Motorists Vestibular Disorientation Syndrome Revisited.

摘要

We present a framework within which to understand the causes of chronic susceptibility to disorientation and how it may be resolved. Motorists Disorientation Syndrome is given as an example disorientation syndrome which may occur without sensory or marked psychological disorder and resembles pilots' disorientation. The syndrome may begin with an episode of disorientation or a sensory impairment and thereafter can cause dysfunctional behaviour. A neglected feature of disorientation is that contextual stimuli such as differential movements of parts of the visual field may support alternative interpretations affecting orientation. These are not necessarily at a conscious level but are still able to induce apprehension or inappropriate behaviour: a susceptibility to subliminal percepts. Once sensitized to the intrinsic ambiguities of a complex environment it becomes difficult to adjust gains and asymmetries or re- establish rules of reference between somaesthetic and vestibular signals. A fundamental problem in establishing rules for interpreting sensory input is circularity of reference between somatic and visual signals and vestibular signals of motion in space. Somatic and visual signals which give relativistic information about motion are referenced to vestibular signals of absolute motion in space for interpretation. Conversely vestibular signals are calibrated by reference to these other sensory input. Should a problem of interpretation arise in this potentially vicious circle the only recourse is to make an exploratory appraisal of the environment in which the natural first choice for perceptual sampling of world events is vision because of it teleceptive and panoramic power. Unfortunately, this tactic creates visual dependency' which, in a complex environment, risks creating increased susceptibility to vection illusions and visual vertigo.