Fig. 3: Simultaneous video imaging colonic wall movements with electrical recordings made from two independent sites along the smooth muscle.

a shows a photomicrograph of the isolated colon and location of two independent extracellular recording electrodes, separated by 30 mm, where one electrode is located in the proximal/mid colon, the other in the distal colon. b Spatio-temporal map with superimposed simultaneous electrical recordings from the mid colon. The white band shows the propagating contraction associated with propulsion of fluid. c Superimposed electrical recordings from the proximal and distal colon. d Wavelet coherence of electrical activities between electrical recordings from electrode 1 (proximal colon) and electrode 2 (distal colon). The yellow band shown from ~6 to 17 s shows ~2 Hz peak coherence. e The relative time alignment between electrical recordings shown in panel c are presented. There is a small temporal difference between EJPs until ~17 s where the time difference increases and the propulsive wavefront passes. fi shows an expanded period represented by the black bar from panel c–e, where the close temporal synchronization between recordings EJPs is shown. fii, shows two different periods of recordings (represented by the two black bars) take from panel fi. The recording on the left hand side shows close synchronicity between EJPs, while the right hand panel recording in fii shows EJPs are phase shifted slightly by ~100–200 ms.