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Nina Kraus - One of the best experts on this subject based on the ideXlab platform.
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non stimulus evoked activity as a measure of neural noise in the Frequency Following Response
Journal of Neuroscience Methods, 2021Co-Authors: Jennifer Krizman, Silvia Bonacina, Rembrandt Ottomeyer, Nina KrausAbstract:Abstract Background The Frequency-Following Response, or FFR, is a neurophysiologic Response that captures distinct aspects of sound processing. Like all evoked Responses, FFR is susceptible to electric and myogenic noise contamination during collection. Click-evoked auditory brainstem Response collection standards have been adopted for FFR collection, however, whether these standards sufficiently limit FFR noise contamination is unknown. Thus, a critical question remains: to what extent do distinct FFR components reflect noise contamination? This is especially relevant for prestimulus amplitude (i.e., activity preceding the evoked Response), as this measure has been used to index both noise contamination and neural noise. New method We performed two experiments. First, using >1000 young-adult FFRs, we ran regressions to determine the variance explained by myogenic and electrical noise, as indexed by artifact rejection count and electrode impedance, on each FFR component. Second, we reanalyzed prestimulus amplitude differences attributed to athletic experience and socioeconomic status, adding covariates of artifact rejection and impedance. Results We found that non-neural noise marginally contributed to FFR components and could not explain group differences on prestimulus amplitude. Comparison with existing method Prestimulus amplitude has been considered a measure of non-neural noise contamination. However, non-neural noise was not the sole contributor to variance in this measure and did not explain group differences. Conclusions Results from the two experiments suggest that the effects of non-neural noise on FFR components are minimal and do not obscure individual differences in the FFR and that prestimulus amplitude indexes neural noise.
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case studies in neuroscience cortical contributions to the Frequency Following Response depend on subcortical synchrony
Journal of Neurophysiology, 2021Co-Authors: Travis Whiteschwoch, Jennifer Krizman, Trent Nicol, Nina KrausAbstract:A listener with auditory neuropathy, an absence of subcortical neural synchrony, did not have electrophysiological Frequency-Following Responses synchronized to an octave of musical notes, with fun...
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Auditory neurophysiology reveals central nervous system dysfunction in HIV-infected individuals.
Clinical Neurophysiology, 2020Co-Authors: Travis White-schwoch, Nina Kraus, Albert Magohe, Abigail M. Fellows, Catherine C. Rieke, Brandon Vilarello, Trent Nicol, Enica Richard Massawe, Ndeserua Moshi, Jay C. BuckeyAbstract:Abstract Objective To test the hypothesis that human immunodeficiency virus (HIV) affects auditory-neurophysiological functions. Methods A convenience sample of 68 HIV+ and 59 HIV- normal-hearing adults was selected from a study set in Dar es Salaam, Tanzania. The speech-evoked Frequency-Following Response (FFR), an objective measure of auditory function, was collected. Outcome measures were FFRs to the fundamental Frequency (F0) and to harmonics corresponding to the first formant (F1), two behaviorally relevant cues for understanding speech. Results The HIV+ group had weaker Responses to the F1 than the HIV- group; this effect generalized across multiple stimuli (d = 0.59). Responses to the F0 were similar between groups. Conclusions Auditory-neurophysiological Responses differ between HIV+ and HIV- adults despite normal hearing thresholds. Significance The FFR may reflect HIV-associated central nervous system dysfunction that manifests as disrupted auditory processing of speech harmonics corresponding to the first formant.
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case studies in neuroscience subcortical origins of the Frequency Following Response
Journal of Neurophysiology, 2019Co-Authors: Travis Whiteschwoch, Jennifer Krizman, Trent Nicol, Samira Anderson, Nina KrausAbstract:The Frequency-Following Response (FFR) reflects synchronized and phase-locked neural activity in Response to sound. The authors present a dual case study, comparing FFRs and cortical potentials be...
