In Japanese the seems to be a lot of reoccurring verb endings. Some basic ones are fairly easy to understand, like 動く vs 動かす, here it looks like あ plus す is used to indicate acting upon something instead of being the actor. However, there are some other, more vague verb endings that you see here and there, and I'm wondering if there is literature about what meanings this endings might add. Here are some examples:
I'm sure there are other groupings and more examples. Also assuming this is a complicated topic, Id be interested in finding they keywords for this topic (in Japanese) to further research it in academia.