Scientific Reports 6: Article number: 25101; published online: 06 May 2016; updated: 27 July 2016.

In the original version of this Article, Affiliation 1 was incorrectly given as “Institute for Systems and Robotics, Instituto Superior Técnico, Lisboa, Portugal”. The correct Affiliation is listed below:

“Institute for Systems and Robotics (ISR/IST), LARSyS, Bioengineering Dept, Instituto Superior Técnico, Universidade de Lisboa, Portugal”.

This error has now been corrected in the PDF and HTML versions of this Article.