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the Frequency Following Response a window into human communication
2017Co-Authors: Nina Kraus, Samira Anderson, Travis WhiteschwochAbstract:The Frequency-Following Response (FFR) is a measure of synchronous sound-evoked neural activity that reveals the integrity of sound processing in the brain. Studies of the FFR are organized around two intertwining themes: learning and everyday communication. These studies tie into a conceptual framework wherein making sense of sound is fundamental to everyday life and is at the intersection of cognitive, sensorimotor, and reward networks. Understanding how well an individual listener processes sound provides a snapshot of auditory function and its impact on everyday communication skills. This chapter provides an overview of FFR research and contends that the FFR is a measure that reflects an individual’s past and potential in sound. Despite diverse terminology in the field, it is argued that FFR provides a good umbrella term for these biological approaches. A brief historical perspective illustrates how FFR has a longstanding history in auditory neuroscience and has addressed many basic and clinical questions in hearing. The FFR is on its way to becoming a mainstream tool in neuroscience. Perhaps most exciting is the potential for use in brain screening to assess hearing in newborns to evaluate risk for communication impairments, setting the stage for early interventions that offset a life spent struggling to learn and communicate.
Robert J Zatorre - One of the best experts on this subject based on the ideXlab platform.
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oscillatory entrainment of the Frequency Following Response in auditory cortical and subcortical structures
The Journal of Neuroscience, 2021Co-Authors: Emily B J Coffey, Xiaochen Zhang, Isabelle Arseneaubruneau, Sylvain Baillet, Robert J ZatorreAbstract:There is much debate about the existence and function of neural oscillatory mechanisms in the auditory system. The Frequency-Following Response (FFR) is an index of neural periodicity encoding that can provide a vehicle to study entrainment in Frequency ranges relevant to speech and music processing. Criteria for entrainment include the presence of poststimulus oscillations and phase alignment between stimulus and endogenous activity. To test the hypothesis of entrainment, in experiment 1 we collected FFR data for a repeated syllable using magnetoencephalography (MEG) and electroencephalography in 20 male and female human adults. We observed significant oscillatory activity after stimulus offset in auditory cortex and subcortical auditory nuclei, consistent with entrainment. In these structures, the FFR fundamental Frequency converged from a lower value over 100 ms to the stimulus Frequency, consistent with phase alignment, and diverged to a lower value after offset, consistent with relaxation to a preferred Frequency. In experiment 2, we tested how transitions between stimulus frequencies affected the MEG FFR to a train of tone pairs in 30 people. We found that the FFR was affected by the Frequency of the preceding tone for up to 40 ms at subcortical levels, and even longer durations at cortical levels. Our results suggest that oscillatory entrainment may be an integral part of periodic sound representation throughout the auditory neuraxis. The functional role of this mechanism is unknown, but it could serve as a fine-scale temporal predictor for Frequency information, enhancing stability and reducing susceptibility to degradation that could be useful in real-life noisy environments. SIGNIFICANCE STATEMENT Neural oscillations are proposed to be a ubiquitous aspect of neural function, but their contribution to auditory encoding is not clear, particularly at higher frequencies associated with pitch encoding. In a magnetoencephalography experiment, we found converging evidence that the Frequency-Following Response has an oscillatory component according to established criteria: poststimulus resonance, progressive entrainment of the neural Frequency to the stimulus Frequency, and relaxation toward the original state on stimulus offset. In a second experiment, we found that the Frequency and amplitude of the Frequency-Following Response to tones are affected by preceding stimuli. These findings support the contribution of intrinsic oscillations to the encoding of sound, and raise new questions about their functional roles, possibly including stabilization and low-level predictive coding.
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oscillatory entrainment of the Frequency Following Response in auditory cortical and subcortical structures
bioRxiv, 2020Co-Authors: Emily B J Coffey, Xiaochen Zhang, Isabelle Arseneaubruneau, Sylvain Baillet, Robert J ZatorreAbstract:Abstract There is much debate about the existence and function of neural oscillatory entrainment mechanisms in the auditory system. The Frequency-Following Response (FFR) is an index of neural periodicity encoding that can provide a vehicle to study entrainment in Frequency ranges relevant to speech and music processing. Criteria for entrainment include the presence of post-stimulus oscillations and phase alignment between stimulus and endogenous activity. To test the hypothesis of entrainment, in experiment 1 we collected FFR data to a repeated syllable using magneto- (MEG) and electroencephalography in 20 healthy adults. We observed significant oscillatory activity after stimulus offset in auditory cortex and subcortical auditory nuclei, consistent with entrainment. In these structures the FFR fundamental Frequency converged from a lower value over 100 ms to the stimulus Frequency, consistent with phase alignment, and diverged to a lower value after offset, consistent with relaxation to a preferred Frequency. In experiment 2, we tested how transitions between stimulus frequencies affected the MEG-FFR to a train of pure-tone pairs in 30 adults. We found that the FFR was affected by the Frequency of the preceding tone for up to 40 ms at subcortical levels, and even longer durations at cortical levels. Our results suggest that oscillatory entrainment may be an integral part of periodic sound representation throughout the auditory neuraxis. The functional role of this mechanism is unknown, but it could serve as a fine-scale temporal predictor for Frequency information, enhancing stability and reducing susceptibility to degradation that could be useful in real-life noisy environments.
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evolving perspectives on the sources of the Frequency Following Response
Nature Communications, 2019Co-Authors: Jennifer Krizman, Travis Whiteschwoch, Bharath Chandrasekaran, Trent Nicol, Emily B J Coffey, Erika Skoe, Robert J ZatorreAbstract:The auditory Frequency-Following Response (FFR) is a non-invasive index of the fidelity of sound encoding in the brain, and is used to study the integrity, plasticity, and behavioral relevance of the neural encoding of sound. In this Perspective, we review recent evidence suggesting that, in humans, the FFR arises from multiple cortical and subcortical sources, not just subcortically as previously believed, and we illustrate how the FFR to complex sounds can enhance the wider field of auditory neuroscience. Far from being of use only to study basic auditory processes, the FFR is an uncommonly multifaceted Response yielding a wealth of information, with much yet to be tapped.
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Individual Differences in the Frequency-Following Response: Relation to Pitch Perception
PLOS ONE, 2016Co-Authors: Emily B J Coffey, Alexandre Lehmann, Emilia M. G. Colagrosso, Marc Schönwiesner, Robert J ZatorreAbstract:The scalp-recorded Frequency-Following Response (FFR) is a measure of the auditory nervous system’s representation of periodic sound, and may serve as a marker of training-related enhancements, behavioural deficits, and clinical conditions. However, FFRs of healthy normal subjects show considerable variability that remains unexplained. We investigated whether the FFR representation of the Frequency content of a complex tone is related to the perception of the pitch of the fundamental Frequency. The strength of the fundamental Frequency in the FFR of 39 people with normal hearing was assessed when they listened to complex tones that either included or lacked energy at the fundamental Frequency. We found that the strength of the fundamental representation of the missing fundamental tone complex correlated significantly with people's general tendency to perceive the pitch of the tone as either matching the Frequency of the spectral components that were present, or that of the missing fundamental. Although at a group level the fundamental representation in the FFR did not appear to be affected by the presence or absence of energy at the same Frequency in the stimulus, the two conditions were statistically distinguishable for some subjects individually, indicating that the neural representation is not linearly dependent on the stimulus content. In a second experiment using a within-subjects paradigm, we showed that subjects can learn to reversibly select between either fundamental or spectral perception, and that this is accompanied both by changes to the fundamental representation in the FFR and to cortical-based gamma activity. These results suggest that both fundamental and spectral representations coexist, and are available for later auditory processing stages, the requirements of which may also influence their relative strength and thus modulate FFR variability. The data also highlight voluntary mode perception as a new paradigm with which to study top-down vs bottom-up mechanisms that support the emerging view of the FFR as the outcome of integrated processing in the entire auditory system.
Gavin M Bidelman - One of the best experts on this subject based on the ideXlab platform.
