Passive discouragement and less supportive senior colleagues: What should I do?
You may be reading too much into their behavior. It is normal for academics to be interested in their own stuff and whatever supports it directly and uninterested in everything else. There may also be the effect that some of them have a long history of trust with others, but not yet with you. Hopefully this will change over time, and, in any case, if you stick around long enough then they will disappear and you will be the "older colleague". 

But, under the circumstances, you seem to be doing the right thing: publishing your work. You can also seek the positive feedback you'd like to have outside your own institution, by attending conferences and expanding your circle of contacts. 

But maybe they are just jerks. Don't let them wear you down. Finish your degree and look for employment at a more collegial place.