Biology subjects

Sedley, W.

Publications and source records attributed to Sedley, W..

14 recordsLinked to original sources

bioRxiv2026

Auditory Working Memory and Sound Segregation Ability Predict Speech-in-Noise in Adult Cochlear Implant Users

ObjectivesOutcomes following cochlear implantation vary substantially across adult recipients, and the cognitive and perceptual factors contributing to this variability are not fully understood. This poses a challenge for developing strategies to improve cochlear implant outcomes, as such approaches require a clearer understanding of the mechanisms underlying individual listening difficulties. In this study, we investigated auditory cognitive measures in cochlear implant (CI) users to further elucidate the origins of this variability. DesignThirty-seven adult cochlear implant users completed measures of auditory cognition, comprising auditory working memory (AWM) and sound segregation ability, measured using an auditory figure-ground task (AFG), as well as measures of peripheral temporal and spectral processing, comprising the temporal modulation detection threshold (TMDT) and spectral ripple discrimination threshold (SRDT). Speech perception outcomes were assessed using word-in-noise (WIN) and sentence-in-noise (SIN) tasks. Separate multiple linear regression models evaluated the unique contribution of the auditory cognition measures to WIN and SIN performance, after accounting for the peripheral measures. ResultsBoth regression models explained a substantial proportion of variance in speech-in-noise outcomes (WIN: adjusted R{superscript 2} = 0.55; SIN: adjusted R{superscript 2}=0.57, both p < 0.001). For WIN performance, AFG and AWM were significant predictors. A similar pattern was found for SIN performance, where lower AWM ability and poorer AFG segregation were linked to poorer sentence listening in noise. No significant effects of spectral ripple discrimination or temporal modulation detection were observed in either model, even though both were significantly correlated with WIN performance. ConclusionsThese findings indicate that auditory working memory and sound segregation ability are robust predictors of speech-in-noise outcomes in adult cochlear implant users, across both word- and sentence-level measures. Together, the results may help explain why speech-in-noise outcomes remain highly variable among CI users, even when basic sensory encoding abilities are taken into account. Incorporating measures of auditory working memory and fundamental sound segregation may therefore improve outcome prediction and help in developing more individualised rehabilitation strategies.

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bioRxiv2026

Auditory Working Memory Mediates the Relationship between Musical Sophistication and Speech-in-noise Perception

Understanding speech in noisy environments (SPIN) is an important everyday ability, and engaging in musical activities has been proposed as a factor that may support this ability. However, the cognitive mechanisms underlying a potential musical advantage in SPIN perception remain unclear. Here we investigated whether musical sophistication is associated with better SPIN perception in a large population-based sample, and whether this relationship is mediated by auditory working memory (AWM), verbal working memory (VWM), or non-verbal intelligence. We recruited 203 participants and measured SPIN perception at both word and sentence levels. Musical sophistication was assessed using the Goldsmiths Musical Sophistication Index (Gold-MSI). AWM was measured using delayed matching of tone frequency or the modulation rate of amplitude modulated white noise, VWM was based on backward digit span task, and non-verbal intelligence used matrix reasoning. Mediation analyses revealed that AWM fully mediated the relationship between musical sophistication and SPIN perception, whereas VWM showed no mediation effect. Non-verbal intelligence showed a partial mediating effect. Additional control analyses using structural equation modelling revealed that the indirect effect through AWM remained significant after accounting for age, hearing thresholds, and non-verbal intelligence. Together, these findings suggest that individuals with greater musical sophistication demonstrate better daily life listening abilities, and that superior auditory working memory may be the key cognitive mechanism underlying this advantage.

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bioRxiv2025

Alterations in steady-state synchronisation between Acute and Chronic Tinnitus suggests reduction in both tinnitus and central gain.

The mechanism of tinnitus remains unclear as the generation and persistence of tinnitus is not widely understood. The acute tinnitus population serves as an ideal group for investigating the mechanisms behind the origin and persistence of tinnitus, from its initial onset to its subsequent chronification. One of the neural markers for measuring tinnitus such as neural synchrony or central gain is the Auditory Steady State Response (ASSR). The experiment was carried out on 39 participants with acute tinnitus (18 followed back six months post baseline), 30 with chronic tinnitus, and 27 controls. The results reveal that both cross sectionally and longitudinally, there were no significant differences in absolute amplitudes of ASSR across intensities and the slope of ASSR growth function between the groups. However, Controls tend to have an overall increase in ASSR amplitude when compared to Acute and Chronic Tinnitus which can be attributed to changes in neural synchronisation, attentional modulation, tinnitus-related distress, and diminished GABAergic inhibition coinciding with the presence of tinnitus. As there were no changes in the ASSR amplitude between Acute and Chronic Tinnitus or between Acute and Post Acute Tinnitus despite variations in distress and tinnitus loudness, we infer that auditory sensitivity/neural sensitvity is independent of the tinnitus.

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bioRxiv2025

Perceptual Novelty in Tinnitus a Causative Factor for its Persistence. A Stimulus Novelty Based P300 Paradigm on Acute, Chronic, and Non-Tinnitus Controls

Our understanding of tinnitus pathophysiology may be greatly advanced by understanding how the condition evolves from its initial onset or acute stage to its chronic manifestation. Such a transition likely reflects dynamic neurophysiological changes within central auditory and non-auditory networks. Previous studies have highlighted that individuals with acute tinnitus tend to have increased activity in the regions of anterior cingulate cortex, inferior parietal lobe, and insula all of which are essential in constituting the salience network. We therefore aimed at tapping into the salience network of tinnitus through a novelty based P300 paradigm in individuals with Acute, Post Acute (six months follow up since tinnitus onset) Chronic, and Controls. Participants were presented with an auditory oddball paradigm comprising three deviant types: (1) novel environmental sounds, (2) low-frequency tonal deviants, and (3) high-frequency tonal deviants, embedded within a sequence of frequent standard tones. Our results indicate a significant drop in P300 amplitude during the Post Acute stage across the three deviant stimuli, highlighting the substantial influence of the anterior cingulate cortex/salience network in possible generation of tinnitus and inferior parietal lobe in the persistence of tinnitus.

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bioRxiv2025

Evidence for a Transient State of Auditory Hypersensitivity During Initial Onset of Tinnitus, Evidenced by Intensity Dependence of the Auditory Evoked Potential (IDAEP)

Our understanding of tinnitus pathophysiology may be greatly advanced by understanding how the condition evolves from its initial onset or acute stage to its chronic manifestation. Such a transition likely reflects dynamic neurophysiological changes within central auditory and non-auditory networks. Our integrated model of tinnitus posits that sensory precision (sensory weighting) may be heightened during the acute stages of tinnitus to resolve degraded auditory input, but in chronic tinnitus, its role may diminish as plastic processes take over the percepts maintenance. Consequently, we hypothesize that bottom-up neural mechanisms linked to initiation of tinnitus, such as central gain and neural synchrony, are maximal around the time of tinnitus onset, but later subside by way of regression to the mean. We evaluated this hypothesis by measuring central auditory reactivity through the Intensity Dependence of Auditory Evoked Potential (IDAEP), a non-invasive index of higher-order inhibitory processing within the auditory system. A steeper IDAEP slope is associated with heightened sensory reactivity (higher sensitivity to changes in auditory stimuli), indicative of reduced central inhibition. Conversely, a shallower slope reflects greater inhibitory control. Studying a group with acute tinnitus (onset within six weeks), with a repeated assessment after six months from onset, we found an initially increased IDAEP slope in the acute stage, which had significantly reduced at follow-up, supporting our hypothesis that there is increased sensory reactivity during tinnitus onset, which need not persist in order for tinnitus to become chronic.

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bioRxiv2025

Neural entrainment to pitch changes of auditory targets in noise

Neural entrainment to certain acoustic features can predict speech-in-noise perception, but these features are difficult to separate. We measured neural responses to both natural speech-in-noise and stimuli (auditory figure-ground) that simulate speech-in-noise without any acoustic or linguistic confound such as stress contour and semantics. The figure-ground stimulus is formed by multiple temporally coherent pure-tone components embedded in a random tone cloud. Previous work has shown that discrimination of dynamic figure-ground based on the fundamental frequency (F0) of natural speech predicts speech-in-noise recognition independent of hearing and age. In this study, we compared the brain substrate for the figure-ground analysis based on the F0 contour and a statistically similar 1/f contour with speech-in-noise. We used the temporal response function to predict the electroencephalography responses to the frequency trajectories of the auditory targets. We demonstrate that the brain significantly tracked the pitch changes in both AFG conditions (F0 and 1/F tracking) and a sentence-in-noise condition (F0 tracking) at similar latencies, but at similar magnitudes only when tracking the F0 contour. The pitch-tracking accuracy was consistently high across the delta and theta bands for the AFG condition but not for speech. Sensor-space analysis revealed that speech-in-noise performance correlated with the positive peak amplitude of the F0 figure-ground at 100 ms. Source-space analysis revealed bilateral temporal lobe and hippocampal generators, and strong tracking in the superior parietal lobe for auditory figures and natural speech. In conclusion, our findings demonstrate that the human brain reliably tracks the F0 trajectory of both speech and a non-linguistic figure in noise, with speech tracking showing reduced accuracy in the theta band compared to figure-ground tracking. Despite the difference in prediction accuracy, we reveal striking similarities in neural entrainment patterns and source locations between the two paradigms. These results suggest that neural entrainment engages high-level cortical mechanisms independent of linguistic content. Furthermore, we show that TRF peak amplitude serves as a potential biomarker for speech-in-noise ability, highlighting possible clinical applications.

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bioRxiv2025

Brain bases for navigating acoustic features

Whether physical navigation shares neural substrates with mental travel in other behaviourally relevant domains is debated. With respect to sound, pure-tone working memory in humans elicits hippocampal as well as auditory cortical and inferior frontal activity, and rodent work suggests that hippocampal cells that usually track an animals physical location can also map to tone frequency when task-relevant. We generated a sound dimension based on the density of random-frequency tones in a stack, resulting in a percept ranging from low- ("beepy") to high-density ("noisy"). We established that unlike tone frequency, which listeners automatically associate with vertical position, this density dimension elicited no consistent spatial mapping. During functional magnetic resonance imaging, human participants held in mind the density of a series of tone stacks and, after a short maintenance period, adjusted further stacks to match the target ("navigation"). Density of the currently heard sound was represented most strongly in bilateral non-primary auditory cortex, specifically bilateral planum polare, while density of the maintained target was represented in right anterior hippocampus and left inferior temporal gyrus. Encoding and maintenance activity in bilateral hippocampus, inferior frontal gyrus, planum polare and posterior cingulate was positively associated with subsequent navigation success. Bilateral inferior frontal gyrus and hippocampus were among regions with elevated activity during adjustment, compared to a parity-judgment condition with closely matched acoustics and motor demands. Bilateral orbitofrontal cortex was more active when navigation was toward a target density than when participants adjusted density in a control condition with no particular target. We find that self-initiated travel along a non-spatial auditory dimension engages a brain system overlapping with that supporting physical navigation. Key PointsO_LIWork in rodents suggests that navigation in physical space and the active analysis of sounds share a neural substrate in the hippocampus, supporting the use of common computational mechanisms. C_LIO_LIWe examined the human brain system for navigation through an acoustic environment to a remembered target. C_LIO_LIIn addition to high-level auditory cortex we demonstrate involvement of the hippocampus in acoustic navigation along with other sites in frontal and cingulate cortex that also support physical navigation. C_LI

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bioRxiv2024

Relationships between migraine and interoception: normal accuracy but altered sensibility and behaviour

BackgroundMigraine is typically precipitated by unaccustomed changes in ones internal state and/or external environment. Migraine symptoms largely involve increased, noxious, awareness of bodily changes and external stimuli. Links have been proposed between migraine and interoception (sensing and interpreting internal states), but direct evidence is limited. MethodsUnmedicated, otherwise healthy, age-matched female participants were grouped by migraine tendency: control (no unprovoked headaches, n=19); low-frequency (<=3 migraines/month, n=20); high-frequency (>=4 migraines/month, n=19). Interoception was assessed, interictally, with standardised questionnaires such as MAIA-2 and a widely used heartbeat counting task. ResultsThe notable significant questionnaire-based difference was in the noticing, not distracting domain of the MAIA-2; controls were least likely to continue activities despite experiencing physical discomfort, and high-frequency migraineurs most likely. Follow-up questioning clarified that this behaviour related predominantly to migraine-related symptoms. The heartbeat task found no differences in accuracy, but lower confidence in the low-frequency migraine group than the control and high-frequency groups. ConclusionsWe suggest that low interoceptive confidence is a risk factor for migraine, whilst amplification of interoceptive signals caused by migraine restores this confidence, but at the price of migraines disabling symptoms. Self-reported tendency to deliberately ignore physical discomfort, including that caused by migraine, may result in more migraine attacks.

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bioRxiv2024

Predicting speech-in-noise ability with static and dynamic auditory figure-ground analysis using structural equation modelling

Auditory figure-ground paradigms assess the ability to extract a foreground figure from a random background, a crucial part of central hearing. Previous studies have shown that the ability to extract static figures (with fixed frequencies) predicts real-life listening: speech-in-noise ability. In this study we assessed both fixed and dynamic figures: the latter comprised component frequencies that vary over time like natural speech. 159 participants (aged 18-79) with a range of peripheral hearing sensitivity were studied. We used hierarchal linear regression and structural equation modelling to examine how well speech-in-noise ability (for words and sentences) could be predicted by age, peripheral hearing, and static and dynamic figure-ground. Regression demonstrated that in addition to the audiogram and age, the low-frequency dynamic figure-ground accounted for significant variance of speech-in-noise, higher than the static figure-ground. The structural models showed that a combination of all types of figure-ground tasks predicted speech-in-noise with a higher effect size than the audiogram or age. Age influenced word perception in noise directly but sentence perception indirectly via effects on peripheral and central hearing. Overall, this study demonstrates that dynamic figure-ground explains more variance of real-life listening than static figure-ground, and the combination of both predicts real-life listening better than hearing sensitivity or age.

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bioRxiv2024

Distinct profiles of tinnitus and hyperacusis in intensity deviant responses and auditory evoked potentials

ERPs in response to intensity deviant stimuli are assessed in four age and hearing matched groups of various combinations of tinnitus and hyperacusis (both conditions, one of the conditions, neither condition). Distinct profiles for tinnitus and hyperacusis are shown, as well as additional more nuanced interactions. This not only moves our understanding of each condition, but also speaks directly to possible mechanistic subtypes of tinnitus (and of hyperacusis) which might be disentangled through the cheap and available technique that is single-channel EEG. The current findings may also explain some discrepant findings in past literature.

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bioRxiv2024

Intensity mismatch asymmetry in tinnitus: in which direction should participants pay attention?

The effects attention has on intensity deviant Mismatch Negativity responses is an unknown factor in basic sensory neuroscience. It would be useful to understand how attention would affect responses to intensity deviants compared to each other (upward vs downward), and compared to other sensory dimensions such as frequency. Overall, previous research indicates that attention may modulate neuronal gain in healthy participants and change the amplitudes of evoked responses, and may mainly affect the responses to regularly repeating (standard) stimuli rather than deviants. Gain may respond differently in participants with tinnitus and/or hyperacusis under the same conditions compared to controls. Overall, results of the passive task condition were consistent with previous research. Auditory attention magnified MMN in response to upward deviants, while visual attention attenuated it in both control and tinnitus groups. However, auditory attention selectively enhanced downward deviant MMN in the tinnitus group (compared to passive attention). Using the auditory attention paradigm may be advantageous in MMN studies on tinnitus/hyperacusis because the observed differences would be particularly large.

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bioRxiv2024

Effects of the overall paradigm context on intensity deviant responses in healthy subjects

Three experiments have been carried out to explore Mismatch Negativity responses to intensity deviants in a roving intensity deviant paradigm in control and tinnitus groups. The first experiment used interspersed blocks of two tinnitus-like frequencies set by each participant with tinnitus, which were usually around 1/3 of an octave apart. On the other hand, two later studies used interspersed blocks tones at tinnitus-like frequencies and at 1 kHz. This was the only difference in the paradigms used, however, there were differences in the patterns displayed by the control group in the first study compared to the other two. Three groups of healthy controls were recruited to measure responses to intensity deviants when different frequencies were used for the alternating blocks. For one group, the whole experiment was set at a single frequency; for the next, blocks were played at 6 kHz and at a frequency 1/3 octave below 6 kHz (small difference); the last group was presented with blocks that had tones at 6 kHz and 1 kHz frequencies (large difference). Overall, the Mismatch Negativity responses in the small difference group were opposite to the large difference and the single frequency group. It would be useful to see whether these results generalise to other experiment designs such as attended and ignored stimulus conditions, different stimulus durations, non-isochronous, or paradigms with frequency deviants.

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bioRxiv2022

EEG Responses to Auditory Figure-Ground Perception

Speech-in-noise difficulty is commonly reported among hearing-impaired individuals. Recent work has established generic behavioural measures of sound segregation and grouping that are related to speech-in-noise processing but do not require language. In this study, we assessed potential clinical electroencephalographic (EEG) measures of central auditory grouping (stochastic figure-ground test) and speech-in-noise perception (speech-in-babble test) with and without relevant tasks. Auditory targets were presented within background noise (16 talker-babble or randomly generated pure-tones) in 50% of the trials and composed either a figure (pure-tone frequency chords repeating over time) or speech (English names). EEG was recorded while participants were presented with the target stimuli (figure or speech) under different attentional states (relevant task or visual-distractor task). EEG time-domain analysis demonstrated enhanced negative responses during detection of both types of auditory targets within the time window 650-850 ms but only figure detection produced significantly enhanced responses under the distracted condition. Further single-channel analysis showed that simple vertex-to-mastoid acquisition defines a very similar response to more complex arrays based on multiple channels. Evoked-potentials to the generic figure-ground task therefore represent a potential clinical measure of grouping relevant to real-world listening that can be assessed irrespective of language knowledge and expertise even without a relevant task.

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bioRxiv2019

Phantom auditory perception (tinnitus) is characterised by stronger anticipatory auditory predictions

How phantom perceptions arise and the factors that make individuals prone to such experiences are not well understood. An attractive phenomenon to study these questions is tinnitus, a very common auditory phantom perception which is not explained by hyperactivity in the auditory pathway alone. Our framework posits that a predisposition to developing (chronic) tinnitus is dependent on individual traits relating to the formation and utilization of sensory predictions. Predictions of auditory stimulus frequency (remote from tinnitus frequency) were studied using a paradigm parametrically modulating regularity (i.e. predictability) of tone sequences and applying decoding techniques on magnetoencephalographic (MEG) data. For processes likely linked to short-term memory, individuals with tinnitus showed an enhanced anticipatory prediction pattern associated with increasing sequence regularity. In contrast, individuals without tinnitus engaged the same processes following the onset of the to-be-decoded sound. We posit that this tendency to optimally anticipate static and changing auditory inputs may determine which individuals faced with persistent auditory pathway hyperactivity factor it into auditory predictions, and thus perceive it as tinnitus. While our study constitutes a first step relating vulnerability to tinnitus with predictive processing, longitudinal studies are needed to confirm the predisposition model of tinnitus development.

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