Fig. 4. The poc-triggered gastric mill rhythm requires the activation of CoG projection neurons. (A) During normal saline superfusion of the CoGs, tonic poc stimulation (15 Hz, 30 s) triggered the gastric mill rhythm. (B) During superfusion of 5x Mg²⁺/5x Ca²⁺ saline selectively to the CoGs and OG (grey shading in STNS schematic), the same poc stimulation did not trigger the gastric mill rhythm. (C) After washout of the 5x Mg²⁺/5x Ca²⁺ saline, poc stimulation again triggered the gastric mill rhythm. Note that the black bar in each STNS schematic represents a Vaseline wall that enabled separate saline superfusion of the anterior (CoGs, OG) and posterior (STG) aspects of the STNS. All panels are from the same preparation.