[The influence of rates of pressure change on pressure-induced vestibular response in guinea pigs].

Ambient pressure changes are known to induce vertigo and bodily disequilibrium, e.g. alternobaric vertigo. It is predicted, based on clinical observations of such vertigo, that the rates of pressure change are responsible for alternobaric vertigo. The aim of the present study was to clarify the influence of the rates of pressure change on the activities of primary vestibular neurons using an animal model of alternobaric vertigo. The responses of primary vestibular neurons to middle ear pressure stimuli were investigated in guinea pigs under 2 different rates of pressure change (+/- 50, +/- 100 mmH2O/sec). The following results were obtained. 1. The response rates and the gains of firing rates with pressure stimuli were larger under +/- 100 mmH2O/sec than under +/- 50 mmH2O/sec. 2. The onsets of responses to pressure stimuli were faster under +/- 100 mmH2O/sec than under +/- 50 mmH2O/sec. The results obtained in the present study reveal that vestibular activities are altered by the rates of ambient pressure change.