Depends on how deep you want to go. You need to find out what people are working on, and you do this by searching on PubMed and talking to people working in that field.
This sounds similar to what my friends in academia describe while exploring their fields. They build an impressive repository of knowledge regarding who's working on different topics/subfields over time. This may be one advantage of pursuing a PhD. Would be cool to see someone make the process of acclimating to a new field more accessible.