Biology subjects

Henry, M. J.

Publications and source records attributed to Henry, M. J..

10 recordsLinked to original sources

bioRxiv2025

Reduced neural sensitivity to musical tempo despite enhanced neural tracking of musical features in older adults

A substantial body of prior research has focused on how aging affects the neural processing of speech, whereas less is known about how older adults encode naturalistic music. Here, we investigated whether the neural tracking of different features in naturalistic music differs between age groups. Younger and older adults (both sexes) listened to excerpts of naturalistic music with different tempi (1-4 Hz) while electroencephalography (EEG) was recorded. The results show an age-related enhancement of neural responses to sound onsets, suggesting a loss of inhibition in the aged auditory cortex that is thought to arise from peripheral decline. This hyperresponsiveness generalized to the neural tracking of multiple features (amplitude envelope, onsets, beat, and spectral flux) in naturalistic music. Crucially, older adults showed reduced sensitivity of early brain responses (0-130 ms) to tempo: Unlike younger adults, whose neural tracking decreased systematically with increasing tempo, older listeners maintained uniformly enhanced tracking across tempi. Spectral flux best predicted tempo- related changes in EEG activity, but this was reduced in older compared to younger adults. In sum, the current study demonstrates that cortical hyperactivity in aging enhances the tracking of different features during naturalistic music listening but impairs the sensitivity to musical tempo. This dissociation highlights the complex changes and functional consequences of auditory aging related to the processing of naturalistic music. SIGNIFICANCE STATEMENTHow aging affects the encoding of ecologically-valid, naturalistic music is not well understood, although music is an important part of older peoples lives. Here, we used electroencephalography and temporal response function approaches to investigate how younger and older adults encode different features of naturalistic music at different tempi (1 to 4 Hz). The results reveal a fundamental trade-off in the aging auditory system: enhanced neural tracking of acoustic features coexists with declined sensitivity to musical tempo. This dissociation between hyperactivity for feature encoding and impaired temporal sensitivity highlights complex changes in the aged auditory system that can have implications for music perception in older adulthood.

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bioRxiv2024

Superiority of Rhythmic Auditory Signals over Electrical Stimulation to Entrain Behavior

Neural tracking (entrainment) of auditory rhythms enhances perception. We previously demonstrated that transcranial alternating current stimulation (tACS) can enhance or suppress entrainment to rhythmic auditory stimuli, depending on the timing between the electrical and auditory signals, although tACS effects are primarily modulatory. This study further investigated entrainment to tACS and auditory rhythms when the electrical and auditory signals were presented together (Experiment 1, N = 34) or independently (Experiment 2, N = 24; Experiment 3, N = 12). We hypothesized that tACS effects would be more pronounced when the auditory rhythm was made less perceptually salient to reduce the competition with the electrical rhythm. Participants detected silent gaps in modulated or unmodulated noise stimuli. In Experiment 1, auditory stimuli predominated in entraining behavior. While behavioral entrainment to sound rhythms was affected by the modulation depth of the auditory stimulus, entrainment to tACS was not. In Experiment 2, with no rhythmic information from the sound, 16 of 24 participants showed significant behavioral entrainment to tACS, although the most effective tACS frequency varied across participants. An oscillator model with a free parameter for the individual resonance frequency produced profiles similar to those we observed behaviorally. In Experiment 3, both neural and behavioral entrainment to rhythmic sounds were affected by the auditory stimulus frequency, but again the most effective entraining frequency varied across participants. Our findings suggest that tACS effects depend on the individuals preferred frequency when there is no competition with sensory stimuli, emphasizing the importance of targeting individual frequencies in tACS experiments. When both sensory and electrical stimuli are rhythmic and compete, sensory stimuli prevail, indicating the superiority of sensory stimulation in modulating behavior.

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bioRxiv2023

Convolutional neural networks can identify brain interactions involved in decoding spatial auditory attention

Human listeners have the ability to direct their attention to a single speaker in a multi-talker environment. The neural correlates of selective attention can be decoded from a single trial of electroencephalography (EEG) data. In this study, leveraging the source-reconstructed and anatomically-resolved EEG data as inputs, we sought to employ CNN as an interpretable model to uncover task-specific interactions between brain regions, rather than simply to utilize it as a black box decoder. To this end, our CNN model was specifically designed to learn pairwise interaction representations for 10 cortical regions from five-second input trials. By exclusively utilizing these features for decoding, our model was able to attain a median accuracy of 77.56% for within-participant and 65.14% for cross-participant classification. Through ablation analysis together with dissecting the features of the models and applying cluster analysis, we were able to discern the presence of alpha-band-dominated inter-hemisphere interactions, as well as alpha-and beta-band dominant interactions that were either hemisphere-specific or were characterized by a contrasting pattern between the right and left hemispheres. These interactions were more pronounced in parietal and central regions for within-participant decoding, but in parietal, central, and partly frontal regions for cross-participant decoding. These findings demonstrate that our CNN model can effectively utilize features known to be important in auditory attention tasks and suggest that the application of domain knowledge inspired CNNs on source-reconstructed EEG data can offer a novel computational framework for studying task-relevant brain interactions.

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bioRxiv2022

Modulating behavioral signatures of rhythmic auditory entrainment with tACS

Synchronization between auditory stimuli and brain rhythms is beneficial for perception. In principle, auditory perception could be improved by facilitating neural entrainment to sounds via brain stimulation. However, high inter-individual variability of brain stimulation effects questions the usefulness of this approach. Here we aimed to modulate auditory perception by modulating neural entrainment to frequency modulated (FM) sounds using transcranial alternating current stimulation (tACS). In addition, we evaluated the advantage of using tACS montages spatially optimized for each individuals anatomy and functional data compared to a standard montage applied to all participants. Across two different sessions, 2-Hz tACS was applied targeting auditory brain regions. Concurrent with tACS, participants listened to FM stimuli with modulation rate matching the tACS frequency but with different phase lags relative to the tACS, and detected silent gaps embedded in the FM sound. We observed that tACS modulated the strength of behavioral entrainment to the FM sound in a phase-lag specific manner. Both the optimal tACS lag and the magnitude of the tACS effect were variable across participants and sessions. Inter-individual variability of tACS effects was best explained by the strength of the inward electric field, depending on the field focality and proximity to the target brain region. Although additional evidence is necessary, our results also provided suggestive insights that spatially optimizing the electrode montage could be a promising tool to reduce inter-individual variability of tACS effects. This work demonstrates that tACS effectively modulates entrainment to sounds depending on the optimality of the electric field. However, the lack of reliability on optimal tACS lags calls for caution when planning tACS experiments based on separate sessions.

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bioRxiv2022

Age-related changes in the neural mechanics of dynamic auditory attention in time

Listening in everyday life requires attention to be deployed dynamically - when listening is expected to be difficult and when relevant information is expected to occur - to conserve mental resources. Conserving mental resources may be particularly important for older adults who often experience difficulties understanding speech. In the current study, we use electro- and magnetoencephalography to investigate the neural and behavioral mechanics of attention regulation during listening and the effects that aging has on these. We show that neural alpha oscillatory activity indicates when in time attention is deployed (Experiment 1) and that deployment depends on listening difficulty (Experiment 2). Older adults (54-72 years) also show successful attention regulation but appear to utilize timing information differently compared to younger adults (20-33 years). We further show a notable age-group dissociation in recruited brain regions. In younger adults, superior parietal cortex underlies alpha power during attention regulation, whereas, in older adults, alpha power emerges from more ventro-lateral areas (posterior temporal cortex; Experiment 3). This difference in the sources of alpha activity between age groups only occurred during task performance and was absent during rest (Experiment S1). In sum, our study suggests that older adults employ different neural control strategies compared to younger adults to regulate attention in time under listening challenges.

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bioRxiv2022

Individual neurophysiological signatures of spontaneous rhythm processing

When sensory input conveys rhythmic regularity, we can form predictions about the timing of upcoming events. Although rhythm processing capacities differ considerably between individuals, these differences are often obscured by participant- and trial-level data averaging procedures in M/EEG research. Here, we systematically assessed the neurophysiological variability displayed by individuals listening to isochronous equitone sequences interspersed with unexpected deviant tones. We first focused on rhythm tracking and tested the anticipatory phase alignment of delta-band activity to expected tone onsets. These analyses confirmed that individuals encode temporal regularities and form temporal predictions, but highlight clear inter- and intra-participant variability. This observation may indicate individual and flexible tracking mechanisms, which show consistency at the single-trial level, but variability over trials. We then modelled single-trial time-locked neural responses in the beta-band to investigate individual tendencies to spontaneously employ binary grouping ("tic-toc effect"). This approach identified binary (strong-weak), ternary (strong-weak-weak), and mixed accentuation patterns, confirming the superimposition of a basic beat pattern. Furthermore, we characterized individual grouping preferences and tendencies to use binary, ternary, or combined patterns over trials. Importantly, the processing of standard and deviant tones was modulated by the employed pattern. The current approach supports individualized neurophysiological profiling as a sensitive strategy to identify dynamically evolving neural signatures of rhythm and beat processing. We further suggest that close examination of neurophysiological variability is critical to improve our understanding of the individual and flexible mechanisms underlying the capacities to rapidly evaluate and adapt to environmental rhythms. Significance statementFor decades, music, speech and rhythm research investigated how humans process, predict, and adapt to environmental rhythms. By adopting a single-trial and -participant approach, we avert the common pooling of EEG data in favor of individual time-varying neural signatures of rhythm tracking and beat processing. The results highlight large inter- and intra-individual differences in rhythm tracking, arguing against the typically documented phase-specificity for entrainment. On top of that, we characterize individual variability in beat processing, by showing that binary, ternary and other accentuation patterns are used over time, and ultimately affect the processing of (un-)expected auditory events. The approach aids individual neural profiling and may therefore allow identifying altered neural activity and its consequences in natural listening contexts.

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bioRxiv2021

Neural entrainment is strongest to the spectral flux of slow music and depends on familiarity and beat salience

Neural activity in the auditory system synchronizes to sound rhythms, and brain-environment synchronization is thought to be fundamental to successful auditory perception. Sound rhythms are often operationalized in terms of the sounds amplitude envelope. We hypothesized that - especially for music - the envelope might not best capture the complex spectro-temporal fluctuations that give rise to beat perception and synchronized neural activity. This study investigated 1) neural synchronization to different musical features, 2) tempo-dependence of neural synchronization, and 3) dependence of synchronization on familiarity, enjoyment, and ease of beat perception. In this electroencephalography study, 37 human participants listened to tempo-modulated music (1-4 Hz). Independent of whether the analysis approach was based on temporal response functions (TRFs) or reliable components analysis (RCA), the spectral flux of music - as opposed to the amplitude envelope - evoked strongest neural synchronization. Moreover, music with slower beat rates, high familiarity, and easy-to-perceive beats elicited the strongest neural response. Our results demonstrate the importance of spectro-temporal fluctuations in music for driving neural synchronization, and highlight its sensitivity to musical tempo, familiarity, and beat salience.

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bioRxiv2020

Test-retest reliability of neural entrainment in the human auditory system

Auditory stimuli are often rhythmic in nature. Brain activity synchronizes with auditory rhythms via neural entrainment, and entrainment seems to be beneficial for auditory perception. However, it is not clear to what extent neural entrainment in the auditory system is reliable over time - a necessary prerequisite for targeted intervention. The current study aimed to establish the reliability of neural entrainment over time and to predict individual differences in auditory perception from associated neural activity. Across two different sessions, human listeners detected silent gaps presented at different phase locations of a 2-Hz frequency modulated (FM) noise while EEG activity was recorded. As expected, neural activity was entrained by the 2-Hz FM noise. Moreover, gap detection was sinusoidally modulated by the phase of the 2-Hz FM into which the gap fell. Critically, both the strength of neural entrainment as well as the modulation of performance by the stimulus rhythm were highly reliable over sessions. Moreover, gap detection was predictable from pre-gap neural 2-Hz phase and alpha amplitude. Our results demonstrate that neural entrainment in the auditory system and the resulting behavioral modulation are reliable over time, and that both entrained delta and non-entrained alpha oscillatory activity contribute to near-threshold stimulus perception. The latter suggests that improving auditory perception might require simultaneously targeting entrained brain rhythms as well as the alpha rhythm.

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bioRxiv2018

Temporal evolution from retinal image size to perceived size in human visual cortex

Our visual system affords a distance-invariant percept of object size by integrating retinal image size with viewing distance (size constancy). Single-unit studies with animals have shown that real changes in distance can modulate the firing rate of neurons in primary visual cortex and even subcortical structures, which raises an intriguing possibility that the required integration for size constancy may occur in the initial visual processing in V1 or even earlier. In humans, however, EEG and brain imaging studies have typically manipulated the apparent (not real) distance of stimuli using pictorial illusions, in which the cues to distance are sparse and not congruent. Here, we physically moved the monitor to different distances from the observer, a more ecologically valid paradigm that emulates what happens in everyday life. Using this paradigm in combination with electroencephalography (EEG), we were able for the first time to examine how the computation of size constancy unfolds in real time under real-world viewing conditions. We showed that even when all distance cues were available and congruent, size constancy took about 150 ms to emerge in the activity of visual cortex. The 150-ms interval exceeds the time required for the visual signals to reach V1, but is consistent with the time typically associated with later processing within V1 or recurrent processing from higher-level visual areas. Therefore, this finding provides unequivocal evidence that size constancy does not occur during the initial signal processing in V1 or earlier, but requires subsequent processing, just like any other feature binding mechanisms.

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bioRxiv2017

Temporal expectation modulates cortical dynamics of sensory memory

Increased memory load is often signified by enhanced neural oscillatory power in the alpha range (8-13 Hz), taken to reflect inhibition of task-irrelevant brain regions. The corresponding neural correlates of memory decay, however, are not yet well-understood. Here, we investigated auditory sensory memory decay using a delayed matching-to-sample task with pure-tone sequences. First, in a behavioral experiment we modeled memory behavior over six different delay-phase durations. Second, in a magnetoencephalography (MEG) experiment, we assessed alpha-power modulations over three different delay-phase durations. In both experiments, the temporal expectation for the to-be-remembered sound was manipulated, so that it was either temporally expected or not. In both studies, memory performance declined over time but this decline was less strong under a more precise temporal expectation. Similarly, patterns of alpha power in and alpha-tuned connectivity between sensory cortices changed parametrically with delay duration (i.e., decrease in occipito-parietal regions, increase in temporal regions). Notably, temporal expectation counteracted alpha-power decline in heteromodal brain areas (i.e., supramarginal gyrus), in line with its memory-decay counteracting effect on performance. Correspondingly, temporal expectation also boosted alpha connectivity within attention networks known to play an active role during memory maintenance. The present data outline how patterns of alpha power orchestrate sensory memory decay, and encourage a refined perspective on alpha power and its inhibitory role across brain space and time.\n\nSignificance StatementOur sensory memories of the physical world fade quickly. We show here that this decay of sensory memory can be counteracted by so-called temporal expectation, that is, knowledge of when to expect the to-be-remembered sensory event (here, brief sound patterns). We also show that distinct patterns and modulations of neural oscillations in the \"alpha\" (8-13 Hz) range index both, the degree of memory decay, and any benefit from temporal expectation, both of which affect memory performance. Critically, spatially distributed cortical patterns of alpha power, with opposing effects in auditory vs. visual sensory cortices and alpha-tuned connectivity changes within supramodal attention networks, reflect the allocation of neural resources as sensory memory representations fade.

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