Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:As TrkB-FL mediates the majority of BDNF’s functions, we next
examined the influence of BDNF on myelination in the presence of the Trk receptor inhibitor K252a (Knüsel and Hefti, 1992).
Category: