Ask HN: How do you become an expert in a field, starting from scratch?

I’m a CS student, but I’m also very interested in Neuroscience and biotechnology. It’s a field in which I’m not very well versed in, my knowledge currently consists of listening to Huberman Lab. How do I go from there to being an expert, or at least, knowing the fundamentals so that I can understand research papers I read? I know it takes time, but how do I maximise the amount of stuff I learn in that timeframe? Any advice about the topic would be appreciated. Cheers!