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:fMRI studies using motor tasks in children with CP-U demonstrated abnormal pattern of activation, which included reduced activation in the affected hemisphere and existence of ipsilateral activation (Guzzetta et al. 2007; Sutcliffe et al. 2007, 2009; You et al. 2005).
Category: