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 145 records · Page 8Linked to original sources

PubMed2006

[Functional neuroimaging in psychotherapy research].

Only recently has functional neuroimaging been used increasingly in the context of psychotherapy research. Based on a literature survey, procedures, methodological underpinnings and paradigms relevant for psychotherapy research are explored regarding functional magnetic resonance imaging (fMRI) and positron emission tomography (PET). Current studies on changes of brain functions and potential mechanisms are presented based on obsessive-compulsive disorders, depression, phobia, panic and borderline personality disorders. Findings and implications are discussed regarding the use of functional neuroimaging in psychotherapy research. Systematic changes of brain activation were demonstrated following successful psychotherapy, partially resembling and partially differing from those induced by psychopharmacological treatments. Thus the traditional split between pharmacological procedures "acting on the brain" and psychological procedures making the patient "feel better" has been rendered obsolete. Procedures of functional neuroimaging have been developed to such an extent that they can be used to study issues of great relevance for psychotherapy, e. g. biological underpinnings of psychiatric disorders, plasticity of neural networks, mechanisms of change and prognostic factors of psychotherapy, etc.

Biomedical Research↗

PubMed2004

[N-methyl-11C]Mirtazapine for positron emission tomography neuroimaging of antidepressant actions in humans.

RATIONALE: Many actions of antidepressant drugs cannot yet be studied using positron emission tomography (PET) neuroimaging due to lack of suitable radioligands. We believe that mirtazapine, radiolabeled with C-11, might be suitable for PET neuroimaging of alpha2-adrenoceptors in selected regions of the living human brain. OBJECTIVE: To determine the regional central biodistribution and pharmacokinetics of [N-methyl-11C]mirtazapine in humans. METHODS: Five healthy volunteers received an intravenous injection of [N-methyl-11C]mirtazapine for evaluating its metabolism, biodistribution and pharmacokinetics. RESULTS: [N-methyl-11C]Mirtazapine entered the brain readily, with initial clearance from blood to tissue (K1) ranging from 0.31 ml/ml/min in amygdala to 0.54 ml/ml/min in thalamus. The rate of metabolism of [N-methyl-11C]mirtazapine in the bloodstream was relatively slow, with 20-40% of [11C]-derived radioactivity still present as parent compound at 60 min post-injection. The clearance of [N-methyl-11C]mirtazapine from the tissue compartment (k2') ranged from a low of 0.03 min(-1) in amygdala to a high of 0.06-0.07 min(-1) in thalamus and cerebellum. The volume of distribution (Ve') of [N-methyl-11C]mirtazapine was markedly greater in hippocampus and amygdala (11.3-12.0) than in cerebellum (6.7), with intermediate levels in the thalamus (9.4). CONCLUSIONS: [N-methyl-11C]Mirtazapine has suitable properties for PET neuroimaging. We envision [N-methyl-11C]mirtazapine as a molecular probe for PET imaging of antidepressant actions at sites such as alpha2-adrenoceptors in the living human brain.

Adrenergic alpha-Agonists↗

PubMed2002

Structural brain abnormalities specific to childhood-onset schizophrenia identified by neuroimaging techniques.

This review discusses functional and structural brain abnormalities in childhood-onset schizophrenia identified by neuroimaging techniques. Published literature regarding both morphological and functional neuroimaging is discussed, regarding also the diversity of neuroimaging findings which partly reduces their reliability. The findings in early onset schizophrenia are compared with those of adult patients. The results of long-term investigations of structural abnormalities in early onset schizophrenia are given particular attention. The most consistent findings are ventricular enlargement and reduced total brain volume. Further, volumetric changes in the temporal and frontal cortex, thalamus, basal ganglia and limbic system are reported, as are hemispheric asymmetries and, conversely, reduction of normal differences. Findings regarding the corpus callosum and cerebellum are less consistent. In patients whose schizophrenia commenced in early childhood, the differences were generally more marked than in adolescence- or adult-onset schizophrenia. Atrophy of total brain volume was progressive throughout the course of the disorder. It is probable that neuroanatomical cerebral abnormalities present prior to disease onset play an etiopathogenic role in the development of schizophrenia.

