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Rossi D, Cartocci G, Inguscio BMS, Capitolino G, Borghini G, Di Flumeri G, Ronca V, Giorgi A, Vozzi A, Capotorto R, Babiloni F, Scorpecci A, Giannantonio S, Marsella P, Leone CA, Grassia R, Galletti F, Ciodaro F, Galletti C, Aricò P. Characterization of Cochlear Implant Artifact and Removal Based on Multi-Channel Wiener Filter in Unilateral Child Patients. Bioengineering (Basel) 2024; 11:753. [PMID: 39199711 PMCID: PMC11352012 DOI: 10.3390/bioengineering11080753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2024] [Revised: 07/15/2024] [Accepted: 07/23/2024] [Indexed: 09/01/2024] Open
Abstract
Cochlear implants (CI) allow deaf patients to improve language perception and improving their emotional valence assessment. Electroencephalographic (EEG) measures were employed so far to improve CI programming reliability and to evaluate listening effort in auditory tasks, which are particularly useful in conditions when subjective evaluations are scarcely appliable or reliable. Unfortunately, the presence of CI on the scalp introduces an electrical artifact coupled to EEG signals that masks physiological features recorded by electrodes close to the site of implant. Currently, methods for CI artifact removal have been developed for very specific EEG montages or protocols, while others require many scalp electrodes. In this study, we propose a method based on the Multi-channel Wiener filter (MWF) to overcome those shortcomings. Nine children with unilateral CI and nine age-matched normal hearing children (control) participated in the study. EEG data were acquired on a relatively low number of electrodes (n = 16) during resting condition and during an auditory task. The obtained results obtained allowed to characterize CI artifact on the affected electrode and to significantly reduce, if not remove it through MWF filtering. Moreover, the results indicate, by comparing the two sample populations, that the EEG data loss is minimal in CI users after filtering, and that data maintain EEG physiological characteristics.
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Affiliation(s)
- Dario Rossi
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy; (G.C.); (B.M.S.I.); (G.B.); (G.D.F.)
| | - Giulia Cartocci
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy; (G.C.); (B.M.S.I.); (G.B.); (G.D.F.)
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
| | - Bianca M. S. Inguscio
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy; (G.C.); (B.M.S.I.); (G.B.); (G.D.F.)
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
| | - Giulia Capitolino
- Department of Computer, Control, and Management Engineering “Antonio Ruberti”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Gianluca Borghini
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy; (G.C.); (B.M.S.I.); (G.B.); (G.D.F.)
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
| | - Gianluca Di Flumeri
- Department of Molecular Medicine, Sapienza University of Rome, Viale Regina Elena 291, 00161 Rome, Italy; (G.C.); (B.M.S.I.); (G.B.); (G.D.F.)
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
| | - Vincenzo Ronca
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
- Department of Computer, Control, and Management Engineering “Antonio Ruberti”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Andrea Giorgi
- Department of Anatomical, Histological, Forensic & Orthopedic Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (A.G.); (R.C.)
| | - Alessia Vozzi
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
| | - Rossella Capotorto
- Department of Anatomical, Histological, Forensic & Orthopedic Sciences, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy; (A.G.); (R.C.)
| | - Fabio Babiloni
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
- Department of Physiology and Pharmacology “Vittorio Erspamer”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
- Department of Computer Science, Hangzhou Dianzi University, Hangzhou 310018, China
| | - Alessandro Scorpecci
- Audiology and Otosurgery Unit, “Bambino Gesù” Pediatric Hospital and Research Institute, Piazza di Sant’Onofrio 4, 00165 Rome, Italy; (A.S.); (S.G.); (P.M.)
| | - Sara Giannantonio
- Audiology and Otosurgery Unit, “Bambino Gesù” Pediatric Hospital and Research Institute, Piazza di Sant’Onofrio 4, 00165 Rome, Italy; (A.S.); (S.G.); (P.M.)
| | - Pasquale Marsella
- Audiology and Otosurgery Unit, “Bambino Gesù” Pediatric Hospital and Research Institute, Piazza di Sant’Onofrio 4, 00165 Rome, Italy; (A.S.); (S.G.); (P.M.)
| | - Carlo Antonio Leone
- Department of Otolaringology Head-Neck Surgery, Monaldi Hospital, Via Leonardo Bianchi, 80131 Naples, Italy; (C.A.L.); (R.G.)
| | - Rosa Grassia
- Department of Otolaringology Head-Neck Surgery, Monaldi Hospital, Via Leonardo Bianchi, 80131 Naples, Italy; (C.A.L.); (R.G.)
| | - Francesco Galletti
- Department of Otorhinolaryngology, University of Messina, Piazza Pugliatti 1, 98122 Messina, Italy; (F.G.); (F.C.); (C.G.)
| | - Francesco Ciodaro
- Department of Otorhinolaryngology, University of Messina, Piazza Pugliatti 1, 98122 Messina, Italy; (F.G.); (F.C.); (C.G.)
| | - Cosimo Galletti
- Department of Otorhinolaryngology, University of Messina, Piazza Pugliatti 1, 98122 Messina, Italy; (F.G.); (F.C.); (C.G.)
| | - Pietro Aricò
- BrainSigns srl, Via Tirso 14, 00198 Rome, Italy; (V.R.); (A.V.); (F.B.)
- Department of Computer, Control, and Management Engineering “Antonio Ruberti”, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
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Callejón-Leblic MA, Lazo-Maestre M, Fratter A, Ropero-Romero F, Sánchez-Gómez S, Reina-Tosina J. A full-head model to investigate intra and extracochlear electric fields in cochlear implant stimulation. Phys Med Biol 2024; 69:155010. [PMID: 38925131 DOI: 10.1088/1361-6560/ad5c38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Accepted: 06/26/2024] [Indexed: 06/28/2024]
Abstract
Objective.Despite the widespread use and technical improvement of cochlear implant (CI) devices over past decades, further research into the bioelectric bases of CI stimulation is still needed. Various stimulation modes implemented by different CI manufacturers coexist, but their true clinical benefit remains unclear, probably due to the high inter-subject variability reported, which makes the prediction of CI outcomes and the optimal fitting of stimulation parameters challenging. A highly detailed full-head model that includes a cochlea and an electrode array is developed in this study to emulate intracochlear voltages and extracochlear current pathways through the head in CI stimulation.Approach.Simulations based on the finite element method were conducted under monopolar, bipolar, tripolar (TP), and partial TP modes, as well as for apical, medial, and basal electrodes. Variables simulated included: intracochlear voltages, electric field (EF) decay, electric potentials at the scalp and extracochlear currents through the head. To better understand CI side effects such as facial nerve stimulation, caused by spurious current leakage out from the cochlea, special emphasis is given to the analysis of the EF over the facial nerve.Main results.The model reasonably predicts EF magnitudes and trends previously reported in CI users. New relevant extracochlear current pathways through the head and brain tissues have been identified. Simulated results also show differences in the magnitude and distribution of the EF through different segments of the facial nerve upon different stimulation modes and electrodes, dependent on nerve and bone tissue conductivities.Significance.Full-head models prove useful tools to model intra and extracochlear EFs in CI stimulation. Our findings could prove useful in the design of future experimental studies to contrast FNS mechanisms upon stimulation of different electrodes and CI modes. The full-head model developed is freely available for the CI community for further research and use.
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Affiliation(s)
- M A Callejón-Leblic
- Otorhinolaryngology Department, Virgen Macarena University Hospital, Seville 41009, Spain
- Oticon Medical, 28108 Madrid, Spain
- Dept. Signal Theory and Communications, Biomedical Engineering Group, University of Seville, Seville 41092, Spain
| | - M Lazo-Maestre
- Otorhinolaryngology Department, Virgen Macarena University Hospital, Seville 41009, Spain
| | - A Fratter
- Oticon Medical, 06220 Vallauris, France
| | - F Ropero-Romero
- Otorhinolaryngology Department, Virgen Macarena University Hospital, Seville 41009, Spain
| | - S Sánchez-Gómez
- Otorhinolaryngology Department, Virgen Macarena University Hospital, Seville 41009, Spain
| | - J Reina-Tosina
- Dept. Signal Theory and Communications, Biomedical Engineering Group, University of Seville, Seville 41092, Spain
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Hu H, Ewert SD, Kollmeier B, Vickers D. Rate dependent neural responses of interaural-time-difference cues in fine-structure and envelope. PeerJ 2024; 12:e17104. [PMID: 38680894 PMCID: PMC11055513 DOI: 10.7717/peerj.17104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/22/2024] [Indexed: 05/01/2024] Open
Abstract
Advancements in cochlear implants (CIs) have led to a significant increase in bilateral CI users, especially among children. Yet, most bilateral CI users do not fully achieve the intended binaural benefit due to potential limitations in signal processing and/or surgical implant positioning. One crucial auditory cue that normal hearing (NH) listeners can benefit from is the interaural time difference (ITD), i.e., the time difference between the arrival of a sound at two ears. The ITD sensitivity is thought to be heavily relying on the effective utilization of temporal fine structure (very rapid oscillations in sound). Unfortunately, most current CIs do not transmit such true fine structure. Nevertheless, bilateral CI users have demonstrated sensitivity to ITD cues delivered through envelope or interaural pulse time differences, i.e., the time gap between the pulses delivered to the two implants. However, their ITD sensitivity is significantly poorer compared to NH individuals, and it further degrades at higher CI stimulation rates, especially when the rate exceeds 300 pulse per second. The overall purpose of this research thread is to improve spatial hearing abilities in bilateral CI users. This study aims to develop electroencephalography (EEG) paradigms that can be used with clinical settings to assess and optimize the delivery of ITD cues, which are crucial for spatial hearing in everyday life. The research objective of this article was to determine the effect of CI stimulation pulse rate on the ITD sensitivity, and to characterize the rate-dependent degradation in ITD perception using EEG measures. To develop protocols for bilateral CI studies, EEG responses were obtained from NH listeners using sinusoidal-amplitude-modulated (SAM) tones and filtered clicks with changes in either fine structure ITD (ITDFS) or envelope ITD (ITDENV). Multiple EEG responses were analyzed, which included the subcortical auditory steady-state responses (ASSRs) and cortical auditory evoked potentials (CAEPs) elicited by stimuli onset, offset, and changes. Results indicated that acoustic change complex (ACC) responses elicited by ITDENV changes were significantly smaller or absent compared to those elicited by ITDFS changes. The ACC morphologies evoked by ITDFS changes were similar to onset and offset CAEPs, although the peak latencies were longest for ACC responses and shortest for offset CAEPs. The high-frequency stimuli clearly elicited subcortical ASSRs, but smaller than those evoked by lower carrier frequency SAM tones. The 40-Hz ASSRs decreased with increasing carrier frequencies. Filtered clicks elicited larger ASSRs compared to high-frequency SAM tones, with the order being 40 > 160 > 80> 320 Hz ASSR for both stimulus types. Wavelet analysis revealed a clear interaction between detectable transient CAEPs and 40-Hz ASSRs in the time-frequency domain for SAM tones with a low carrier frequency.
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Affiliation(s)
- Hongmei Hu
- SOUND Lab, Cambridge Hearing Group, Department of Clinical Neuroscience, Cambridge University, Cambridge, United Kingdom
- Department of Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Stephan D. Ewert
- Department of Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Birger Kollmeier
- Department of Medical Physics and Acoustics, Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
| | - Deborah Vickers
- SOUND Lab, Cambridge Hearing Group, Department of Clinical Neuroscience, Cambridge University, Cambridge, United Kingdom
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Aldag N, Nogueira W. Psychoacoustic and electroencephalographic responses to changes in amplitude modulation depth and frequency in relation to speech recognition in cochlear implantees. Sci Rep 2024; 14:8181. [PMID: 38589483 PMCID: PMC11002021 DOI: 10.1038/s41598-024-58225-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Accepted: 03/26/2024] [Indexed: 04/10/2024] Open
Abstract
Temporal envelope modulations (TEMs) are one of the most important features that cochlear implant (CI) users rely on to understand speech. Electroencephalographic assessment of TEM encoding could help clinicians to predict speech recognition more objectively, even in patients unable to provide active feedback. The acoustic change complex (ACC) and the auditory steady-state response (ASSR) evoked by low-frequency amplitude-modulated pulse trains can be used to assess TEM encoding with electrical stimulation of individual CI electrodes. In this study, we focused on amplitude modulation detection (AMD) and amplitude modulation frequency discrimination (AMFD) with stimulation of a basal versus an apical electrode. In twelve adult CI users, we (a) assessed behavioral AMFD thresholds and (b) recorded cortical auditory evoked potentials (CAEPs), AMD-ACC, AMFD-ACC, and ASSR in a combined 3-stimulus paradigm. We found that the electrophysiological responses were significantly higher for apical than for basal stimulation. Peak amplitudes of AMFD-ACC were small and (therefore) did not correlate with speech-in-noise recognition. We found significant correlations between speech-in-noise recognition and (a) behavioral AMFD thresholds and (b) AMD-ACC peak amplitudes. AMD and AMFD hold potential to develop a clinically applicable tool for assessing TEM encoding to predict speech recognition in CI users.
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Affiliation(s)
- Nina Aldag
- Department of Otolaryngology, Hannover Medical School and Cluster of Excellence 'Hearing4all', Hanover, Germany
| | - Waldo Nogueira
- Department of Otolaryngology, Hannover Medical School and Cluster of Excellence 'Hearing4all', Hanover, Germany.
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Zhou L, Xu Y, Song F, Li W, Gao F, Zhu Q, Qian Z. The effect of TENS on sleep: A pilot study. Sleep Med 2023; 107:126-136. [PMID: 37167876 DOI: 10.1016/j.sleep.2023.04.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/20/2023] [Accepted: 04/27/2023] [Indexed: 05/13/2023]
Abstract
BACKGROUND Insomnia is the second most common neuropsychiatric disorder, but the current treatments are not very effective. There is therefore an urgent need to develop better treatments. Transcutaneous electrical nerve stimulation (TENS) may be a promising means of treating insomnia. OBJECTIVE This work aims to explore whether and how TENS modulate sleep and the effect of stimulation waveforms on sleep. METHODS Forty-five healthy subjects participated in this study. Electroencephalography (EEG) data were recorded before and after four mode low-frequency (1 Hz) TENS with different waveforms, which were formed by superimposing sine waves of different high frequencies (60-210 Hz) and low frequencies (1-6 Hz). The four waveform modes are formed by combining sine waves of varying frequencies. Mode 1 (M1) consists of a combination of high frequencies (60-110 Hz) and low frequencies (1-6 Hz). Mode 2 (M2) is made up of high frequencies (60-210 Hz) and low frequencies (1-6 Hz). Mode 3 (M3) consists of high frequencies (110-160 Hz) and low frequencies (1-6 Hz), while mode 4 (M4) is composed of high frequencies (160-210 Hz) and low frequencies (1-6 Hz). For M1, M3 and M4, the high frequency portions of the stimulus waveforms account for 50%, while for M2, the high frequency portion of the waveform accounts for 65%. For each mode, the current intensities ranged from 4 mA to 7 mA, with values for each participant adjusted according to individual tolerance. During stimulation, the subjects were stimulated at the greater occipital nerve by the four mode TENS. RESULTS M1, M3, and M4 slowed down the frequency of neural activity, broadened the distribution of theta waves, and caused a decrease in activity in wakefulness-related regions and an increase in activity in sleep-related regions. However, M2 has the opposite modulation effect. CONCLUSION These results indicated that low-frequency TENS (1 Hz) may facilitate sleep in a waveform-specific manner. Our findings provide new insights into the mechanisms of sleep modulation by TENS and the design of effective insomnia treatments.
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Affiliation(s)
- Lu Zhou
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China
| | - Yixuan Xu
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China
| | - Fanlei Song
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China
| | - Weitao Li
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China
| | - Fan Gao
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China
| | - Qiaoqiao Zhu
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China.
| | - Zhiyu Qian
- Department of Biomedical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, China; Key Laboratory of Multimodal Brain-Computer Precision Drive Ministry of Industry and Information Technology, Nanjing, 210016, China; Key Laboratory of Digital Medical Equipment and Technology of Jiangsu Province, Nanjing, 210016, China.
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Guérit F, Deeks JM, Arzounian D, Gransier R, Wouters J, Carlyon RP. Using Interleaved Stimulation and EEG to Measure Temporal Smoothing and Growth of the Sustained Neural Response to Cochlear-Implant Stimulation. J Assoc Res Otolaryngol 2023; 24:253-264. [PMID: 36754938 PMCID: PMC10121955 DOI: 10.1007/s10162-023-00886-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 01/04/2023] [Indexed: 02/10/2023] Open
Abstract
Two EEG experiments measured the sustained neural response to amplitude-modulated (AM) high-rate pulse trains presented to a single cochlear-implant (CI) electrode. Stimuli consisted of two interleaved pulse trains with AM rates F1 and F2 close to 80 and 120 Hz respectively, and where F2 = 1.5F1. Following Carlyon et al. (J Assoc Res Otolaryngol, 2021), we assume that such stimuli can produce a neural distortion response (NDR) at F0 = F2-F1 Hz if temporal dependencies ("smoothing") in the auditory system are followed by one or more neural nonlinearities. In experiment 1, the rate of each pulse train was 480 pps and the gap between pulses in the F1 and F2 pulse trains ranged from 0 to 984 µs. The NDR had a roughly constant amplitude for gaps between 0 and about 200-400 µs, and decreased for longer gaps. We argue that this result is consistent with a temporal dependency, such as facilitation, operating at the level of the auditory nerve and/or with co-incidence detection by cochlear-nucleus neurons. Experiment 2 first measured the NDR for stimuli at each listener's most comfortable level ("MCL") and for F0 = 37, 40, and 43 Hz. This revealed a group delay of about 42 ms, consistent with a thalamic/cortical source. We then showed that the NDR grew steeply with stimulus amplitude and, for most listeners, decreased by more than 12 dB between MCL and 75% of the listener's dynamic range. We argue that the NDR is a potentially useful objective estimate of MCL.
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Affiliation(s)
- François Guérit
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, Cambridge, England
| | - John M Deeks
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, Cambridge, England
| | - Dorothée Arzounian
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, Cambridge, England
| | - Robin Gransier
- ExpORL, Dept. of Neurosciences, KU Leuven, Leuven, Belgium
| | - Jan Wouters
- ExpORL, Dept. of Neurosciences, KU Leuven, Leuven, Belgium
| | - Robert P Carlyon
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, Cambridge, England.
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Dolhopiatenko H, Nogueira W. Selective attention decoding in bimodal cochlear implant users. Front Neurosci 2023; 16:1057605. [PMID: 36711138 PMCID: PMC9874229 DOI: 10.3389/fnins.2022.1057605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 12/20/2022] [Indexed: 01/12/2023] Open
Abstract
The growing group of cochlear implant (CI) users includes subjects with preserved acoustic hearing on the opposite side to the CI. The use of both listening sides results in improved speech perception in comparison to listening with one side alone. However, large variability in the measured benefit is observed. It is possible that this variability is associated with the integration of speech across electric and acoustic stimulation modalities. However, there is a lack of established methods to assess speech integration between electric and acoustic stimulation and consequently to adequately program the devices. Moreover, existing methods do not provide information about the underlying physiological mechanisms of this integration or are based on simple stimuli that are difficult to relate to speech integration. Electroencephalography (EEG) to continuous speech is promising as an objective measure of speech perception, however, its application in CIs is challenging because it is influenced by the electrical artifact introduced by these devices. For this reason, the main goal of this work is to investigate a possible electrophysiological measure of speech integration between electric and acoustic stimulation in bimodal CI users. For this purpose, a selective attention decoding paradigm has been designed and validated in bimodal CI users. The current study included behavioral and electrophysiological measures. The behavioral measure consisted of a speech understanding test, where subjects repeated words to a target speaker in the presence of a competing voice listening with the CI side (CIS) only, with the acoustic side (AS) only or with both listening sides (CIS+AS). Electrophysiological measures included cortical auditory evoked potentials (CAEPs) and selective attention decoding through EEG. CAEPs were recorded to broadband stimuli to confirm the feasibility to record cortical responses with CIS only, AS only, and CIS+AS listening modes. In the selective attention decoding paradigm a co-located target and a competing speech stream were presented to the subjects using the three listening modes (CIS only, AS only, and CIS+AS). The main hypothesis of the current study is that selective attention can be decoded in CI users despite the presence of CI electrical artifact. If selective attention decoding improves combining electric and acoustic stimulation with respect to electric stimulation alone, the hypothesis can be confirmed. No significant difference in behavioral speech understanding performance when listening with CIS+AS and AS only was found, mainly due to the ceiling effect observed with these two listening modes. The main finding of the current study is the possibility to decode selective attention in CI users even if continuous artifact is present. Moreover, an amplitude reduction of the forward transfer response function (TRF) of selective attention decoding was observed when listening with CIS+AS compared to AS only. Further studies to validate selective attention decoding as an electrophysiological measure of electric acoustic speech integration are required.
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Intartaglia B, Prud'homme MA, Foster NE, Zeitouni AG, Lehmann A. Visual cortex plasticity in cochlear implant users revealed in a visual motion detection task. Clin Neurophysiol 2022; 137:11-24. [DOI: 10.1016/j.clinph.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 01/24/2022] [Accepted: 02/01/2022] [Indexed: 11/25/2022]
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Recording EEG in Cochlear Implant Users: Guidelines for Experimental Design and Data Analysis for Optimizing Signal Quality and Minimizing Artifacts. J Neurosci Methods 2022; 375:109592. [PMID: 35367234 DOI: 10.1016/j.jneumeth.2022.109592] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 03/26/2022] [Accepted: 03/27/2022] [Indexed: 11/22/2022]
Abstract
Cochlear implants (CI) are neural prostheses that can restore hearing in individuals with severe to profound hearing loss. Although CIs significantly improve quality of life, clinical outcomes are still highly variable. An important part of this variability is explained by the brain reorganization following cochlear implantation. Therefore, clinicians and researchers are seeking objective measurements to investigate post-implantation brain plasticity. Electroencephalography (EEG) is a promising technique because it is objective, non-invasive, and implant-compatible, but is nonetheless susceptible to massive artifacts generated by the prosthesis's electrical activity. CI artifacts can blur and distort brain responses; thus, it is crucial to develop reliable techniques to remove them from EEG recordings. Despite numerous artifact removal techniques used in previous studies, there is a paucity of documentation and consensus on the optimal EEG procedures to reduce these artifacts. Herein, and through a comprehensive review process, we provide a guideline for designing an EEG-CI experiment minimizing the effect of the artifact. We provide some technical guidance for recording an accurate neural response from CI users and discuss the current challenges in detecting and removing CI-induced artifacts from a recorded signal. The aim of this paper is also to provide recommendations to better appraise and report EEG-CI findings.
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Nogueira W, Dolhopiatenko H. Predicting speech intelligibility from a selective attention decoding paradigm in cochlear implant users. J Neural Eng 2022; 19. [PMID: 35234663 DOI: 10.1088/1741-2552/ac599f] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/01/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVES Electroencephalography (EEG) can be used to decode selective attention in cochlear implant (CI) users. This work investigates if selective attention to an attended speech source in the presence of a concurrent speech source can predict speech understanding in CI users. APPROACH CI users were instructed to attend to one out of two speech streams while EEG was recorded. Both speech streams were presented to the same ear and at different signal to interference ratios (SIRs). Speech envelope reconstruction of the to-be-attended speech from EEG was obtained by training decoders using regularized least squares. The correlation coefficient between the reconstructed and the attended (ρ_(A_SIR )) or the unattended (ρ_(U_SIR )) speech stream at each SIR was computed. Additionally, we computed the difference correlation coefficient at the same 〖(ρ〗_Diff= ρ_(A_SIR )-ρ_(U_SIR )) and opposite SIR (ρ_DiffOpp= ρ_(A_SIR )-ρ_(U_(-SIR) )). ρ_Diff compares the attended and unattended correlation coefficient to speech sources presented at different presentation levels depending on SIR. In contrast, ρ_DiffOpp compares the attended and unattended correlation coefficients to speech sources presented at the same presentation level irrespective of SIR. MAIN RESULTS Selective attention decoding in CI users is possible even if both speech streams are presented monaurally. A significant effect of SIR on ρ_(A_SIR ), ρ_Diff and ρ_DiffOpp, but not on ρ_(U_SIR ), was observed. Finally, the results show a significant correlation between speech understanding performance and ρ_(A_SIR ) as well as with ρ_(U_SIR ) across subjects. Moreover, ρ_DiffOpp which is less affected by the CI artifact, also demonstrated a significant correlation with speech understanding. SIGNIFICANCE Selective attention decoding in CI users is possible, however care needs to be taken with the CI artifact and the speech material used to train the decoders. These results are important for future development of objective speech understanding measures for CI users.
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Affiliation(s)
- Waldo Nogueira
- Department of Otolaryngology and Cluster of Excellence "Hearing4all", Hannover Medical School, Karl-Wiechert Allee, 3, Hannover, Niedersachsen, 30625, GERMANY
| | - Hanna Dolhopiatenko
- Department of Otolaryngology and Cluster of Excellence "Hearing4all", Hannover Medical School, Karl-Wiechert Allee, 3, Hannover, Niedersachsen, 30625, GERMANY
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11
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Venâncio LGA, Leal MDC, da Hora LCD, Griz SMS, Muniz LF. Frequency-Following Response (FFR) in cochlear implant users: a systematic review of acquisition parameters, analysis, and outcomes. Codas 2022; 34:e20210116. [PMID: 35081198 PMCID: PMC9886122 DOI: 10.1590/2317-1782/20212021116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 09/22/2021] [Indexed: 02/03/2023] Open
Abstract
PURPOSE To characterize the acquisition parameters, analysis, and results of the frequency-following response (FFR) in cochlear implant users. RESEARCH STRATEGIES The search was conducted in Cochrane Library, Latin American and Caribbean Health Sciences Literature (LILACS), Ovid Technologies, PubMed, SciELO, ScienceDirect, Scopus, Web of Science, and gray literature. SELECTION CRITERIA Studies on FFR in cochlear implant users or that compared them with normal-hearing people, with no restriction of age, were included. Secondary and experimental studies were excluded. There was no restriction of language or year of publication. DATA ANALYSIS The data were analyzed and reported according to the stages in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), 2020. The methodological quality was analyzed with the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Divergences were solved by a third researcher. RESULTS Six studies met the inclusion criteria. Only one study was comparative, whose control group comprised normal-hearing people. The variations in acquisition parameters were common and the analysis predominantly approached the time domain. Cochlear implant users had different FFR results from those of normal-hearing people, considering the existing literature. Most articles had low methodological quality. CONCLUSION There is no standardized FFR acquisition and analysis protocol for cochlear implant users. The results have a high risk of bias.
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Affiliation(s)
| | - Mariana de Carvalho Leal
- Programa de Pós-graduação em Saúde da Comunicação Humana, Departamento de Cirurgia, Universidade Federal de Pernambuco – UFPE - Recife (PE), Brasil.
| | - Laís Cristine Delgado da Hora
- Programa de Pós-graduação em Saúde da Comunicação Humana, Universidade Federal de Pernambuco – UFPE - Recife (PE), Brasil.
| | - Silvana Maria Sobral Griz
- Programa de Pós-graduação em Saúde da Comunicação Humana, Departamento de Fonoaudiologia, Universidade Federal de Pernambuco – UFPE - Recife (PE), Brasil.
| | - Lilian Ferreira Muniz
- Programa de Pós-graduação em Saúde da Comunicação Humana, Departamento de Fonoaudiologia, Universidade Federal de Pernambuco – UFPE - Recife (PE), Brasil.
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Abstract
The auditory cortex of people with sensorineural hearing loss can be re-afferented using a cochlear implant (CI): a neural prosthesis that bypasses the damaged cells in the cochlea to directly stimulate the auditory nerve. Although CIs are the most successful neural prosthesis to date, some CI users still do not achieve satisfactory outcomes using these devices. To explain variability in outcomes, clinicians and researchers have increasingly focused their attention on neuroscientific investigations that examined how the auditory cortices respond to the electric signals that originate from the CI. This chapter provides an overview of the literature that examined how the auditory cortex changes its functional properties in response to inputs from the CI, in animal models and in humans. We focus first on the basic responses to sounds delivered through electrical hearing and, next, we examine the integrity of two fundamental aspects of the auditory system: tonotopy and processing of binaural cues. When addressing the effects of CIs in humans, we also consider speech-evoked responses. We conclude by discussing to what extent this neuroscientific literature can contribute to clinical practices and help to overcome variability in outcomes.
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Affiliation(s)
- Francesco Pavani
- Center for Mind/Brain Sciences - CIMeC, University of Trento, Rovereto, Italy.
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Mai G, Howell P. Causal Relationship between the Right Auditory Cortex and Speech-Evoked Envelope-Following Response: Evidence from Combined Transcranial Stimulation and Electroencephalography. Cereb Cortex 2021; 32:1437-1454. [PMID: 34424956 PMCID: PMC8971082 DOI: 10.1093/cercor/bhab298] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 11/27/2022] Open
Abstract
Speech-evoked envelope-following response (EFR) reflects brain encoding of speech periodicity that serves as a biomarker for pitch and speech perception and various auditory and language disorders. Although EFR is thought to originate from the subcortex, recent research illustrated a right-hemispheric cortical contribution to EFR. However, it is unclear whether this contribution is causal. This study aimed to establish this causality by combining transcranial direct current stimulation (tDCS) and measurement of EFR (pre- and post-tDCS) via scalp-recorded electroencephalography. We applied tDCS over the left and right auditory cortices in right-handed normal-hearing participants and examined whether altering cortical excitability via tDCS causes changes in EFR during monaural listening to speech syllables. We showed significant changes in EFR magnitude when tDCS was applied over the right auditory cortex compared with sham stimulation for the listening ear contralateral to the stimulation site. No such effect was found when tDCS was applied over the left auditory cortex. Crucially, we further observed a hemispheric laterality where aftereffect was significantly greater for tDCS applied over the right than the left auditory cortex in the contralateral ear condition. Our finding thus provides the first evidence that validates the causal relationship between the right auditory cortex and EFR.
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Affiliation(s)
- Guangting Mai
- Hearing Theme, National Institute for Health Research Nottingham Biomedical Research Centre, Nottingham NG1 5DU, UK.,Division of Clinical Neuroscience, School of Medicine, University of Nottingham, Nottingham NG7 2UH, UK.,Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Peter Howell
- Department of Experimental Psychology, University College London, London WC1H 0AP, UK
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Zhang M, Alamatsaz N, Ihlefeld A. Hemodynamic Responses Link Individual Differences in Informational Masking to the Vicinity of Superior Temporal Gyrus. Front Neurosci 2021; 15:675326. [PMID: 34366772 PMCID: PMC8339305 DOI: 10.3389/fnins.2021.675326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/13/2021] [Indexed: 01/20/2023] Open
Abstract
Suppressing unwanted background sound is crucial for aural communication. A particularly disruptive type of background sound, informational masking (IM), often interferes in social settings. However, IM mechanisms are incompletely understood. At present, IM is identified operationally: when a target should be audible, based on suprathreshold target/masker energy ratios, yet cannot be heard because target-like background sound interferes. We here confirm that speech identification thresholds differ dramatically between low- vs. high-IM background sound. However, speech detection thresholds are comparable across the two conditions. Moreover, functional near infrared spectroscopy recordings show that task-evoked blood oxygenation changes near the superior temporal gyrus (STG) covary with behavioral speech detection performance for high-IM but not low-IM background sound, suggesting that the STG is part of an IM-dependent network. Moreover, listeners who are more vulnerable to IM show increased hemodynamic recruitment near STG, an effect that cannot be explained based on differences in task difficulty across low- vs. high-IM. In contrast, task-evoked responses near another auditory region of cortex, the caudal inferior frontal sulcus (cIFS), do not predict behavioral sensitivity, suggesting that the cIFS belongs to an IM-independent network. Results are consistent with the idea that cortical gating shapes individual vulnerability to IM.
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Affiliation(s)
- Min Zhang
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
- Rutgers Biomedical and Health Sciences, Rutgers University, Newark, NJ, United States
| | - Nima Alamatsaz
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
- Rutgers Biomedical and Health Sciences, Rutgers University, Newark, NJ, United States
| | - Antje Ihlefeld
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, United States
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Neural Modulation Transmission Is a Marker for Speech Perception in Noise in Cochlear Implant Users. Ear Hear 2021; 41:591-602. [PMID: 31567565 DOI: 10.1097/aud.0000000000000783] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Cochlear implants (CIs) restore functional hearing in persons with a severe hearing impairment. Despite being one of the most successful bionic prosthesis, performance with CI (in particular speech understanding in noise) varies considerably across its users. The ability of the auditory pathway to encode temporal envelope modulations (TEMs) and the effect of degenerative processes associated with hearing loss on TEM encoding is assumed to be one of the reasons underlying the large intersubject differences in CI performance. The objective of the present study was to investigate how TEM encoding of the stimulated neural ensembles of human CI recipients is related to speech perception in noise (SPIN). DESIGN We used electroencephalography as a noninvasive electrophysiological measure to assess TEM encoding in the auditory pathway of CI users by means of the 40-Hz electrically evoked auditory steady state response (EASSR). Nine CI users with a wide range of SPIN outcome were included in the present study. TEM encoding was assessed for each stimulation electrode of each subject and new metrics; the CI neural modulation transmission difference (CIMTD) and the CI neural modulation transmission index (CIMTI) were developed to quantify the amount of variability in TEM encoding across the stimulated neural ensembles of the CI electrode array. RESULTS EASSR patterns varied across the CI electrode array and subjects. We found a strong correlation (r = 0.89, p = 0.001) between the SPIN outcomes and the variability in EASSR amplitudes across the array as assessed with CIMTD/CIMTI. CONCLUSIONS The results of the present study show that the 40-Hz EASSR can be used to objectively assess the neural encoding of TEMs in human CI recipients. Overall reduced or largely variable TEM encoding of the neural ensembles across the electrode array, as quantified with the CIMTD/CIMTI, is highly correlated with speech perception in noise outcome with a CI.
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Alemi R, Nozaradan S, Lehmann A. Free-Field Cortical Steady-State Evoked Potentials in Cochlear Implant Users. Brain Topogr 2021; 34:664-680. [PMID: 34185222 DOI: 10.1007/s10548-021-00860-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 06/18/2021] [Indexed: 11/25/2022]
Abstract
Auditory steady-state evoked potentials (SS-EPs) are phase-locked neural responses to periodic stimuli, believed to reflect specific neural generators. As an objective measure, steady-state responses have been used in different clinical settings, including measuring hearing thresholds of normal and hearing-impaired subjects. Recent studies are in favor of recording these responses as a part of the cochlear implant (CI) device-fitting procedure. Considering these potential benefits, the goals of the present study were to assess the feasibility of recording free-field SS-EPs in CI users and to compare their characteristics between CI users and controls. By taking advantage of a recently developed dual-frequency tagging method, we attempted to record subcortical and cortical SS-EPs from adult CI users and controls and measured reliable subcortical and cortical SS-EPs in the control group. Independent component analysis (ICA) was used to remove CI stimulation artifacts, yet subcortical responses of several CIs were heavily contaminated by these artifacts. Consequently, only cortical SS-EPs were compared between groups, which were found to be larger in the controls. The lower cortical SS-EPs' amplitude in CI users might indicate a reduction in neural synchrony evoked by the modulation rate of the auditory input across different neural assemblies in the auditory pathway. The brain topographies of cortical auditory SS-EPs, the time course of cortical responses, and the reconstructed cortical maps were highly similar between groups, confirming their neural origin and possibility to obtain such responses also in CI recipients. As for subcortical SS-EPs, our results highlight a need for sophisticated denoising algorithms to pinpoint and remove artifactual components from the biological response.
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Affiliation(s)
- Razieh Alemi
- Faculty of Medicine, Department of Otolaryngology, McGill University, Montreal, QC, Canada.
- Centre for Research On Brain, Language & Music (CRBLM), Montreal, Canada.
- International Laboratory for Brain, Music & Sound Research (BRAMS), Montreal, QC, Canada.
| | - Sylvie Nozaradan
- Institute of Neuroscience (IONS), Université Catholique de Louvain (UCL), Ottignies-Louvain-la-Neuve, Belgium
| | - Alexandre Lehmann
- Faculty of Medicine, Department of Otolaryngology, McGill University, Montreal, QC, Canada
- Centre for Research On Brain, Language & Music (CRBLM), Montreal, Canada
- International Laboratory for Brain, Music & Sound Research (BRAMS), Montreal, QC, Canada
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17
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Gransier R, Guérit F, Carlyon RP, Wouters J. Frequency following responses and rate change complexes in cochlear implant users. Hear Res 2021; 404:108200. [PMID: 33647574 PMCID: PMC8052190 DOI: 10.1016/j.heares.2021.108200] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 01/25/2021] [Accepted: 02/06/2021] [Indexed: 01/05/2023]
Abstract
The upper limit of rate-based pitch perception and rate discrimination can differ substantially across cochlear implant (CI) users. One potential reason for this difference is the presence of a biological limitation on temporal encoding in the electrically-stimulated auditory pathway, which can be inherent to the electrical stimulation itself and/or to the degenerative processes associated with hearing loss. Electrophysiological measures, like the electrically-evoked frequency following response (eFFR) and auditory change complex (eACC), could potentially provide valuable insights in the temporal processing limitations at the level of the brainstem and cortex in the electrically-stimulated auditory pathway. Obtaining these neural responses, free from stimulation artifacts, is challenging, especially when the neural response is phase-locked to the stimulation rate, as is the case for the eFFR. In this study we investigated the feasibility of measuring eFFRs, free from stimulation artifacts, to stimulation rates ranging from 94 to 196 pulses per second (pps) and eACCs to pulse rate changes ranging from 36 to 108%, when stimulating in a monopolar configuration. A high-sampling rate EEG system was used to measure the electrophysiological responses in five CI users, and linear interpolation was applied to remove the stimulation artifacts from the EEG. With this approach, we were able to measure eFFRs for pulse rates up to 162 pps and eACCs to the different rate changes. Our results show that it is feasible to measure electrophysiological responses, free from stimulation artifacts, that could potentially be used as neural correlates for rate and pitch processing in CI users.
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Affiliation(s)
- Robin Gransier
- KU Leuven, Department of Neurosciences, ExpORL, Herestraat 49, Box 721, Leuven 3000, Belgium.
| | - Franҫois Guérit
- Cambridge Hearing Group, MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - Robert P Carlyon
- Cambridge Hearing Group, MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge CB2 7EF, United Kingdom
| | - Jan Wouters
- KU Leuven, Department of Neurosciences, ExpORL, Herestraat 49, Box 721, Leuven 3000, Belgium
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18
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Undurraga JA, Van Yper L, Bance M, McAlpine D, Vickers D. Characterizing Cochlear implant artefact removal from EEG recordings using a real human model. MethodsX 2021; 8:101369. [PMID: 34430265 PMCID: PMC8374497 DOI: 10.1016/j.mex.2021.101369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/05/2021] [Accepted: 04/20/2021] [Indexed: 11/21/2022] Open
Abstract
Electroencephography (EEG) recordings from CI listeners are contaminated by electrical artefacts that make it difficult to extract neural responses. Previously, we have removed these artefacts by means of interpolation and spatial filtering. However, the extent to which this method can effectively reduce electrical artefacts has not been fully investigated. Here, we assessed the effectiveness of interpolation and spatial filtering to remove electrical artefacts using recordings from a human head specimen implanted with a CI.•Electrical artefacts were obtained using amplitude-modulated (AM'ed) pulse trains presented at several pulse rates (100-to-902 pps) or using high rate pulse trains (902 pps) in which either a pair of electrodes or AM frequencies alternated periodically at a rate of 1Hz.•By adding auditory change complex (ACC), auditory steady-state response (ASSR), or auditory change following response (AC-FR) template waveforms to the contaminated recordings, we show that interpolation allows for effective artefact removal for pulse rates below 400 pps whilst interpolation and spatial filtering are effective at higher pulse rates, with minimal distortions for ACC and AC-FR, and with a degree of amplitude- and phase-distortions for ASSR.•Recordings from CI listeners agreed with simulations, demonstrating that reliable responses can be recovered.
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Affiliation(s)
- Jaime A. Undurraga
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Lindsey Van Yper
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Manohar Bance
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
| | - David McAlpine
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Deborah Vickers
- Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
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19
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Carlyon RP, Guérit F, Deeks JM, Harland A, Gransier R, Wouters J, de Rijk SR, Bance M. Using Interleaved Stimulation to Measure the Size and Selectivity of the Sustained Phase-Locked Neural Response to Cochlear Implant Stimulation. J Assoc Res Otolaryngol 2021; 22:141-159. [PMID: 33492562 PMCID: PMC7943679 DOI: 10.1007/s10162-020-00783-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/21/2020] [Indexed: 02/08/2023] Open
Abstract
We measured the sustained neural response to electrical stimulation by a cochlear implant (CI). To do so, we interleaved two stimuli with frequencies F1 and F2 Hz and recorded a neural distortion response (NDR) at F2-F1 Hz. We show that, because any one time point contains only the F1 or F2 stimulus, the instantaneous nonlinearities typical of electrical artefact should not produce distortion at this frequency. However, if the stimulus is smoothed, such as by charge integration at the nerve membrane, subsequent (neural) nonlinearities can produce a component at F2-F1 Hz. We stimulated a single CI electrode with interleaved sinusoids or interleaved amplitude-modulated pulse trains such that F2 = 1.5F1, and found no evidence for an NDR when F2-F1 was between 90 and 120 Hz. However, interleaved amplitude-modulated pulse trains with F2-F1~40 Hz revealed a substantial NDR with a group delay of about 45 ms, consistent with a thalamic and/or cortical response. The NDR could be measured even from recording electrodes adjacent to the implant and at the highest pulse rates (> 4000 pps) used clinically. We then measured the selectivity of this sustained response by presenting F1 and F2 to different electrodes and at different between-electrode distances. This revealed a broad tuning that, we argue, reflects the overlap between the excitation elicited by the two electrodes. Our results also provide a glimpse of the neural nonlinearity in the auditory system, unaffected by the biomechanical cochlear nonlinearities that accompany acoustic stimulation. Several potential clinical applications of our findings are discussed.
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Affiliation(s)
- Robert P Carlyon
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge, CB2 7EF, England.
| | - François Guérit
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge, CB2 7EF, England
| | - John M Deeks
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge, CB2 7EF, England
| | - Andrew Harland
- Cambridge Hearing Group, MRC Cognition & Brain Sciences Unit, University of Cambridge, 15 Chaucer Rd, Cambridge, CB2 7EF, England
| | - Robin Gransier
- Dept. of Neurosciences, ExpORL, KU Leuven, Herestraat 49 box 721, 3000, Leuven, Belgium
| | - Jan Wouters
- Dept. of Neurosciences, ExpORL, KU Leuven, Herestraat 49 box 721, 3000, Leuven, Belgium
| | - Simone R de Rijk
- Cambridge Hearing Group, Dept. Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, England
| | - Manohar Bance
- Cambridge Hearing Group, Dept. Clinical Neurosciences, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0QQ, England
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20
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EEG-based diagnostics of the auditory system using cochlear implant electrodes as sensors. Sci Rep 2021; 11:5383. [PMID: 33686155 PMCID: PMC7940426 DOI: 10.1038/s41598-021-84829-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 02/18/2021] [Indexed: 01/31/2023] Open
Abstract
The cochlear implant is one of the most successful medical prostheses, allowing deaf and severely hearing-impaired persons to hear again by electrically stimulating the auditory nerve. A trained audiologist adjusts the stimulation settings for good speech understanding, known as "fitting" the implant. This process is based on subjective feedback from the user, making it time-consuming and challenging, especially in paediatric or communication-impaired populations. Furthermore, fittings only happen during infrequent sessions at a clinic, and therefore cannot take into account variable factors that affect the user's hearing, such as physiological changes and different listening environments. Objective audiometry, in which brain responses evoked by auditory stimulation are collected and analysed, removes the need for active patient participation. However, recording of brain responses still requires expensive equipment that is cumbersome to use. An elegant solution is to record the neural signals using the implant itself. We demonstrate for the first time the recording of continuous electroencephalographic (EEG) signals from the implanted intracochlear electrode array in human subjects, using auditory evoked potentials originating from different brain regions. This was done using a temporary recording set-up with a percutaneous connector used for research purposes. Furthermore, we show that the response morphologies and amplitudes depend crucially on the recording electrode configuration. The integration of an EEG system into cochlear implants paves the way towards chronic neuro-monitoring of hearing-impaired patients in their everyday environment, and neuro-steered hearing prostheses, which can autonomously adjust their output based on neural feedback.
