[Thresholds of long-latency evoked potentials and of the sensations of motion occurring during human exposure to linear accelerations].

Forty-seven healthy test subjects were exposed several times each to linear acceleration of varying value. Depending on the acceleration value, they reported subjectively three types of sensations at the threshold level: nondiscriminated in terms of direction (P1, a = 8.0 +/- 2.5 cm/sec2), inverted (P2, a = 12.4 +/- 2.5 cm/sec2) and discriminated (P3, a = 16.1 +/- 3.5 cm/sec2). The acceleration value at which P2 was recorded caused most typical responses in different test subjects whereas that at which P3 was recorded induced greatest individual variations. Evoked potentials in response to linear acceleration were recorded in such a manner which excluded potential instrumental artefacts or possible contribution of eye movements, excitation of the hearing organ and muscle tone changes. The data obtained indicate that acceleration-induced evoked potentials are predominantly of vestibular origin and consist of three peaks, viz. P1, N1, and P2, the latencies of which are equal to 31.3 +/- 7.2, 69.1 +/- 9.1 and 157.6 +/- 10.5 msec at the threshold where they emerge. The peak P1 is most variable, the peak N1 is most stable and the peak P2 is characterized by the largest ratio of the interindividual variation to the individual variation.