Biology subjects

Irsik, V. C.

Publications and source records attributed to Irsik, V. C..

3 recordsLinked to original sources

bioRxiv2024

Musical training does not enhance neural sound encoding at early stages of the auditory system: A large-scale multisite investigation

Musical training has been associated with enhanced neural processing of sounds, as measured via the frequency following response (FFR), implying the potential for human subcortical neural plasticity. We conducted a large-scale multi-site preregistered study (n > 260) to replicate and extend the findings underpinning this important relationship. We failed to replicate any of the major findings published previously in smaller studies. Musical training was related neither to enhanced spectral encoding strength of a speech stimulus (/da/) in babble nor to a stronger neural-stimulus correlation. Similarly, the strength of neural tracking of a speech sound with a time-varying pitch was not related to either years of musical training or age of onset of musical training. Our findings provide no evidence for plasticity of early auditory responses based on musical training and exposure.

neuroscience↗

bioRxiv2021

Synchronized Neural Activity Indexes Engagement with Spoken Stories under Acoustic Masking

Older people with hearing problems often experience difficulties understanding speech in the presence of background sound. As a result, they may disengage in social situations, which has been associated with negative psychosocial health outcomes. Measuring listening (dis-)engagement during challenging listening situations has received little attention thus far. We recruit young, normal-hearing human adults (both sexes) and investigate how speech intelligibility and engagement during naturalistic story listening is affected by the level of acoustic masking (12-talker babble) at different signal-to-noise ratios (SNRs). In Experiment 1, we observed that word-report scores were above 80% for all but the lowest SNR (-3 dB SNR) we tested, at which performance dropped to 54%. In Experiment 2, we calculated inter-subject correlation (ISC) using electroencephalography (EEG) data to identify dynamic spatial patterns of shared neural activity evoked by the stories. ISC has previously been used as a neural measure of participants engagement with naturalistic materials. Our results show that ISC was stable across all but the lowest SNRs, despite reduced speech intelligibility. Comparing ISC and intelligibility demonstrated that word-report performance declined more strongly with decreasing SNR compared to ISC. Our measure of neural engagement suggests that individuals remain engaged in story listening despite missing words due to background noise. Our work provides a potentially fruitful approach to investigate listener engagement with naturalistic, spoken stories that may be used to investigate (dis)engagement in older adults with hearing impairment.

neuroscience↗

bioRxiv2020

Cortical Responses to the Amplitude Envelopes of Sounds Change with Age

Many older listeners have difficulty understanding speech in noise, when cues to speech-sound identity are less redundant. The amplitude envelope of speech fluctuates dramatically over time, and features such as the rate of amplitude change at onsets (attack) and offsets (decay) signal critical information about the identity of speech sounds. Aging is also thought to be accompanied by increases in cortical excitability, which may differentially alter sensitivity to envelope dynamics. Here, we recorded electroencephalography in younger and older human adults (of both sexes) to investigate how aging affects neural synchronization to 4-Hz amplitude-modulated noises with different envelope shapes (ramped: slow attack & sharp decay; damped: sharp attack & slow decay). We observed that subcortical responses did not differ between age groups, whereas older compared to younger adults exhibited larger cortical responses to sound onsets, consistent with an increase in auditory cortical excitability. Neural activity in older adults synchronized more strongly with rapid-onset, slow-offset (damped) envelopes, was less sinusoidal, and more peaked. Younger adults demonstrated the opposite pattern, showing stronger synchronization with slow-onset, rapid-offset (ramped) envelopes, as well as a more sinusoidal neural response shape. The current results suggest that age-related changes in the excitability of auditory cortex alter responses to envelope dynamics. This may be part of the reason why older adults experience difficulty understanding speech in noise. Significance StatementMany middle aged and older adults report difficulty understanding speech when there is background noise, which can trigger social withdrawal and negative psychosocial health outcomes. The difficulty may be related to age-related changes in how the brain processes temporal sound features. We tested younger and older people on their sensitivity to different envelope shapes, using EEG. Our results demonstrate that aging is associated with heightened sensitivity to sounds with a sharp attack and gradual decay, and sharper neural responses that deviate from the sinusoidal features of the stimulus, perhaps reflecting increased excitability in the aged auditory cortex. Altered responses to temporal sound features may be part of the reason why older adults often experience difficulty understanding speech in social situations.

neuroscience↗