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:…of the insect brain such as the central complex with its proven key role in sensory/motor coordination (Strauss 2002; Heinze and Homberg 2007; Strausfeld 2009) and spatial memory and orientation (Liu et al. 2006; Neuser et al. 2008) are built according to an elaborate molecular program whose…
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