Laura Gwilliams

All Publications

• Time after time: neural codes of speech comprehension. Trends in cognitive sciences Gwilliams, L. 2026

  Abstract

  The acoustic signal of speech is fleeting and unfolds linearly; yet listeners must derive temporally extended and hierarchically organized linguistic structures to comprehend it. This article reviews evidence that the human brain transforms the transient auditory signal into neural representations that are persistent, parallel, and time-stamped. First, neural persistence allows information to remain available after it has disappeared from the acoustic input. Second, parallel encoding of recent inputs across multiple levels of language structure enables composition and interactions across the speech hierarchy. Third, dynamic neural representations encode both content and elapsed time, providing a flexible mechanism for preserving sequence order. Together, these representational properties reveal how the human brain transforms a continuously disappearing signal into temporally extended linguistic structures.

  View details for DOI 10.1016/j.tics.2026.09.003

  View details for PubMedID 42830249

• Human cortical dynamics of auditory word form encoding. Neuron Zhang, Y., Leonard, M. K., Bhaya-Grossman, I., Gwilliams, L., Chang, E. F. 2025

  Abstract

  We perceive continuous speech as a series of discrete words, despite the lack of clear acoustic boundaries. The superior temporal gyrus (STG) encodes phonetic elements like consonants and vowels, but it is unclear how whole words are encoded. Using high-density cortical recordings and spoken narratives, we investigated how the human brain represents auditory word forms. STG activity exhibits a distinctive reset at word boundaries, marked by a sharp drop in cortical activity. Between resets, STG encodes acoustic-phonetic, prosodic, and lexical features, supporting integration of phonological features into coherent word forms. This process tracks the relative elapsed time within words, independent of absolute duration, providing a flexible encoding of variable word lengths. Similar dynamics were found in deeper layers of a self-supervised artificial speech network. Finally, a bistable word perception task revealed trial-by-trial STG responses to perceived word boundaries. Together, these findings support a new dynamical model of auditory word forms.

  View details for DOI 10.1016/j.neuron.2025.10.011

  View details for PubMedID 41205609

• Hierarchical dynamic coding coordinates speech comprehension in the human brain. Proceedings of the National Academy of Sciences of the United States of America Gwilliams, L., Marantz, A., Poeppel, D., King, J. R. 2025; 122 (42): e2422097122

  Abstract

  Speech comprehension involves transforming an acoustic waveform into meaning. To do so, the human brain generates a hierarchy of features that converts the sensory input into increasingly abstract language properties. However, little is known about how rapid incoming sequences of hierarchical features are continuously coordinated. Here, we propose that each language feature is supported by a dynamic neural code, which represents the sequence history of hierarchical features in parallel. To test this "hierarchical dynamic coding" (HDC) hypothesis, we use time-resolved decoding of brain activity to track the construction, maintenance, and update of a comprehensive hierarchy of language features spanning phonetic, word form, lexical-syntactic, syntactic, and semantic representations. For this, we recorded 21 native English participants with magnetoencephalography (MEG), while they listened to two hours of short stories in English. Our analyses reveal three main findings. First, the brain represents and simultaneously maintains a sequence of hierarchical features. Second, the duration of these representations depends on their level in the language hierarchy. Third, each representation is maintained by a dynamic neural code, which evolves at a speed commensurate with its corresponding linguistic level. This HDC preserves the maintenance of information over time while limiting destructive interference between successive features. Overall, HDC reveals how the human brain maintains and updates the continuously unfolding language hierarchy during natural speech comprehension, thereby anchoring linguistic theories to their biological implementations.

  View details for DOI 10.1073/pnas.2422097122

  View details for PubMedID 41105708

• Neural dynamics of phoneme sequences reveal position-invariant code for content and order. Nature communications Gwilliams, L., King, J. R., Marantz, A., Poeppel, D. 2022; 13 (1): 6606

  Abstract

  Speech consists of a continuously-varying acoustic signal. Yet human listeners experience it as sequences of discrete speech sounds, which are used to recognise discrete words. To examine how the human brain appropriately sequences the speech signal, we recorded two-hour magnetoencephalograms from 21 participants listening to short narratives. Our analyses show that the brain continuously encodes the three most recently heard speech sounds in parallel, and maintains this information long past its dissipation from the sensory input. Each speech sound representation evolves over time, jointly encoding both its phonetic features and the amount of time elapsed since onset. As a result, this dynamic neural pattern encodes both the relative order and phonetic content of the speech sequence. These representations are active earlier when phonemes are more predictable, and are sustained longer when lexical identity is uncertain. Our results show how phonetic sequences in natural speech are represented at the level of populations of neurons, providing insight into what intermediary representations exist between the sensory input and sub-lexical units. The flexibility in the dynamics of these representations paves the way for further understanding of how such sequences may be used to interface with higher order structure such as lexical identity.

  View details for DOI 10.1038/s41467-022-34326-1

  View details for PubMedID 36329058

  View details for PubMedCentralID PMC9633780

• In Spoken Word Recognition, the Future Predicts the Past JOURNAL OF NEUROSCIENCE Gwilliams, L., Linzen, T., Poeppel, D., Marantz, A. 2018; 38 (35): 7585-7599

  Abstract

  Speech is an inherently noisy and ambiguous signal. To fluently derive meaning, a listener must integrate contextual information to guide interpretations of the sensory input. Although many studies have demonstrated the influence of prior context on speech perception, the neural mechanisms supporting the integration of subsequent context remain unknown. Using MEG to record from human auditory cortex, we analyzed responses to spoken words with a varyingly ambiguous onset phoneme, the identity of which is later disambiguated at the lexical uniqueness point. Fifty participants (both male and female) were recruited across two MEG experiments. Our findings suggest that primary auditory cortex is sensitive to phonological ambiguity very early during processing at just 50 ms after onset. Subphonemic detail is preserved in auditory cortex over long timescales and re-evoked at subsequent phoneme positions. Commitments to phonological categories occur in parallel, resolving on the shorter timescale of ∼450 ms. These findings provide evidence that future input determines the perception of earlier speech sounds by maintaining sensory features until they can be integrated with top-down lexical information.SIGNIFICANCE STATEMENT The perception of a speech sound is determined by its surrounding context in the form of words, sentences, and other speech sounds. Often, such contextual information becomes available later than the sensory input. The present study is the first to unveil how the brain uses this subsequent information to aid speech comprehension. Concretely, we found that the auditory system actively maintains the acoustic signal in auditory cortex while concurrently making guesses about the identity of the words being said. Such a processing strategy allows the content of the message to be accessed quickly while also permitting reanalysis of the acoustic signal to minimize parsing mistakes.

  View details for DOI 10.1523/JNEUROSCI.0065-18.2018

  View details for Web of Science ID 000442995700004

  View details for PubMedID 30012695

  View details for PubMedCentralID PMC6113903

• Noise Optimization of Basic Signal Component Extraction for Cryogenic and On-Scalp Magnetoencephalography (MEG). bioRxiv : the preprint server for biology McPherson, A., Sanchirico, S., Xu, A., Larson, E., Kaestner, M., Turner, W., Gwilliams, L., Taulu, S. 2026

  Abstract

  Magnetoencephalography (MEG) measures human neural activity non-invasively with spatio-temporal precision, and has been foundational in enabling impactful discoveries in cognitive neuroscience. New on-scalp MEG sensor technologies, such as OPM-MEG, offer the opportunity to capture more information about the neuronal magnetic fields with higher sensitivity to more complex, higher order spatial components, leading to improved source localization. The accuracy of MEG and OPM-MEG source localization relies on data preprocessing techniques to isolate the neuronal fields from other magnetic and biomagnetic sources through signal space separation, rejection, and suppression methods. Current preprocessing methods risk rejecting brain signals of interest, or can spread sensor noise artifacts unknowingly. Here we propose a novel preprocessing method for MEG, and test the extent to which it overcomes limitations of prior methods. Specifically, we derive, apply, and assess a novel signal space separation (SSS) method with Foster's inverse, a weighted matrix inversion protocol that can utilize information about the MEG sensor noise and artifacts to reconstruct neuronal activity. With simulations, phantom head cryogenic MEG recordings, and subject recordings with two OPM-MEG systems, we show that Foster's inverse with SSS offers a more robust and stable reconstruction of the neuronal magnetic fields, especially in the face of sensor noise and artifacts. As the field of cognitive neuroscience continues to embrace MEG and OPM-MEG, Foster's inverse with SSS offers a robust and powerful data preprocessing technique for reducing noise and improving source localization of the underlying neuronal currents.

