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Introduction
Additional affiliations
October 2015 - present
February 2011 - October 2015
January 2005 - December 2011
Education
September 2000 - February 2004
September 1996 - July 2000
Publications
Publications (185)
Objective:
A greater extent of resection of the temporal portion of the piriform cortex (PC) has been shown to be associated with higher likelihood of seizure freedom in adults undergoing anterior temporal lobe resection (ATLR) for drug-resistant temporal lobe epilepsy (TLE). There have been no such studies in children, therefore this study aimed...
Background and purpose:
Prior studies have found an association between calcification and the epileptogenicity of tubers in tuberous sclerosis complex. Quantitative susceptibility mapping is a novel tool sensitive to magnetic susceptibility alterations due to tissue calcification. We assessed the utility of quantitative susceptibility mapping in i...
Background
The presence of visual imagery in dreams of congenitally blind people has long been a matter of substantial controversy. We set to systematically review body of published work on the presence and nature of oneiric visuo-spatial impressions in congenitally and early blind subjects across different areas of research, from experimental psyc...
Objectives
We assessed cortical changes in children with drug-resistant focal epilepsy using surface-based T1 and T2 relaxometry (qT1 and qT2), to probe alterations in tissue-microstructure, and their relationship to clinical parameters.
Methods
Data Acquisition89 children were scanned unsedated on a 3T Achieva-TX scanner (Philips Healthcare) – 43...
Low-field (<1T) magnetic resonance imaging (MRI) scanners remain in widespread use in low- and middle-income countries (LMICs) and are commonly used for some applications in higher income countries e.g. for small child patients with obesity, claustrophobia, implants, or tattoos. However, low-field MR images commonly have lower resolution and poorer...
Low-field (<1T) magnetic resonance imaging (MRI) scanners remain in widespread use in low- and middle-income countries (LMICs) and are commonly used for some applications in higher income countries e.g. for small child patients with obesity, claustrophobia, implants, or tattoos. However, low-field MR images commonly have lower resolution and poorer...
Background: EEG-fMRI is a useful additional test to localize the epileptogenic zone (EZ) particularly in MRI negative
cases. However subject motion presents a particular challenge owing to its large effects on both MRI and EEG signal.
Traditionally it is assumed that prospective motion correction (PMC) of fMRI precludes EEG artifact correction. Met...
In this chapter, we first describe the main MRI data acquisition methods and some more recent advances. The requirement of a fMRI pulse sequence is BOLD sensitivity, which means predominantly T2*-weighted sequences such as gradient echo-echo-planar imaging (GE-EPI), although spin echo sequences such as spin echo-EPI (SE-EPI) can also be used (Bande...
The epilepsies are devastating neurological disorders for which progress developing effective new therapies has slowed over recent decades, primarily due to the complexity of the brain at all scales. This reality has shifted the focus of experimental and clinical practice toward complex systems approaches to overcoming current barriers. Organized b...
Our current understanding of focal epilepsy is evolving as increasing evidence suggests that tissue abnormalities may extend beyond the focus. In adults, widespread structural changes remote from the putative epileptic focus have been demonstrated with MRI, predominantly using morphological markers. However, the underlying pathophysiology of these...
Purpose
The MP2RAGE sequence is typically optimized for either T1-weighted uniform image (UNI) or gray matter–dominant fluid and white matter suppression (FLAWS) contrast images. Here, the purpose was to optimize an MP2RAGE protocol at 7 Tesla to provide UNI and FLAWS images simultaneously in a clinically applicable acquisition time at <0.7 mm isot...
Epilepsy is well-recognized as a disorder of brain networks. There is a growing body of research to identify critical nodes within dynamic epileptic networks with the aim to target therapies that halt the onset and propagation of seizures. In parallel, intracranial neuromodulation, including deep brain stimulation and responsive neurostimulation, a...
The large-scale organization of functional connectivity (FC) – the functional connectome – traverses distinct spatial patterns in a dynamic trajectory as demonstrated independently in fMRI and electrophysiological studies. These patterns are thought to satisfy ever-changing processing demands. FMRI and electrophysiology capture partly non-overlappi...
Purpose:
To evaluate specific absorption rate (SAR) and temperature distributions resulting from pediatric exposure to a 7T head coil.
Methods:
Exposure from a 297-MHz birdcage head transmit coil (CP mode single-channel transmission) was simulated in several child models (ages 3-14, mass 13.9-50.4 kg) and one adult, using time-domain electromagn...
Objectives
Simultaneous intracranial EEG and functional MRI (icEEG-fMRI) recordings in humans, whereby EEG is recorded from electrodes implanted inside the cranium during fMRI scanning, were made possible following safety studies on test phantoms and our specification of a rigorous data acquisition protocol. In parallel with this work, other invest...
Objective MRI is a cornerstone in presurgical evaluation of epilepsy. Despite guidelines, clinical practice varies. In light of the E‐PILEPSY pilot reference network, we conducted a systematic review and meta‐analysis on the diagnostic value of MRI in the presurgical evaluation of epilepsy patients.
Methods We included original research articles on...
The data quality of simultaneously acquired electroencephalography and functional magnetic resonance imaging (EEG-fMRI) can be strongly affected by motion. Recent work has shown that the quality of fMRI data can be improved by using a Moiré-Phase-Tracker (MPT)-camera system for prospective motion correction. The use of the head position acquired by...
Automatic detection or highlighting of neonatal brain injury could be a valuable adjunct to radiological interpretation. Here we propose a normative modeling-based detection method for preterm neonatal neuroimaging using gaussian processes (GPs). These GPs incorporates local image intensity information from image patches and demographics such as ag...
Background: Potentially curative epilepsy surgery can be offered if a single, discrete epileptogenic zone (EZ) can be identified. For individuals in whom there is no clear concordance between clinical localization, scalp EEG, and imaging data, intracranial EEG (icEEG) may be needed to confirm a predefined hypothesis regarding irritative zone (IZ),...
Background
Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation whose potential as a cognitive therapy is hindered by our limited understanding of how participant and experimental factors influence its effects. Using functional MRI to study brain networks, we have previously shown in healthy controls that the ph...
OBJECTIVE: Whilst stimulation of the anterior nucleus of the thalamus has shown efficacy for reducing seizure frequency in adults, alterations in thalamic connectivity have not been explored in children. We tested the hypotheses that (a) the anterior thalamus has increased functional connectivity in children with focal epilepsy, and (b) this altera...
Objective
Malformations of cortical development (MCD), including focal cortical dysplasia (FCD), are the most common cause of drug-resistant focal epilepsy in children. Histopathological lesion characterisation demonstrates abnormal cell types and lamination, alterations in myelin (typically co-localised with iron), and sometimes calcification. Qua...
BACKGROUND AND PURPOSE: Head motion causes image degradation in brain MR imaging examinations, negatively impacting image quality, especially in pediatric populations. Here, we used a retrospective motion correction technique in children and assessed image quality improvement for 3D MR imaging acquisitions.
MATERIALS AND METHODS: We prospectively...
The propagation of epileptic seizure activity in the brain is a widespread pathophysiology that, in principle, should yield to intervention techniques guided by mathematical models of neuronal ensemble dynamics. During a seizure, neural activity will deviate from its current dynamical regime to one in which there are significant signal fluctuations...
Epileptic networks, defined as brain regions involved in epileptic brain activity, have been mapped by functional connectivity in simultaneous electroencephalography and functional magnetic resonance imaging (EEG-fMRI) recordings. This technique allows to define brain hemodynamic changes, measured by the Blood Oxygen Level Dependent (BOLD) signal,...
Background
Transcranial direct current stimulation (tDCS) is a form of noninvasive brain stimulation whose potential as a cognitive therapy is hindered by our limited understanding of how participant and experimental factors influence its effects. Using functional MRI to study brain networks, we have previously shown in healthy controls that the ph...
Identification of neonatal brain abnormalities on MRI requires expert knowledge of both brain development and pathologies particular to this age group. To aid this process we propose an automated technique to highlight abnormal brain tissue while accommodating normal developmental changes. To train a developmental model, we used 185 T2 weighted neu...
Objective
Malformations of cortical development (MCD), including focal cortical dysplasia (FCD), are the most common cause of drug-resistant focal epilepsy in children. Histopathological lesion characterisation demonstrates abnormal cell types and lamination, alterations in myelin (typically co-localised with iron), and sometimes calcification. Qua...
Head motion causes image degradation in brain MRI examinations, negatively impacting image quality and increasing costs, especially in pediatric populations. Here, we used a retrospective motion correction technique in children and assessed image quality improvement for 3D MRI acquisitions.
Material and Methods: We prospectively acquired brain MRI...
The application of intracranial electroencephalography (icEEG) recording during functional magnetic resonance imaging (icEEG-fMRI) has allowed the study of the hemodynamic correlates of epileptic activity and of the neurophysiological basis of the blood oxygen level-dependent (BOLD) signal. However, the applicability of this technique is affected b...
Seizure activity is a ubiquitous and pernicious pathophysiology that, in principle, should yield to mathematical treatments of (neuronal) ensemble dynamics - and therefore interventions on stochastic chaos. A seizure can be characterised as a deviation of neural activity from a stable dynamical regime, i.e. one in which signals fluctuate only withi...
