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:2D and (Klingner et al., 2010; Shmuel et al., 2002)), led us to investigate the contribution of local and global intrinsic vascular signals to BOLD response variabilitymeasured from the bilateral sensory network across all experiments.
Category: