Welcome to the wonderful world of neuroscience nursing! I started as a new grad in Neuro ICU and I'm one of those rare nurses who prefer that my patients are neurologically impaired.
It is totally normal for you to feel intimidated by your new career. In the next few months, you are going to be overwhelmed with information, technical stuff, classes, etc. You are going to learn more in the first six weeks than you ever did in nursing school, much of which is probably going to contradict what you've already been taught.
Please keep in mind that you will not be expected to retain every detail, nor will you be expected to recognize the signs and symptoms of every neuro condition that exists. The key to your success in these first few months is learning to organize and prioritize your patient care. You will become more and more comfortable with all the technical stuff over time, and your co-workers will expect you to be unfamiliar with it in the beginning.
Make sure that you and your preceptor are a good fit, and if you're not, talk to management or your new-grad coordinator ASAP. Keep in mind that it cost the hospital a small fortune to orient a new nurse and they want you to be successful. I had a terrible preceptor one time and if I had not advocated for myself and changed the situation, I would have probably left my job.
Ask lots of questions, even if you just need to clarify something. Be aware of your strengths and limitations and don't be afraid to share them with you co-workers.
In my opinion, a good ICU nurse is one that is in tune with her/his patients and can anticipate problems and intervene before they become bigger problems. This is another acquired skill that will take some time, but before long, you'll have a patient that your gut instinct says "there's something not quite right" and you'll know what to do.
I wish you the best of luck and if you have any specific questions, please feel free to PM me.