Objectives
To demonstrate feasibility of a 3 T multiparametric mapping (MPM) quantitative pipeline for perinatal post-mortem MR (PMMR) imaging.
Methods
Whole body quantitative PMMR imaging was acquired in four cases, mean gestational age 34 weeks, range (29–38 weeks) on a 3 T Siemens Prisma scanner. A multicontrast protocol yielded proton density,...
1.5T or 3T scanners are the current standard for clinical MRI, but low-field (<1T) scanners are still common in many lower- and middle-income countries for reasons of cost and robustness to power failures. Compared to modern high-field scanners, low-field scanners provide images with lower signal-to-noise ratio at equivalent resolution, leaving pra...
Objective:
Focal cortical dysplasia (FCD) lesion detection and subtyping remain challenging on conventional MRI. New diffusion models such as the spherical mean technique (SMT) and neurite orientation dispersion and density imaging (NODDI) provide measurements that potentially produce more specific maps of abnormal tissue microstructure. This stud...
We compared the results of Quantitative Susceptibility Mapping (QSM) in each of the Proton Density (PD-), Magnetization Transfer (MT-) and T1-weighted Multi-Echo Gradient-Echo (ME-GRE) sequences in Multi-Parametric Mapping (MPM) with QSM from a conventional ME-GRE sequence. In deep grey matter (GM) regions, we found significant susceptibility (χ) c...
In 15 homozygous sickle-cell disease patients (SCD; hemoglobin-SS) and 12 healthy controls (HC; 10 Hb-AA, 2 Hb-AS), we compared a quantitative susceptibility mapping (QSM)-based estimate of venous oxygen saturation (Yv) with T2-relaxation-under-spin-tagging (TRUST)-based estimates using bovine-hemoglobin (TRUST-HbBV), hemoglobin-S (TRUST-HbS), or h...
MR images scanned at low magnetic field (<1T) have lower resolution in the slice direction and lower contrast, due to a relatively small signal-to-noise ratio (SNR) than those from high field (typically 1.5T and 3T). We adapt the recent idea of Image Quality Transfer (IQT) to enhance very low-field structural images aiming to estimate the resolutio...
MR images scanned at low magnetic field ($<1$T) have lower resolution in the slice direction and lower contrast, due to a relatively small signal-to-noise ratio (SNR) than those from high field (typically 1.5T and 3T). We adapt the recent idea of Image Quality Transfer (IQT) to enhance very low-field structural images aiming to estimate the resolut...
Non-invasive brain stimulation has been widely investigated as a potential treatment for a range of neurological and psychiatric conditions, including brain injury. However, the behavioural effects of brain stimulation are variable, for reasons that are poorly understood. This is a particular challenge for traumatic brain injury, where patterns of...
FIGURE S1 ROC curves for each TR for the lowest (A) and highest (B) rate of presentation obtained with conservative autocorrelation estimates (fMRIstat AR5). ROC curves were also calculated for each autoregressive model at a TR of 842 ms for the lowest (C) and highest rate of presentation (D). All ROC curves were produced using a group level mask (...
Recent evidence suggests that three specific brain networks show state‐dependent levels of synchronization before, during, and after episodes of generalized spike‐wave discharges (GSW) in patients with genetic generalized epilepsy (GGE). Here, we investigate whether synchronization in these networks differs between patients with GGE (n = 13), their...
MR images scanned at low magnetic field (<1 T) have lower resolution in the slice direction and lower contrast, due to a relatively small signal-to-noise ratio (SNR) than those from high field (typically 1.5T and 3T). We adapt the recent idea of Image Quality Transfer (IQT) to enhance very low-field structural images aiming to estimate the resoluti...
Quantitative proton density (PD) maps measure the amount of free water, which is important for non-invasive tissue characterization in pathology and across lifespan. PD mapping requires the estimation and subsequent removal of factors influencing the signal intensity other than PD. These factors include the T1, T2* relaxation effects, transmit fiel...
Despite its widespread use in cognitive studies, there is still limited understanding of whether and how transcranial direct current stimulation (tDCS) modulates brain network function. To clarify its physiological effects, we assessed brain network function using functional magnetic resonance imaging (fMRI) simultaneously acquired during tDCS stim...
Objectives
Simultaneous intracranial EEG and functional MRI (icEEG-fMRI) can be used to map the haemodynamic (BOLD) changes associated with the generation of IEDs. Unlike scalp EEG-fMRI, in most patients who undergo icEEG-fMRI, IEDs recorded intracranially are numerous and show variability in terms of field amplitude and morphology. Therefore, visu...
The Salience Network (SN) and its interactions are important for cognitive control. We have previously shown that structural damage to the SN is associated with abnormal functional connectivity between the SN and Default Mode Network (DMN), abnormal DMN deactivation, and impaired response inhibition, which is an important aspect of cognitive contro...
Purpose
Short TRs are increasingly used for fMRI as fast sequences such as simultaneous multislice excitation become available. These have been associated with apparent sensitivity improvements, although greater temporal autocorrelation at shorter TRs can inflate sensitivity measurements leading to uncertainty regarding the optimal approach.
Metho...
Objective
In contrast to adult cohorts, neocortical changes in epileptic children with hippocampal damage are not well characterized. Here, we mapped multimodal neocortical markers of epilepsy‐related structural compromise in a pediatric cohort of temporal lobe epilepsy and explored how they relate to clinical factors.
Methods
We measured cortical...
Generalized spike-wave discharges in idiopathic generalized epilepsy are conventionally assumed to have abrupt onset and offset. However, in rodent models, discharges emerge during a dynamic evolution of brain network states, extending several seconds before and after the discharge. In human idiopathic generalized epilepsy, simultaneous EEG and fun...
Objective:
To investigate the potential of advanced diffusion imaging in Post-Mortem MRI (PMMR) at 3T. Methods: We acquired PMMR brain and body imaging in 12 neonates, mean gestational age 33.4 weeks (range 29-37 weeks) at 3T and 1.5T. Head and body diffusion imaging at 1.5T using bipolar diffusion encoding and single-shot echo-planar imaging (EPI...
Focal cortical dysplasia is a congenital abnormality of cortical development and the leading cause of surgically remediable drug-resistant epilepsy in children. Post-surgical outcome is improved by presurgical lesion detection on structural MRI. Automated computational techniques have improved detection of focal cortical dysplasias in adults but ha...
Focal cortical dysplasia is a congenital abnormality of cortical development and the leading cause of surgically remediable drug-resistant epilepsy in children. Post-surgical outcome is improved by presurgical lesion detection on structural MRI. Automated computational techniques have improved detection of focal cortical dysplasias in adults but ha...
There are considerable gaps in our understanding of the relationship between human brain activity measured at different temporal and spatial scales by intracranial electroencephalography and fMRI. By comparing individual features and summary descriptions of intracranial EEG activity we determined which best predict fMRI changes in the sensorimotor...
Objective:
Patients with genetic generalized epilepsy (GGE) have subtle morphologic abnormalities of the brain revealed with magnetic resonance imaging (MRI), particularly in the thalamus. However, it is unclear whether morphologic abnormalities of the brain in GGE are a consequence of repeated seizures over the duration of the disease, or are a c...
Cognitive Neuroscience and Neuropsychiatry Section, Institute of Child Health, 30 Guildford Street, London, UK
Background
Transposition of the great arteries (TGA) is congenital heart defect which is associated with a risk of systemic hypoxia/ischaemic (HI) brain injury in the neonatal period. Children and adolescents with corrected TGA have been...
Understanding the brain and its activity is one of the great challenges of modern science. Normal brain activity (cognitive processes, etc.) has been extensively studied using electroencephalography (EEG) since the 1930's, in the form of spontaneous fluctuations in rhythms, and patterns, and in a more experimentally-driven approach in the form of e...
For the first time in research in humans, we used simultaneous icEEG-fMRI to examine the link between connectivity in haemodynamic signals during the resting-state (rs) and connectivity derived from electrophysiological activity in terms of the inter-modal connectivity correlation (IMCC). We quantified IMCC in nine patients with drug-resistant epil...
Transcranial direct current stimulation (TDCS) has been widely used to improve cognitive function. However, current deficiencies in mechanistic understanding hinders wider applicability. To clarify its physiological effects, we acquired fMRI whilst simultaneously acquiring TDCS to the right inferior frontal gyrus (rIFG) of healthy human participant...
Objective:
Surgical treatment in epilepsy is effective if the epileptogenic zone (EZ) can be correctly localized and characterized. Here we use simultaneous electroencephalography-functional magnetic resonance imaging (EEG-fMRI) data to derive EEG-fMRI and electrical source imaging (ESI) maps. Their yield and their individual and combined ability...
Focal cortical dysplasias (FCDs) are a range of malformations of cortical development each with specific histopathological features. Conventional radiological assessment of standard structural MRI is useful for the localization of lesions but is unable to accurately predict the histopathological features. Quantitative MRI offers the possibility to...
This table contains the mean reaction time and BOLD parameter estimates used for the correlation in Figure 3B.DOI:
http://dx.doi.org/10.7554/eLife.22001.010
This folder contains the MRI contrast maps in Figure 4—figure supplement 1, both thresholded (that is, corrected for multiple comparison using cluster correction) and non-thresholded.The maps are in NIfTI format and can be opened with freely available data viewers such as FSLView or MRIcron.DOI:
http://dx.doi.org/10.7554/eLife.22001.013