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result(s) for
"Croxson, P. L."
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Social Network Size Affects Neural Circuits in Macaques
by
Croxson, P. L.
,
Mars, R. B.
,
Jenkinson, M.
in
Anatomical correlates of behavior
,
Animal cognition
,
Animals
2011
It has been suggested that variation in brain structure correlates with the sizes of individuals' social networks. Whether variation in social network size causes variation in brain structure, however, is unknown. To address this question, we neuroimaged 23 monkeys that had been living in social groups set to different sizes. Subject comparison revealed that living in larger groups caused increases in gray matter in mid-superior temporal sulcus and rostral prefrontal cortex and increased coupling of activity in frontal and temporal cortex. Social network size, therefore, contributes to changes both in brain structure and function. The changes have potential implications for an animal's success in a social context; gray matter differences in similar areas were also correlated with each animal's dominance within its social network.
Journal Article
Mapping the topography of fibres contributing to the fornix in the human brain using diffusion tractography
2009
In animal models of amnesia, transection of the fornix produces significant impairments in memory tasks such as delayed matching-to-sample (Charles et al., 2004) and object-in-place scene learning (Gaffan, 1994).
Journal Article
Causal effect of disconnection lesions on interhemispheric functional connectivity in rhesus monkeys
by
Miller, Karla L.
,
Noonan, MaryAnn P.
,
Wilson, Charles R. E.
in
Animal cognition
,
Animals
,
Behavioral neuroscience
2013
In the absence of external stimuli or task demands, correlations in spontaneous brain activity (functional connectivity) reflect patterns of anatomical connectivity. Hence, resting-state functional connectivity has been used as a proxy measure for structural connectivity and as a biomarker for brain changes in disease. To relate changes in functional connectivity to physiological changes in the brain, it is important to understand how correlations in functional connectivity depend on the physical integrity of brain tissue. The causal nature of this relationship has been called into question by patient data suggesting that decreased structural connectivity does not necessarily lead to decreased functional connectivity. Here we provide evidence for a causal but complex relationship between structural connectivity and functional connectivity: we tested interhemispheric functional connectivity before and after corpus callosum section in rhesus monkeys. We found that forebrain commissurotomy severely reduced interhemispheric functional connectivity, but surprisingly, this effect was greatly mitigated if the anterior commissure was left intact. Furthermore, intact structural connections increased their functional connectivity in line with the hypothesis that the inputs to each node are normalized. We conclude that functional connectivity is likely driven by corticocortical white matter connections but with complex network interactions such that a near-normal pattern of functional connectivity can be maintained by just a few indirect structural connections. These surprising results highlight the importance of network-level interactions in functional connectivity and may cast light on various paradoxical findings concerning changes in functional connectivity in disease states.
Journal Article
The extreme capsule fiber complex in humans and macaque monkeys: a comparative diffusion MRI tractography study
by
Andersson, Jesper L.
,
Miller, Karla L.
,
Noonan, MaryAnn P.
in
Adult
,
Animals
,
Biomedical and Life Sciences
2016
We compared the course and cortical projections of white matter fibers passing through the extreme capsule in humans and macaques. Previous comparisons of this tract have suggested a uniquely human posterior projection, but these studies have always employed different techniques in the different species. Here we used the same technique, diffusion MRI, in both species to avoid attributing differences in techniques to differences in species. Diffusion MRI-based probabilistic tractography was performed from a seed area in the extreme capsule in both human and macaques. We compared in vivo data of humans and macaques as well as one high-resolution ex vivo macaque dataset. Tractography in the macaque was able to replicate most results known from macaque tracer studies, including selective innervation of frontal cortical areas and targets in the superior temporal cortex. In addition, however, we also observed some tracts that are not commonly reported in macaque tracer studies and that are more reminiscent of results previously only reported in the human. In humans, we show that the ventrolateral prefrontal cortex innervations are broadly similar to those in the macaque. These results suggest that evolutionary changes in the human extreme capsule fiber complex are likely more gradual than punctuated. Further, they demonstrate both the potential and limitations of diffusion MRI tractography.
Journal Article
Novel succinate dehydrogenase subunit B (SDHB) mutations in familial phaeochromocytomas and paragangliomas, but an absence of somatic SDHB mutations in sporadic phaeochromocytomas
by
Marsh, Deborah J
,
Delbridge, Leigh
,
Benn, Diana E
in
Adolescent
,
Adrenal Gland Neoplasms - enzymology
,
Adrenal Gland Neoplasms - genetics
2003
Phaeochromocytomas arising in adrenal or extra-adrenal sites and paragangliomas of the head and neck, in particular of the carotid bodies, occur sporadically and also in a familial setting. In addition to mutations in
RET
and
VHL
in familial disease, germline mutations in
SDHD
and
SDHB
genes that encode subunits of mitochondrial complex II have also been associated with the development of familial phaeochromocytomas. To further investigate the role of
SDHD
and
SDHB
in the development of these tumours we determined the occurrence of germline
SDHD
and
SDHB
mutations in four patients with a family history of phaeochromocytoma with associated head and neck paraganglioma, one patient with a family history of phaeochromocytoma only and two patients with apparently sporadic extra-adrenal phaeochromocytoma, one of whom had early onset disease. Secondly, we investigated whether somatic
SDHB
mutations correlated with loss of heterozygosity at 1p36 in a subgroup of 11 sporadic and three MEN 2-associated
RET
-mutation-positive phaeochromocytomas. Novel
SDHB
mutations were identified in the probands from four families and two apparently sporadic cases (six of seven probands studied), including two missense mutations, a single nonsense and frameshift mutation, as well as two splice site mutations, one of which was shown to have partial penetrance resulting in ‘leaky’ splicing. Further, five intronic polymorphisms in
SDHB
were found. No
SDHD
mutations were identified. In addition, no somatic
SDHB
mutations were found in the remaining allele of the 11 sporadic adrenal phaeochromocytomas with allelic loss at 1p36 or the three MEN 2-associated
RET-
mutation-positive phaeochromocytomas. Therefore, we conclude that SDHB has a major role in the pathogenesis of familial phaeochromocytomas, but the possible role of SDHB in sporadic tumours showing allelic loss at 1p36 has yet to be ascertained.
Journal Article
The funding and organization of infection control in NHS hospital trusts: a study of infection control professionals' views
by
Allen, P.
,
Archibald, K.
,
Taylor, L.
in
Attitude of Health Personnel
,
Budgets
,
Clinical Competence
2003
The problems associated with hospital-acquired infection have been causing increasing concern in England in recent years. This paper reports the results of a nationwide survey of hospital infection control professionals' views concerning the organizational structures used to manage and obtain funding for control of infection. A complex picture with significant variation between hospitals emerges. Although government policy dictates that specific funding for hospital infection control is formally made available, it is not always the case that infection control professionals have adequate resources to undertake their roles. In some cases this reflects the failure of hospitals' infection control budgetary mechanisms; in others it reflects the effects of decentralizing budgets to directorate or ward level. Some use was made of informal mechanisms either to supplement or to substitute for the formal ones. But almost all infection control professionals still believed they were constrained in their ability to protect the hospital population from the risk of infectious disease. It is clear that recent government announcements that increased effort will be made to support local structures and thereby improve the control of hospital acquired infection are to be welcomed.
Journal Article
Drugs and the older population
2000
This book is designed for all those with a scientific interest in drug treatment and the older population. The authors have all been chosen for their expertise in the field and have been drawn from both sides of the Atlantic and South Africa. The contents fall into two parts — general principles of drug use as they apply to the elderly, and specific chapters dealing with common clinical areas. The editors aim to provide a concise up to date, evidence-based, resource book.
An open resource for nonhuman primate imaging
by
Kastner, Sabine
,
Zarco, Wilbert
,
Balezeau, Fabien
in
Data collection
,
Datasets
,
Magnetic resonance imaging
2017
Non-human primate neuroimaging is a rapidly growing area of research that promises to transform and scale translational and cross-species comparative neuroscience. Unfortunately, the technological and methodological advances of the past two decades have outpaced the accrual of data, which is particularly challenging given the relatively few centers that have the necessary facilities and capabilities. The PRIMate Data Exchange (PRIME-DE) addresses this challenge by aggregating independently acquired non-human primate magnetic resonance imaging (MRI) datasets and openly sharing them via the International Neuroimaging Data-sharing Initiative (INDI). Here, we present the rationale, design and procedures for the PRIME-DE consortium, as well as the initial release, consisting of 13 independent data collections aggregated across 11 sites (total = 98 macaque monkeys). We also outline the unique pitfalls and challenges that should be considered in the analysis of the non-human primate MRI datasets, including providing automated quality assessment of the contributed datasets.
Health professionals' views of contracting for infection control in the NHS internal market
by
Roberts, Jennifer
,
Allen, Pauline
,
Crawshaw, Shirley
in
Attitude of Health Personnel
,
Attitudes
,
Contract Services - organization & administration
2002
This paper reports a national study which investigated the involvement of infection control professionals in (and their views about) the formal processes of contracting for health care in the NHS internal market. Health care professionals needed to be involved contracting, if it was to be effective. The study found that many infection control professionals were not, in fact, involved in contracting, while the importance of both contracts and informal professional networks were recognised. But respondents did not think that their professional networks entirely compensated for their lack of involvement in contracting. As formal agreements continue to be central to achieving quality of care in the post-internal market NHS, infection control professionals need to be involved in specification and implementation of these arrangements.
Journal Article