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:Resting-state corticostriatal functional connectivity is correlated with executive performance in both healthy subjects and in diseases such as schizophrenia, Huntington’s disease and ADHD (Mennes et al., 2011; Unschuld et al., 2012; Su et al., 2013; Gordon et al., 2015).
Category: