Laura Gwilliams

Laura Gwilliams
University of California, San Francisco | UCSF · Department of Neurological Surgery

About

33
Publications
6,344
Reads
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293
Citations
Additional affiliations
August 2013 - August 2015
New York University Abu Dhabi
Position
  • Research Assistant

Publications

Publications (33)
Preprint
Full-text available
A fundamental unit of neural computation is the action potential. While significant advances have been made in the ability to sample action potentials of large numbers of individual neurons in animal models, translation of these methodologies to humans has been lacking due to clinical time constraints, electrical noise in the operating room, and re...
Article
The ability to process and respond to external input is critical for adaptive behavior. Why, then, do neural and behavioral responses vary across repeated presentations of the same sensory input? Ongoing fluctuations of neuronal excitability are currently hypothesized to underlie the trial-by-trial variability in sensory processing. To test this, w...
Preprint
Full-text available
The ability to process and respond to external input is critical for adaptive behavior. Why, then, do neural and behavioral responses vary across repeated presentations of the same sensory input? Spontaneous fluctuations of neuronal excitability are currently hypothesized to underlie the trial-by-trial variability in sensory processing. To test thi...
Article
Full-text available
Speech is a complex and ambiguous acoustic signal that varies significantly within and across speakers. Despite the processing challenge that such variability poses, humans adapt to systematic variations in pronunciation rapidly. The goal of this study is to uncover the neurobiological bases of the attunement process that enables such fluent compre...
Article
Full-text available
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...
Article
Full-text available
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...
Article
Full-text available
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...
Preprint
Speech perception relies on the rapid resolution of uncertainty. Here we explore whether auditory experiences contribute to this process of ambiguity resolution. ~8000 participants were surveyed online for their (i) subjective percept of a speech stimulus with ambiguous formant allocation; (ii) demographic profile and auditory experiences. Both lin...
Preprint
Full-text available
Listeners experience speech as a sequence of discrete words. However, the real input is a continuously varying acoustic signal that blends words and phonemes into one another. Here we recorded two-hour magnetoencephalograms from 21 subjects listening to stories, in order to investigate how the brain concurrently solves three competing demands: 1) p...
Article
Full-text available
This article provides an overview of research that uses magnetoencephalography to understand the brain basis of human language. The cognitive processes and brain networks that have been implicated in written and spoken language comprehension and production are discussed in relation to different methodologies: we review event-related brain responses...
Article
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This is a commentary on Meyer, Sun, and Martin (2020), Synchronous, but not entrained: exogenous and endogenous cortical rhythms of speech and language processing.
Article
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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 operator...
Preprint
Full-text available
Speech is a complex and ambiguous acoustic signal that varies significantly within and across speakers. A prevalent and ubiquitous example of such variation is accented speech, to which humans adapt extremely rapidly. The goal of this study is to uncover the neurobiological bases of the attunement process that enables such fluent comprehension. Twe...
Preprint
Full-text available
Mounting evidence suggests that perception depends on a largely-feedforward brain network. However, the discrepancy between (i) the latency of the corresponding feedforward responses (150-200 ms) and (ii) the time it takes human subjects to recognize brief images (often >500 ms) suggests that recurrent neuronal activity is critical to visual proces...
Article
Full-text available
We revisit a long-standing question in the psycholinguistic and neurolinguistic literature on comprehending morphologically complex words: are prefixes and suffixes processed using the same cognitive mechanisms? Recent work using Magnetoencephalography (MEG) to uncover the dynamic temporal and spatial responses evoked by visually presented complex...
Article
Full-text available
Speech is an inherently noisy and ambiguous signal. In order to fluently derive meaning, a listener must integrate contextual information to guide interpretations of the sensory input. While many studies have demonstrated the influence of prior context on speech perception, the neural mechanisms supporting the integration of subsequent context rema...
Article
Full-text available
The field of psycho- and neuro-linguistics has long-debated the decompositional model of visual word processing: Are written words processed via the visual forms of stem and affix morphemes, or as complex wholes? Although many have now settled upon a decompositional view, it is unclear what heuristic the brain uses to generate these visual morpheme...
Preprint
Full-text available
Speech is an inherently noisy and ambiguous signal. In order to fluently derive meaning, a listener must integrate contextual information to guide interpretations of the sensory input. While many studies have demonstrated the influence of prior context on speech perception, the neural mechanisms supporting the integration of subsequent context rema...
Preprint
Full-text available
Models of perceptual decision making have historically been designed to maximally explain behaviour and brain activity independently of their ability to actually perform tasks. More recently, performance-optimized models have been shown to correlate with brain responses to images and thus present a complementary approach to understand perceptual pr...
Article
Full-text available
Spoken word recognition involves at least two basic computations. First is matching acoustic input to phonological categories (e.g. /b/, /p/, /d/). Second is activating words consistent with those phonological categories. Here we test the hypothesis that the listener's probability distribution over lexical items is weighted by the outcome of both c...
Article
Full-text available
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...
Article
Full-text available
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 (M...
Article
Full-text available
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 pote...
Conference Paper
Recent MEG experiments find evidence for at least two spatiotemporally distinct neural responses sensitive to morphological complexity: the M350/N400m response (200-450ms) originating in left STG/MTG, first sensitive to factors plausibly associated with complex word-stem lexical access (stem lemma frequency and morphological family size, frequency...
Article
Full-text available
Clausal analysis within Systemic Functional Linguistics (SFL) is generally based upon a classification of the clause into one of six process types. Although this allocation is often portrayed as clear-cut, in practice process distinction can be unclear, and a single verb may meet the coding criteria of a number of categories. The aim of this paper...
Article
Full-text available
Although the significance of morphological structure is established in visual word processing, its role in auditory processing remains unclear. Using magnetoencephalography we probe the significance of the root morpheme for spoken Arabic words with two experimental manipulations. First we compare a model of auditory processing that calculates proba...
Article
Full-text available
Access to morphological structure during lexical processing has been established across a number of languages; however, it remains unclear which constituents are held as mental representations in the lexicon. The present study examined the auditory recognition of different noun types across 2 experiments. The critical manipulations were morphologic...
Article
The present study investigated the neural correlates of the realisation of scalar inferences, i.e., the interpretation of some as meaning some but not all. We used magnetoencephalography, which has high temporal resolution, to measure neural activity while participants heard stories that included the scalar inference trigger some in contexts that e...
Conference Paper
Full-text available
Conducting a clausal analysis using Systemic Functional Linguistics hinges upon the classification of a main verb into one of six ‘Process Types’. Although this allocation is often portrayed as clear-cut, the reality is often less obvious, and a single verb may meet the coding criteria of a number of categories. When putting this classification to...

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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 aims to unveil how the brain uses such subsequent information to aid speech comprehension.