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subcortical rather than cortical sources of the Frequency Following Response ffr relate to speech in noise perception in normal hearing listeners
Neuroscience Letters, 2021Co-Authors: Gavin M Bidelman, Sara MomtazAbstract:Abstract Scalp-recorded Frequency-Following Responses (FFRs) reflect a mixture of phase-locked activity across the auditory pathway. FFRs have been widely used as a neural barometer of complex listening skills, especially speech-in noise (SIN) perception. Applying individually optimized source reconstruction to speech-FFRs recorded via EEG (FFREEG), we assessed the relative contributions of subcortical [auditory nerve (AN), brainstem/midbrain (BS)] and cortical [bilateral primary auditory cortex, PAC] source generators with the aim of identifying which source(s) drive the brain-behavior relation between FFRs and SIN listening skills. We found FFR strength declined precipitously from AN to PAC, consistent with diminishing phase-locking along the ascending auditory neuroaxis. FFRs to the speech fundamental (F0) were robust to noise across sources, but were largest in subcortical sources (BS > AN > PAC). PAC FFRs were only weakly observed above the noise floor and only at the low pitch of speech (F0≈100 Hz). Brain-behavior regressions revealed (i) AN and BS FFRs were sufficient to describe listeners’ QuickSIN scores and (ii) contrary to neuromagnetic (MEG) FFRs, neither left nor right PAC FFREEG related to SIN performance. Our findings suggest subcortical sources not only dominate the electrical FFR but also the link between speech-FFRs and SIN processing in normal-hearing adults as observed in previous EEG studies.
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subcortical rather than cortical sources of the Frequency Following Response ffr relate to speech in noise perception
bioRxiv, 2020Co-Authors: Gavin M Bidelman, Sara MomtazAbstract:ABSTRACT Scalp-recorded Frequency-Following Responses (FFRs) reflect a mixture of phase-locked activity across the auditory pathway. FFRs have been widely used as a neural barometer of complex listening skills, especially speech-in noise (SIN) perception. Applying individually optimized source reconstruction to speech-FFRs recorded via EEG (FFREEG), we assessed the relative contributions of subcortical [auditory nerve (AN), brainstem/midbrain (BS)] and cortical [bilateral primary auditory cortex, PAC] source generators with the aim of identifying which source(s) drive the brain-behavior relation between FFRs and SIN listening skills. We found FFR strength declined precipitously from AN to PAC, consistent with diminishing phase-locking along the ascending auditory neuroaxis. FFRs to the speech fundamental (F0) were robust to noise across sources, but were largest in subcortical sources (BS > AN > PAC). PAC FFRs were only weakly observed above the noise floor and only at the low pitch of speech (F0≈100 Hz). Brain-behavior regressions revealed (i) AN and BS FFRs were sufficient to describe listeners’ QuickSIN scores and (ii) contrary to neuromagnetic (MEG) FFRs, neither left nor right PAC FFREEG predicted SIN performance. Our preliminary findings suggest subcortical sources not only dominate the electrical FFR but also the link between speech-FFRs and SIN processing as observed in previous EEG studies.
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brainstem correlates of cochlear nonlinearity measured via the scalp recorded Frequency Following Response
Neuroreport, 2020Co-Authors: Gavin M Bidelman, Shaum P BhagatAbstract:The Frequency-Following Response (FFR) is an EEG-based potential used to characterize the brainstem encoding of complex sounds. Adopting techniques from auditory signal processing, we assessed the degree to which FFRs encode important properties of cochlear processing (e.g. nonlinearities) and their relation to speech-in-noise (SIN) listening skills. Based on the premise that normal cochlear transduction is characterized by rectification and compression, we reasoned these nonlinearities would create measurable harmonic distortion in FFRs in Response to even pure tone input. We recorded FFRs to nonspeech (pure- and amplitude-modulated-tones) stimuli in normal-hearing individuals. We then compared conventional indices of cochlear nonlinearity, via distortion product otoacoustic emission (DPOAE) I/O functions, to total harmonic distortion measured from neural FFRs (FFRTHD). Analysis of DPOAE growth and the FFRTHD revealed listeners with higher cochlear compression thresholds had lower neural FFRTHD distortion (i.e. more linear FFRs), thus linking cochlear and brainstem correlates of auditory nonlinearity. Importantly, FFRTHD was also negatively correlated with SIN perception whereby listeners with higher FFRTHD (i.e. more nonlinear Responses) showed better performance on the QuickSIN. We infer individual differences in SIN perception and FFR nonlinearity even in normal-hearing individuals may reflect subtle differences in auditory health and suprathreshold hearing skills not captured by normal audiometric evaluation. Future studies in hearing-impaired individuals and animal models are necessary to confirm the diagnostic utility of FFRTHD and its relation to cochlear hearing loss or peripheral neurodegeneration in humans.
