Author
Serena J. Counsell
Other affiliations: Imperial College Healthcare, St Thomas' Hospital, Hammersmith Hospital ...read more
Bio: Serena J. Counsell is an academic researcher from King's College London. The author has contributed to research in topics: Diffusion MRI & White matter. The author has an hindex of 73, co-authored 273 publications receiving 16946 citations. Previous affiliations of Serena J. Counsell include Imperial College Healthcare & St Thomas' Hospital.
Papers published on a yearly basis
Papers
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TL;DR: A stratified analysis based on the presence or absence of microbleeds revealed diffusion tensor imaging to be more sensitive than gradient-echo imaging to white matter damage and the location of white matter abnormality predicted cognitive function to some extent.
Abstract: White matter disruption is an important determinant of cognitive impairment after brain injury, but conventional neuroimaging underestimates its extent. In contrast, diffusion tensor imaging provides a validated and sensitive way of identifying the impact of axonal injury. The relationship between cognitive impairment after traumatic brain injury and white matter damage is likely to
be complex. We applied a flexible technique—tract-based spatial statistics—to explore whether damage to specific white matter tracts is associated with particular patterns of cognitive impairment. The commonly affected domains of memory, executive function and information processing speed were investigated in 28 patients in the post-acute / chronic phase following traumatic brain injury and in 26 age-matched controls. Analysis of fractional anisotropy and diffusivity maps revealed widespread differences
in white matter integrity between the groups. Patients showed large areas of reduced fractional anisotropy, as well as increased mean and axial diffusivities, compared with controls, despite the small amounts of cortical and white matter damage visible on standard imaging. A stratified analysis based on the presence or absence of microbleeds (a marker of diffuse axonal injury) revealed diffusion tensor imaging to be more sensitive than gradient-echo imaging to white matter damage. The location of white matter abnormality predicted cognitive function to some extent. The structure of the fornices was correlated with associative learning and memory across both patient and control groups, whilst the structure of frontal lobe connections showed relationships with executive function that differed in the two groups. These results highlight the complexity of the relationships
between white matter structure and cognition. Although widespread and, sometimes, chronic abnormalities of white matter are identifiable following traumatic brain injury, the impact of these changes on cognitive function is likely to depend on damage to key pathways that link nodes in the distributed brain networks supporting high-level cognitive functions.
602 citations
TL;DR: The results place the emergence of RSNs largely during the period of rapid neural growth in the third trimester of gestation, suggesting that they are formed before the acquisition of cognitive competencies in later childhood.
Abstract: The functions of the resting state networks (RSNs) revealed by functional MRI remain unclear, but it has seemed possible that networks emerge in parallel with the development of related cognitive functions. We tested the alternative hypothesis: that the full repertoire of resting state dynamics emerges during the period of rapid neural growth before the normal time of birth at term (around 40 wk of gestation). We used a series of independent analytical techniques to map in detail the development of different networks in 70 infants born between 29 and 43 wk of postmenstrual age (PMA). We characterized and charted the development of RSNs from recognizable but often fragmentary elements at 30 wk of PMA to full facsimiles of adult patterns at term. Visual, auditory, somatosensory, motor, default mode, frontoparietal, and executive control networks developed at different rates; however, by term, complete networks were present, several of which were integrated with thalamic activity. These results place the emergence of RSNs largely during the period of rapid neural growth in the third trimester of gestation, suggesting that they are formed before the acquisition of cognitive competencies in later childhood.
470 citations
TL;DR: Diffuse white matter abnormalities and post–hemorrhagic ventricular dilation are common at term and seem to correlate with reduced developmental quotients, while early lesions, except for cerebellar hemorrhage and major destructive lesions, do not show clear relationships with outcomes.
Abstract: OBJECTIVES. The aim was to survey the range of cerebral injury and abnormalities of cerebral development in infants born between 23 and 30 weeks’ gestation using serial MRI scans of the brain from birth, and to correlate those findings with neurodevelopmental outcome after 18 months corrected age. METHODS. Between January 1997 and November 2000, consecutive infants born at RESULTS. A total of 327 MRI scans were obtained from 119 surviving infants born at 23 to 30 weeks of gestation. Four infants had major destructive brain lesions, and tissue loss was seen at term for the 2 survivors. Fifty-one infants had early hemorrhage; 50% of infants with term scans after intraventricular hemorrhage had ventricular dilation. Twenty-six infants had punctate white matter lesions on early scans; these persisted for 33% of infants assessed at term. Early scans showed cerebellar hemorrhagic lesions for 8 infants and basal ganglia abnormalities for 17. At term, 53% of infants without previous hemorrhage had ventricular dilation and 80% of infants had diffuse excessive high signal intensity within the white matter on T2-weighted scans. Complete follow-up data were available for 66% of infants. Adverse outcomes were associated with major destructive lesions, diffuse excessive high signal intensity within the white matter, cerebellar hemorrhage, and ventricular dilation after intraventricular hemorrhage but not with punctate white matter lesions, hemorrhage, or ventricular dilation without intraventricular hemorrhage. CONCLUSIONS. Diffuse white matter abnormalities and post–hemorrhagic ventricular dilation are common at term and seem to correlate with reduced developmental quotients. Early lesions, except for cerebellar hemorrhage and major destructive lesions, do not show clear relationships with outcomes.
434 citations
TL;DR: Comparing apparent diffusion coefficient values in DEHSI with infants with normal imaging and those with overt brain damage to determine whether DEHSi shows the diffusion characteristics of normal or abnormal tissue provides objective evidence thatDEHSI represents diffuse white matter abnormality.
Abstract: Objective The most common finding on magnetic resonance imaging (MRI) of the brain in preterm infants at term-equivalent age is diffuse excessive high signal intensity (DEHSI) in the white matter It is unclear whether DEHSI represents a biological abnormality This study used diffusion-weighted imaging (DWI) to compare apparent diffusion coefficient (ADC) values in DEHSI with infants with normal imaging and those with overt brain damage to determine whether DEHSI shows the diffusion characteristics of normal or abnormal tissue Methods MRI, using conventional and diffusion-weighted imaging (DWI), was performed in 50 preterm infants at term-equivalent age using a 15 Tesla MR scanner The infants were divided into 3 groups on the basis of their MRI results: 1) normal white matter, 2) DEHSI, or 3) overt white matter pathology ADC values were measured in the frontal, central, and posterior white matter at the level of the centrum semiovale ADC values in the 3 groups of preterm infants were compared using a 1-way analysis of variance with a Bonferroni test for multiple comparisons Results ADC values were significantly higher in infants with DEHSI and infants with overt white matter pathology than in infants with normal white matter There was no significant difference between ADC values in infants with DEHSI and those with overt white matter pathology Conclusions This study provides objective evidence that DEHSI represents diffuse white matter abnormality
393 citations
TL;DR: The results support a direct relationship between white matter organization within the brain's structural core, functional connectivity within the default mode network and cognitive function following brain injury.
Abstract: Traumatic brain injury often results in cognitive impairments that limit recovery. The underlying pathophysiology of these impairments is uncertain, which restricts clinical assessment and management. Here, we use magnetic resonance imaging to test the hypotheses that: (i) traumatic brain injury results in abnormalities of functional connectivity within key cognitive networks; (ii) these changes are correlated with cognitive performance; and (iii) functional connectivity within these networks is influenced by underlying changes in structural connectivity produced by diffuse axonal injury. We studied 20 patients in the chronic phase after traumatic brain injury compared with age-matched controls. Network function was investigated in detail using functional magnetic resonance imaging to analyse both regional brain activation, and the interaction of brain regions within a network (functional connectivity). We studied patients during performance of a simple choice-reaction task and at ‘rest’. Since functional connectivity reflects underlying structural connectivity, diffusion tensor imaging was used to quantify axonal injury, and test whether structural damage correlated with functional change. The patient group showed typical impairments in information processing and attention, when compared with age-matched controls. Patients were able to perform the task accurately, but showed slow and variable responses. Brain regions activated by the task were similar between the groups, but patients showed greater deactivation within the default mode network, in keeping with an increased cognitive load. A multivariate analysis of ‘resting’ state functional magnetic resonance imaging was then used to investigate whether changes in network function were present in the absence of explicit task performance. Overall, default mode network functional connectivity was increased in the patient group. Patients with the highest functional connectivity had the least cognitive impairment. In addition, functional connectivity at rest also predicted patterns of brain activation during later performance of the task. As expected, patients showed widespread white matter damage compared with controls. Lower default mode network functional connectivity was seen in those patients with more evidence of diffuse axonal injury within the adjacent corpus callosum. Taken together, our results demonstrate altered patterns of functional connectivity in cognitive networks following injury. The results support a direct relationship between white matter organization within the brain's structural core, functional connectivity within the default mode network and cognitive function following brain injury. They can be explained by two related changes: a compensatory increase in functional connectivity within the default mode network; and a variable degree of structural disconnection that modulates this change in network function.
392 citations
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Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or
7,563 citations
TL;DR: An efficient and effective dense training scheme which joins the processing of adjacent image patches into one pass through the network while automatically adapting to the inherent class imbalance present in the data, and improves on the state-of-the‐art for all three applications.
2,842 citations
01 Jan 2010
TL;DR: In this paper, the authors describe a scenario where a group of people are attempting to find a solution to the problem of "finding the needle in a haystack" in the environment.
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2,716 citations
TL;DR: The method is based on registering the individual volumes to a model free prediction of what each volume should look like, thereby enabling its use on high b-value data where the contrast is vastly different in different volumes.
2,431 citations
TL;DR: The thesis of this Review is that the encephalopathy of prematurity is a complex amalgam of primary destructive disease and secondary maturational and trophic disturbances.
Abstract: Brain injury in premature infants is of enormous public health importance because of the large number of such infants who survive with serious neurodevelopmental disability, including major cognitive deficits and motor disability. This type of brain injury is generally thought to consist primarily of periventricular leukomalacia (PVL), a distinctive form of cerebral white matter injury. Important new work shows that PVL is frequently accompanied by neuronal/axonal disease, affecting the cerebral white matter, thalamus, basal ganglia, cerebral cortex, brain stem, and cerebellum. This constellation of PVL and neuronal/axonal disease is sufficiently distinctive to be termed "encephalopathy of prematurity". The thesis of this Review is that the encephalopathy of prematurity is a complex amalgam of primary destructive disease and secondary maturational and trophic disturbances. This Review integrates the fascinating confluence of new insights into both brain injury and brain development during the human premature period.
2,039 citations