  View details for DOI 10.64898/2026.07.21.739883

  View details for PubMedID 42539285

  View details for PubMedCentralID PMC13419842

• On the speed of conscious perception: how soon is now? The Behavioral and brain sciences Turner, W., Hogendoorn, H., Gwilliams, L. 2026; 49: e195

  Abstract

  Fleming and Michel propose that conscious perception is "slow", with a delay of 350-450ms. But this claim is premature. Here, we will show that the speed of conscious perception remains unresolved. Examining evidence from vision and language research, we will explore how this fundamental question may ultimately be answered to test the validity of this foundational claim.

  View details for DOI 10.1017/S0140525X25103051

  View details for PubMedID 42342577

• Measuring naturalistic speech comprehension in real time. Behavior research methods Ergin, I., Kries, J., Gupta, S., Papworth Burrel, M., Gwilliams, L. 2026; 58 (4)

  Abstract

  Speech comprehension has been described as an effortless and robust process; yet, in real-world contexts, it is common for a listener to misunderstand what was said or fail to derive meaning entirely. Typically, methods of measuring speech comprehension are applied 'post hoc' - that is, after the comprehension has happened. This approach fails to capture comprehension as it occurs, limiting the field's understanding of the cognitive processes involved in real-time comprehension. To overcome these challenges, we designed and tested a novel method of measuring real-time speech comprehension during naturalistic listening. We built a slider device that synchronizes with experimental software and provides millisecond read-out. In three experiments, participants listened to audiobook segments while providing continuous comprehension ratings using the slider. To vary comprehension success, we presented speech segments at speed factors of 1-5 times faster than normal. We validated the time-resolved slider data against established speech comprehension assessment methods. Overall, our findings validate our novel time-resolved comprehension measure and demonstrate that it is possible to derive an online behavioral measure of real-time speech comprehension. We also confirmed numerous limitations of static post hoc assessments, including challenges with multiple-choice question design and the confounding of potential effects due to recency bias and comprehension for summarization. The measure proposed here overcomes the constraints of static post hoc assessments and can be effectively integrated with neuroimaging techniques, offering a valuable tool for future research on dynamic processes during naturalistic listening.

  View details for DOI 10.3758/s13428-026-02941-1

  View details for PubMedID 41896392

  View details for PubMedCentralID PMC13031255

• The spatio-temporal dynamics of phoneme encoding in aging and aphasia. The Journal of neuroscience : the official journal of the Society for Neuroscience Kries, J., Vandermosten, M., Gwilliams, L. 2025

  Abstract

  During successful language comprehension, speech sounds (phonemes) are encoded within a series of neural patterns that evolve over time. Here we tested whether these neural dynamics of speech encoding are altered for individuals with a language disorder. We recorded EEG responses from human brains of 39 individuals with post-stroke aphasia (13♀/26♂) and 24 healthy age-matched controls (i.e., older adults; 8♀/16♂) during 25 minutes of natural story listening. We estimated the duration of phonetic feature encoding, speed of evolution across neural populations, and the spatial location of encoding over EEG sensors. First, we establish that phonetic features are robustly encoded in EEG responses of healthy older adults. Second, when comparing individuals with aphasia to healthy controls, we find significantly decreased phonetic encoding in the aphasic group after shared initial processing pattern (0.08-0.25s after phoneme onset). Phonetic features were less strongly encoded over left-lateralized electrodes in the aphasia group compared to controls, with no difference in speed of neural pattern evolution. Finally, we observed that healthy controls, but not individuals with aphasia, encode phonetic features longer when uncertainty about word identity is high, indicating that this mechanism - encoding phonetic information until word identity is resolved - is crucial for successful comprehension. Together, our results suggest that aphasia may entail failure to maintain lower-order information long enough to recognize lexical items.Significance statement This study reveals robust decoding of speech sound properties, so-called phonetic features, from EEG recordings in older adults, as well as decreased phonetic processing in individuals with a language disorder (aphasia) compared to healthy controls. This was most prominent over left-hemispheric electrodes. Additionally, we observed that healthy controls, but not individuals with aphasia, encode phonetic features longer when uncertainty about word identity is high, indicating that this mechanism - encoding phonetic information until word identity is resolved - is crucial for successful language processing. These insights deepen our understanding of disrupted mechanisms in a language disorder, and show how the integration between language processing levels works in the healthy aging, neurotypical brain.

  View details for DOI 10.1523/JNEUROSCI.1001-25.2025

  View details for PubMedID 41461535

• Shared and language-specific phonological processing in the human temporal lobe NATURE Bhaya-Grossman, I., Leonard, M. K., Zhang, Y., Gwilliams, L., Johnson, K., Lu, J., Chang, E. F. 2025

  Abstract

  All spoken languages are produced by the human vocal tract, which defines the limited set of possible speech sounds. Despite this constraint, however, there exists incredible diversity in the world's 7,000 spoken languages, each of which is learned through extensive experience hearing speech in language-specific contexts1. It remains unknown which elements of speech processing in the brain depend on daily language experience and which do not. In this study, we recorded high-density cortical activity from adult participants with diverse language backgrounds as they listened to speech in their native language and an unfamiliar foreign language. We found that, regardless of language experience, both native and foreign languages elicited similar cortical responses in the superior temporal gyrus (STG), associated with shared acoustic-phonetic processing of foundational speech sound features2,3, such as vowels and consonants. However, only during native language listening did we observe enhanced neural encoding in the STG for word boundaries, word frequency and language-specific sound sequence statistics. In a separate cohort of bilingual participants, this encoding of word- and sequence-level information appeared for both familiar languages in the same individual and in the same STG neural populations. These results indicate that experience-dependent language processing involves dynamic integration of both shared acoustic-phonetic and language-specific sequence- and word-level information in the STG.

  View details for DOI 10.1038/s41586-025-09748-8

  View details for Web of Science ID 001618064000001

  View details for PubMedID 41261133

  View details for PubMedCentralID 4350233

• Dynamics of pitch perception in the auditory cortex. The Journal of neuroscience : the official journal of the Society for Neuroscience Abrams, E. B., Marantz, A., Krementsov, I., Gwilliams, L. 2025

  Abstract

  The ability to perceive pitch allows human listeners to experience music, recognize the identity and emotion conveyed by conversational partners, and make sense of their auditory environment. A pitch percept is formed by weighting different acoustic cues (e.g., signal fundamental frequency and inter-harmonic spacing) and contextual cues (expectation). How and when such cues are neurally encoded and integrated remains debated. In this study, twenty-eight participants (16 female) listened to tone sequences with different acoustic cues (pure tones, complex missing fundamental tones, and tones with an ambiguous mixture), placed in predictable and less predictable sequences, while magnetoencephalography was recorded. Decoding analyses revealed that pitch was encoded in neural responses to all three tone types, in the low-to-mid auditory cortex and sensorimotor cortex bilaterally, with right-hemisphere dominance. The pattern of activity generalized across cue-types, offset in time: pitch was neurally encoded earlier for harmonic tones (∼85ms) than pure tones (∼95ms). For ambiguous tones, pitch emerged significantly earlier in predictable contexts than unpredictable. The results suggest that a unified neural representation of pitch emerges by integrating independent pitch cues, and that context alters the dynamics of pitch generation when acoustic cues are ambiguous.Significance Statement Pitch enables humans to enjoy music, understand the emotional intent of a conversational partner, distinguish lexical items in tonal languages, and make sense of the acoustic environment. The study of pitch has lasted over a century, with conflicting accounts of how and when the brain integrates spectrotemporal information to map different sound sources onto a single and stable pitch percept. Our results answer crucial questions about the emergence of perceptual pitch in the brain: namely, that place and temporal cues to pitch seem to be accounted for by early auditory cortex, that a common representation of perceptual pitch emerges early in the right hemisphere, and that the temporal dynamics of pitch representations are modulated by expectation.

  View details for DOI 10.1523/JNEUROSCI.1111-24.2025

  View details for PubMedID 39909567

• Computational Architecture of Speech Comprehension in the Human Brain ANNUAL REVIEW OF LINGUISTICS Gwilliams, L., Bhaya-Grossman, I., Zhang, Y., Scott, T., Harper, S., Levy, D. 2025; 11: 209-226

  View details for DOI 10.1146/annurev-linguistics-031120-111245

  View details for Web of Science ID 001447460100001

• What we mean when we say semantic: Toward a multidisciplinary semantic glossary. Psychonomic bulletin & review Reilly, J., Shain, C., Borghesani, V., Kuhnke, P., Vigliocco, G., Peelle, J. E., Mahon, B. Z., Buxbaum, L. J., Majid, A., Brysbaert, M., Borghi, A. M., De Deyne, S., Dove, G., Papeo, L., Pexman, P. M., Poeppel, D., Lupyan, G., Boggio, P., Hickok, G., Gwilliams, L., Fernandino, L., Mirman, D., Chrysikou, E. G., Sandberg, C. W., Crutch, S. J., Pylkkänen, L., Yee, E., Jackson, R. L., Rodd, J. M., Bedny, M., Connell, L., Kiefer, M., Kemmerer, D., de Zubicaray, G., Jefferies, E., Lynott, D., Siew, C. S., Desai, R. H., McRae, K., Diaz, M. T., Bolognesi, M., Fedorenko, E., Kiran, S., Montefinese, M., Binder, J. R., Yap, M. J., Hartwigsen, G., Cantlon, J., Bi, Y., Hoffman, P., Garcea, F. E., Vinson, D. 2024

  Abstract

  Tulving characterized semantic memory as a vast repository of meaning that underlies language and many other cognitive processes. This perspective on lexical and conceptual knowledge galvanized a new era of research undertaken by numerous fields, each with their own idiosyncratic methods and terminology. For example, "concept" has different meanings in philosophy, linguistics, and psychology. As such, many fundamental constructs used to delineate semantic theories remain underspecified and/or opaque. Weak construct specificity is among the leading causes of the replication crisis now facing psychology and related fields. Term ambiguity hinders cross-disciplinary communication, falsifiability, and incremental theory-building. Numerous cognitive subdisciplines (e.g., vision, affective neuroscience) have recently addressed these limitations via the development of consensus-based guidelines and definitions. The project to follow represents our effort to produce a multidisciplinary semantic glossary consisting of succinct definitions, background, principled dissenting views, ratings of agreement, and subjective confidence for 17 target constructs (e.g., abstractness, abstraction, concreteness, concept, embodied cognition, event semantics, lexical-semantic, modality, representation, semantic control, semantic feature, simulation, semantic distance, semantic dimension). We discuss potential benefits and pitfalls (e.g., implicit bias, prescriptiveness) of these efforts to specify a common nomenclature that other researchers might index in specifying their own theoretical perspectives (e.g., They said X, but I mean Y).

  View details for DOI 10.3758/s13423-024-02556-7

  View details for PubMedID 39231896

  View details for PubMedCentralID 4215955

• Speech prosody enhances the neural processing of syntax. Communications biology Degano, G., Donhauser, P. W., Gwilliams, L., Merlo, P., Golestani, N. 2024; 7 (1): 748

  Abstract

  Human language relies on the correct processing of syntactic information, as it is essential for successful communication between speakers. As an abstract level of language, syntax has often been studied separately from the physical form of the speech signal, thus often masking the interactions that can promote better syntactic processing in the human brain. However, behavioral and neural evidence from adults suggests the idea that prosody and syntax interact, and studies in infants support the notion that prosody assists language learning. Here we analyze a MEG dataset to investigate how acoustic cues, specifically prosody, interact with syntactic representations in the brains of native English speakers. More specifically, to examine whether prosody enhances the cortical encoding of syntactic representations, we decode syntactic phrase boundaries directly from brain activity, and evaluate possible modulations of this decoding by the prosodic boundaries. Our findings demonstrate that the presence of prosodic boundaries improves the neural representation of phrase boundaries, indicating the facilitative role of prosodic cues in processing abstract linguistic features. This work has implications for interactive models of how the brain processes different linguistic features. Future research is needed to establish the neural underpinnings of prosody-syntax interactions in languages with different typological characteristics.

  View details for DOI 10.1038/s42003-024-06444-7

  View details for PubMedID 38902370

  View details for PubMedCentralID 3216045

• Negation mitigates rather than inverts the neural representations of adjectives. PLoS biology Zuanazzi, A., Ripollés, P., Lin, W. M., Gwilliams, L., King, J. R., Poeppel, D. 2024; 22 (5): e3002622

  Abstract

  Combinatoric linguistic operations underpin human language processes, but how meaning is composed and refined in the mind of the reader is not well understood. We address this puzzle by exploiting the ubiquitous function of negation. We track the online effects of negation ("not") and intensifiers ("really") on the representation of scalar adjectives (e.g., "good") in parametrically designed behavioral and neurophysiological (MEG) experiments. The behavioral data show that participants first interpret negated adjectives as affirmative and later modify their interpretation towards, but never exactly as, the opposite meaning. Decoding analyses of neural activity further reveal significant above chance decoding accuracy for negated adjectives within 600 ms from adjective onset, suggesting that negation does not invert the representation of adjectives (i.e., "not bad" represented as "good"); furthermore, decoding accuracy for negated adjectives is found to be significantly lower than that for affirmative adjectives. Overall, these results suggest that negation mitigates rather than inverts the neural representations of adjectives. This putative suppression mechanism of negation is supported by increased synchronization of beta-band neural activity in sensorimotor areas. The analysis of negation provides a steppingstone to understand how the human brain represents changes of meaning over time.

  View details for DOI 10.1371/journal.pbio.3002622

  View details for PubMedID 38814982

  View details for PubMedCentralID PMC11139306

• Hierarchical dynamic coding coordinates speech comprehension in the brain. bioRxiv : the preprint server for biology Gwilliams, L., Marantz, A., Poeppel, D., King, J. R. 2024

  Abstract

  Speech comprehension requires the human brain to transform an acoustic waveform into meaning. To do so, the brain generates a hierarchy of features that converts the sensory input into increasingly abstract language properties. However, little is known about how these hierarchical features are generated and continuously coordinated. Here, we propose that each linguistic feature is dynamically represented in the brain to simultaneously represent successive events. To test this 'Hierarchical Dynamic Coding' (HDC) hypothesis, we use time-resolved decoding of brain activity to track the construction, maintenance, and integration of a comprehensive hierarchy of language features spanning acoustic, phonetic, sub-lexical, lexical, syntactic and semantic representations. For this, we recorded 21 participants with magnetoencephalography (MEG), while they listened to two hours of short stories. Our analyses reveal three main findings. First, the brain incrementally represents and simultaneously maintains successive features. Second, the duration of these representations depend on their level in the language hierarchy. Third, each representation is maintained by a dynamic neural code, which evolves at a speed commensurate with its corresponding linguistic level. This HDC preserves the maintenance of information over time while limiting the interference between successive features. Overall, HDC reveals how the human brain continuously builds and maintains a language hierarchy during natural speech comprehension, thereby anchoring linguistic theories to their biological implementations.

  View details for DOI 10.1101/2024.04.19.590280

  View details for PubMedID 38659750

  View details for PubMedCentralID PMC11042271

• Introducing MEG-MASC a high-quality magneto-encephalography dataset for evaluating natural speech processing. Scientific data Gwilliams, L., Flick, G., Marantz, A., Pylkkänen, L., Poeppel, D., King, J. R. 2023; 10 (1): 862

  Abstract

  The "MEG-MASC" dataset provides a curated set of raw magnetoencephalography (MEG) recordings of 27 English speakers who listened to two hours of naturalistic stories. Each participant performed two identical sessions, involving listening to four fictional stories from the Manually Annotated Sub-Corpus (MASC) intermixed with random word lists and comprehension questions. We time-stamp the onset and offset of each word and phoneme in the metadata of the recording, and organize the dataset according to the 'Brain Imaging Data Structure' (BIDS). This data collection provides a suitable benchmark to large-scale encoding and decoding analyses of temporally-resolved brain responses to speech. We provide the Python code to replicate several validations analyses of the MEG evoked responses such as the temporal decoding of phonetic features and word frequency. All code and MEG, audio and text data are publicly available to keep with best practices in transparent and reproducible research.

  View details for DOI 10.1038/s41597-023-02752-5

  View details for PubMedID 38049487

  View details for PubMedCentralID 7513462

• Top-down information shapes lexical processing when listening to continuous speech LANGUAGE COGNITION AND NEUROSCIENCE Gwilliams, L., Marantz, A., Poeppel, D., King, J. 2024; 39 (8): 1045-1058

  View details for DOI 10.1080/23273798.2023.2171072

  View details for Web of Science ID 000941737400001

• Exploring age-related changes in inter-brain synchrony during verbal communication COGNITIVE AGING Dikker, S., Mech, E. N., Gwilliams, L., West, T., Dumas, G., Federmeier, K. D. edited by Federmeier, K. D., Payne, B. R. 2022; 77: 29-68

  View details for DOI 10.1016/bs.plm.2022.08.003

  View details for Web of Science ID 000894544700002

• Recurrent processes support a cascade of hierarchical decisions ELIFE Gwilliams, L., King, J. 2020; 9

  Abstract

  Perception depends on a complex interplay between feedforward and recurrent processing. Yet, while the former has been extensively characterized, the computational organization of the latter remains largely unknown. Here, we use magneto-encephalography to localize, track and decode the feedforward and recurrent processes of reading, as elicited by letters and digits whose level of ambiguity was parametrically manipulated. We first confirm that a feedforward response propagates through the ventral and dorsal pathways within the first 200 ms. The subsequent activity is distributed across temporal, parietal and prefrontal cortices, which sequentially generate five levels of representations culminating in action-specific motor signals. Our decoding analyses reveal that both the content and the timing of these brain responses are best explained by a hierarchy of recurrent neural assemblies, which both maintain and broadcast increasingly rich representations. Together, these results show how recurrent processes generate, over extended time periods, a cascade of decisions that ultimately accounts for subjects' perceptual reports and reaction times.

  View details for DOI 10.7554/eLife.56603

  View details for Web of Science ID 000573420300001

  View details for PubMedID 32869746

  View details for PubMedCentralID PMC7513462

• Hierarchical oscillators in speech comprehension: a commentary on Meyer, Sun, and Martin (2019) LANGUAGE COGNITION AND NEUROSCIENCE Gwilliams, L. 2020; 35 (9): 1114-1118

  View details for DOI 10.1080/23273798.2020.1740749

  View details for Web of Science ID 000520559100001

• How the brain composes morphemes into meaning PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Gwilliams, L. 2020; 375 (1791): 20190311

  Abstract

  Morphemes (e.g. [tune], [-ful], [-ly]) are the basic blocks with which complex meaning is built. Here, I explore the critical role that morpho-syntactic rules play in forming the meaning of morphologically complex words, from two primary standpoints: (i) how semantically rich stem morphemes (e.g. explode, bake, post) combine with syntactic operators (e.g. -ion, -er, -age) to output a semantically predictable result; (ii) how this process can be understood in terms of mathematical operations, easily allowing the brain to generate representations of novel morphemes and comprehend novel words. With these ideas in mind, I offer a model of morphological processing that incorporates semantic and morpho-syntactic operations in service to meaning composition, and discuss how such a model could be implemented in the human brain. This article is part of the theme issue 'Towards mechanistic models of meaning composition'.