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subcortical sources dominate the neuroelectric auditory Frequency Following Response to speech
NeuroImage, 2018Co-Authors: Gavin M BidelmanAbstract:Abstract Frequency-Following Responses (FFRs) are neurophonic potentials that provide a window into the encoding of complex sounds (e.g., speech/music), auditory disorders, and neuroplasticity. While the neural origins of the FFR remain debated, renewed controversy has reemerged after demonstration that FFRs recorded via magnetoencephalography (MEG) are dominated by cortical rather than brainstem structures as previously assumed. Here, we recorded high-density (64 ch) FFRs via EEG and applied state-of-the art source imaging techniques to multichannel data (discrete dipole modeling, distributed imaging, independent component analysis, computational simulations). Our data confirm a mixture of generators localized to bilateral auditory nerve (AN), brainstem inferior colliculus (BS), and bilateral primary auditory cortex (PAC). However, Frequency-specific scrutiny of source waveforms showed the relative contribution of these nuclei to the aggregate FFR varied across stimulus frequencies. Whereas AN and BS sources produced robust FFRs up to ∼700 Hz, PAC showed weak phase-locking with little FFR energy above the speech fundamental (100 Hz). Notably, CLARA imaging further showed PAC activation was eradicated for FFRs >150 Hz, above which only subcortical sources remained active. Our results show (i) the site of FFR generation varies critically with stimulus Frequency; and (ii) opposite the pattern observed in MEG, subcortical structures make the largest contribution to electrically recorded FFRs (AN ≥ BS > PAC). We infer that cortical dominance observed in previous neuromagnetic data is likely due to the bias of MEG to superficial brain tissue, underestimating subcortical structures that drive most of the speech-FFR. Cleanly separating subcortical from cortical FFRs can be achieved by ensuring stimulus frequencies are >150–200 Hz, above the phase-locking limit of cortical neurons.
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Response properties of the human Frequency Following Response ffr to speech and non speech sounds level dependence adaptation and phase locking limits
International Journal of Audiology, 2018Co-Authors: Gavin M Bidelman, Louise PowersAbstract:AbstractObjective: The Frequency-Following Response (FFR) is a neurophonic potential used to assess auditory neural encoding at subcortical stages. Despite the FFR’s empirical and clinical utility, basic Response properties of this evoked potential remain undefined.Design: We measured FFRs to speech and nonspeech (pure tone, chirp sweeps) stimuli to quantify three key properties of this potential: level-dependence (I/O functions), adaptation and the upper limit of neural phase-locking.Study sample: n = 13 normal-hearing listeners.Results: I/O functions showed FFR amplitude increased with increasing stimulus presentation level between 25 and 80 dB SPL; FFR growth was steeper for tones than speech when measured at the same Frequency. FFR latency decreased 4–5 ms with decreasing presentation level from 25 and 80 dB SPL but Responses were ∼2 ms earlier for speech than tones. FFR amplitudes showed a 50% reduction over 6 min of recording with the strongest adaptation in the first 60 s (250 trials). Estimates of...
Emily B J Coffey - One of the best experts on this subject based on the ideXlab platform.
