Biology subjects

Dimitrijevic, A.

Publications and source records attributed to Dimitrijevic, A..

3 recordsLinked to original sources

bioRxiv2025

Association between high-frequency hearing sensitivity and visual cross-modal plasticity in typical-hearing adults

Visual cross-modal plasticity after deafness describes when auditory cortical regions increase responsiveness to visual stimulation. Such neuroplasticity demonstrates that sensory cortex adapts to profound peripheral impairment by upregulating healthy sensory function. However, whether cross-modal plasticity occurs for mild, partial hearing loss is less clear. Here we investigated cross-modal plasticity in "normal" hearing adults who had varying high-frequency hearing sensitivity, and if cross-modal plasticity was linked to adaptive visual behaviours. Twenty-five participants (aged 18 to 78) were tested in a modified Sternberg task with text-based visual words. Participants viewed a five-word sentence presented word-by-word during an encoding period and were asked to hold those words in short-term memory during a retention period. After, they reported if a target word probe was present in the encoding period. Multichannel EEG recorded visual cortical activity throughout. Results showed separate effects of high-frequency hearing sensitivity and age on visual cortical responses. At scalp sensors, visual N1 amplitudes were larger with worse hearing sensitivity, and P2 latencies were longer. In contrast, age was associated with shorter P2 latencies. Source analysis found that N1 amplitude increased with worse hearing sensitivity in right auditory cortex, but no effects were found in visual cortex, or for age. Hearing sensitivity and visual encoding activity did not correlate with behavioural performance or neural oscillations during the retention period. Results suggest for the first time that even a slight hearing decline in the high-frequency range is associated with higher visual activation of right auditory cortex, consistent with cross-modal plasticity.

neuroscience↗

bioRxiv2025

When Melodies Cue Memories: Electrophysiological Correlates of Autobiographically Salient Music Listening in Older Adults

Autobiographical memory is essential for older adults, providing a foundation for self-identity. Healthy aging is accompanied by changes in memory retrieval. However, musical memory remains relatively preserved, suggesting it may serve as an effective cue for autobiographical memory recall. Autobiographically salient (ABS) music (i.e., deeply encoded songs associated to important people, places, and events) is posited to engage distinct memory processes than familiar (FAM) music (i.e., songs that are recognized but lack personal significance). We tested this in 36 older adults (70.6 {+/-} 6.6 years, 20 females) who listened to music of varying degrees of personal significance, including ABS, FAM, and unfamiliar (UFAM) music. In Experiment 1, participants pressed a button as quickly as possible when they recognized the excerpt as ABS, FAM, or UFAM. In Experiment 2, we measured event-related potentials and time-frequency responses while participants listened to the same stimuli and rated familiarity and memory at the end of each excerpt. Participants had the fastest reaction times for ABS, followed by FAM, then UFAM music. We observed a sustained evoked response from 2238 to 5000 ms post-stimulus onset that was largest in amplitude for ABS music, compared to FAM and UFAM music, over right frontal-central regions. We also observed less beta power suppression for ABS than FAM music between 1300 and 5000 ms over bilateral frontal-central-parietal areas. Our behavioral and neurophysiological findings show that ABS music is associated with faster and stronger memory-related activity distinct from FAM music.

neuroscience↗

bioRxiv2022

Neural responses to movie naturalistic stimuli are related to listening demand in cochlear implant users

There is a weak relationship between clinical and self-reported speech perception outcomes in cochlear implant (CI) listeners. Such poor correspondence may be due to differences in clinical and "real-world" listening environments and stimuli. Speech sounds in the real world are often accompanied by visual cues, background environmental noise and is generally in the context of a connected conversation. The aims of this study were to determine if brain responses to naturalistic speech could index speech perception and listening demand in CI users. Accordingly, we recorded high density EEG while CI users listened/watched a naturalistic stimulus (i.e., the television show, "The Office"). We used continuous EEG to quantify "speech neural tracking" (i.e., TRFs, temporal response functions) to the television show audio track and additionally 8-12 Hz (alpha) brain rhythms commonly related to listening effort. Background noise at three different signal-to-noise ratios (SNRs), +5, +10, and +15 dB were presented to vary the difficulty of following the television show mimicking a natural noisy environment. The task included an additional condition of audio-only (no video). After each condition, participants subjectively rated listening demand and the degree of words and conversations they felt they could understand. Fifteen CI users reported progressively higher degrees of listening demand and less words and conversation with increasing background noise. Listening demand and conversation understanding in the audio-only condition was comparable to that of the highest noise condition (+5 dB). The addition of the background noise reduced the degree of speech neural tracking. Mixed effect modeling showed that listening demand and conversation understanding were correlated to cortical speech tracking such that high demand and low conversation understanding lower associated with lower amplitude TRFs. In the high noise condition, greater listening demand was negatively correlated to parietal alpha power such that higher demand was related to lower alpha power. No significant correlations were observed between TRF/alpha and clinical speech perception scores. These results are similar to previous findings showing little relationship between speech perception and quality of life in CI users. However, the physiological responses to complex natural speech may anticipate aspects of quality-of-life measures such as self-perceived listening demand.

neuroscience↗