Biology subjects

Har-shai Yahav, P.

Publications and source records attributed to Har-shai Yahav, P..

3 recordsLinked to original sources

bioRxiv2025

Toward precision EEG: Assessing the reliability of individual-level ERPs across EEG Systems

Event-related potentials (ERPs) are among the most established tools for studying the neural mechanisms of perception and cognition. Advancing toward precision EEG, however, places new demands for a better understanding of how reliable neural markers are at the individual subject level. We conducted two complementary experiments to examine the reliability of N100 and P300 components in an auditory oddball paradigm with three sounds (Standard, Target, and Novel). In Experiment 1, we evaluated the consistency at both the group level and the individual level across four EEG systems: one research-grade wired system (BioSemi) and three mobile devices--Smarting, DSI-24, and EPOC X. At the group level, all systems demonstrated the canonical N100 and P300 components; however, the EPOC X system showed a significantly reduced signal-to-noise ratio compared to the others. At the individual level, temporal and spatial clustering analyses showed that N100 and P300 components were detectable in most individuals (70-85%), with additional significant responses appearing outside this range. We further calculated the similarity of individual responses across participants ("typicality index"), which revealed highly consistent responses to Standard and Novel sounds, alongside divergent patterns of responses to Targets. In Experiment 2, we assessed the within-participant reliability of N100 and P300 using a test-retest design. Results indicated high within-participant consistency of response patterns for all three stimuli, demonstrating that individual ERPs remain reliably stable over time, even when they deviate from canonical group-level patterns. The current study contributes to the ongoing discussion regarding the utility and reliability of ERP-based metrics for precision imaging and highlights important methodological considerations for their practical implementation.

neuroscience↗

bioRxiv2023

Neural Speech-Tracking During Selective Attention and Attention-Switching Between Concurrent Talkers: A spatially realistic audiovisual study

Paying attention to a target talker in multi-talker scenarios is associated with its more accurate neural-tracking relative to competing non-target speech. This "neural-bias" to target speech has largely been demonstrated in experimental setups where target and non-target speech are acoustically controlled and interchangeable. However, in real-life situations this is rarely the case. For example, listeners often look at the talker they are paying attention to while non-target speech is heard (but not seen) from peripheral locations. To enhance the ecological-relevance of attention research, here we studied whether neural-bias towards target speech is observed in a spatially realistic audiovisual context, and how this is affected by switching the identity of the target talker. Group-level results show robust neural-bias towards target speech, an effect that persisted and generalized after switching the identity of the target talker. In line with previous studies, this supports the utility of the speech-tracking approach for studying speech processing and attention in spatially realistic settings. However, a more nuanced picture emerges when inspecting data of individual participants. Although reliable neural speech-tracking could be established in most participants, this was not correlated with neural-bias or with behavioral performance, and >50% of participant showed similarly robust neural tracking of both target and non-target speech. These results indicate that neural-bias toward the target is not a ubiquitous, or necessary, marker of selective attention (at least as measured from scalp-EEG), and suggest that individuals diverge in their internal prioritization among concurrent speech, perhaps reflecting different listening strategies or capabilities under realistic conditions. Significance StatementThis work contributes to ongoing efforts to study the neural mechanisms involved in selective attention to speech under ecologically relevant conditions, emulating the type of speech materials, multisensory experience, and spatial realism of natural environments. Group-level results show that under these more realistic conditions, the hallmark signature of selective attention - namely the modulation of sensory representation, and its robustness to switches in target-identity - is conserved, at least at the group level. At the same time, results point to an underlying diversity among participants in how that this modulation manifests, raising the possibility that differences in listening strategies, motivation or personal traits lead to differences in the way that individuals encode and process competing stimuli, under ecological conditions.

neuroscience↗

bioRxiv2020

Linguistic processing of task-irrelevant speech at a Cocktail Party

Paying attention to one speaker in noisy environments can be extremely difficult, because to-be-attended and task-irrelevant speech compete for processing resources. We tested whether this competition is restricted to acoustic-phonetic interference or if it extends to competition for linguistic processing as well. Neural activity was recorded using Magnetoencephalography as human participants were instructed to attended to natural speech presented to one ear, and task-irrelevant stimuli were presented to the other. Task-irrelevant stimuli consisted either of random sequences of syllables, or syllables structured to form coherent sentences, using hierarchical frequency-tagging. We find that the phrasal structure of structured task-irrelevant stimuli was represented in the neural response in left inferior frontal and posterior parietal regions, indicating that selective attention does not fully eliminate linguistic processing of task-irrelevant speech. Additionally, neural tracking of to-be-attended speech in left inferior frontal regions was enhanced when competing with structured task-irrelevant stimuli, suggesting inherent competition between them for linguistic processing. Impact StatementSyntactic structure-building processes can be applied to speech that is task-irrelevant and should be ignored, demonstrating that Selective Attention does not fully eliminate linguistic processing of competing speech.

neuroscience↗