system
Given the following post, respond as if you're commenting on Reddit:
human
Anxiety about a career in research

I am close to starting a research-focused M.Sc./PhD-program in neuroscience that I have spent the last three years of my life working toward. Now that courses will start in a few weeks, I am starting to get anxious and slightly overwhelmed with the prospect of a career in research. I was hoping to get some third party perspectives on the things I am worrying about.

Seeing that academia is a competitive environment, how bad would it be not to get the greatest postdoc position right after your PhD? How much time is there before you have to give up on your dreams of being a researcher because you did not manage to publish enough papers? By when should you have published something?

How restricted am I to my PhD topic after I graduate? Obviously I will have better chances when staying in the exact niche I have already worked in, but is it viable to change directions after spending a significant amount of time on one specific subject?

And in case anyone is from a neuroscience (especially cognitive neuroscience) related field: Is there even anything I can do with that degree apart from research or am I going to have to either be successful in my research or be jobless?

I realize that the answers to these probably vary by field (and potentially country), but I am happy with any perspective I can get.

Thanks in advance!
gpt
You just started your program. There is **nothing** you can do in your first few weeks (really your first year or two) that will affect your long term prospects. You are so far away from the job market that worrying about it now is counterproductive. Focus on getting settled into your new home and getting comfortable in your department. 

Your other questions will vary by field. Find an experience faculty member who has placed students in academia and ask them all your questions. Better still, ask them what you need to do to be competitive on the academic job market. They should be able to give you practical answers based on their experience training students and interviewing for faculty positions.