Biology subjects

Agmon, G.

Publications and source records attributed to Agmon, G..

5 recordsLinked to original sources

bioRxiv2026

Speech Tracking in fMRI Reveals a Distinct Response to Sentence Boundaries During Comprehension

Psycholinguistic research and linguistic theory suggest that comprehending continuous speech involves segmenting it into sentences. Yet, direct neuroimaging evidence for this process remains scarce, partly because sentence boundaries coincide with acoustic, prosodic, lexical, and syntactic changes. Here, we used whole-brain fMRI to test whether sentence boundaries elicit a neural response beyond these accompanying speech properties during spontaneous speech comprehension. We modelled BOLD responses to sentence-final words alongside continuous regressors characterizing accompanying speech properties. This approach revealed sensitivity to continuously varying features of speech across multiple brain regions. Notably, the acoustic envelope predicted BOLD responses in bilateral primary auditory cortices. Responses associated with prosodic breaks and emphasis were found in right temporal cortex, syntactic bottom-up node count in the left superior temporal sulcus, and word concreteness in the parahippocampal gyri. Critically, sentence-final words were associated with an increased activation in right temporal regions, after accounting for acoustic, prosodic, lexical, semantic and syntactic properties. These findings provide evidence for a neural response to sentence boundaries consistent with active sentence segmentation. More generally, this study demonstrates the value of continuous-regressor modelling for investigating speech comprehension with fMRI.

neuroscience↗

bioRxiv2022

"Um... it's really difficult to... um.. speak fluently": Neural tracking of spontaneous speech

Spontaneous real-life speech is imperfect in many ways. It contains disfluencies and ill-formed utterances and has a highly variable rate. When listening to spontaneous speech, the brain needs to contend with these features in order to extract the speakers meaning. Here, we studied how the neural response is affected by four specific factors that are prevalent in spontaneous colloquial speech: (1) the presence of non-lexical fillers, (2) the need to detect syntactic boundaries in disfluent speech, and (3) variability in speech rate. Neural activity (EEG) was recorded from individuals as they listened to an unscripted, spontaneous narrative, which was analyzed in a time-resolved fashion to identify fillers and detect syntactic boundaries. When considering these factors in a speech-tracking analysis, which estimates a temporal response function (TRF) to describe the relationship between the stimulus and the neural response it generates, we found that the TRF was affected by both of them. This response was observed for lexical words but not for fillers, and it had an earlier onset for opening words vs. closing words of a clause and for clauses with slower speech rates. These findings broaden ongoing efforts to understand neural processing of speech under increasingly realistic conditions. They highlight the importance of considering the imperfect nature of real-life spoken language, linking past research on linguistically well-formed and meticulously controlled speech to the type of speech that the brain actually deals with on a daily basis.

neuroscience↗

bioRxiv2021

Attention to speech: Mapping distributed and selective attention systems

Daily life is full of situations where many people converse at the same time. Under these noisy circumstances, individuals can employ different listening strategies to deal with the abundance of sounds around them. In this fMRI study we investigated how applying two different listening strategies - Selective vs. Distributed attention - affects the pattern of neural activity. Specifically, in a simulated cocktail party paradigm, we compared brain activation patterns when listeners attend selectively to only one speaker and ignore all others, versus when they distribute their attention and attempt to follow two or four speakers at the same time. Results indicate that the two attention types activate a highly overlapping, bilateral fronto-temporal-parietal network of functionally connected regions. This network includes auditory association cortex (bilateral STG/STS) and higher-level regions related to speech processing and attention (bilateral IFG/insula, right MFG, left IPS). Within this network, responses in specific areas were modulated by the type of attention required. Specifically, auditory and speech-processing regions exhibited higher activity during Distributed attention, whereas fronto-parietal regions were activated more strongly during Selective attention. This pattern suggests that a common perceptual-attentional network is engaged when dealing with competing speech-inputs, regardless of the specific task at hand. At the same time, local activity within nodes of this network varies when implementing different listening strategies, reflecting the different cognitive demands they impose. These results nicely demonstrate the systems flexibility to adapt its internal computations to accommodate different task requirements and listener goals. Significance StatementHearing many people talk simultaneously poses substantial challenges for the human perceptual and cognitive systems. We compared neural activity when listeners applied two different listening strategy to deal with these competing inputs: attending selectively to one speaker vs. distributing attention among all speakers. A network of functionally connected brain regions, involved in auditory processing, language processing and attentional control was activated when applying both attention types. However, activity within this network was modulated by the type of attention required and the number of competing speakers. These results suggest a common attention to speech network, providing the computational infrastructure to deal effectively with multi-speaker input, but with sufficient flexibility to implement different prioritization strategies and to adapt to different listener goals.

neuroscience↗

bioRxiv2020

The Role of Spatial Separation on Selective and Distributed Attention to Speech

AO_SCPLOWBSTRACTC_SCPLOWProcessing speech in multi-speaker environments poses substantial challenges to the human perceptual and attention system. Moreover, different contexts may require employing different listening strategies. For instance, in some cases individuals pay attention Selectively to one speaker and attempt to ignore all other task-irrelevant sounds, whereas other contexts may require listeners to Distribute their attention among several speakers. Spatial and spectral acoustic cues both play an important role in assisting listeners to segregate concurrent speakers. However, how these cues interact with varying demands for allocating top-down attention is less clear. In the current study, we test and compare how spatial cues are utilized to benefit performance on these different types of attentional tasks. To this end, participants listened to a concoction of two or four speakers, presented either as emanating from different locations in space or with no spatial separation. In separate trials, participants were required to employ different listening strategies, and detect a target-word spoken either by one pre-defined speaker (Selective Attention) or spoken by any of the speakers (Distributed Attention). Results indicate that the presence of spatial cues improved performance, particularly in the two-speaker condition, which is in line with the important role of spatial cues in stream segregation. However, spatial cues provided similar benefits to performance under Selective and Distributed attention. This pattern suggests that despite the advantage of spatial cues for stream segregation, they were nonetheless insufficient for directing a more focused attentional spotlight towards the location of a designated speaker in the Selective attention condition.

neuroscience↗

bioRxiv2019

Paying Attention to Speech: The Role of Cognitive Capacity and Acquired Experience

Managing attention in multi-speaker environments is a challenging feat that is critical for human performance. However, why some people are better than others in allocating attention appropriately, remains highly unknown. Here we investigated the contribution of two factors - Cognitive Capacity and Acquired Experience - to performance on two different types of Attention task: Selective Attention to one speaker and Distributed Attention among multiple concurrent speakers. We compared performance across three groups: Individuals with low (n=20) and high cognitive capacity (n=26), and Aircraft Pilots (n=25), who have gained extensive experience on both Selective and Distributed attention to speech through their training and profession. Results indicate that both types of Attention benefit from higher Cognitive Capacity, suggesting reliance on common capacity-limited resources. However, only Selective Attention was further improved in the Pilots, pointing to its flexible and trainable nature, whereas Distributed Attention seems to suffer from more fixed and hard-wired processing-bottlenecks.

neuroscience↗