does pursuing a research career in artificial intelligence requires deep understanding of higher mathematics?
I believe it depends on the sort of research you want to do. 

If your goal is to better understand machine learning models, then you'd benefit from a solid mathematics background. Mathematics is necessary to understand how models work, intuit potential improvements, and prove various properties about the models. Researchers that rely on a foundational understanding of machine learning models are typically trying to push the state of the art regarding existing problems; they want to solve problems more efficiently, with more accuracy, with less data, with more explainability, etc., than the current best solutions.

If your goal is to apply existing models to solve novel problems, then it won't be as necessary for you to have a strong math background. It will be more important for you to have a general understanding of how different models work and when you'd pick one over another. Researchers that don't rely on mathematics as heavily will often attempt to push our understanding of what machines are capable of, rather than trying to make the machine better at a known problem.

This is my understanding from my experiences in the field. Hopefully it helps.