Behaviors exhibited by animals during galvanic vestibular stimulation: <b><i>A,</i></b> sinusoidal head roll at the frequency of the stimulus; <b><i>B,</i></b> nystagmus; <b><i>C,</i></b> frequent licking; <b><i>D,</i></b> retching; <b><i>E,</i></b> excessive salivation; <b><i>F,</i></b> sinusoidal pinna movement at the frequency of the stimulus; <b><i>G,</i></b> vocalization; <b><i>H,</i></b> panting; <b><i>I,</i></b> thrashing in the restraint bag, presumably as an attempt to escape the stimulus; <b><i>J,</i></b> defecation during the stimulation session; <b><i>K,</i></b> urination during the stimulation session; <b><i>L,</i></b> sinusoidal limb movements at the frequency of the stimulus; <b><i>M,</i></b> sedation (sleeping during the majority of the stimulation session).

The behaviors were graded as either being overt (++) or only weakly perceptible (+). Blank cells indicate that the behavior was not present. Based on these behaviors, we classified the stimulus as being highly effective in generating responses (1), moderately effective in generating responses (2), or ineffective (3). The later category includes two animals (C83 and C84) that served as unstimulated controls. A score sum was generated by assigning a score of 2 to overt symptoms (++), and a score of 1 to weak symptoms (+).