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:OX1 expression can be upregulated on microglia during CNS inflammation (Sedgwick et al., 1991) and there was some overlap of OX1 fluorescence between
our FSChigh OX1high and FSClow OX1low populations.
Category: