Document Detail

Improved electrically evoked auditory steady-state response thresholds in humans.
MedLine Citation:
PMID:  22569837     Owner:  NLM     Status:  MEDLINE    
Electrically evoked auditory steady-state responses (EASSRs) are EEG potentials in response to periodic electrical stimuli presented through a cochlear implant. For low-rate pulse trains in the 40-Hz range, electrophysiological thresholds derived from response amplitude growth functions correlate well with behavioral T levels at these rates. The aims of this study were: (1) to improve the correlation between electrophysiological thresholds and behavioral T levels at 900 pps by using amplitude-modulated (AM) and pulse-width-modulated (PWM) high-rate pulse trains, (2) to develop and evaluate the performance of a new statistical method for response detection which is robust in the presence of stimulus artifacts, and (3) to assess the ability of this statistical method to determine reliable electrophysiological thresholds without any stimulus artifact removal. For six users of a Nucleus cochlear implant and a total of 12 stimulation electrode pairs, EASSRs to symmetric biphasic bipolar pulse trains were recorded with seven scalp electrodes. Responses to six different stimuli were analyzed: two low-rate pulse trains with pulse rates in the 40-Hz range as well as two AM and two PWM high-rate pulse trains with a carrier rate of 900 pps and modulation frequencies in the 40-Hz range. Responses were measured at eight different stimulus intensities for each stimulus and stimulation electrode pair. Artifacts due to the electrical stimulation were removed from the recordings. To determine the presence of a neural response, a new statistical method based on a two-sample Hotelling T (2) test was used. Measurements from different recording electrodes and adjacent stimulus intensities were combined to increase statistical power. The results show that EASSRs to modulated high-rate pulse trains account for some of the temporal effects at 900 pps and result in improved electrophysiological thresholds that correlate very well with behavioral T levels at 900 pps. The proposed statistical method for response detection based on a two-sample Hotelling T (2) test has comparable performance to previously used one-sample tests and does not require stimulus artifacts to be removed from the EEG signal for the determination of reliable electrophysiological thresholds.
Michael Hofmann; Jan Wouters
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Publication Detail:
Type:  Evaluation Studies; Journal Article; Research Support, Non-U.S. Gov't     Date:  2012-05-09
Journal Detail:
Title:  Journal of the Association for Research in Otolaryngology : JARO     Volume:  13     ISSN:  1438-7573     ISO Abbreviation:  J. Assoc. Res. Otolaryngol.     Publication Date:  2012 Aug 
Date Detail:
Created Date:  2012-07-03     Completed Date:  2013-01-02     Revised Date:  2013-08-14    
Medline Journal Info:
Nlm Unique ID:  100892857     Medline TA:  J Assoc Res Otolaryngol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  573-89     Citation Subset:  IM    
ExpORL, Department Neurosciences, K.U.Leuven, O&N 2, Herestraat 49 bus 721, 3000, Leuven, Belgium.
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MeSH Terms
Auditory Threshold / physiology*
Cochlear Implants*
Electric Stimulation
Electrodes, Implanted*
Electrophysiological Phenomena / physiology
Evoked Potentials, Auditory / physiology*
Middle Aged
Models, Statistical*
Reaction Time / physiology

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