Click on a link to retrieve supplementary data submitted for this article:

• Video 1: 2 electrode, 01 Hz
• (MPG format, 2,653)

• Video 2: 2 electrode, 16 Hz
• (MPG format, 729)

• Video 3: 3 electrode, 01 Hz
• (MPG format, 2,500)

• Video 4: 3 electrode, 16 Hz
• (MPG format, 729)

• Video 5: 4 electrode, 01 Hz
• (MPG format, 2,095)

• Video 6: 4 electrode, 16 Hz (top and side views)
• (MPG format, 267)