Transitioning from languages to neuroscience/cognitive science for PhD, how to increase chances of success? I have background in languages (BA in English Literature and Teaching in China, MA Conference Interpreting in Manchester, UK) and I am eager to do a PhD in cognitive science in the UK.

During my MA studies, we were studying fundamentals of psychology and cognitive sciences related to translating/interpreting. During the course of this study, some modern research techniques such as FMRI, EEG were touched upon but the course was not very comprehensive, as the focus of the field was never really on how the interpreters’ brain works during simultaneous interpreting or other language activities.

I found languages and cognitive sciences closely related, because it is very natural to bring up questions in one area while discussing the other. It’s close to instinct that an interest in one can seep into another, at least that was the case for me.

I am really keen to further my education in the area of Cognitive Sciences, and it's been the case for the last couple of years. But it’s a bit saddening to see that the minimum entry for these programs usually require a science degree in relevant fields, for example, CS, EE, Psychology, Neuroscience, etc. And at the moment (I'm 26), I can't really do one more undergraduate degree.

However, I understand that there are gaps to fill for a person to change their area of study. Usually in the UK, PhD programs would encourage the students to do the 1+3 program, where first years have the opportunity to fill this gap. But I fell that even for these 1+3 programs, students who have a liberal arts degree are still discouraged from applying because these PhD programs specifically require students to have background in relevant science fields.

So what should I do to be more qualified and have a better chance to be accepted as a PhD student?  

My plan is to learn some fundamentals by finishing online courses in the following areas: Math (e.g. Calculus, Linear Algebra, Probability, to be more comfortable with fundamentals), Computer Science (such as basics of algorithms and Python to be able to perform some scientific computing), and Neuroscience (as it is fundamental to Cognitive Sciences). What about MOOC courses, more specifically, how are they viewed in the academia in the context of someone who is using them to fill in the gaps when changing fields?

I would like to know whether or not I have underestimated the difficulty and hard work required to put myself on this track.
I studied at Edinburgh with a few friends who had come for the arts world into CogSci and CS Masters courses, they shared many lectures with us (Bio-Informatics).    I would suggest either doing a Masters in a related field, before jumping into the PhD.

I took some CogSci and Neuroinformatics modules for my MSc and I struggled not coming from that background, if I were doing it again and wanted to prepare I would look to the online courses. Many of them are excellent.

MIT have an Opencourseware section on CogSci: http://ocw.mit.edu/courses/brain-and-cognitive-sciences/
No one will look down on you for saying you have worked through an MIT course. They also have extensive CompSci resources. Coursera also has many excellent course, that will help fill in gaps in you education.

I don't think you will find many people in academia who will look badly on people using any resources they can find to expand their knowledge and understanding of a given field.