Changes in gastric EMG resulting from differences in direction of linear acceleration in rabbits

The role of direction of linear acceleration in stimulation of the otolith organ, which leads to alteration of autonomic activities in the form of inhibition of gastric motility, has not been fully studied. With a view to elucidating this problem, we placed healthy adult rabbits unanesthetized and unrestrained in individual cages, and subjected them to the three different linear acclerations to study changes in gastric EMG. As a result, the forward-and-backward movement was found to inhibit the EMG activity most potently, and was followed in decreasing order by side-to-side movement and up-and-down movement. These findings, when viewed from the standpoint of the accepted concept that optimum stimulation to the otolith organ constitutes the shearing force, account well for the supposition that forward-and-backward movement stimulates both the sacculi and utriculi, while up-and-down movement stimulates the sacculi alone.