Erratum

In the original publication of this article [1], Fig. 4b contains a recording trace which was duplicated. In this Erratum the original Fig. 4b (Fig. 1) and the corrected Fig. 4b (Fig. 2) are published.

Fig. 1
figure 1

Original version of Fig. 4b as published on 13 December 2016

Fig. 2
figure 2

Correct version of Fig. 4b, the second trace has been corrected