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At least 595 records · Page 33Linked to original sources
PubMed1999

Visual and mental exploration of visuo-spatial configurations: behavioral and neuroimaging approaches.

Do mental imagery and perception involve common processing mechanisms? Imagery researchers have devoted a great deal of effort to establishing the functional and structural similarities between images and perceptual events. Recent studies have focused on the comparison of images that are reconstructions of previous perceptual experience and images constructed from verbal descriptions. This article reports the findings of a research program based on the mental scanning paradigm; they reveal the similarities and differences between the two kinds of mental images. Neuroimaging studies have also provided evidence that the parieto-occipital cortex is involved in the processing of visual images, whether they are based on perceptual experience or constructed from linguistic inputs. However, the PET studies conducted by our research groups provide no evidence that the primary visual cortex is engaged in the generation of visual images. As there is contradictory evidence about this, further research is needed to clarify the role of the early visual areas in mental visual imagery.

Brain Mapping↗
PubMed2004

PET neuroimaging and mutations in the DJ-1 gene.

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson's disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson's disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene.

Brain↗
PubMed2005

Testing models of thalamic dysfunction in schizophrenia using neuroimaging.

Neural models of schizophrenia have implicated the thalamus in deficits of early sensory processing and multimodal integration. We have reviewed the existing neuroimaging literature for evidence in support of models that propose abnormalities of thalamic relay nuclei, the mediodorsal thalamic nucleus, and large-scale cortico-thalamic networks. Thalamic volume reduction was found in some but not all studies. Studies of the early stages of schizophrenia suggest that thalamic volume reduction is present early in the course of the illness. Functional imaging studies have revealed task related abnormalities in several cortical and subcortical areas including the thalamus, suggesting a disruption of distributed thalamocortical networks. Chemical imaging studies have provided evidence for a loss of thalamic neuronal integrity in schizophrenia. There is, at present, inadequate data to support the hypothesis that schizophrenia is associated with abnormalities of sensory relay or association nuclei. There is evidence for a perturbation of cortico-thalamic networks, but further research is needed to elucidate the underlying mechanisms at the cellular and systems levels. The challenges ahead include better delineation of thalamic structure and function in vivo, the combination of genetic and imaging techniques to elucidate the genetic contributions to a thalamic phenotype of schizophrenia, and longitudinal studies of thalamic structure and function.

Animals↗
PubMed2001

Seizure disorder mimicking an acute confusional state as clinical presentation of neurocysticercosis: neuroimaging, EEG findings and clinical correlations.

Epilepsy is the main clinical manifestation of neurocysticercosis (NC). We studied an adult subject who presented a seizure disorder mimicking an acute confusional state as clinical expression of NC. Diagnosis was made with neuroimaging and western blot determination of specific antibodies on serum. Computed tomography and magnetic resonance imaging displayed multiple calcifications and a few transitional cysts in the cerebral parenchyma. Electroencephalography showed a pattern of periodic lateralized epileptiform discharges (PLEDs) which could be related topographically to a cystic lesion located in the left parietal lobe. In our view there was a clear pathogenic correlation between the seizure disorder and the parasitic cyst located in the left parietal lobe. Neither antiepileptic drugs nor steroids were prescribed. Follow-up to one year ruled out other clinical manifestations of the disease. This case is an example of acute symptomatic seizure related to a transitional cystic lesion of NC.

Acute Disease↗
PubMed2003

Progression of preexisting trigeminalgia to Tolose-Hunt-like syndrome. The importance of neuroimaging for early differential diagnosis.