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Macherey O, Stahl P, Intartaglia B, Meunier S, Roman S, Schön D. Temporal integration of short-duration pulse trains in cochlear implant listeners: Psychophysical and electrophysiological measurements. Hear Res 2021; 403:108176. [PMID: 33524792 DOI: 10.1016/j.heares.2021.108176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 01/05/2021] [Accepted: 01/15/2021] [Indexed: 01/11/2023]
Abstract
While electrically-evoked auditory brainstem response (eABR) thresholds for low-rate pulse trains correlate well with behavioral thresholds measured at the same rate, the correlation is much weaker with behavioral thresholds measured at high rates, such as used clinically. This implies that eABRs to low-rate stimuli cannot be reliably used for objective programming of threshold levels in cochlear implant (CI) users. Here, we investigate whether the use of bunched-up pulses (BUPS), consisting of groups of closely-spaced pulses may be used as an alternative stimulus. Experiment 1 measured psychophysical detection thresholds for several stimuli having a period of 32 ms in nine CI subjects implanted with a Med-EL device. The stimuli differed in the number of pulses present in each period (from 1 to 32), the pulse rate within period (1000 pps and as high as possible for BUPS) and the electrode location (apical or basal). The correlation between psychophysical thresholds obtained for a high-rate (1000 pps) clinical stimulus and for the BUPS stimuli increased as the number of pulses per period of BUPS increased from 1 to 32. This first psychophysical experiment suggests that the temporal processes affecting the threshold of clinical stimuli are also present for BUPS. Experiment 2 measured eABRs on the apical electrode of eight CI subjects for BUPS having 1, 2, 4, 8, 16 or 32 pulses per period. For most subjects, wave V was visible for BUPS having up to 16 pulses per period. The latency of wave V at threshold increased as a function of the number of pulses per period, suggesting that the eABR reflects the integration of multiple pulses at such low levels or that the neural response to each individual pulse increases along the sequence due to facilitation processes. There was also a strong within-subject correlation between electrophysiological and behavioral thresholds for the different BUPS stimuli. This demonstrates that the drop in behavioral threshold obtained when increasing the number of pulses per period of the BUPS can be measured electrophysiologically using eABRs. In contrast, the across-subject correlation between eABR thresholds for BUPS and clinical thresholds remained relatively weak and did not increase with the number of pulses per period. Implications of the use of BUPS for objective programming of CIs are discussed.
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Affiliation(s)
- Olivier Macherey
- Aix Marseille Univ, CNRS, Centrale Marseille, LMA, 4 Impasse Nikola Tesla, CS 40006, 13453 Marseille Cedex 13, France.
| | - Pierre Stahl
- Aix Marseille Univ, CNRS, Centrale Marseille, LMA, 4 Impasse Nikola Tesla, CS 40006, 13453 Marseille Cedex 13, France
| | | | - Sabine Meunier
- Aix Marseille Univ, CNRS, Centrale Marseille, LMA, 4 Impasse Nikola Tesla, CS 40006, 13453 Marseille Cedex 13, France
| | - Stéphane Roman
- Aix Marseille Univ, Inserm, INS, Inst Neurosci Syst, Marseille, France; Department Pediatric Otolaryngology and Neck Surgery, Aix Marseille Univ, Marseille, France
| | - Daniele Schön
- Aix Marseille Univ, Inserm, INS, Inst Neurosci Syst, Marseille, France
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Gransier R, Hofmann M, van Wieringen A, Wouters J. Stimulus-evoked phase-locked activity along the human auditory pathway strongly varies across individuals. Sci Rep 2021; 11:143. [PMID: 33420231 PMCID: PMC7794304 DOI: 10.1038/s41598-020-80229-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 12/14/2020] [Indexed: 11/23/2022] Open
Abstract
Phase-locking to the temporal envelope of speech is associated with envelope processing and speech perception. The phase-locked activity of the auditory pathway, across modulation frequencies, is generally assessed at group level and shows a decrease in response magnitude with increasing modulation frequency. With the exception of increased activity around 40 and 80 to 100 Hz. Furthermore, little is known about the phase-locked response patterns to modulation frequencies ≤ 20 Hz, which are modulations predominately present in the speech envelope. In the present study we assess the temporal modulation transfer function (TMTFASSR) of the phase-locked activity of the auditory pathway, from 0.5 to 100 Hz at a high-resolution and by means of auditory steady-state responses. Although the group-averaged TMTFASSR corresponds well with those reported in the literature, the individual TMTFASSR shows a remarkable intersubject variability. This intersubject variability is especially present for ASSRs that originate from the cortex and are evoked with modulation frequencies ≤ 20 Hz. Moreover, we found that these cortical phase-locked activity patterns are robust over time. These results show the importance of the individual TMTFASSR when assessing phase-locked activity to envelope fluctuations, which can potentially be used as a marker for auditory processing.
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Affiliation(s)
- Robin Gransier
- Research Group Experimental Oto-rhino-laryngology (ExpORL), Department of Neurosciences, KU Leuven, Herestraat 49, Box 721, 3000, Leuven, Belgium.
| | - Michael Hofmann
- Research Group Experimental Oto-rhino-laryngology (ExpORL), Department of Neurosciences, KU Leuven, Herestraat 49, Box 721, 3000, Leuven, Belgium
| | - Astrid van Wieringen
- Research Group Experimental Oto-rhino-laryngology (ExpORL), Department of Neurosciences, KU Leuven, Herestraat 49, Box 721, 3000, Leuven, Belgium
| | - Jan Wouters
- Research Group Experimental Oto-rhino-laryngology (ExpORL), Department of Neurosciences, KU Leuven, Herestraat 49, Box 721, 3000, Leuven, Belgium
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Undurraga JA, Van Yper L, Bance M, McAlpine D, Vickers D. Neural encoding of spectro-temporal cues at slow and near speech-rate in cochlear implant users. Hear Res 2020; 403:108160. [PMID: 33461048 DOI: 10.1016/j.heares.2020.108160] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 10/22/2022]
Abstract
The ability to process rapid modulations in the spectro-temporal structure of sounds is critical for speech comprehension. For users of cochlear implants (CIs), spectral cues in speech are conveyed by differential stimulation of electrode contacts along the cochlea, and temporal cues in terms of the amplitude of stimulating electrical pulses, which track the amplitude-modulated (AM'ed) envelope of speech sounds. Whilst survival of inner-ear neurons and spread of electrical current are known factors that limit the representation of speech information in CI listeners, limitations in the neural representation of dynamic spectro-temporal cues common to speech are also likely to play a role. We assessed the ability of CI listeners to process spectro-temporal cues varying at rates typically present in human speech. Employing an auditory change complex (ACC) paradigm, and a slow (0.5Hz) alternating rate between stimulating electrodes, or different AM frequencies, to evoke a transient cortical ACC, we demonstrate that CI listeners-like normal-hearing listeners-are sensitive to transitions in the spectral- and temporal-domain. However, CI listeners showed impaired cortical responses when either spectral or temporal cues were alternated at faster, speech-like (6-7Hz), rates. Specifically, auditory change following responses-reliably obtained in normal-hearing listeners-were small or absent in CI users, indicating that cortical adaptation to alternating cues at speech-like rates is stronger under electrical stimulation. In CI listeners, temporal processing was also influenced by the polarity-behaviourally-and rate of presentation of electrical pulses-both neurally and behaviorally. Limitations in the ability to process dynamic spectro-temporal cues will likely impact speech comprehension in CI users.
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Affiliation(s)
- Jaime A Undurraga
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia.
| | - Lindsey Van Yper
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Manohar Bance
- Cambridge Hearing Group, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
| | - David McAlpine
- Department of Linguistics, 16 University Avenue, Macquarie University, NSW 2109, Australia
| | - Deborah Vickers
- Cambridge Hearing Group, Department of Clinical Neurosciences, Cambridge Biomedical Campus, University of Cambridge, CB2 0QQ, UK
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Gransier R, Carlyon RP, Wouters J. Electrophysiological assessment of temporal envelope processing in cochlear implant users. Sci Rep 2020; 10:15406. [PMID: 32958791 PMCID: PMC7506023 DOI: 10.1038/s41598-020-72235-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 08/18/2020] [Indexed: 11/12/2022] Open
Abstract
Cochlear-implant (CI) users rely on temporal envelope modulations (TEMs) to understand speech, and clinical outcomes depend on the accuracy with which these TEMs are encoded by the electrically-stimulated neural ensembles. Non-invasive EEG measures of this encoding could help clinicians identify and disable electrodes that evoke poor neural responses so as to improve CI outcomes. However, recording EEG during CI stimulation reveals huge stimulation artifacts that are up to orders of magnitude larger than the neural response. Here we used a custom-built EEG system having an exceptionally high sample rate to accurately measure the artefact, which we then removed using linear interpolation so as to reveal the neural response during continuous electrical stimulation. In ten adult CI users, we measured the 40-Hz electrically evoked auditory steady-state response (eASSR) and electrically evoked auditory change complex (eACC) to amplitude-modulated 900-pulses-per-second pulse trains, stimulated in monopolar mode (i.e. the clinical default), and at different modulation depths. We successfully measured artifact-free 40-Hz eASSRs and eACCs. Moreover, we found that the 40-Hz eASSR, in contrast to the eACC, showed substantial responses even at shallow modulation depths. We argue that the 40-Hz eASSR is a clinically feasible objective measure to assess TEM encoding in CI users.
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Affiliation(s)
- Robin Gransier
- Department of Neurosciences, KU Leuven, ExpORL, Herestraat 49, Box 721, 3000, Leuven, Belgium.
| | - Robert P Carlyon
- Cambridge Hearing Group, MRC Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, UK
| | - Jan Wouters
- Department of Neurosciences, KU Leuven, ExpORL, Herestraat 49, Box 721, 3000, Leuven, Belgium
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Van Canneyt J, Wouters J, Francart T. From modulated noise to natural speech: The effect of stimulus parameters on the envelope following response. Hear Res 2020; 393:107993. [PMID: 32535277 DOI: 10.1016/j.heares.2020.107993] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/28/2020] [Accepted: 05/04/2020] [Indexed: 11/28/2022]
Abstract
Envelope following responses (EFRs) can be evoked by a wide range of auditory stimuli, but for many stimulus parameters the effect on EFR strength is not fully understood. This complicates the comparison of earlier studies and the design of new studies. Furthermore, the most optimal stimulus parameters are unknown. To help resolve this issue, we investigated the effects of four important stimulus parameters and their interactions on the EFR. Responses were measured in 16 normal hearing subjects evoked by stimuli with four levels of stimulus complexity (amplitude modulated noise, artificial vowels, natural vowels and vowel-consonant-vowel combinations), three fundamental frequencies (105 Hz, 185 Hz and 245 Hz), three fundamental frequency contours (upward sweeping, downward sweeping and flat) and three vowel identities (Flemish /a:/, /u:/, and /i:/). We found that EFRs evoked by artificial vowels were on average 4-6 dB SNR larger than responses evoked by the other stimulus complexities, probably because of (unnaturally) strong higher harmonics. Moreover, response amplitude decreased with fundamental frequency but response SNR remained largely unaffected. Thirdly, fundamental frequency variation within the stimulus did not impact EFR strength, but only when rate of change remained low (e.g. not the case for sweeping natural vowels). Finally, the vowel /i:/ appeared to evoke larger response amplitudes compared to /a:/ and /u:/, but analysis power was too small to confirm this statistically. Vowel-dependent differences in response strength have been suggested to stem from destructive interference between response components. We show how a model of the auditory periphery can simulate these interference patterns and predict response strength. Altogether, the results of this study can guide stimulus choice for future EFR research and practical applications.