Adolescent↗

PubMed2004

Role of neuroimaging in our understanding of the pathogenesis of primary headaches.

This article reviews new advances in neuroimaging of primary headaches. Imaging of the brain is reaching a new stage of maturity as the basic neural systems that participate in the pathogenesis of headaches are identified. Given the rapid advances in functional neuroimaging, it is no surprise that recent studies have supported the neurovascular theory of migraine and cluster headache. It is clear that functional neuroimaging will continue to be of paramount importance and ultimately may serve as the bridge between molecular and clinical domains in the field of headache research.

Brain↗

PubMed2003

Neuroimaging and neurocircuitry in post-traumatic stress disorder: what is currently known?

Neurobiologic, psychologic, and social factors interact jointly to create and perpetuate the symptoms of post-traumatic stress disorder (PTSD). The fear conditioning paradigm in animal research helped researchers gather preclinical evidence for the possible contribution of several brain areas to PTSD symptoms. In the past 10 years, highly sophisticated neuroimaging techniques made it possible for researchers to look at the brain of patients with PTSD and draw conclusions about the neurocircuitry underlying PTSD symptoms. In this article, the author will review the evidence from neuroimaging studies for the involvement of the following brain areas in PTSD neurocircuitry: the amygdala, the anterior cingulate cortex and subcallosal gyrus, the inferior frontal gyrus, the posterior cingulate cortex, and the hippocampus. Neuroimaging studies have shown these areas as altered in structure or function in patients with PTSD. The author also presents the normal functions that these areas subserve and, whenever possible based on the evidence, infer how their dysfunction may contribute importantly to the symptomatology of PTSD.

Animals↗

PubMed2006

Functional neuroimaging applications for assessment and rehabilitation planning in patients with disorders of consciousness.

OBJECTIVE: To describe the theoretic framework, design, and potential clinical applications of functional neuroimaging protocols in patients with disorders of consciousness. DATA SOURCES: Recent published literature and authors' own work. STUDY SELECTION: Studies using functional neuroimaging techniques to investigate cognitive processing in patients diagnosed with vegetative and minimally conscious state. DATA EXTRACTION: Not applicable. DATA SYNTHESIS: Positron-emission tomography activation studies suggest that the vegetative state represents a global disconnection syndrome in which higher order association cortices are functionally disconnected from primary cortical areas. In contrast, patterns of activation in functional magnetic resonance imaging studies of patients in the minimally conscious state show preservation of large-scale cortical networks associated with language and visual processing. CONCLUSIONS: Novel applications of functional neuroimaging in patients with disorders of consciousness may aid in differential diagnosis, prognostic assessment and identification of pathophysiologic mechanisms. Improvements in patient characterization may, in turn, provide new opportunities for restoration of function through interventional neuromodulation.

Auditory Perception↗

PubMed2005

Neuroimaging studies of practice-related change: fMRI and meta-analytic evidence of a domain-general control network for learning.

Functional magnetic resonance imaging and a meta-analysis of prior neuroimaging studies were used to characterize cortical changes resulting from extensive practice and to evaluate a dual-processing account of the neural mechanisms underlying human learning. Three core predictions of the dual processing theory are evaluated: 1) that practice elicits generalized reductions in regional activity by reducing the load on the cognitive control mechanisms that scaffold early learning; 2) that these control mechanisms are domain-general; and 3) that no separate processing pathway emerges as skill develops. To evaluate these predictions, a meta-analysis of prior neuroimaging studies and a within-subjects fMRI experiment contrasting unpracticed to practiced performance in a paired-associate task were conducted. The principal effect of practice was found to be a reduction in the extent and magnitude of activity in a cortical network spanning bilateral dorsal prefrontal, left ventral prefrontal, medial frontal (anterior cingulate), left insular, bilateral parietal, and occipito-temporal (fusiform) areas. These activity reductions are shown to occur in common regions across prior neuroimaging studies and for both verbal and nonverbal paired-associate learning in the present fMRI experiment. The implicated network of brain regions is interpreted as a domain-general system engaged specifically to support novice, but not practiced, performance.

Adult↗

PubMed2003

Assessment of neuroimaging techniques as biomarkers of the progression of Parkinson's disease.

A major goal of research in Parkinson's disease (PD) has been the development of treatments to slow the progressive degeneration of the nigrostriatal dopaminergic system and to reduce the functional decline of patients. Because of the uncertainty in the ability of the clinical evaluation to reflect the status of the nigrostriatal dopaminergic system once dopaminergic therapy has commenced, investigators in PD have sought to develop alternative measures of disease. One approach, which has been extensively explored, is neuroimaging with radiotracers that interact with processes central to dopaminergic neurotransmission in the nigrostriatal dopaminergic axons-conversion of levodopa to dopamine through aromatic amino acid decarboxylase (AADC), [(18)F]fluorodopa PET, storage of dopamine in synaptic vesicles via the vesicular monoamine transporter 2 (VMAT2), (+)-[(11)C]dihydrotetrabenazine PET, and reuptake of dopamine into axons via the dopamine transporter (DAT), [(123)I]beta-CIT SPECT, and a number of other PET and SPECT ligands. During the 54(th) Annual Meeting of the American Academy of Neurology, a group of investigators active in the fields of biomakers, neuroimaging, and neuroprotection met to review the three techniques mentioned above. Prior to the meeting, the participants developed consensus on a set of 10 criteria for a neuroimaging technique to be considered adequate as a biomarker for progression of PD and levels at which the available data for each technique indicate that the criterion was met. The criteria and each of the three imaging techniques mentioned above were reviewed, and the results of that meeting are presented.

Animals↗

PubMed2006

The neuroimaging research process from the participants' perspective.

The aim of this study was to investigate participants' experiences of taking part in research conducted using fMRI or MEG procedures. Forty-four participants completed a questionnaire after taking part in either fMRI or MEG experiments; the questionnaire asked about experiences of and attitudes toward fMRI/MEG. Ten follow-up interviews were conducted to enable an in-depth analysis of these attitudes and experiences. The findings were generally positive: all participants thought fMRI and MEG were safe procedures, 93% would recommend participating in neuroimaging research to their friends and family, and participants were positive about participating in future neuroimaging research. However, some negative issues were identified. Some participants reported feeling nervous prior to scanning procedures, several participants reported side-effects after taking part, a number of participants were upset at being in a confined space and some participants did not feel confident about exiting the scanner in an emergency. Several recommendations for researchers are made, including a virtual tour of the scanning equipment during the consenting process in order to better prepare potential participants for the scanning experience and to minimize the potential psychological discomfort sometimes experienced in neuroimaging research.

Adolescent↗

PubMed2004

Acute ocular motor mononeuropathies: prospective study of the roles of neuroimaging and clinical assessment.

The role for immediate neuroimaging in patients 50 years of age or older with acute isolated third, fourth, and sixth nerve palsies is controversial. We prospectively evaluated 66 patients, aged 50 years and older (median 67 years, range 50-85), with acute isolated ocular motor mononeuropathies. Our purpose was to evaluate both the role of neuroimaging and the role of clinical assessment in determining etiology. We found that clinical features, including time to maximal diplopic symptoms, were not predictive of etiology (median 2 days to maximal diplopic symptoms for both peripheral microvascular and other etiologies). The presence of any common vascular risk factor, including diabetes mellitus, hypertension, hypercholesterolemia, or coronary artery disease, was significantly associated with peripheral microvascular etiology in this cohort (p=0.0004, Fisher's exact test). Despite the high prevalence of peripheral microvascular ischemia as an etiology in this age group, other causes were identified by magnetic resonance imaging (MRI) or computed tomography (CT) scanning in 14% of patients. Diagnoses included brainstem and skull base neoplasms, brainstem infarcts, aneurysms, demyelinating disease, and pituitary apoplexy. Neuroimaging procedures may have a role in the initial evaluation of patients 50 years of age or older with acute ocular motor mononeuropathies.

