Dataset Information

Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

ABSTRACT: OBJECTIVES:Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption. DESIGN:Event-related potentials were recorded to a synthesized vowel /a/ with a 170- or 400-ms duration. RESULTS:The P2 response, which occurs between 150 and 250?ms, was corrupted by the DC artifact removal algorithm for a 170-ms stimulus duration but was relatively uncorrupted for a 400-ms stimulus duration. CONCLUSIONS:To avoid response waveform corruption from DC artifact removal, one should choose a stimulus duration such that the offset of the stimulus does not temporally coincide with the specific peak of interest. While our data have been analyzed with only one specific algorithm, we argue that the length of the stimulus may be a critical factor for any DC artifact removal algorithm.

SUBMITTER: Presacco A

PROVIDER: S-EPMC5659925 | biostudies-literature | 2017 Nov/Dec

REPOSITORIES: biostudies-literature

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Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

Presacco Alessandro A Innes-Brown Hamish H Goupell Matthew J MJ Anderson Samira S

Ear and hearing 20171101 6

<h4>Objectives</h4>Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption.<h4>Design</h4>Event-related potentials ...[more]

PMID: 28475545

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Project description:The role of the spatial separation between the stimulating electrodes (electrode separation) in sequential stream segregation was explored in cochlear implant (CI) listeners using a deviant detection task. Twelve CI listeners were instructed to attend to a series of target sounds in the presence of interleaved distractor sounds. A deviant was randomly introduced in the target stream either at the beginning, middle or end of each trial. The listeners were asked to detect sequences that contained a deviant and to report its location within the trial. The perceptual segregation of the streams should, therefore, improve deviant detection performance. The electrode range for the distractor sounds was varied, resulting in different amounts of overlap between the target and the distractor streams. For the largest electrode separation condition, event-related potentials (ERPs) were recorded under active and passive listening conditions. The listeners were asked to perform the behavioral task for the active listening condition and encouraged to watch a muted movie for the passive listening condition. Deviant detection performance improved with increasing electrode separation between the streams, suggesting that larger electrode differences facilitate the segregation of the streams. Deviant detection performance was best for deviants happening late in the sequence, indicating that a segregated percept builds up over time. The analysis of the ERP waveforms revealed that auditory selective attention modulates the ERP responses in CI listeners. Specifically, the responses to the target stream were, overall, larger in the active relative to the passive listening condition. Conversely, the ERP responses to the distractor stream were not affected by selective attention. However, no significant correlation was observed between the behavioral performance and the amount of attentional modulation. Overall, the findings from the present study suggest that CI listeners can use electrode separation to perceptually group sequential sounds. Moreover, selective attention can be deployed on the resulting auditory objects, as reflected by the attentional modulation of the ERPs at the group level.

Project description:Background/Aims: Exposure toward positive emotional cues with - and without - reproductive significance plays a crucial role in daily life and regarding well-being as well as mental health. While possible adverse effects of oral contraceptive (OC) use on female mental and sexual health are widely discussed, neural processing of positive emotional stimuli has not been systematically investigated in association with OC use. Considering reported effects on mood, well-being and sexual function, and proposed associations with depression, it was hypothesized that OC users showed reduced neural reactivity toward positive and erotic emotional stimuli during early as well as later stages of emotional processing and also rated these stimuli as less pleasant and less arousing compared to naturally cycling (NC) women. Method: Sixty-two female subjects (29 NC and 33 OC) were assessed at three time points across the natural menstrual cycle and corresponding time points of the OC regimen. Early (early posterior negativity, EPN) and late (late positive potential, LPP) event-related potentials in reaction to positive, erotic and neutral stimuli were collected during an Emotional Picture Stroop Paradigm (EPSP). At each appointment, subjects provided saliva samples for analysis of gonadal steroid concentration. Valence and arousal ratings were collected at the last appointment. Results: Oral contraceptive users had significantly lower endogenous estradiol and progesterone concentrations compared to NC women. No significant group differences in either subjective stimulus evaluations or neural reactivity toward positive and erotic emotional stimuli were observed. For the OC group, LPP amplitudes in reaction to erotic vs. neutral pictures differed significantly between measurement times across the OC regimen. Discussion: In this study, no evidence regarding alterations of neural reactivity toward positive and erotic stimuli in OC users compared to NC was found. Possible confounding factors and lines for future research are elaborated and discussed.

Dataset Information

Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

Publications

Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

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