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oscillatory entrainment of the Frequency Following Response in auditory cortical and subcortical structures
The Journal of Neuroscience, 2021Co-Authors: Emily B J Coffey, Xiaochen Zhang, Isabelle Arseneaubruneau, Sylvain Baillet, Robert J ZatorreAbstract:There is much debate about the existence and function of neural oscillatory mechanisms in the auditory system. The Frequency-Following Response (FFR) is an index of neural periodicity encoding that can provide a vehicle to study entrainment in Frequency ranges relevant to speech and music processing. Criteria for entrainment include the presence of poststimulus oscillations and phase alignment between stimulus and endogenous activity. To test the hypothesis of entrainment, in experiment 1 we collected FFR data for a repeated syllable using magnetoencephalography (MEG) and electroencephalography in 20 male and female human adults. We observed significant oscillatory activity after stimulus offset in auditory cortex and subcortical auditory nuclei, consistent with entrainment. In these structures, the FFR fundamental Frequency converged from a lower value over 100 ms to the stimulus Frequency, consistent with phase alignment, and diverged to a lower value after offset, consistent with relaxation to a preferred Frequency. In experiment 2, we tested how transitions between stimulus frequencies affected the MEG FFR to a train of tone pairs in 30 people. We found that the FFR was affected by the Frequency of the preceding tone for up to 40 ms at subcortical levels, and even longer durations at cortical levels. Our results suggest that oscillatory entrainment may be an integral part of periodic sound representation throughout the auditory neuraxis. The functional role of this mechanism is unknown, but it could serve as a fine-scale temporal predictor for Frequency information, enhancing stability and reducing susceptibility to degradation that could be useful in real-life noisy environments. SIGNIFICANCE STATEMENT Neural oscillations are proposed to be a ubiquitous aspect of neural function, but their contribution to auditory encoding is not clear, particularly at higher frequencies associated with pitch encoding. In a magnetoencephalography experiment, we found converging evidence that the Frequency-Following Response has an oscillatory component according to established criteria: poststimulus resonance, progressive entrainment of the neural Frequency to the stimulus Frequency, and relaxation toward the original state on stimulus offset. In a second experiment, we found that the Frequency and amplitude of the Frequency-Following Response to tones are affected by preceding stimuli. These findings support the contribution of intrinsic oscillations to the encoding of sound, and raise new questions about their functional roles, possibly including stabilization and low-level predictive coding.
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oscillatory entrainment of the Frequency Following Response in auditory cortical and subcortical structures
bioRxiv, 2020Co-Authors: Emily B J Coffey, Xiaochen Zhang, Isabelle Arseneaubruneau, Sylvain Baillet, Robert J ZatorreAbstract:Abstract There is much debate about the existence and function of neural oscillatory entrainment mechanisms in the auditory system. The Frequency-Following Response (FFR) is an index of neural periodicity encoding that can provide a vehicle to study entrainment in Frequency ranges relevant to speech and music processing. Criteria for entrainment include the presence of post-stimulus oscillations and phase alignment between stimulus and endogenous activity. To test the hypothesis of entrainment, in experiment 1 we collected FFR data to a repeated syllable using magneto- (MEG) and electroencephalography in 20 healthy adults. We observed significant oscillatory activity after stimulus offset in auditory cortex and subcortical auditory nuclei, consistent with entrainment. In these structures the FFR fundamental Frequency converged from a lower value over 100 ms to the stimulus Frequency, consistent with phase alignment, and diverged to a lower value after offset, consistent with relaxation to a preferred Frequency. In experiment 2, we tested how transitions between stimulus frequencies affected the MEG-FFR to a train of pure-tone pairs in 30 adults. We found that the FFR was affected by the Frequency of the preceding tone for up to 40 ms at subcortical levels, and even longer durations at cortical levels. Our results suggest that oscillatory entrainment may be an integral part of periodic sound representation throughout the auditory neuraxis. The functional role of this mechanism is unknown, but it could serve as a fine-scale temporal predictor for Frequency information, enhancing stability and reducing susceptibility to degradation that could be useful in real-life noisy environments.
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evolving perspectives on the sources of the Frequency Following Response
Nature Communications, 2019Co-Authors: Jennifer Krizman, Travis Whiteschwoch, Bharath Chandrasekaran, Trent Nicol, Emily B J Coffey, Erika Skoe, Robert J ZatorreAbstract:The auditory Frequency-Following Response (FFR) is a non-invasive index of the fidelity of sound encoding in the brain, and is used to study the integrity, plasticity, and behavioral relevance of the neural encoding of sound. In this Perspective, we review recent evidence suggesting that, in humans, the FFR arises from multiple cortical and subcortical sources, not just subcortically as previously believed, and we illustrate how the FFR to complex sounds can enhance the wider field of auditory neuroscience. Far from being of use only to study basic auditory processes, the FFR is an uncommonly multifaceted Response yielding a wealth of information, with much yet to be tapped.
