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:Although it has been shown by Valencia-Torres et al. (2011, 2012) that both PFC and NAC are involved in temporal discrimination, we conclude that the mPFC may structure future behavior and organize it, but it is known that temporal control involves the integration of multiple neural systems (Meck,‚Äö√Ñ¬∂
Category: