DANIEL MERFELD

..These measured responses are consistent with our internal model predictions that the nervous system can develop a non-zero estimate of linear acceleration even when no true linear acceleration is present...

..The review is timely because of the recent advances in the field and because MED-EL has recently announced that they are developing a vestibular implant for clinical applications...

..We benchmarked the method with simulated movements and obtain proof-of-concept with one healthy subject. The method was robust to misalignment, required little data, and minimal processing...

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..One-interval recognition is generally favored over two-interval recognition because it assesses vestibular bias and can require substantially less time than two-interval tasks...

..While electrical stimulation is a standard means of stimulation, optical stimulation is also being investigated as a way to improve prosthetic stimulation specificity...

..This suggests that long-term functional replacement of absent vestibular function is feasible...

..In fact, after many such off-to-on or on-to-off transitions, little nystagmus was evoked by turning the stimulation on or off. These findings show that the brain acclimates to constant-rate stimulation...

..We conclude that internal models govern human perception of tilt and translation at 0.8 Hz and that high-pass filtering governs the human translational VOR at this same frequency...

..More generally, these findings are consistent with the hypothesis that the nervous system uses internal models to process and interpret sensory motor cues...

..Therefore these modeled response characteristics are consistent with available data and with the hypothesis that the nervous system uses internal models to estimate tilt and translation in the presence of ambiguous sensory cues...

..2 hz...

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..005) and is consistent with the prediction that illusory tilt should be accompanied by a non-zero neural estimate of linear velocity that, if large enough (supra-threshold), contributes to translation perception...

..The experiments also show that the nervous system adapts to the artificial rotational cue provided via electrical stimulation...

..These components evoke a horizontal angular VOR and linear VOR, which combine additively in the supine orientation, but subtract in the prone orientation, thus accounting for the majority of the observed prone/supine asymmetry...

..The results provided by this pilot study suggest that it may be feasible to study central adaptation by chronically modifying the afferent vestibular cue with a prosthetic semicircular canal...

..These results demonstrate that the brain can adaptively modify the gain, axis, and symmetry of the VOR when provided with chronic motion-modulated electrical stimulation by a canal prosthesis...

..However, at least for short-term stimulation such as that studied herein, no inherent advantage in terms of the response time constant ("velocity storage") was found...

..This new methodology sets the stage for innovative experimental approaches that will help to elucidate the neural mechanisms underlying the perception of spatial orientation...

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..In conclusion, OT and PR appear governed by qualitatively different neural mechanisms. OT appears mostly influenced by central low-pass filtering of interaural graviceptor cues, while PR appears mostly influenced by roll tilt of the GIF...

..Specifically, rotational cues provided by the semicircular canals help the CNS resolve ambiguous otolith cues during head tilt, yielding more accurate tilt perception...

..In contrast, such stimulation did not affect performance of a low-imagery control task. These data document previously unsuspected interactions between the vestibular system and the high-level visual system...

..71 deg s(-1) and a cut-off frequency of 0.23 Hz, which corresponds to a time constant of approximately 0.70 s. These findings provide no evidence for an influence of velocity storage on perceptual yaw rotation thresholds...

..Therefore, the clinical goal for the research proposed herein is to establish precise efficient methods to quantify motion perception in general and, more specifically, to assay perceptual thresholds. ..

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..3) Investigate the influence of efferent copy and neck receptor cues on the neural processes by which ambiguous otolith cues yield tilt and/or translation responses. ..

..All of these proposed specific aims will be investigated by measuring changes in the vestibulo-ocular responses induced by changes in chronic, patterned, electrical stimulation of the peripheral vestibular system. ..

..The experimental specific aims will be addressed by measuring eye movements and perceptual responses. The modeling specific aim will be addressed using numerical computer simulations. ..

..Therefore, the clinical goal for the research proposed herein is to establish precise efficient methods to quantify motion perception in general and, more specifically, to assay perceptual thresholds. ..