About
69
Publications
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1,303
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Introduction
Current institution
Additional affiliations
January 2013 - April 2017
Position
- Research Assistant
Description
- Research focused on transient and sustained mechanisms of visual attention, the intrinsic functional organization of the visual system, and the effects of macular degeneration on structure and function in primary visual cortex.
August 2021 - May 2024
Omniscient Neurotechnology
Position
- Engineer
November 2020 - August 2021
Education
July 2012 - April 2017
August 2007 - December 2011
Publications
Publications (69)
Current theories of language recovery after stroke are limited by a reliance on small studies. Here, we aimed to test predictions of current theory and resolve inconsistencies regarding right hemispheric contributions to long-term recovery. We first defined the canonical semantic network in 43 healthy controls. Then, in a group of 43 patients with...
The preservation of near-typical function in distributed brain networks is associated with less severe deficits in chronic stroke patients. However, it remains unclear how task-evoked responses in networks that support complex cognitive functions such as semantic processing relate to the post-stroke brain anatomy. Here, we used recently developed m...
Stroke causes focal brain lesions that disrupt functional connectivity (FC), a measure of activity synchronization , throughout distributed brain networks. It is often assumed that FC disruptions reflect damage to specific cortical regions. However, an alternative explanation is that they reflect the structural disconnection (SDC) of white matter p...
Lesion studies are an important tool for cognitive neuroscientists and neurologists. However, while brain lesion studies have traditionally aimed to localize neurological symptoms to specific anatomical loci, a growing body of evidence indicates that neurological diseases such as stroke are best conceptualized as brain network disorders. While rese...
The traditional analytical framework taken by neuroimaging studies in general, and lesion-behavior studies in particular, has been inferential in nature and has focused on identifying and interpreting statistically significant effects within the sample under study. While this framework is well-suited for hypothesis testing approaches, achieving the...
The traditional analytical framework taken by neuroimaging studies in general, and lesion‐behavior studies in particular, has been inferential in nature and has focused on identifying and interpreting statistically significant effects within the sample under study. While this framework is well‐suited for hypothesis testing approaches, achieving the...
Temporal lobe (TL) epilepsy surgery is an effective treatment option for patients with drug-resistant epilepsy. However, neurosurgery poses a risk for cognitive deficits - up to one third of patients have a decline in naming ability following TL surgery. In this study, we aimed to better understand the neural correlates associated with reduced nami...
Computational whole-brain models describe the resting activity of each brain region based on a local model, inter-regional functional interactions, and a structural connectome that specifies the strength of inter-regional connections. Strokes damage the healthy structural connectome that forms the backbone of these models and produce large alterati...
Computational whole-brain models describe the resting activity of each brain region based on a local model, inter-regional functional interactions, and a structural connectome that specifies the strength of inter-regional connections. Strokes damage the healthy structural connectome that forms the backbone of these models and produce large alterati...
Understanding the effect of focal lesions (stroke) on brain structure-function traditionally relies on behavioral analyses and correlation with neuroimaging data. Here we use structural disconnection maps from individual lesions to derive a causal mechanistic generative whole-brain model able to explain both functional connectivity alterations and...
In vivo tracking of white matter fibres catalysed a modern perspective on the pivotal role of brain connectome disruption in neuropsychological deficits. However, the examination of white matter integrity in neurological patients by diffusion-weighted magnetic resonance imaging bears conceptual limitations and is not widely applicable, as it requir...
The mechanisms controlling dynamical patterns in spontaneous brain activity are poorly understood. Here, we provide evidence that cortical dynamics in the ultra-slow frequency range (<0.01–0.1 Hz) requires intact cortical-subcortical communication. Using functional magnetic resonance imaging (fMRI) at rest, we identify Dynamic Functional States (DF...
Studies investigating the effects of brain lesions on cognition and behavior have played a key role in shaping modern theories of brain function. While early studies in this domain typically involved post-mortem dissections of selected patients who presented with cognitive and/or behavioral deficits following brain injuries or neurological disease,...
Functional magnetic resonance imaging (fMRI) has been widely employed to study stroke pathophysiology. In particular, analyses of fMRI signals at rest were directed at quantifying the impact of stroke on spatial features of brain networks. However, brain networks have intrinsic time features that were, so far, disregarded in these analyses. In cons...
The UK Biobank (UKB) is a highly promising dataset for brain biomarker research into population mental health due to its unprecedented sample size and extensive phenotypic, imaging, and biological measurements. In this study, we aimed to provide a shared foundation for UKB neuroimaging research into mental health with a focus on anxiety and depress...
Recent resting-state functional MRI studies in stroke patients have identified two robust biomarkers of acute brain dysfunction: a reduction of inter-hemispheric functional connectivity between homotopic regions of the same network, and an abnormal increase of ipsi-lesional functional connectivity between task-negative and task-positive resting-sta...
Background
Research indicates intermittent theta burst stimulation (iTBS) is a potential treatment of post-stroke aphasia.
Material/Methods
In this double-blind, sham-controlled trial (NCT 01512264) participants were randomized to receive 3 weeks of sham (G0), 1 week of iTBS/2 weeks of sham (G1), 2 weeks of iTBS/1 week of sham (G2), or 3 weeks of...
The UK Biobank (UKB) is a highly promising dataset for brain biomarker research into population mental health due to its unprecedented sample size and extensive phenotypic, imaging, and biological measurements. In this study, we aimed to provide a shared foundation for UKB neuroimaging research into mental health with a focus on anxiety and depress...
Functional magnetic resonance imaging (fMRI) has been widely employed to study stroke pathophysiology. In particular, analyses of fMRI signals at rest were directed at quantifying the impact of stroke on spatial features of brain networks. However, brain networks have intrinsic time features that were, so far, disregarded in these analyses. In cons...
Recent resting-state fMRI studies in stroke patients have identified two robust biomarkers of acute brain dysfunction: a reduction of inter-hemispheric functional connectivity (FC) between homotopic regions of the same network, and an abnormal increase of ipsilesional FC between task-negative and task-positive resting-state networks (RSNs). Whole-b...
Lesion studies are an important tool for cognitive neuroscientists and neurologists. However, while brain lesion studies have traditionally aimed to localize neurological symptoms to specific anatomical loci, a growing body of evidence indicates that neurological diseases such as stroke are best conceptualized as brain network disorders. While rese...
Focal brain lesions disrupt resting-state functional connectivity, but the underlying structural mechanisms are unclear. Here, we examined the direct and indirect effects of structural disconnections on resting-state functional connectivity in a large sample of sub-acute stroke patients with heterogeneous brain lesions. We estimated the impact of e...
Focal brain lesions disrupt resting-state functional connectivity, but the underlying structural mechanisms are unclear. Here, we examined the direct and indirect effects of structural disconnections on resting-state functional connectivity in a large sample of sub-acute stroke patients with heterogeneous brain lesions. We defined direct disconnect...
Functional connectivity (FC) studies have identified physiological signatures of stroke that correlate with behavior. Using structural and functional MRI data from 114 stroke patients, 24 matched controls, and the Human Connectome Project, we tested the hypothesis that structural disconnection, not damage to critical regions, underlies FC disruptio...
Available online xxxx Previously, we demonstrated an association between cortical hyperexcitability and mood disturbance in healthy adults. Studies have documented hyperexcitability in patients with idiopathic generalized epilepsies (IGEs; long-interval intracortical inhibition [LICI]) and high prevalence of mood comorbidities. This study aimed to...
We recently found that higher cortical excitability is associated with poorer attention performance in healthy adults. While patients with idiopathic generalized epilepsies (IGEs), previously termed genetic generalized epilepsies , are known to demonstrate increased cortical excitability and cognitive deficits, a relationship between these variable...
Purpose:
The purpose of this feasibility study was to assess whether combined intermittent theta burst suppression (iTBS) applied to the ipsilesional hemisphere and modified constraint-induced aphasia therapy (mCIAT) are safe and logistically feasible within the time interval associated with iTBS induced long-term potentiation in patients with pos...
Purpose:
Reports of the relationship between the default mode network (DMN) and alpha power are conflicting. Our goal was to assess this relationship by analyzing concurrently obtained EEG/functional MRI data using hypothesis-independent methods.
Methods:
We collected functional MRI and EEG data during eyes-closed rest in 20 participants aged 19...
Evidence from clinical populations, such as epilepsy and attention deficit/hyperactivity disorder, suggests a relationship between hyperexcitability and cognitive impairment, but this relationship has not been demonstrated in healthy individuals. Here, we investigate the relationship between cortical excitability and cognitive functioning in health...
