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:…frequency-dependent synaptic transmission
In order to examine frequency-dependent synapses in a quantitative manner it is possible to examine only the averaged response to a high frequency train of APs (Markram and Tsodyks, 1996, Markram, 1997,
Markram et al., 1998, Tsodyks and Markram, 1997).
Category: