Investigating head-neck stabilization using combined mechanical and galvanic vestibular stimuli

The goal of this study was to assess if the superposition principle is valid in head-neck stabilization during combined torso perturbations and continuous galvanic vestibular stimulation. Nine seated subjects were perturbed in lateral direction on a motion platform while GVS was simultaneously applied. Both the mechanical and galvanic input signals consisted of multisine signals and were designed to be mathematically uncorrelated. For the motion perturbations, two direction and two amplitude variations were included. The GVS signal was applied in a bilateral bipolar configuration at 4 mA. During trials subjects had their eyes closed and were asked to perform a natural stabilization task. Displacements of the head, torso and platform were recorded using a motion capture system. System identification techniques were used to identify the relationship between respectively inputs GVS and torso motion and output head motion. Results show that it is feasible to apply low-level torso perturbations together with continuous galvanic stimulation in studying the head-neck system as high coherencies and consistent behavior are found for the transfer functions from mechanical and galvanic inputs to head motion over all subjects. It is concluded that superposition principle does not hold as gain, phase and coherence modulations were found with the addition of GVS.

Subject

galvanic vestibular stimulation
mechanical torso perturbations
head stabilization
system identification
sensory integration

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http://resolver.tudelft.nl/uuid:7216f06e-4d52-41dc-80c0-2917845d5cec

Embargo date

2012-11-20

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Student theses

Document type

master thesis

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Thesis_Anoek_Geers.pdf

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