Figure 1: Segmentation activity in the intestine in the presence of nerve blockade.

(a) Spatio–temporal map of in vivo mouse small intestine segmentation contractions. We describe it here as a checkered pattern, very similar to the original description of Cannon (c). The top shows stomach peristaltic contractions. White represents narrowing of the lumen caused by circular muscle contraction in this and subsequent figures. Scale bars, 0.5 cm, 5 s. Rectangle identifies the section enlarged in d. (b) Spatio–temporal map of in vivo mouse small intestine peristaltic activity. Typical propulsive contractions are seen at the slow-wave frequency of 32 c.p.m. The top shows stomach peristaltic contractions. Scale bars, 0.5 cm, 5 s. (c) The segmentation motor pattern as drawn by Cannon¹⁶. Reproduced with permission. From Cannon's original description: A length of mass of food (top line) is cut into a series of uniform segments (2nd line). A moment later each of these segments is divided into two particles (along dotted lines in a and b). Then neighbouring particles merge to form new segments ( a and b form into c). (d) A section cut out of panel a and turned 90 degrees for direct comparison with the drawing from Canon (c). Scale bars, 1 cm, 1 s. (e) Spatio–temporal map of segmentation motor activity in the isolated whole-mouse intestine in the presence of TTX (1 μM). Scale bars, 1 cm, 1 s. (f) Still image from the intestine from which e was derived. Scale bar, 1 cm. (g) Spatio–temporal map of segmentation motor activity from the same experiment as panel e, but displayed for a longer period of time. Scale bars, 1 cm, 10 s.