I'm from a social science background and, like you, I often find myself hopelessly lost when it comes to what feels like very basic concepts in statistics. I think that's partly due to how statistics is taught in all non-mathematics disciplines - in theory we're taught how to use and evaluate quite complex statistical procedures, but with only 1-2 hours per week teaching, it's impossible for our lecturers to cover the fundamental building blocks that help us to understand what's actually going on.
Because of this, I've recently started a few MOOCs on Coursera, and I've found these massively helpful for covering research methods and statistics in far more depth than my undergraduate and postgraduate lecturers ever had time to delve into. In particular, a couple of courses I'd recommend are:
- Methods and Statistics in Social Sciences - This is particularly focused on quantitative methods in the social sciences (including quite a bit on behavioural and self-report research) so I'm not sure if it will be directly relevant with respect to neuroimaging and cognitive neuroscience, but this gives a great introduction to research methods in general. I've actually only done the first course in this series (Quantitative Research Methods), but they're very comprehensive and well made, so I'm confident that the whole series will be useful for any researcher.
- Probability and statistics: To p or not to p? - This one is a little bit more maths-heavy so might be a bit intimidating if you don't find that sort of material easy, but it's a good introduction to some of the core concepts in quantitative research, including some you mentioned (e.g. probability distributions). You don't really have to fully engage with or grasp the maths for it to be useful either.
In terms of textbooks, I personally use Andy Field's Discovering Statistics Using R, and find that very helpful. Field is a psychologist who is very open about his difficulties with learning statistics, and I've found it quite useful and re-assuring to learn from someone with that mindset. He's also tried writing a statistics textbook in the form of a graphic novel, An Adventure in Statistics: The Reality Enigma, so if that sounds like something that might help you, check it out.
I think a few people from a 'purer' statistics background are a bit more critical about Field's books because they're not as comprehensive as a book written by, for example, a statistics professor - and there might be some advice in there that's a little bit out-of-date or not quite correct. He also has a very hit-and-miss cheesy sense of humour, which you'll either love or find very annoying. But I think he takes the right sort of approach for helping people who aren't necessarily mathematically-inclined to dip their toes into the world of statistics.