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:These results contrast with those found by previous studies in young adults (Aznarez-Sanado et al. 2013; Doyon et al. 2002; Fern√°ndez-Seara et al. 2009; Leh√©ricy et al. 2005; M√ºller et al. 2002) where prefrontal regions diminished their activity as learning progressed.
Category: