SEARCH · PubMed Health

Results for “Neuroimaging”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources

PubMed2006

Neuroimaging in late-life depression.

Late-life depression may be associated with vasculopathy. Neuroimaging has been a critical tool in exploring the relationship between this form of depression and vascular factors. Magnetic resonance imaging has been the most widely used tool, but there is potential to use other structural imaging techniques as well as functional neuroimaging methodologies. Neuroimaging may potentially be utilized at some point as a biomarker for late-life depression, thus helping with diagnosis and guiding treatment.

Age of Onset↗

PubMedDate not supplied

Neuroimaging-genetic paradigms: a new approach to investigate the pathophysiology and treatment of cognitive deficits in schizophrenia.

Cognitive impairment is a prominent and debilitating feature of schizophrenia. Genetic predisposition likely accounts for a large proportion of these cognitive deficits. Direct associations between candidate genes and cognitive dysfunction have been difficult to establish, however, largely due to the subtle effects of these genes on observable behavior. Neuroimaging techniques can provide a sensitive means to bridge the neurobiology of genes and behavior. Here we illustrate the use of neuroimaging-genetics paradigms to elaborate the relationship between genes and cognitive dysfunction in schizophrenia. After reviewing principles important for the selection of genes, neuroimaging techniques, and subjects, we describe how imaging-genetics investigations have helped clarify the contribution of five candidate genes (COMT, GRM3, G72, DISC1, and BDNF) to cognitive deficits in schizophrenia. The potential of this approach for improving patient care will depend on its ability to predict outcomes with greater accuracy and sensitivity than current clinical measures.

Brain↗

PubMed2004

Human functional neuroimaging in nicotine and tobacco research: basics, background, and beyond.

Modern functional neuroimaging techniques allow nicotine and tobacco researchers to investigate the neurobiological basis of addiction in humans. We introduce the methods and measures of the following neuroimaging techniques: Electroencephalography and event-related cortical potentials, positron emission tomography, and functional magnetic resonance imaging. We outline strengths and limitations across modalities and describe new and emerging technologies. We provide summaries of recent neuroimaging findings in the field of nicotine and tobacco research for neurochemistry, smoking and nicotine administration, craving and cue-reactivity, cognitive and affective information processing, and tobacco withdrawal. We address limitations of studies to date and identify opportunities for future research.

Affect↗

PubMed2005

Neuroimaging in psychopathy.

OBJECTIVE: The biological basis of psychopathy remains to be fully elucidated. Evidence suggests a genetic contribution and dysfunction of the serotonin system. The objective of this article is to review the contribution of the neuroimaging of the last decade to our understanding of psychopathy. METHOD: A literature search was conducted using PubMed and the words psychopath, antisocial personality disorder, dissocial personality disorder, violence, image and imaging. In addition, the reference lists of the identified papers, and recent textbooks, were perused for additional sources. RESULTS: Five structural and 15 functional neuroimaging studies were selected and examined. Structural studies have reported decreased prefrontal grey matter, decreased posterior hippocampal volume and increased callosal white matter, but to this point, these have not been replicated. Functional studies suggest reduced perfusion and metabolism in the frontal and temporal lobes. Abnormalities of function have been reported, predominantly in frontal and temporal lobe structures during classical conditioning and response inhibition tasks, and in the processing of emotional words and pictures. CONCLUSION: Functional neuroimaging strongly suggests dysfunction of particular frontal and temporal lobe structures in psychopathy. However, there are difficulties in selecting homogeneous index cases and appropriate control groups. Further studies are necessary. Responses depend on genetic endowment, early life experience, the sociocultural context and the significance of any stimulus to the individual.

Brain↗

PubMed2000

Neurophysiologic basis of functional neuroimaging: animal studies.

Functional neuroimaging adds metabolic or biochemical information to that obtained with anatomic imaging, allowing localization of a neural function. Positron emission tomography and single photon emission tomography make use of radioactive tracers tagged to a molecule which can indicate glucose metabolism, oxygen consumption, or blood flow. Functional magnetic resonance imaging uses the different magnetic properties of oxyhemoglobin and deoxyhemoglobin to identify areas of increased blood flow, which, in turn, reflects neuronal activation. Magnetic resonance spectroscopic imaging, with magnetically labeled molecules, can be used to follow biochemical pathways. Functional neuroimaging is based on the experimental data that neuronal activation leads to increased metabolism. Uptake of glucose and oxygen increases to meet increased energy needs. The fractionally increased glucose appears to be taken up mostly by glia, which metabolize it through glycolysis. The end product, lactate, is released for neuronal uptake and subsequent oxidative phosphorylation. To meet these metabolic needs, blood flow increases to such an extent that overall capillary oxyhemoglobin concentration increases. This changes the magnetic signal in the region and permits functional magnetic resonance imaging studies. Recent data suggest that there is an initial decrease in the concentration of oxyhemoglobin which may be more spatially specific to the area of neuronal activation. Further refinements in functional neuroimaging will lead to improved understanding of the normal functional anatomy of the brain and will shed further light on the pathophysiology of many neurologic disorders.

Animals↗

PubMed2000

Neuroimaging: applications in disorders of early brain development.

Neuroimaging techniques have established new connections between etiological factors and disorders of early brain development. Neuroimaging has also strengthened the link between patterns of selective vulnerability in the developing brain and clinical syndromes, especially cerebral palsy. Both computed tomography (CT) and magnetic resonance imaging (MRI) identify early developmental malformations, including neural tube defects, callosal dysgenesis, neuronal migration disorders, posterior fossa malformations, and hydrocephalus. Periventricular white matter damage, most commonly seen in premature infants, is best visualized by cranial ultrasonography in the neonatal period and on MRI later in childhood. In term infants and children with genetic metabolic diseases, various applications of nuclear magnetic resonance, including MRI, have important diagnostic roles. The utility of diffusion-weighted imaging, MR spectroscopy, and functional MRI to further understanding of brain injury, biochemistry, and function is under active investigation. In summary, selecting the appropriate neuroimaging technique can improve diagnosis and management of childhood neurodevelopmental disorders.

Brain↗

PubMed2000

Homonymous visual field defects in patients without corresponding structural lesions on neuroimaging.

Homonymous visual field defects usually occur with structural processes affecting retrochiasmal visual pathways. The responsible lesion is usually evident on magnetic resonance imaging or on other neuroimaging studies. When results of neuroimaging are normal, functional illness is often suspected. The authors report four patients with homonymous visual field defects who presented with no evident corresponding lesion on magnetic resonance or computed tomography imaging. Etiologies for the visual field defects included the Heidenhain variant of Creutzfeldt-Jacob disease, degenerative dementia, subtle occipital ischemia demonstrated only on positron-emission tomography scanning, and nonketotic hyperglycemia. Clinicians should be aware of the alternative etiologies of organic homonymous visual field loss in patients with normal neuroimaging.

Aged↗

PubMed2003

Neuroimaging studies of violence and antisocial behavior.

The neurobiological basis of violence and antisocial behavior is poorly understood. Lesion studies have implicated the frontal and temporal lobes in such phenomena. Recent neuroimaging studies have provided more detailed information on the neurobiological correlates of violence and antisocial behavior. Moreover, the results of such imaging studies extend findings from prior lesion studies. These results suggest that violent and antisocial behavior is associated with disruptions in frontotemporal neural systems. This article reviews the neuroimaging literature on violence and antisocial behavior and discusses the strengths and weaknesses of the different methods that have been used in such studies. The author reviews findings from cerebral psychophysiology studies (electroencephalographic studies and evoked potentials), as well as from studies using positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI). The article concludes with a discussion of useful directions for future research. It is clear that the use of neuroimaging methods in combination offers the greatest promise for progress in the understanding of the neural basis of violence and antisocial behavior.

Journal Article↗

PubMed2003

Neuroimaging in developmental disorders.

PURPOSE OF REVIEW: This review considers the role of neuroimaging in developmental disorders by highlighting recent studies in two distinct, but overlapping, developmental disorders: autism and fragile X syndrome. RECENT FINDINGS: After a decade of conflicting results in neuroimaging studies of autism, recent studies have provided some convergent data. One well-replicated finding is that autistic subjects have larger brains. Further, this enlargement, present as early as 3 years of age, appears to represent accelerated growth in infancy and may be followed by slowed growth in late childhood. Other findings are discussed but considered preliminary in the absence of converging evidence or replication studies. Recent work in fragile X syndrome suggests aberrant fronto-striatal and fronto-parietal networks and relates these abnormalities "forward" to behavior and "backward" to decreased protein expression. SUMMARY: As the field of neuroimaging has matured, it has revealed its promise as a safe, reliable, in-vivo tool in the study of developmental disorders. By insisting on larger, more homogeneous patient groups and longitudinal rather than cross-sectional studies, the field is poised to fulfill its ultimate role of linking defects in molecular biology to aberrant behavior.

Autistic Disorder↗

PubMed2006

An update on functional neuroimaging of parkinsonism and dystonia.

PURPOSE OF REVIEW: The aim of this article is to review current advances in functional magnetic resonance imaging and positron emission tomography of the motor system in parkinsonism and dystonia. RECENT FINDINGS: In Parkinson's disease, recent functional magnetic resonance imaging studies have shown that the pattern of regional activity changes in the motor system are strongly modulated by the amount of attention patients pay to task performance. In focal hand dystonia, functional magnetic resonance imaging has disclosed several functional alterations in the basal ganglia in addition to the well-known cortical abnormalities. Neuroimaging has also been successfully used to assess the impact of pharmacological or surgical interventions. In patients with monogenetically inherited parkinsonism or dystonia, positron emission tomography and functional magnetic resonance imaging have opened up exciting possibilities to link molecular biology with functional changes at a systems level. Neuroimaging of genetically defined at-risk populations has shown great potential to study motor reorganization at the preclinical stage and to identify adaptive mechanisms that prevent or delay clinical manifestation. SUMMARY: Functional neuroimaging plays a key role in understanding the pathophysiology of parkinsonism and dystonia. A future challenge will be to clarify how these disorders impair the functional integration within the motor system and how these changes in connectivity are influenced by therapeutic interventions.

Antiparkinson Agents↗

PubMed1999

If neuroimaging is the answer, what is the question?

It is unclear that we will come to a better understanding of mental processes simply by observing which neural loci are activated while subjects perform a task. Rather, I suggest here that it is better to come armed with a question that directs one to design tasks in ways that take advantage of the strengths of neuroimaging techniques (particularly positron emission tomography and functional magnetic resonance imaging). Here I develop a taxonomy of types of questions that can be easily addressed by such techniques. The first class of questions focuses on how information processing is implemented in the brain; these questions can be posed at a very coarse scale, focusing on the entire system that confers a particular ability, or at increasingly more specific scales, ultimately focusing on individual structures or processes. The second class of questions focuses on specifying when particular processes and structures are invoked; these questions focus on how one can use patterns of activation to infer that specific processes and structures were invoked, and on how processing changes in different circumstances. The use of neuroimaging to address these questions is illustrated with results from experiments on visual cognition, and caveats regarding the logic of inference in each case are noted. Finally, the necessary interplay between neuroimaging and behavioural studies is stressed.

Brain↗

PubMed2005

Adult growth hormone replacement therapy and neuroimaging surveillance in brain tumour survivors.

OBJECTIVE: Systematic collections of neuroimaging data are nonexistent in brain tumour survivors treated with adult growth hormone replacement therapy (AGHRT). We present our surveillance data. DESIGN: In 1993, our unit implemented a policy of performing brain scans on every brain tumour survivor before starting AGHRT, with repeat neuroimaging at least once after 12-18 months' treatment. Reports for baseline scans and most recent scans were analysed for this retrospective study. PATIENTS: All brain tumour survivors who received AGHRT (60 patients) were included in the analysis. MEASUREMENTS: Evidence and extent of residual tumour, tumour progression, tumour recurrence, and secondary neoplasms (SN) on baseline scan and latest follow-up scan. RESULTS: All patients had baseline scans performed. Follow-up scans were available in 41/45 (91%) patients who received AGHRT for more than 1 year (mean duration +/- SD of GHRT was 6.7 +/- 3.6 years). Sixteen patients had residual tumours, and SNs (all meningiomas) were demonstrated in three patients on baseline scans. Appearances remained stable in 34 (83%) patients during follow-up (extending to 17.4 +/- 8.3 years after tumour diagnosis). Of the 16 residual primary tumours, an incurable ependymoma continued to grow, and one meningioma progressed slightly in size over 7.7 years. Follow-up scans also revealed continued growth of the SNs detected at baseline, and five additional meningiomas (two in patients with a previous SN, confirming an excess risk in this subgroup, P = 0.02). All SNs occurred on average 22.8 (range 17-37) years after radiotherapy. CONCLUSIONS: Our data do not suggest an increased rate of recurrence or progression of childhood brain tumours during AGHRT. Nonetheless, vigilance and long-term surveillance are needed in these patients in order to detect and monitor SNs, in particular in patients with a previous history of a SN. We endorse a proactive neuroimaging policy, preferably as part of a larger, controlled trial in the future.

Adolescent↗

PubMed2006

Molecular mechanisms for Alzheimer's disease: implications for neuroimaging and therapeutics.

Alzheimer's disease is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are beta-amyloid (Abeta) plaques, neurofibrillary tangles, synaptic loss and reactive gliosis. The current therapeutic effort is directed towards developing drugs that reduce Abeta burden or toxicity by inhibiting secretase cleavage, Abeta aggregation, Abeta toxicity, Abeta metal interactions or by promoting Abeta clearance. A number of clinical trials are currently in progress based on these different therapeutic strategies and they should indicate which, if any, of these approaches will be efficacious. Current diagnosis of Alzheimer's disease is made by clinical, neuropsychologic and neuroimaging assessments. Routine structural neuroimaging evaluation with computed tomography and magnetic resonance imaging is based on non-specific features such as atrophy, a late feature in the progression of the disease, hence the crucial importance of developing new approaches for early and specific recognition at the prodromal stages of Alzheimer's disease. Functional neuroimaging techniques such as functional magnetic resonance imaging, magnetic resonance spectroscopy, positron emission tomography and single photon emission computed tomography, possibly in conjunction with other related Abeta biomarkers in plasma and CSF, could prove to be valuable in the differential diagnosis of Alzheimer's disease, as well as in assessing prognosis. With the advent of new therapeutic strategies there is increasing interest in the development of magnetic resonance imaging contrast agents and positron emission tomography and single photon emission computed tomography radioligands that will permit the assessment of Abeta burden in vivo.

Alzheimer Disease↗

PubMed2003

Neuroimaging studies of amygdala function in anxiety disorders.

Neuroimaging research has helped to advance neurobiological models of anxiety disorders. The amygdala is known to play an important role in normal fear conditioning and is implicated in the pathophysiology of anxiety disorders. The amygdala may also be a target for the beneficial effects of cognitive-behavioral and medication treatments for anxiety disorders. In the current paper, we review neuroimaging research pertaining to the role of the amygdala in anxiety disorders and their treatment. Moreover, we discuss the development of new neuroimaging paradigms for measuring aspects of amygdala function, as well as the function of related brain regions. We conclude that such tools hold great promise for facilitating progress in relevant basic neuroscience as well as clinical research domains.

Amygdala↗

PubMed1999

What do neurologists think about their role in neuroimaging training and practice?

In 1996, a survey of the members of the American Academy of Neurology revealed the following facts and opinions: (1) On an average month, each respondent ordered 15 computed tomography, 22 magnetic resonance imaging, 13 ultrasound and 1 single-photon emission computerized tomography studies. (2) Most respondents did not read their own studies for reimbursement, but relied on their own reading for patient management. (3) Respondents felt that neurologists are appropriate specialists to read imaging studies; however, they favored certification for neurologists credentialed in neuroimaging. (4) Organized neurology should provide certification in neuroimaging for neurologists with appropriate training and defend their right and their need to practice neuroimaging, including endovascular procedures.

Diagnostic Imaging↗

PubMed2002

Neuroimaging studies of language production and comprehension.

The 1990s were dubbed the "Decade of the Brain." During this time there was a marked increase in the amount of neuroimaging work observing how the brain accomplishes many tasks, including the processing of language. In this chapter we review the past 15 years of neuroimaging research on language production and comprehension. The findings of these studies indicate that the processing involved in language use occurs in diffuse brain regions. These regions include Broca's and Wernicke's areas, primary auditory and visual cortex, and frontal regions in the left hemisphere, as well as in the right hemisphere homologues to these regions. We conclude the chapter by discussing the future of neuroimaging research into language production and comprehension.

Brain Mapping↗

PubMed1997

Children with headache: clinical predictors of surgical space-occupying lesions and the role of neuroimaging.

PURPOSE: To determine clinical predictors useful in differentiation of surgical lesions from medically treated disorders and the role of neuroimaging in children with headache. MATERIALS' AND METHODS: In a 4-year retrospective study, 315 patients with headache and no known neurologic disorder underwent brain magnetic resonance (MR) imaging. Sixty-nine patients also underwent brain computed tomography (CT). Clinical data were correlated with findings from MR imaging and CT and the final diagnosis by means of logistic regression. RESULTS: Thirteen (4%) patients had surgical space-occupying lesions. Seven independent multivariate predictors of a surgical lesion were identified. Sleep-related headache and no family history of migraine were the strongest predictors. Other predictors included vomiting, absence of visual symptoms, headache of less than 6 months duration, confusion, and abnormal neurologic examination findings. A positive correlation between number of predictors and risk of surgical lesion was noted (P < .0001). No difference between MR imaging and CT was noted in detection of surgical space-occupying lesions, and there were no false-positive or false-negative surgical lesions detected with either modality on the basis of clinical follow-up. CONCLUSION: Children at high risk on the basis of these criteria usually require neuroimaging, while children at low risk may be safely followed up clinically without neuroimaging.

Adolescent↗

PubMed1998

Choristoma of the optic nerve: neuroimaging characteristics and association with spinal cord lipoma.

A 54-year-old patient presented with amaurosis of the right eye that resulted from a dysontogenetic tumor of the right optic nerve. The tumor involved the intraorbital, intracanalicular and intracerebral portion of the right optic nerve, without involvement of the chiasm. Although the patient had refused further diagnostic surgical exploration, we show that it is possible to establish the diagnosis of choristoma of the optic nerve by means of modern neuroimaging techniques based on computed tomography and magnetic resonance imaging. It appears from neuroimaging that choristomata of the optic nerve and spinal cord lipomas represent different manifestations of the same type of tumor. The neuroimaging characteristics of both kinds of tumors are discussed.

Blindness↗