  View details for DOI 10.1098/rstb.2019.0311

  View details for Web of Science ID 000502785400010

  View details for PubMedID 31840591

  View details for PubMedCentralID PMC6939360

• Language in Context: MEG Evidence for Modality-General and - Specific Responses to Reference esolution ENEURO Brodbeck, C., Gwilliams, L., Pylkkanen, L. 2016; 3 (6)

  Abstract

  Successful language comprehension critically depends on our ability to link linguistic expressions to the entities they refer to. Without reference resolution, newly encountered language cannot be related to previously acquired knowledge. The human experience includes many different types of referents, some visual, some auditory, some very abstract. Does the neural basis of reference resolution depend on the nature of the referents, or do our brains use a modality-general mechanism for linking meanings to referents? Here we report evidence for both. Using magnetoencephalography (MEG), we varied both the modality of referents, which consisted either of visual or auditory objects, and the point at which reference resolution was possible within sentences. Source-localized MEG responses revealed brain activity associated with reference resolution that was independent of the modality of the referents, localized to the medial parietal lobe and starting ∼415 ms after the onset of reference resolving words. A modality-specific response to reference resolution in auditory domains was also found, in the vicinity of auditory cortex. Our results suggest that referential language processing cannot be reduced to processing in classical language regions and representations of the referential domain in modality-specific neural systems. Instead, our results suggest that reference resolution engages medial parietal cortex, which supports a mechanism for referential processing regardless of the content modality.

  View details for DOI 10.1523/ENEURO.0145-16.2016

  View details for Web of Science ID 000391930900006

  View details for PubMedID 28058272

  View details for PubMedCentralID PMC5200920

• Functional characterisation of letter-specific responses in time, space and current polarity using magnetoencephalography NEUROIMAGE Gwilliams, L., Lewis, G. A., Marantz, A. 2016; 132: 320-333

  Abstract

  Recent neurophysiological evidence suggests that a hierarchical neural network of low-to-high level processing subserves written language comprehension. While a considerable amount of research has identified distinct regions and stages of processing, the relations between them and to this hierarchical model remain unclear. Magnetoencephalography (MEG) is a technique frequently employed in such investigations; however, no studies have sought to test whether the conventional method of reconstructing currents at the source of the magnetic field is best suited for such across-subject designs. The present study details the results of three MEG experiments addressing these issues. Neuronal populations supporting responses to low-level orthographic properties were housed posteriorly near the primary visual cortex. More anterior regions along the fusiform gyrus encoded higher-level processes and became active ~80ms later. A functional localiser of these early letter-specific responses was developed for the production of functional regions of interest in future studies. Previously established response components were successfully grouped based on proximity to the localiser, which characterised location, latency and functional sensitivity. Unconventional anatomically constrained signed minimum norm estimates of MEG data were most sensitive to the primary experimental manipulation, suggesting that the conventional unsigned unconstrained method is sub-optimal for studying written word processing.

  View details for DOI 10.1016/j.neuroimage.2016.02.057

  View details for Web of Science ID 000374832200033

  View details for PubMedID 26926792

• EEG can Track the Time Course of Successful Reference Resolution in Small Visual Worlds FRONTIERS IN PSYCHOLOGY Brodbeck, C., Gwilliams, L., Pylkkaenen, L. 2015; 6: 1787

  Abstract

  Previous research has shown that language comprehenders resolve reference quickly and incrementally, but not much is known about the neural processes and representations that are involved. Studies of visual short-term memory suggest that access to the representation of an item from a previously seen display is associated with a negative evoked potential at posterior electrodes contralateral to the spatial location of that item in the display. In this paper we demonstrate that resolving the reference of a noun phrase in a recently seen visual display is associated with an event-related potential that is analogous to this effect. Our design was adapted from the visual world paradigm: in each trial, participants saw a display containing three simple objects, followed by a question about the objects, such as Was the pink fish next to a boat?, presented word by word. Questions differed in whether the color adjective allowed the reader to identify the referent of the noun phrase or not (i.e., whether one or more objects of the named color were present). Consistent with our hypothesis, we observed that reference resolution by the adjective was associated with a negative evoked potential at posterior electrodes contralateral to spatial location of the referent, starting approximately 333 ms after the onset of the adjective. The fact that the laterality of the effect depended upon the location of the referent within the display suggests that reference resolution in visual domains involves, at some level, a modality-specific representation. In addition, the effect gives us an estimate of the time course of processing from perception of the written word to the point at which its meaning is brought into correspondence with the referential domain.

  View details for DOI 10.3389/fpsyg.2015.01787

  View details for Web of Science ID 000366174100001

  View details for PubMedID 26635689

  View details for PubMedCentralID PMC4653275