Damage to the white matter underlying the left posterior
temporal lobe leads to deficits in multiple language functions. The
posterior temporal white matter may correspond to a bottleneck where both
dorsal and ventral language pathways are vulnerable to simultaneous
damage. Damage to a second putative white matter bottleneck in the left
deep prefro...
Neuroimaging evidence indicates that normalized processing in pre-existing language networks underlies language recovery after left hemisphere stroke. Damage to connections among language areas might be expected to impede recovery by disabling long-range communication and preventing the re-integration of surviving areas into coherent networks for l...
The cerebral cortex changes throughout the lifespan, and the cortical grey matter in many brain regions becomes thinner with advancing age. Effects of aging on cortical thickness have been observed in many brain regions, including areas involved in basic perceptual functions such as processing visual inputs. An important property of early visual co...
Damage to the white matter underlying the left posterior temporal lobe leads to deficits in multiple language functions. The posterior temporal white matter may correspond to a bottleneck where both dorsal and ventral language pathways are vulnerable to simultaneous damage. Damage to a second putative white matter bottleneck in the left deep prefro...
Current theories of language recovery after stroke are limited by a reliance on small studies. Here, we aimed to test predictions of current theory and resolve inconsistencies regarding right hemispheric contributions to long-term recovery. We first defined the canonical semantic network in 43 healthy controls. Then, in a group of 43 patients with...
Psychophysical and neurobiological evidence suggests that central and peripheral
vision are specialized for different functions. This specialization of function might be
expected to lead to differences in the large-scale functional interactions of early
cortical areas that represent central and peripheral visual space. Here, we
characterize differe...
Cortical excitability is related to attention, executive function, and mood in healthy adults
We describe the effects of a combined rTMS and CIAT intervention on neuropsychological tests of language function and on fMRI activity during a semantic decision task.
We investigate how damage to different anatomical structures relates to improvements in naming following a combined rTMS+CIAT intervention in chronic aphasia patients.
Better understanding of the extent and scope of visual cortex plasticity following central vision loss is essential both for clarifying the mechanisms of brain plasticity and for future development of interventions to retain or restore visual function. This study investigated structural differences in primary visual cortex between normally-sighted...
Note: Newest version is in the "Linked Research" (changes to default settings) because I couldn't replace the "full text" without deleting the whole thing.
Background: Manual lesion delineation by an expert is the standard for lesion identification in MRI scans, but is time-consuming and can introduce subjective bias. Alternative methods often require multi-modal MRI data, user interaction, scans from a control population, and/or arbitrary statistical thresholding.
New Method: We present an approach...
The effects of noninvasive neurostimulation on brain structure and function in chronic poststroke aphasia are poorly understood.We investigated the effects of intermittent theta burst stimulation (iTBS) applied to residual language-responsive cortex in chronicpatients using functional and anatomical MRI data acquired before and after iTBS. Laterali...
The Supplementary Material show raw BOLD time-series from each ROI for both patients with lesion-ROI overlaps in Supplementary Figure 1. The purpose of this figure is to illustrate that the time-series from the left IFG ROI, although it overlaps partially with the lesion, shows phasic responses that are similar to those observed for the right IFG R...
Task sets are task-specific configurations of cognitive processes that facilitate task-appropriate reactions to stimuli. While it is established that the trial-by-trial deployment of visual attention to expected stimuli influences neural responses in primary visual cortex (V1) in a retinotopically specific manner, it is not clear whether the mechan...
Central and peripheral vision have different functions. For example, we regularly attend to objects in central vision, and only occasionally attend to objects in peripheral vision. However, aside for compensating for the cortical magnification factor, neuroscientists tend to treat centrally-and peripherally-responsive cortical areas as if they were...
A fast algorithm for automated lesion masking in stroke patients
Neural activity in residual frontal cortex correlates with verbal ability in post-stroke aphasia
Structural correlates of residual language capacity in patients with post-stroke aphasia
Attention facilitates the processing of task-relevant visual information and suppresses interference from task-irrelevant information. Modulations of neural activity in visual cortex depend on attention, and likely result from signals originating in fronto-parietal and cingulo-opercular regions of cortex. Here, we tested the hypothesis that attenti...
Task-related Modulations of Functional Connectivity in Primary Visual Cortex are Eccentricity-Dependent.
Task Set Modulates the Response of Human V1 during Auditory and Visual Tasks
