Eye movement responses to caloric vestibular irrigations reveal the contribution of voluntary processes to autonomic reflexes

editorial reviewedCan autonomic reflexes inform us about higher-order cognitive processes ? To address this issue, we studied habituation (a form of non-associative learning) of the slow, uncontrolled eye movement response (nystagmus) following repetitive caloric (warm water) vestibular irrigation. After a 30s irrigation trial (total trials=6), participants (n=26) either kept their gaze fixated, or let their gaze free, testing voluntary adaptations of the nystagmus response measured with electrooculography (EOG). Participants also reported the intensity of the vertigo that they experienced after each irrigation. We found that the amplitude of the nystagmus response decreased over repetitive irrigations, revealing a clear habituation (repeated measures ANOVA with participants as random factor, F(5)=-18.8, p