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Individual Differences in the Frequency-Following Response: Relation to Pitch Perception
PLOS ONE, 2016Co-Authors: Emily B J Coffey, Alexandre Lehmann, Emilia M. G. Colagrosso, Marc Schönwiesner, Robert J ZatorreAbstract:The scalp-recorded Frequency-Following Response (FFR) is a measure of the auditory nervous system’s representation of periodic sound, and may serve as a marker of training-related enhancements, behavioural deficits, and clinical conditions. However, FFRs of healthy normal subjects show considerable variability that remains unexplained. We investigated whether the FFR representation of the Frequency content of a complex tone is related to the perception of the pitch of the fundamental Frequency. The strength of the fundamental Frequency in the FFR of 39 people with normal hearing was assessed when they listened to complex tones that either included or lacked energy at the fundamental Frequency. We found that the strength of the fundamental representation of the missing fundamental tone complex correlated significantly with people's general tendency to perceive the pitch of the tone as either matching the Frequency of the spectral components that were present, or that of the missing fundamental. Although at a group level the fundamental representation in the FFR did not appear to be affected by the presence or absence of energy at the same Frequency in the stimulus, the two conditions were statistically distinguishable for some subjects individually, indicating that the neural representation is not linearly dependent on the stimulus content. In a second experiment using a within-subjects paradigm, we showed that subjects can learn to reversibly select between either fundamental or spectral perception, and that this is accompanied both by changes to the fundamental representation in the FFR and to cortical-based gamma activity. These results suggest that both fundamental and spectral representations coexist, and are available for later auditory processing stages, the requirements of which may also influence their relative strength and thus modulate FFR variability. The data also highlight voluntary mode perception as a new paradigm with which to study top-down vs bottom-up mechanisms that support the emerging view of the FFR as the outcome of integrated processing in the entire auditory system.
Ananthanarayan Krishnan - One of the best experts on this subject based on the ideXlab platform.
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Human Frequency Following Response: Neural Representation of Envelope and Temporal Fine Structure in Listeners with Normal Hearing and Sensorineural Hearing Loss.
Ear and Hearing, 2016Co-Authors: Saradha Ananthakrishnan, Ananthanarayan Krishnan, Edward L. BartlettAbstract:OBJECTIVE: Listeners with sensorineural hearing loss (SNHL) typically experience reduced speech perception, which is not completely restored with amplification. This likely occurs because cochlear damage, in addition to elevating audiometric thresholds, alters the neural representation of speech transmitted to higher centers along the auditory neuroaxis. While the deleterious effects of SNHL on speech perception in humans have been well-documented using behavioral paradigms, our understanding of the neural correlates underlying these perceptual deficits remains limited. Using the scalp-recorded Frequency Following Response (FFR), the authors examine the effects of SNHL and aging on subcortical neural representation of acoustic features important for pitch and speech perception, namely the periodicity envelope (F0) and temporal fine structure (TFS; formant structure), as reflected in the phase-locked neural activity generating the FFR. DESIGN: FFRs were obtained from 10 listeners with normal hearing (NH) and 9 listeners with mild-moderate SNHL in Response to a steady-state English back vowel /u/ presented at multiple intensity levels. Use of multiple presentation levels facilitated comparisons at equal sound pressure level (SPL) and equal sensation level. In a second follow-up experiment to address the effect of age on envelope and TFS representation, FFRs were obtained from 25 NH and 19 listeners with mild to moderately severe SNHL to the same vowel stimulus presented at 80 dB SPL. Temporal waveforms, Fast Fourier Transform and spectrograms were used to evaluate the magnitude of the phase-locked activity at F0 (periodicity envelope) and F1 (TFS). RESULTS: Neural representation of both envelope (F0) and TFS (F1) at equal SPLs was stronger in NH listeners compared with listeners with SNHL. Also, comparison of neural representation of F0 and F1 across stimulus levels expressed in SPL and sensation level (accounting for audibility) revealed that level-related changes in F0 and F1 magnitude were different for listeners with SNHL compared with listeners with NH. Furthermore, the degradation in subcortical neural representation was observed to persist in listeners with SNHL even when the effects of age were controlled for. CONCLUSIONS: Overall, our results suggest a relatively greater degradation in the neural representation of TFS compared with periodicity envelope in individuals with SNHL. This degraded neural representation of TFS in SNHL, as reflected in the brainstem FFR, may reflect a disruption in the temporal pattern of phase-locked neural activity arising from altered tonotopic maps and/or wider filters causing poor Frequency selectivity in these listeners. Finally, while preliminary results indicate that the deleterious effects of SNHL may be greater than age-related degradation in subcortical neural representation, the lack of a balanced age-matched control group in this study does not permit us to completely rule out the effects of age on subcortical neural representation.
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aging alters the perception and physiological representation of Frequency evidence from human Frequency Following Response recordings
Hearing Research, 2010Co-Authors: Christopher G Clinard, Kelly L Tremblay, Ananthanarayan KrishnanAbstract:Abstract Older adults, even with clinically normal hearing sensitivity, have auditory perceptual deficits relative to their younger counterparts. This difficulty may in part, be related to a decline in the neural representation of Frequency. The purpose of this study was to examine the effect of age on behavioral and physiological measures of Frequency representation. Thirty two adults (ages 22–77), with hearing thresholds ⩽25 dB HL at octave frequencies 0.25–8.0 kHz, participated in this experiment. Frequency discrimination difference limens (FDLs) were obtained at 500 and 1000 Hz using a two-interval, two-alternative forced choice procedure. Linear regression analyses showed significant declines in FDLs at both frequencies as age increased. Frequency-Following Responses (FFRs) were elicited by 500 and 1000 Hz tonebursts, as well as at frequencies within and outside those FDLs. Linear regression of FFR phase coherence and FFR amplitude at frequencies at and slightly below 1000 Hz showed significant decreases as age increased. Therefore, pitch discrimination, as measured by FDLs, and neural representation of Frequency, as reflected by FFR, declined as age increased. Although perception and neural representation concurrently declined, one was not predictive of the other.
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human Frequency Following Response to speech like sounds correlates of off Frequency masking
Audiology and Neuro-otology, 2010Co-Authors: Ananthanarayan Krishnan, Smita AgrawalAbstract:Off-Frequency masking of the second formant by energy at the first formant has been shown to influence both identification and discrimination of the second formant in normal-hearing and hearing-impair
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human Frequency Following Response correlates of the distortion product at 2f1 f2
Journal of The American Academy of Audiology, 2004Co-Authors: Pritesh K Pandya, Ananthanarayan KrishnanAbstract:We characterized the 2F1-F2 distortion product reflected in the human Frequency-Following Response (FFR). In the first experiment, we evaluated the input-output growth functions of the distortion product at 2F1-F2 (FFR-DP) for three primary pairs. In the second experiment, we tested the effect of primary tone level variation on the FFR-DP. The results for all three stimulus pairs showed that while the amplitude of FFR-DP increased with stimulus intensity, the slope of the amplitude growth decreased with increasing Frequency. Consistent with distortion product otoacoustic emission (DPOAE) data, our observations suggest that there is a distinct region where the separation of the primary tone levels produces maximal distortion. The robust FFR-DP measure could complement the less reliable DPOAE at low frequencies and when middle ear pathology precludes its measurement.
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human Frequency Following Response representation of pitch contours in chinese tones
Hearing Research, 2004Co-Authors: Ananthanarayan Krishnan, Jackson T Gandour, Peter CarianiAbstract:Abstract Auditory nerve single-unit population studies have demonstrated that phase-locking plays a dominant role in the neural encoding of both the spectrum and voice pitch of speech sounds. Phase-locked neural activity underlying the scalp-recorded human Frequency-Following Response (FFR) has also been shown to encode certain spectral features of steady-state and time-variant speech sounds as well as pitch of several complex sounds that produce time-invariant pitch percepts. By extension, it was hypothesized that the human FFR may preserve pitch-relevant information for speech sounds that elicit time-variant as well as steady-state pitch percepts. FFRs were elicited in Response to the four lexical tones of Mandarin Chinese as well as to a complex auditory stimulus which was spectrally different but equivalent in fundamental Frequency ( f 0 ) contour to one of the Chinese tones. Autocorrelation-based pitch extraction measures revealed that the FFR does indeed preserve pitch-relevant information for all stimuli. Phase-locked interpeak intervals closely followed f 0 . Spectrally different stimuli that were equivalent in F 0 similarly showed robust interpeak intervals that followed f 0 . These FFR findings support the viability of early, population-based ‘predominant interval’ representations of pitch in the auditory brainstem that are based on temporal patterns of phase-locked neural activity.