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Affiliation(s)
- Jana Van Canneyt
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 Bus 721, 3000, Leuven, Belgium.
| | - Jan Wouters
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 Bus 721, 3000, Leuven, Belgium.
| | - Tom Francart
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 Bus 721, 3000, Leuven, Belgium.
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Reducing Artifacts in Intracochlear Pressure Measurements to Study Sound Transmission by Bone Conduction Stimulation in Humans. Otol Neurotol 2019; 40:e858-e867. [DOI: 10.1097/mao.0000000000002394] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Deprez H, Gransier R, Hofmann M, van Wieringen A, Wouters J, Moonen M. Independent component analysis for cochlear implant artifacts attenuation from electrically evoked auditory steady-state response measurements. J Neural Eng 2019; 15:016006. [PMID: 29211684 DOI: 10.1088/1741-2552/aa87ce] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
OBJECTIVE Electrically evoked auditory steady-state responses (EASSRs) are potentially useful for objective cochlear implant (CI) fitting and follow-up of the auditory maturation in infants and children with a CI. EASSRs are recorded in the electro-encephalogram (EEG) in response to electrical stimulation with continuous pulse trains, and are distorted by significant CI artifacts related to this electrical stimulation. The aim of this study is to evaluate a CI artifacts attenuation method based on independent component analysis (ICA) for three EASSR datasets. APPROACH ICA has often been used to remove CI artifacts from the EEG to record transient auditory responses, such as cortical evoked auditory potentials. Independent components (ICs) corresponding to CI artifacts are then often manually identified. In this study, an ICA based CI artifacts attenuation method was developed and evaluated for EASSR measurements with varying CI artifacts and EASSR characteristics. Artifactual ICs were automatically identified based on their spectrum. MAIN RESULTS For 40 Hz amplitude modulation (AM) stimulation at comfort level, in high SNR recordings, ICA succeeded in removing CI artifacts from all recording channels, without distorting the EASSR. For lower SNR recordings, with 40 Hz AM stimulation at lower levels, or 90 Hz AM stimulation, ICA either distorted the EASSR or could not remove all CI artifacts in most subjects, except for two of the seven subjects tested with low level 40 Hz AM stimulation. Noise levels were reduced after ICA was applied, and up to 29 ICs were rejected, suggesting poor ICA separation quality. SIGNIFICANCE We hypothesize that ICA is capable of separating CI artifacts and EASSR in case the contralateral hemisphere is EASSR dominated. For small EASSRs or large CI artifact amplitudes, ICA separation quality is insufficient to ensure complete CI artifacts attenuation without EASSR distortion.
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Affiliation(s)
- Hanne Deprez
- STADIUS Center for Dynamical Systems, Signal Processing and Data Analytics, Department of Electrical Engineering (ESAT), KU Leuven, Kasteelpark Arenberg 10 bus 2440, 3001 LEUVEN, Belgium. Experimental ORL, Department of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 LEUVEN, Belgium
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Van Canneyt J, Hofmann M, Wouters J, Francart T. The effect of stimulus envelope shape on the auditory steady-state response. Hear Res 2019; 380:22-34. [DOI: 10.1016/j.heares.2019.05.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 04/23/2019] [Accepted: 05/23/2019] [Indexed: 01/01/2023]
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Mao D, Innes-Brown H, Petoe MA, Wong YT, McKay CM. Fully objective hearing threshold estimation in cochlear implant users using phase-locking value growth functions. Hear Res 2019; 377:24-33. [DOI: 10.1016/j.heares.2019.02.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 02/21/2019] [Accepted: 02/26/2019] [Indexed: 01/18/2023]
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Verschueren E, Somers B, Francart T. Neural envelope tracking as a measure of speech understanding in cochlear implant users. Hear Res 2019; 373:23-31. [DOI: 10.1016/j.heares.2018.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 10/27/2022]
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Asamoah B, Khatoun A, Mc Laughlin M. tACS motor system effects can be caused by transcutaneous stimulation of peripheral nerves. Nat Commun 2019; 10:266. [PMID: 30655523 PMCID: PMC6336776 DOI: 10.1038/s41467-018-08183-w] [Citation(s) in RCA: 151] [Impact Index Per Article: 30.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 12/19/2018] [Indexed: 01/19/2023] Open
Abstract
Transcranial alternating current stimulation (tACS) is a noninvasive neuromodulation method which has been shown to modulate hearing, motor, cognitive and memory function. However, the mechanisms underpinning these findings are controversial, as studies show that the current reaching the cortex may not be strong enough to entrain neural activity. Here, we propose a new hypothesis to reconcile these opposing results: tACS effects are caused by transcutaneous stimulation of peripheral nerves in the skin and not transcranial stimulation of cortical neurons. Rhythmic activity from peripheral nerves then entrains cortical neurons. A series of experiments in rats and humans isolated the transcranial and transcutaneous mechanisms and showed that the reported effects of tACS on the motor system can be caused by transcutaneous stimulation of peripheral nerves. Whether or not the transcutaneous mechanism will generalize to tACS effects on other systems is debatable but should be investigated. Transcranial alternating current stimulation (tACS) uses weak electrical currents, applied to the head, to modulate brain activity. Here, the authors show that contrary to previous assumptions, the effects of tACS on the brain may be mediated by its effect on peripheral nerves in the skin, not direct.
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Affiliation(s)
- Boateng Asamoah
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium
| | - Ahmad Khatoun
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium
| | - Myles Mc Laughlin
- Exp ORL, Department of Neurosciences, KU Leuven, B-3000, Leuven, Belgium.
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Somers B, Verschueren E, Francart T. Neural tracking of the speech envelope in cochlear implant users. J Neural Eng 2018; 16:016003. [PMID: 30444216 DOI: 10.1088/1741-2552/aae6b9] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE When listening to speech, the brain tracks the speech envelope. It is possible to reconstruct this envelope from EEG recordings. However, in people who hear using a cochlear implant (CI), the artifacts caused by electrical stimulation of the auditory nerve contaminate the EEG. The objective of this study is to develop and validate a method for assessing the neural tracking of speech envelope in CI users. APPROACH To obtain EEG recordings free of stimulus artifacts, the electrical stimulation is periodically interrupted. During these stimulation gaps, artifact-free EEG can be sampled and used to train a linear envelope decoder. EEG recordings obtained during audible and inaudible (i.e. sub-threshold) stimulation were used to characterize the artifacts and their influence on the envelope reconstruction. MAIN RESULTS The present study demonstrates for the first time that neural tracking of the speech envelope can be measured in response to ongoing electrical stimulation. The responses were validated to be truly neural and not affected by stimulus artifact. SIGNIFICANCE Besides applications in audiology and neuroscience, the characterization and elimination of stimulus artifacts will enable future EEG studies involving continuous speech in CI users. Measures of neural tracking of the speech envelope reflect interesting properties of the listener's perception of speech, such as speech intelligibility or attentional state. Successful decoding of neural envelope tracking will open new possibilities to investigate the neural mechanisms of speech perception with a CI.
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Mathew R, Vickers D, Boyle P, Shaida A, Selvadurai D, Jiang D, Undurraga J. Development of electrophysiological and behavioural measures of electrode discrimination in adult cochlear implant users. Hear Res 2018; 367:74-87. [DOI: 10.1016/j.heares.2018.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Revised: 06/20/2018] [Accepted: 07/02/2018] [Indexed: 10/28/2022]
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Torres-Fortuny A, Arnaiz-Marquez I, Hernández-Pérez H, Eimil-Suárez E. Auditory steady-state response in cochlear implant patients. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2018. [DOI: 10.1016/j.otoeng.2018.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Perception of noise-vocoded tone complexes: A time domain analysis based on an auditory filterbank model. Hear Res 2018; 367:1-16. [PMID: 30005269 DOI: 10.1016/j.heares.2018.07.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 06/28/2018] [Accepted: 07/02/2018] [Indexed: 11/21/2022]
Abstract
When a wideband harmonic tone complex (wHTC) is passed through a noise vocoder, the resulting sounds can have spectra with large peak-to-valley ratios, but little or no periodicity strength in the autocorrelation functions. We measured judgments of pitch strength for normal-hearing listeners for noise-vocoded wideband harmonic tone complexes (NV-wHTCs) relative to standard and anchor stimuli. The standard was a 1-channel NV-wHTC and the anchor was either the unprocessed wHTC or an infinitely-iterated rippled noise (IIRN). Although there is variability among individuals, the magnitude judgment functions obtained with the IIRN anchor suggest different listening strategies among individuals. In order to gain some insight into possible listening strategies, test stimuli were analyzed at the output of an auditory filterbank model based on gammatone filters. The weak periodicity strengths of NV-wHTCs observed in the stimulus autocorrelation functions are augmented at the output of the gammatone filterbank model. Six analytical models of pitch strength were evaluated based on summary correlograms obtained from the gammatone tone filterbank. The results of the filterbank analysis suggest that, contrary to the weak or absent periodicity strengths in the stimulus domain, temporal cues contribute to pitch strength perception of noise-vocoded harmonic stimuli such that listeners' judgments of pitch strength reflect a nonlinear, weighted average of the temporal information between the fine structure and the envelope.
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Abstract
: Auditory evoked potentials (AEP) are highly demanded during the whole process of equipping patients with cochlear implants (CI). They play an essential role in preoperative diagnostics, intraoperative testing, and postoperative monitoring of auditory performance and success. The versatility of AEP's is essentially enhanced by their property to be evokable by acoustic as well as electric stimuli. Thus, the electric responses of the auditory system following acoustic stimulation and recorded by the conventional surface technique as well as by transtympanic derivation from the promontory (Electrocochleography [ECochG]) are used for the quantitative determination of hearing loss and, additionally, electrically evoked compound actions potentials (ECAP) can be recorded with the intracochlear electrodes of the implant just adjacent to the stimulation electrode to check the functional integrity of the device and its coupling to the auditory system. The profile of ECAP thresholds is used as basis for speech processor fitting, the spread of excitation (SOE) allows the identification of electrode mislocations such as array foldover, and recovery functions may serve to optimize stimulus pulse rate. These techniques as well as those relying on scalp surface activity originating in the brainstem or the auditory cortex accompany the CI recipient during its whole life span and they offer valuable insights into functioning and possible adverse effects of the CI for clinical and scientific purposes.
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Torres-Fortuny A, Arnaiz-Marquez I, Hernández-Pérez H, Eimil-Suárez E. Auditory steady-state response in cochlear implant patients. ACTA OTORRINOLARINGOLOGICA ESPANOLA 2018; 69:268-274. [PMID: 29566882 DOI: 10.1016/j.otorri.2017.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 08/11/2017] [Accepted: 08/18/2017] [Indexed: 10/17/2022]
Abstract
INTRODUCTION AND OBJECTIVE Auditory steady state responses to continuous amplitude modulated tones at rates between 70 and 110Hz, have been proposed as a feasible alternative to objective frequency specific audiometry in cochlear implant subjects. The aim of the present study is to obtain physiological thresholds by means of auditory steady-state response in cochlear implant patients (Clarion HiRes 90K), with acoustic stimulation, on free field conditions and to verify its biological origin. METHODS 11 subjects comprised the sample. Four amplitude modulated tones of 500, 1000, 2000 and 4000Hz were used as stimuli, using the multiple frequency technique. The recording of auditory steady-state response was also recorded at 0dB HL of intensity, non-specific stimulus and using a masking technique. RESULTS The study enabled the electrophysiological thresholds to be obtained for each subject of the explored sample. There were no auditory steady-state responses at either 0dB or non-specific stimulus recordings. It was possible to obtain the masking thresholds. A difference was identified between behavioral and electrophysiological thresholds of -6±16, -2±13, 0±22 and -8±18dB at frequencies of 500, 1000, 2000 and 4000Hz respectively. CONCLUSIONS The auditory steady state response seems to be a suitable technique to evaluate the hearing threshold in cochlear implant subjects.
