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