Modulation of gastric motor activity by a centrally acting stimulus, circular vection, in humans

The aims of this study were to investigate gastric motor correlates of vect ion, a centrally acting stimulus, and relate these responses to the inducti on of motion sickness symptoms. Antral contractile activity and gastric vol ume retained after a liquid nutrient meal (600 ml) were assessed by magneti c resonance imaging in healthy subjects during two different protocols. Vec tion was induced by an optokinetic drum, and subjects repeatedly rated the intensity of vection and nausea on 0-10 analog scales. Vection delayed gast ric emptying {99% (89-102%) [median (interquartile ranges)] of volume retai ned at 28 min; control situation: 79% (69-81%), P < 0.05}. Antral contracti le activity followed a distinct time course of rapid decrease [-64% (-72 to -59%) change from baseline activity] immediately after onset of drum rotat ion followed by gradual recovery upon withdrawal of the stimulus. No relati onship was found between the severity of nausea and inhibition of gastric e mptying or antral contractile activity. The inhibition of antral contractil e activity appears to be a good measure of the peripheral response to vecti on but is probably independent of subjective symptom induction.