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Affiliation(s)
| | | | - Heivet Hernández-Pérez
- Centre for Language Sciences, Linguistics Department, Macquarie University, Sydney, NSW, Australia
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Bahmer A, Pieper S, Baumann U. Evaluation of an artifact reduction strategy for electrically evoked auditory steady-state responses: Simulations and measurements. J Neurosci Methods 2017; 296:57-68. [PMID: 29291927 DOI: 10.1016/j.jneumeth.2017.12.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 12/26/2017] [Accepted: 12/28/2017] [Indexed: 12/01/2022]
Abstract
BACKGROUND Electrically evoked steady-state response (EASSR) recording is a measure of neuronal response strength after continuous electrical stimulation of the auditory system. In order to suppress the large electrical artifact generated by intracochlear electrical stimulation, a sophisticated artifact reduction processing strategy ("Hofmann procedure") has been proposed (Hofmann and Wouters, 2010). So far, EASSR recordings with artifact reduction procedures were reported only in cochlear implant (CI) users implanted with Cochlear devices (Macquarie, Australia). NEW METHOD Here, we demonstrate the application of the Hofmann procedure in CI users implanted with MED-EL (Innsbruck, Austria) devices. To demonstrate potential limitations of the procedure, we calculated discrete time Fourier transformations (DTFT) of various pulse patterns which may be used for EASSR. RESULTS EASSR recordings were obtained in three subjects and processed with the Hofmann procedure. Neural response amplitude growth functions and phase for modulated and unmodulated pulse trains at various stimulation rates could be assessed. Simulations of three different interpolation methods aimed to suppress the electrical artifact show that the interpolation of a sinusoidal signal in a temporal window between 0 and 1 ms has demonstrated negligible impact on the spectral amplitude of the signal with a superior performance of a spline interpolation. COMPARISON WITH EXISTING METHOD The Hofmann procedure, initially developed for recording EASSRs with CIs from the manufacturer Cochlear, was validated for MED-EL devices. CONCLUSION It is feasible to record EASSRs with the described measurement setup and CIs from the manufacturer MED-EL.
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Affiliation(s)
- Andreas Bahmer
- University of Würzburg, Clinic for Otolaryngology, Comprehensive Hearing Center, 97080 Würzburg, Germany.
| | - Sabrina Pieper
- University of Würzburg, Clinic for Otolaryngology, Comprehensive Hearing Center, 97080 Würzburg, Germany.
| | - Uwe Baumann
- University of Frankfurt Main, Clinic for Otolaryngology, Audiological Acoustics, 60590 Frankfurt, Germany.
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Electrically-evoked auditory steady-state responses as neural correlates of loudness growth in cochlear implant users. Hear Res 2017; 358:22-29. [PMID: 29274947 DOI: 10.1016/j.heares.2017.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 11/29/2017] [Accepted: 12/05/2017] [Indexed: 11/23/2022]
Abstract
Loudness growth functions characterize how the loudness percept changes with current level between the threshold and most comfortable loudness level in cochlear implant users. Even though loudness growth functions are highly listener-dependent, currently default settings are used in clinical devices. This study investigated whether electrically-evoked auditory steady-state response amplitude growth functions correspond to behaviorally measured loudness growth functions. Seven cochlear implant listeners participated in two behavioral loudness growth tasks and an EEG recording session. The 40-Hz sinusoidally amplitude-modulated pulse trains were presented to CI channels stimulating at a more apical and basal region of the cochlea, and were presented at different current levels encompassing the listeners' dynamic ranges. Behaviorally, loudness growth was measured using an Absolute Magnitude Estimation and a Graphic Rating Scale with loudness categories. A good correspondence was found between the response amplitude functions and the behavioral loudness growth functions. The results are encouraging for future advances in individual, more automatic, and objective fitting of cochlear implants.
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Dziemba OC, Hocke T, Müller A, Kaftan H. Excitation characteristic of a bipolar stimulus for broadband stimulation in measurements of electrically evoked auditory potentials. Z Med Phys 2017; 28:73-77. [PMID: 29054678 DOI: 10.1016/j.zemedi.2017.09.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Revised: 08/02/2017] [Accepted: 09/21/2017] [Indexed: 11/17/2022]
Abstract
OBJECTIVE The aim of this study was to determine the optimum electrical stimulation mode for the measurement of electrically evoked potentials. To quantify the broadband excitation electrically evoked compound action potentials were recorded in cochlear implant recipients. The full width half maximum was determined for spread of excitation along the electrode array. DESIGN Prospective clinical study. STUDY SAMPLE The study sample consisted of 20 adult cochlear implant users. RESULTS The applied alternating, intracochlear stimulation mode leads to neural excitation along approximately 80% of the length of the electrode array. The median of the full width at half maximum values covered the range of 18 electrodes on the implant array. CONCLUSION The bipolar, alternating, and intracochlear stimulation mode would provide a sufficient, broadband excitation of the spiral ganglion to measure electrically evoked auditory potentials.
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Affiliation(s)
- Oliver C Dziemba
- University Medicine Greifswald, Department of ENT, Head & Neck Surgery, Germany.
| | - Thomas Hocke
- Cochlear Deutschland GmbH & Co. KG Hannover, Germany
| | - Alexander Müller
- ORL Department Friedrichshain Clinic, Vivantes Hearing Center Berlin, Germany
| | - Holger Kaftan
- University Medicine Greifswald, Department of ENT, Head & Neck Surgery, Germany
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Attina V, Mina F, Stahl P, Duroc Y, Veuillet E, Truy E, Thai-Van H. A New Method to Test the Efficiency of Cochlear Implant Artifacts Removal From Auditory Evoked Potentials. IEEE Trans Neural Syst Rehabil Eng 2017; 25:2453-2460. [PMID: 28692981 DOI: 10.1109/tnsre.2017.2723952] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Auditory evoked potentials are of great interest to objectively evaluate the audition in cochlear implant (CI) recipients. However, these measures are impeded by CI stimulation electrical artifacts present in the EEG. In the first part, this paper investigates the use of a hybrid model approximating CI patient data. This model gives access to both uncontaminated and denoised data, thus allowing for the evaluation of CI artifact removal methods. Here the efficiency of independent component analysis (ICA) is evaluated in the context of auditory steady-state responses (ASSRs). A dedicated experimental setup was developed to simultaneously record EEG data from a normal hearing (NH) participant and CI artifact data from a phantom equipped with a CI. Hybrid data were obtained as a linear mixture of both sources. Amplitude-modulated continuous tones were used as stimuli to elicit ASSRs. After denoising, the comparison of denoised hybrid data and original NH data showed high correlations between the two datasets, demonstrating the efficiency of ICA. In the second part, the ICA was applied to real clinical CI ASSR data. Results support the usefulness of the methodology as regards the performance evaluation of signal processing methods applied to CI patient data prior to clinical application.
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Mina F, Attina V, Duroc Y, Veuillet E, Truy E, Thai-Van H. Auditory steady state responses and cochlear implants: Modeling the artifact-response mixture in the perspective of denoising. PLoS One 2017; 12:e0174462. [PMID: 28350887 PMCID: PMC5370129 DOI: 10.1371/journal.pone.0174462] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 03/09/2017] [Indexed: 11/19/2022] Open
Abstract
Auditory steady state responses (ASSRs) in cochlear implant (CI) patients are contaminated by the spread of a continuous CI electrical stimulation artifact. The aim of this work was to model the electrophysiological mixture of the CI artifact and the corresponding evoked potentials on scalp electrodes in order to evaluate the performance of denoising algorithms in eliminating the CI artifact in a controlled environment. The basis of the proposed computational framework is a neural mass model representing the nodes of the auditory pathways. Six main contributors to auditory evoked potentials from the cochlear level and up to the auditory cortex were taken into consideration. The simulated dynamics were then projected into a 3-layer realistic head model. 32-channel scalp recordings of the CI artifact-response were then generated by solving the electromagnetic forward problem. As an application, the framework’s simulated 32-channel datasets were used to compare the performance of 4 commonly used Independent Component Analysis (ICA) algorithms: infomax, extended infomax, jade and fastICA in eliminating the CI artifact. As expected, two major components were detectable in the simulated datasets, a low frequency component at the modulation frequency and a pulsatile high frequency component related to the stimulation frequency. The first can be attributed to the phase-locked ASSR and the second to the stimulation artifact. Among the ICA algorithms tested, simulations showed that infomax was the most efficient and reliable in denoising the CI artifact-response mixture. Denoising algorithms can induce undesirable deformation of the signal of interest in real CI patient recordings. The proposed framework is a valuable tool for evaluating these algorithms in a controllable environment ahead of experimental or clinical applications.
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Affiliation(s)
- Faten Mina
- Claude Bernard Lyon 1 University, Lyon, France
- Lyon Neuroscience Research Center (Inserm U1028 CNRS UMR5292), Lyon, France
- Department of Audiology and Otoneurological Evaluation, Civil Hospitals of Lyon, Lyon, France
- * E-mail:
| | - Virginie Attina
- Claude Bernard Lyon 1 University, Lyon, France
- Lyon Neuroscience Research Center (Inserm U1028 CNRS UMR5292), Lyon, France
- Department of Audiology and Otoneurological Evaluation, Civil Hospitals of Lyon, Lyon, France
| | - Yvan Duroc
- Claude Bernard Lyon 1 University, Lyon, France
| | - Evelyne Veuillet
- Claude Bernard Lyon 1 University, Lyon, France
- Lyon Neuroscience Research Center (Inserm U1028 CNRS UMR5292), Lyon, France
- Department of Audiology and Otoneurological Evaluation, Civil Hospitals of Lyon, Lyon, France
| | - Eric Truy
- Claude Bernard Lyon 1 University, Lyon, France
- Lyon Neuroscience Research Center (Inserm U1028 CNRS UMR5292), Lyon, France
- ENT Department, Civil Hospitals of Lyon, Lyon, France
| | - Hung Thai-Van
- Claude Bernard Lyon 1 University, Lyon, France
- Lyon Neuroscience Research Center (Inserm U1028 CNRS UMR5292), Lyon, France
- Department of Audiology and Otoneurological Evaluation, Civil Hospitals of Lyon, Lyon, France
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Luke R, Wouters J. Kalman Filter Based Estimation of Auditory Steady State Response Parameters. IEEE Trans Neural Syst Rehabil Eng 2017; 25:196-204. [DOI: 10.1109/tnsre.2016.2551302] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Vercammen C, van Wieringen A, Wouters J, Francart T. Desynchronisation of auditory steady-state responses related to changes in interaural phase differences: an objective measure of binaural hearing. Int J Audiol 2017. [PMID: 28635497 DOI: 10.1080/14992027.2017.1288304] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
OBJECTIVE Binaural processing can be measured objectively as a desynchronisation of phase-locked neural activity to changes in interaural phase differences (IPDs). This was reported in a magnetoencephalography study for 40 Hz amplitude modulated tones. The goal of this study was to measure this desynchronisation using electroencephalography and explore the outcomes for different modulation frequencies. DESIGN Auditory steady-state responses (ASSRs) were recorded to pure tones, amplitude modulated at 20, 40 or 80 Hz. IPDs switched between 0 and 180° at fixed time intervals. STUDY SAMPLE Sixteen young listeners with bilateral normal hearing thresholds (≤25 dB HL at 125-8000 Hz) participated in this study. RESULTS Significant ASSR phase desynchronisations to IPD changes were detected in 14 out of 16 participants for 40 Hz and in 8, respectively 9, out of 13 participants for 20 and 80 Hz modulators. Desynchronisation and restoration of ASSR phase took place significantly faster for 80 Hz than for 40 and 20 Hz. CONCLUSIONS ASSR desynchronisation to IPD changes was successfully recorded using electroencephalography. It was feasible for 20, 40 and 80 Hz modulators and could be an objective tool to assess processing of changes in binaural information.