Abducens Nerve Diseases↗

PubMed2005

Imaginem oblivionis: the prospects of neuroimaging for early detection of Alzheimer's disease.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by the gradual onset of dementia. The pathological hallmarks of the disease are A beta amyloid plaques, neurofibrillary tangles, and reactive gliosis. Current diagnosis of AD is made by clinical, neuropsychologic, and neuroimaging assessments. Routine structural neuroimaging evaluation 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 AD. Functional neuroimaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) could prove to be valuable in the differential diagnosis of AD, as well as in assessing prognosis. With the advent of new therapeutic strategies aimed at reducing the A beta amyloid burden in the brain, there is increasing interest in the development of PET and SPECT radioligands that will permit the assessment of A beta amyloid burden in vivo. From this, the prospect of specific preclinical diagnosis arises, possibly in conjunction with other related A beta biomarkers in plasma and CSF.

Alzheimer Disease↗

PubMed2006

Neuroimaging in manganism.

Neuroimaging such as magnetic resonance imaging (MRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) have been used in the last decade for investigating the neurotoxicolgy of manganese (Mn). Increased signal intensities on a T1-weighted image may reflect increased Mn deposits (e.g., due to exposure to Mn) but not necessarily manganism. In a biologically based dose-response model, our recent results strongly suggest that signal intensities in T1-weighted MRI reflect a target site dose. However, the threshold of signal intensity associated with clinical symptoms of manganism remains to be solved. Functional neuroimaging such as PET or SPECT examines the integrity of the nigrostriatal dopaminergic system, and thus is very important for the differential diagnosis of manganism. However, neuroimaging research should also aim at developing specific and sensitive parameters for manganism in Mn-exposed individuals.

Brain↗

PubMed2004

The LONI Debabeler: a mediator for neuroimaging software.

Brain image analysis often involves processing neuroimaging data with different software packages. Using different software packages together requires exchanging files between them; the output files of one package are used as input files to the next package in the processing sequence. File exchanges become problematic when different packages use different file formats or different conventions within the same file format. Although comprehensive medical image file formats have been developed, no one format exists that satisfies the needs of analyses that involve multiple processing algorithms. The LONI Debabeler acts as a mediator between neuroimaging software packages by automatically using an appropriate file translation to convert files between each pair of linked packages. These translations are built and edited using the Debabeler graphical interface and compensate for package-dependent variations that result in intrapackage incompatibilities. The Debabeler gives neuroimaging processing environments a configurable automaton for file translation and provides users a flexible application for developing robust solutions to translation problems.

Animals↗

PubMed2005

Spatial information is processed even when it is task-irrelevant: implications for neuroimaging task design.

Many neuroimaging studies have been designed to differentiate domain-specific processes in the brain. A common design constraint is to use identical stimuli for different domain-specific tasks. For example, an experiment investigating spatial versus identity processing would present compound spatial-identity stimuli in both spatial and identity tasks, and participants would be instructed to attend to, encode, maintain, or retrieve spatial information in the spatial task, and identity information in the identity task. An assumption in such studies is that spatial information will not be processed in the identity task, as it is irrelevant for that task. We report three experiments demonstrating violations of this assumption. Our results suggest that comparisons of spatial and identity tasks in existing neuroimaging studies have underestimated the amount of brain activation that is spatial-specific. For future neuroimaging studies, we recommend unique stimulus displays for each domain-specific task, and event-related measurement of post-stimulus processing.

Adult↗

PubMed2005

Increased sensitivity in neuroimaging analyses using robust regression.

