Biology subjects

Sammler, D.

Publications and source records attributed to Sammler, D..

7 recordsLinked to original sources

bioRxiv2026

Pitch motor areas contribute to the perception of prosodic categories in speech

Prosody is a fundamental aspect of speech characterized by suprasegmental features such as pitch. Prosodic pitch contours are used to convey speakers intentions, for example, to make a statement or ask a question. Understanding these intentions requires abstracting continuous, variable pitch information into discrete categories. Category perception has been proposed to recruit the motor system in an effector-specific manner, whereby cortical areas controlling motor effectors support speech sound recognition by identifying articulatory gestures. However, it remains unclear whether effectors involved in pitch production similarly contribute to prosodic category perception. To address this question, we collected magnetoencephalography data from 29 participants (15 females) while they first sang pitches arranged in five-tone melodies and then identified the prosody (Statement vs. Question) of single words varying in pitch contour along a five-level continuum. Using a region-restricted searchlight approach to decode singing from rest, we localized two premotor regions for pitch production, corresponding to the ventral and dorsal laryngeal motor cortex (LMC). A separate neural decoding analysis revealed that perceived prosodic categories were decodable in these regions, especially from the dorsal LMC that is more closely associated with pitch regulation. Importantly, decoding performance mirrored behavioral discriminability of prosodic categories across the continuum, suggesting that these regions are involved in perceptual decision-making. Finally, pitch motor areas exchanged category-related information with auditory regions, indicating these areas do not merely echo the processing in auditory regions. Together, these findings highlight effector-specific motor support for prosodic category perception, thereby broadening our understanding of motor involvement in speech perception. Significance StatementSpeech perception has been proposed to recruit the premotor cortex, with different subregions linking speech sounds to the articulatory gestures used to produce them. We investigated this idea through prosody--pitch changes in speech conveying meanings such as statements and questions. Using magnetoencephalography, we identified pitch motor areas during a singing task and tested whether they represent perceived prosodic categories. We found that prosodic categories were distinguishable in these regions and that this neural discriminability mirrored behavioral discriminability across clear and ambiguous prosody, suggesting involvement in perceptual decision-making. These findings are unlikely to reflect passive echoes from auditory regions, as pitch motor areas actively influenced them during categorical processing. Our results highlight effector-specific motor support for forming abstract prosodic representations.

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bioRxiv2025

Shared and distinct representational dynamics of phonemes and prosody in ventral and dorsal speech streams

Phonemes and prosodic contours are fundamental elements of speech used to convey complementary meanings. Perceiving these elements requires mapping variable acoustic cues onto discrete categories along ventral and dorsal speech streams. While traditional models make clear predictions, exactly where and when this acoustic-to-categorical mapping occurs remains unclear. Using magnetoencephalography and behavioural psychophysics, combined with time-resolved representational similarity and multivariate transfer entropy analyses, we show how phonemes and prosody propagate along the dual streams and how their categorical representations are gradually formed. Contrary to theoretical predictions, acoustic and categorical representations occur in parallel, rather than serially, across time and space for both elements. Moreover, prosody categories extend further along both streams than phoneme categories, with differently weighted contributions of posterior temporal areas. These results highlight a shared principle of parallel acoustic and categorical processing, yet partially distinct abstraction mechanisms for phonemes and prosody, key to access the multilayered meaning of speech.

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bioRxiv2024

Neural tracking of auditory statistical regularities is reduced in adults with dyslexia

Listeners implicitly use statistical regularities to segment continuous sound input into meaningful units, e.g., transitional probabilities between syllables to segment a speech stream into separate words. Implicit learning of such statistical regularities in a novel stimulus stream is reflected in a synchronisation of neural responses to the sequential stimulus structure. The present study aimed to test the hypothesis that neural tracking of the statistical stimulus structure is reduced in individuals with dyslexia who have weaker reading and spelling skills, and possibly also weaker statistical learning abilities in general, compared to healthy controls. To this end, adults with and without dyslexia were presented with continuous streams of (non-speech) tones, which were arranged into triplets, such that transitional probabilities between single tones were high within triplets and low between triplets. We found that neural tracking of the triplet structure, i.e., phase coherence of EEG response at the triplet rate relative to the tone rate, was reduced in adults with dyslexia compared to the control group. Moreover, enhanced neural tracking of the statistical structure was associated with better spelling skills. These results suggest that individuals with dyslexia have a rather broad deficit in processing structure in sound instead of a merely phonological deficit.

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bioRxiv2023

The syntax-meter interface in spoken language and music: Same, different, or individually variable?

Considerable debate surrounds syntactic processing similarities in language and music. Yet few studies have investigated how syntax interacts with meter considering that metrical regularity varies across domains. Furthermore, there are reports on individual differences in syntactic and metrical structure processing in music and language. Thus, a direct comparison of individual variation in syntax and meter processing across domains is warranted. In a behavioral (Experiment 1) and EEG study (Experiment 2), participants engaged in syntactic processing tasks with sentence- and melody stimuli that were more or less metrically regular, and followed a preferred or non-preferred (but correct) syntactic structure. We further employed a range of cognitive diagnostic tests, parametrically indexed verbal- and musical abilities using a principal component analysis, and correlated cognitive factors with the behavioral and ERP results (Experiment 3). Based on previous results in the language domain, we expected that a regular meter would facilitate the syntactic integration of non-preferred syntax. While syntactic discrimination was better in regular than irregular meter conditions in both domains (Experiment 1), a P600 effect indicated different integration costs during the processing of syntactic complexities in the two domains (Experiment 2). Metrical regularity altered the P600 response to preferred syntax in language while it modulated non-preferred syntax processing in music. Moreover, experimental results yielded within-domain individual differences, and identified continuous metrics of musical ability more beneficial than grouping musicians or non-musicians (Experiment 3). These combined results suggest that the meter-syntax interface differs uniquely in how it forms syntactic preferences in language and music.

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bioRxiv2020

Lateral prefrontal cortex as a hub for music production with gradation from structural rules to movement sequences

Complex sequential behaviours, such as speaking or playing music, often entail the flexible, rule-based chaining of single acts. However, it remains unclear how the brain translates abstract structural rules into concrete series of movements. Here we demonstrate a multi-level contribution of anatomically distinct cognitive and motor networks to the execution of novel musical sequences. We combined functional and diffusion-weighted neuroimaging to dissociate high-level structural and low-level motor planning of musical chord sequences executed on a piano. Fronto-temporal and fronto-parietal neural networks were involved when sequences violated pianists structural or motor plans, respectively. Prefrontal cortex is identified as a hub where both networks converge within an anterior-to-posterior gradient of action control linking abstract structural rules to concrete movement sequences.

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bioRxiv2020

Modulation of neural activity in frontopolar cortex drives reward-based motor learning

Decision-making is increasingly being recognised to play a role in learning motor skills. Understanding the neural processes regulating motor decision-making is therefore essential to identify mechanisms that contribute to motor skill learning. In decision-making tasks, the frontopolar cortex (FPC) is involved in tracking the reward of different alternative choices, as well as their reliability. Whether this FPC function extends to reward landscapes associated with a continuous movement dimension remains unknown. Here we used anodal transcranial direct current stimulation (tDCS) over the right FPC to investigate its role in reward-based motor learning. Nineteen healthy human participants completed a motor sequence learning task using trial-wise reward feedback to discover a hidden performance goal along a continuous dimension: timing. As a control condition, we modulated contralateral motor cortex (left M1) activity with tDCS, which has been shown to benefit motor skill learning but less consistently reward-based motor learning. Each active tDCS condition was contrasted to sham stimulation. Right FPC-tDCS led to faster learning primarily through a regulation of exploration, without concurrent modulation of motor noise. A Bayesian computational model revealed that following rFPC-tDCS, participants had a higher expectation of reward, consistent with their faster learning. These higher reward estimates were inferred to be less volatile, and thus participants under rFPC-tDCS deemed the mapping between movement and reward to be more stable. Relative to sham, lM1-tDCS did not significantly modulate main behavioral outcomes. The results indicate that brain regions previously linked to decision-making, such as the FPC, are relevant for motor skill learning.

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bioRxiv2017

Fractals in Action: An fMRI study on the Generation of new Hierarchical Levels in Motor Sequences

Generation of hierarchical structures, such as the embedding of subordinate elements into larger structures, is a core feature of human cognition. Discrimination of well-formed hierarchies is thought to rely on lateral prefrontal cortex (PFC). However, the brain bases underlying the active generation of new hierarchical levels remain poorly understood. Here, we created a new motor paradigm to isolate this active generative process. In fMRI, participants planned and performed (identical) movement sequences based on three previously learned rules: (1) a hierarchical fractal rule that involved generation of new levels, (2) a linear iterative rule adding items to existing hierarchical levels, and (3) simple repetition. We found that generation of new hierarchical levels (using the fractal rule) activated a bilateral motor planning-and imagery network, but did not involve lateral PFC. Conversely, adding items to existing hierarchical levels required M1 directly during execution. These results show that the generation of new hierarchical levels can be achieved without involvement of putative domain-general systems such as those ascribed to lateral PFC. We hypothesize that these systems might be important to parse hierarchical sequences in a multi-domain fashion but not necessarily to generate new hierarchical levels.

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