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Affiliation(s)
- Charlotte Vercammen
- a Department of Neurosciences, Research Group Experimental Otorhinolaryngology , KU Leuven-University of Leuven , Leuven , Belgium
| | - Astrid van Wieringen
- a Department of Neurosciences, Research Group Experimental Otorhinolaryngology , KU Leuven-University of Leuven , Leuven , Belgium
| | - Jan Wouters
- a Department of Neurosciences, Research Group Experimental Otorhinolaryngology , KU Leuven-University of Leuven , Leuven , Belgium
| | - Tom Francart
- a Department of Neurosciences, Research Group Experimental Otorhinolaryngology , KU Leuven-University of Leuven , Leuven , Belgium
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Characterization of cochlear implant artifacts in electrically evoked auditory steady-state responses. Biomed Signal Process Control 2017. [DOI: 10.1016/j.bspc.2016.07.013] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Luke R, De Vos A, Wouters J. Source analysis of auditory steady-state responses in acoustic and electric hearing. Neuroimage 2016; 147:568-576. [PMID: 27894891 DOI: 10.1016/j.neuroimage.2016.11.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Revised: 10/06/2016] [Accepted: 11/05/2016] [Indexed: 11/17/2022] Open
Abstract
Speech is a complex signal containing a broad variety of acoustic information. For accurate speech reception, the listener must perceive modulations over a range of envelope frequencies. Perception of these modulations is particularly important for cochlear implant (CI) users, as all commercial devices use envelope coding strategies. Prolonged deafness affects the auditory pathway. However, little is known of how cochlear implantation affects the neural processing of modulated stimuli. This study investigates and contrasts the neural processing of envelope rate modulated signals in acoustic and CI listeners. Auditory steady-state responses (ASSRs) are used to study the neural processing of amplitude modulated (AM) signals. A beamforming technique is applied to determine the increase in neural activity relative to a control condition, with particular attention paid to defining the accuracy and precision of this technique relative to other tomographies. In a cohort of 44 acoustic listeners, the location, activity and hemispheric lateralisation of ASSRs is characterised while systematically varying the modulation rate (4, 10, 20, 40 and 80Hz) and stimulation ear (right, left and bilateral). We demonstrate a complex pattern of laterality depending on both modulation rate and stimulation ear that is consistent with, and extends, existing literature. We present a novel extension to the beamforming method which facilitates source analysis of electrically evoked auditory steady-state responses (EASSRs). In a cohort of 5 right implanted unilateral CI users, the neural activity is determined for the 40Hz rate and compared to the acoustic cohort. Results indicate that CI users activate typical thalamic locations for 40Hz stimuli. However, complementary to studies of transient stimuli, the CI population has atypical hemispheric laterality, preferentially activating the contralateral hemisphere.
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Affiliation(s)
- Robert Luke
- Research Group Experimental ORL, Department of Neurosciences, KU Leuven - University of Leuven, Belgium
| | - Astrid De Vos
- Research Group Experimental ORL, Department of Neurosciences, KU Leuven - University of Leuven, Belgium; Parenting and Special Education Research Unit, Faculty of Psychology and Educational Sciences, KU Leuven - University of Leuven, Belgium
| | - Jan Wouters
- Research Group Experimental ORL, Department of Neurosciences, KU Leuven - University of Leuven, Belgium
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Deprez H, Gransier R, Hofmann M, van Wieringen A, Wouters J, Moonen M. Template Subtraction to Remove CI Stimulation Artifacts in Auditory Steady-State Responses in CI Subjects. IEEE Trans Neural Syst Rehabil Eng 2016; 25:1322-1331. [PMID: 27810831 DOI: 10.1109/tnsre.2016.2622979] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Cochlear implant (CI) stimulation artifacts are currently removed from electrically evoked steady-state response (EASSR) measurements based on a linear interpolation (LI) over the artifact-contaminated signal parts. LI is only successful if CI stimulation artifacts are shorter than the interpulse interval, i.e., for contralateral channels and stimulation pulse rates up to 500 pulses per second (pps). The objective of this paper is to develop and evaluate a template subtraction (TS) method to remove continuous CI stimulation artifacts in order to accurately measure EASSRs. The template construction (TC) is based on an EEG recording containing CI stimulation artifacts but no synchronous neural response. The constructed templates are subtracted from the recording of interest. Response amplitudes and latencies are compared for the TS and LI method, and for different TC durations. The response amplitudes and latencies in contralateral channels are the same after TS and LI, as expected. In ipsilateral channels, response amplitudes and latencies are within the expected range only after TS. The TC duration can be reduced from 5 min to 1 min without a significant effect on response latency. TS with a TC duration of only 1 min allows to remove all CI stimulation artifacts in individual contra- and ipsilateral EEG recording channels.
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Abstract
We assessed neural sensitivity to interaural time differences (ITDs) conveyed in the temporal fine structure (TFS) of low-frequency sounds and ITDs conveyed in the temporal envelope of amplitude-modulated (AM'ed) high-frequency sounds. Using electroencephalography (EEG), we recorded brain activity to sounds in which the interaural phase difference (IPD) of the TFS (or the modulated temporal envelope) was repeatedly switched between leading in one ear or the other. When the amplitude of the tones is modulated equally in the two ears at 41 Hz, the interaural phase modulation (IPM) evokes an IPM following-response (IPM-FR) in the EEG signal. For low-frequency signals, IPM-FRs were reliably obtained, and largest for an IPM rate of 6.8 Hz and when IPD switches (around 0°) were in the range 45-90°. IPDs conveyed in envelope of high-frequency tones also generated IPM-FRs; response maxima occurred for IPDs switched between 0° and 180° IPD. This is consistent with the interpretation that distinct binaural mechanisms generate the IPM-FR at low and high frequencies, and with the reported physiological responses of medial superior olive (MSO) and lateral superior olive (LSO) neurons in other mammals. Low-frequency binaural neurons in the MSO are considered maximally activated by IPDs in the range 45-90°, consistent with their reception of excitatory inputs from both ears. High-frequency neurons in the LSO receive excitatory and inhibitory input from the two ears receptively--as such maximum activity occurs when the sounds at the two ears are presented out of phase.
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Gransier R, Deprez H, Hofmann M, Moonen M, van Wieringen A, Wouters J. Auditory steady-state responses in cochlear implant users: Effect of modulation frequency and stimulation artifacts. Hear Res 2016; 335:149-160. [PMID: 26994660 DOI: 10.1016/j.heares.2016.03.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 03/04/2016] [Accepted: 03/14/2016] [Indexed: 11/29/2022]
Abstract
Previous studies have shown that objective measures based on stimulation with low-rate pulse trains fail to predict the threshold levels of cochlear implant (CI) users for high-rate pulse trains, as used in clinical devices. Electrically evoked auditory steady-state responses (EASSRs) can be elicited by modulated high-rate pulse trains, and can potentially be used to objectively determine threshold levels of CI users. The responsiveness of the auditory pathway of profoundly hearing-impaired CI users to modulation frequencies is, however, not known. In the present study we investigated the responsiveness of the auditory pathway of CI users to a monopolar 500 pulses per second (pps) pulse train modulated between 1 and 100 Hz. EASSRs to forty-three modulation frequencies, elicited at the subject's maximum comfort level, were recorded by means of electroencephalography. Stimulation artifacts were removed by a linear interpolation between a pre- and post-stimulus sample (i.e., blanking). The phase delay across modulation frequencies was used to differentiate between the neural response and a possible residual stimulation artifact after blanking. Stimulation artifacts were longer than the inter-pulse interval of the 500pps pulse train for recording electrodes ipsilateral to the CI. As a result the stimulation artifacts could not be removed by artifact removal on the bases of linear interpolation for recording electrodes ipsilateral to the CI. However, artifact-free responses could be obtained in all subjects from recording electrodes contralateral to the CI, when subject specific reference electrodes (Cz or Fpz) were used. EASSRs to modulation frequencies within the 30-50 Hz range resulted in significant responses in all subjects. Only a small number of significant responses could be obtained, during a measurement period of 5 min, that originate from the brain stem (i.e., modulation frequencies in the 80-100 Hz range). This reduced synchronized activity of brain stem responses in long-term severely-hearing impaired CI users could be an attribute of processes associated with long-term hearing impairment and/or electrical stimulation.
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Affiliation(s)
- Robin Gransier
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 Leuven, Belgium.
| | - Hanne Deprez
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 Leuven, Belgium; STADIUS, Dept. of Electrical Engineering (ESAT), KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium
| | - Michael Hofmann
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 Leuven, Belgium
| | - Marc Moonen
- STADIUS, Dept. of Electrical Engineering (ESAT), KU Leuven, Kasteelpark Arenberg 10, 3001 Leuven, Belgium
| | - Astrid van Wieringen
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 Leuven, Belgium
| | - Jan Wouters
- ExpORL, Dept. of Neurosciences, KU Leuven, Herestraat 49 bus 721, 3000 Leuven, Belgium
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Hu H, Dietz M. Comparison of Interaural Electrode Pairing Methods for Bilateral Cochlear Implants. Trends Hear 2015; 19:19/0/2331216515617143. [PMID: 26631108 PMCID: PMC4771032 DOI: 10.1177/2331216515617143] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In patients with bilateral cochlear implants (CIs), pairing matched interaural electrodes and stimulating them with the same frequency band is expected to facilitate binaural functions such as binaural fusion, localization, and spatial release from masking. Because clinical procedures typically do not include patient-specific interaural electrode pairing, it remains the case that each electrode is allocated to a generic frequency range, based simply on the electrode number. Two psychoacoustic techniques for determining interaurally paired electrodes have been demonstrated in several studies: interaural pitch comparison and interaural time difference (ITD) sensitivity. However, these two methods are rarely, if ever, compared directly. A third, more objective method is to assess the amplitude of the binaural interaction component (BIC) derived from electrically evoked auditory brainstem responses for different electrode pairings; a method has been demonstrated to be a potential candidate for bilateral CI users. Here, we tested all three measures in the same eight CI users. We found good correspondence between the electrode pair producing the largest BIC and the electrode pair producing the maximum ITD sensitivity. The correspondence between the pairs producing the largest BIC and the pitch-matched electrode pairs was considerably weaker, supporting the previously proposed hypothesis that whilst place pitch might adapt over time to accommodate mismatched inputs, sensitivity to ITDs does not adapt to the same degree.
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Affiliation(s)
- Hongmei Hu
- Medizinische Physik, Universität Oldenburg and Cluster of Excellence "Hearing4all", Germany
| | - Mathias Dietz
- Medizinische Physik, Universität Oldenburg and Cluster of Excellence "Hearing4all", Germany
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