Robust regression techniques are a class of estimators that are relatively insensitive to the presence of one or more outliers in the data. They are especially well suited to data that require large numbers of statistical tests and may contain outliers due to factors not of experimental interest. Both these issues apply particularly to neuroimaging data analysis. We use simulations to compare several robust techniques against ordinary least squares (OLS) regression, and we apply robust regression to second-level (group "random effects") analyses in three fMRI datasets. Our results show that robust iteratively reweighted least squares (IRLS) at the 2nd level is a computationally efficient technique that both increases statistical power and decreases false positive rates in the presence of outliers. The benefits of IRLS are apparent with small samples (n = 10) and increase with larger sample sizes (n = 40) in the typical range of group neuroimaging experiments. When no true effects are present, IRLS controls false positive rates at an appropriate level. We show that IRLS can have substantial benefits in analysis of group data and in estimating hemodynamic response shapes from time series data. We provide software to implement IRLS in group neuroimaging analyses.

Algorithms↗

PubMed2005

The role of parietal cortex in visuomotor control: what have we learned from neuroimaging?

Research from macaque neurophysiology and human neuropsychology has implicated the parietal cortex in the sensory control of action. Functional neuroimaging has been very valuable in localizing and characterizing specific regions of the human brain involved in visuomotor actions involving different effectors, such as the eyes, head, arms and hands. Here, we review the areas discovered by human neuroimaging, including the putative functional equivalents of the following macaque regions: parietal eye fields (PEF), ventral intraparietal (VIP) area, parietal reach region (PRR) and the anterior intraparietal (AIP) area. We discuss the challenges of studying realistic movements in the imaging environment, the lateralization of visuomotor function, caveats involved in proposing interspecies homologies and the limitations and future directions for neuroimaging studies of visuomotor control.

Animals↗

PubMed2005

The Alzheimer's disease neuroimaging initiative.

With increasing life expectancy in developed countries, the incidence of Alzheimer's disease (AD) and its socioeconomic impact are growing. Increasing knowledge of the mechanisms of AD facilitates the development of treatment strategies aimed at slowing down or preventing neuronal death. AD treatment trials using clinical outcome measures require long observation times and large patient samples. There is increasing evidence that neuroimaging and cerebrospinal fluid and blood biomarkers may provide information that may reduce sample sizes and observation periods. The Alzheimer's Disease Neuroimaging Initiative will help identify clinical, neuroimaging, and biomarker outcome measures that provide the highest power for measurement of longitudinal changes and for prediction of transitions.

Aged↗

PubMed2006

Neuroimaging abnormalities in infants with congenital hemiparesis.

Clinical and neuroimaging characteristics of congenital hemiparesis were examined in a retrospective cohort study nested within 199,176 births within the Kaiser Permanente Medical Care Program, 1997-2002. Infants with a physician diagnosis of paresis or cerebral palsy were electronically identified, and charts were reviewed to confirm congenital hemiparesis. A neuroradiologist reviewed available head MRI and CT scans. Of 96 infants with congenital hemiparesis (population prevalence 4.8 per 10,000), 81% received either a head magnetic resonance imaging (n = 55) or head computed tomography only (n = 23). Perinatal arterial infarction was the most common (30%) neuroimaging finding in term infants. Infants with right-sided hemiparesis (relative risk 4.6, 95% confidence interval 1.4-14.4) or moderate to severe weakness (relative risk 4.4, 95% confidence interval 1.1-17.7) were more likely to have had a perinatal arterial infarction. Periventricular white matter lesions predominated in preterm infants (71%). Brain malformations observed in 14 (18%) patients included polymicrogyria, heterotopia, and schizencephaly. The 14 infants (18%) with a normal head imaging study were more likely to outgrow all signs of hemiparesis by age 3 than were infants with an abnormal brain image (29% vs 0%, P < 0.001). Neuroimaging studies provide useful diagnostic and prognostic information in infants with congenital hemiparesis.

Brain↗