs. PhD degrees (both are also possible in combined MD/PhD programs), MDs, as you point out, would would have direct patient contact, and when performing research would be able to identify and work with patients as part of research studies, most likely as part of a large academic medical center. PhDs can also work with human subjects, would usually work in basic science departments in academic medical centers, and in addition may work at arts and science university programs. Increasingly, team science approaches are emerging that encourage MDs and PhDs to work together on projects that impact human health.
The training requirements of MDs differ from PhDs:
MD training occurs in a medical school, and professional certification requires professional examinations and meeting professional training benchmarks, a residency and seeking out research opportunities, which can sometimes be difficult n the face of clinical responsibilities. MD/PhD programs include an additional 2-3 years in research training addition to the MD in order to obtain the dual degree (if you have a deep interest in research this is a path to consider). As a physician you’d have the satisfaction of directly helping the sick, and engaging in research that may result in a new treatment or cure.
PhD training occurs in graduate school, and may take 5-6 additional years beyond the 4 year degree. Most PhDs also undertake one or more postdoctoral fellowships to become independent scientists, before striking out on their own to run their own lab. As a PhD researcher you’ll have the satisfaction of helping students and working on important problems that may affect millions of people, or on an interesting and engaging problem that contributes important knowledge to the world. However, being a PhD researcher is very competitive, with less security than being a physician, so if you chose this path you’d need to prepare yourself for multiple career paths including working as a scientist in industry, or teaching as well as research. Both MD and PhD paths are very rewarding, but both require a lot of personal time and energy.
This is very brief, but you should speak to your undergraduate advisors and shadow PhD scientists and physicians to learn more about how they do their work.
It’s really a good sign that you are asking these questions in high school. Best of luck!