The Basal Electrical Rhythm occurs in all pas of GIT, EXCEPT:

Except in the esophagus and the proximal poion of the stomach, the smooth muscle of GIT has spontaneous rhythmic fluctuations in membrane potential between about -65 and -45 mV. Basic electrical rhythm (BER) is initiated by the interstitial cells of Cajal, stellate mesenchymal pacemaker cells with smooth muscle-like features that send long multiply branched processes into the intestinal smooth muscle. In the stomach and the small intestine, these cells are located in the outer circular muscle layer near the myenteric plexus; in the colon, they are at the submucosal border of the circular muscle layer. In the stomach and small intestine, there is a descending gradient in pacemaker frequency, and as in the hea, the pacemaker with the highest frequency usually dominates.