Measuring threshold and latency of motion perception on a swinging bed

Abstract

Introduction Our objective was to develop and to evaluate a system to measure latency and threshold of pendular motion perception based on a swinging bed. Materials and methods This prospective study included 30 healthy adults (age: 32 ± 12 years). All subjects were tested twice with a 10 min. interval. A second trial was conducted 2 to 15 days after. A rehabilitation swinging bed was connected to an electronic device emitting a beep at the beginning of each oscillation phase with an adjustable time lag. Subjects were blindfolded and auditory cues other than the beep were minimized. The acceleration threshold was measured by letting the bed oscillate freely until a natural break and asking the patient when he did not perceive any motion. The perception latency was determined by asking the patient to indicate whether the beep and the peak of each oscillation were synchronous. The time lag between sound and peak of the head position was swept from -750 to +750 ms by 50 ms increments. Results The mean acceleration threshold was 9.2±4.60 cm/s2. The range width of the synchronous perception interval was estimated as 535±190 ms. The point of subjective synchronicity defined as the center of this interval was -195±106 ms (n = 30). The test-retest evaluation in the same trial showed an acceptable reproducibility for the acceleration threshold and good to excellent for all parameters related to sound-movement latency. Conclusion Swinging bed combined to sound stimulation can provide reproducible information on movement perception in a simple and non-invasive manner with highly reproducible results.

Delay and Acceleration Threshold of Movement Perception in Patients Suffering from Vertigo or Dizziness

“…As we showed in the preliminary study on healthy subjects [ 15 ], the range of delays for which the sound and the oscillation peak are perceived as synchronous is around a negative figure (oscillation peak after the beep), suggesting a certain degree of anticipation. We showed that the upper border of this range (i.e., PST) provided consistent results in the control subjects in test–retest.…”

“…A preliminary study was conducted to evaluate and validate the swinging bed [ 15 ]. Thirty healthy young adults without past medical history of balance disorders or hearing disabilities were tested on the swinging bed to evaluate the distribution of the above parameters and their repeatability (16 men and 14 women with a mean age of 32 years, range: 20–61).…”

“…In the light of several experimental reports [ 6 , 14 ], the idea of exploring movement perception appears interesting in addition to the peripheral tests. In a previous study, we showed that measuring sound–movement synchronicity and acceleration thresholds on a swinging rehabilitation bed yielded reproducible results in young healthy individuals [ 15 ].…”

Interaction between Feet and Gaze in Postural Control

“…For low speeds, close to those of natural oscillations, only the foot system works whereas for slightly higher speeds, vision contributes to postural control [ 23 ]. The threshold of the vestibular sensors is greater than the variations linked to postural oscillations in the easy stance [ 19 , 24 ]. The vestibular system controls trunk orientation [ 25 ] and is related to the hip strategy [ 26 ].…”