Recurrent unbearable, paroxysmal, unilateral facial pain in the distribution of one or more branches of the trigeminal nerve often provoked by sensory stimuli is typical for idiopathic trigeminal neuralgia. The less frequent localization in the area of ophthalmic branch (5%) is particularly controversial and should be distinguished from pathological lesions in the brainstem and middle and posterior cranial fossa and from diseases of the orbit and eye. This case study presents a 79-year-old woman with typical clinical features of 1st division trigeminalgia without any neurological loss and with normal results of laryngological, ophthalmological, and stomatological examinations as well as neuroimaging CT, and MR /MRA evaluation. Only the evoked potential blink and masseter reflexes demonstrated the pathological values in the early phase of illness. After 1 year of pharmacological treatment no improvement was achieved and the pain became neuropathic and paresis of 3rd, 4th and 6th nerves developed, as observed in Tolose-Hunt syndrome. MRI of the orbit revealed a pathological mass in its apex with a connection to the superior orbital fissure. However, treatment with steroids was completely ineffective. Surgical resection of the tumor (leiomyosarcoma) only partially reversed oculomotor palsy and diminished aching. In differential diagnosis of idiopathic and symptomatic trigeminalgia, early MR and MRA imaging is the most essential and sometimes may be the best single test to evaluate lesions even in distant areas of the nervous system branches.

Aged↗
PubMed2006

Neuroimaging and pain: a window on the autonomic nervous system.

Pain is one of the most common experiences of humans. Neuroimaging techniques can visualize the main brain areas involved in pain modulation, the pain matrix. It is noteworthy that many of the brain areas forming the pain matrix are also involved in modulating autonomic nervous system (ANS) activity that in turn plays a major role in determining the best adaptive response to the pain experience. The tight connection between the pain system and ANS is also evident from neuroanatomical studies indicating that the lamina 1 neurons receive both painful and visceral stimuli from all visceral organs giving rise to the spinothalamocortical pathway concerned with conveying interoceptive information to central structures. The resulting interoceptive stream projects to the viscerosensory cortex in the mid-insula and onto the right anterior insula and orbitofrontal cortices. Right anterior insula activation is involved in the sympathetic arousal associated with mental tasks. This brain region receives numerous other inputs including pain and painful stimuli are conveyed somatotopically to both insulae. A similar somatotopic organization of painful stimuli has also been shown in the basal ganglia involved in cognitive, affective, motor and autonomic states. This highly specialized organization of nociceptive information in these brain areas may subserve a number of functions, particularly of coupling pain with the most appropriate autonomic states and affective/emotional states. The anterior cingulated cortex, another brain area playing a crucial role in nociception, is also directly involved in the control of autonomic functions such as arousal during volitional behaviour, including effortful cognitive processing. It is evident that the nociceptive system and ANS closely interact in many processes involved in maintaining internal homeostatis and in order to give the most appropriate biological substrate for cognitive, affective and emotional states.

Autonomic Nervous System↗
PubMed2003

Advances in neuroimaging: management of partial epileptic syndromes.

Structural and functional neuroimaging studies are essential in the evaluation of individuals with partial epilepsy syndromes. Magnetic resonance imaging (MRI) is important to delineate structural abnormalities underlying seizure disorders, commonly including hippocampal sclerosis or cortical dysplasias. Identification of a structural lesion is often a reliable indicator of the site of seizure onset. Magnetic resonance spectroscopy (MRS) allows us to investigate cerebral metabolites and some neurotransmitters. Reduction in various metabolite concentrations has proven to be prognostically valuable when no structural abnormality is identified. Positron emission tomography (PET) using deoxyglucose demonstrates areas of reduced glucose metabolism, which are the hallmark of epileptogenic zones and usually extend beyond the underlying anatomical region. It is useful in temporal lobe epilepsy for lateralization; however, results in extratemporal lobe epilepsy have been less favorable. More promising is the use of benzodiazepine receptor ligands, which are reduced in the epileptogenic zone in a more restricted distribution. This appears to be helpful in the localization of extratemporal seizure foci. Peri-ictal single photon emission computed tomography measures increased blood flow during the ictal event and is beneficial in patients with normal MRI studies to determine lateralization and localization of the ictal onset zone. All imaging modalities should be correlated with clinical and neurophysiological data.

Brain↗
PubMedDate not supplied

Toward the validation of functional neuroimaging as a potential biomarker for Alzheimer's disease: implications for drug development.

Despite investments carried out in the research since Alzheimer's disease (AD) was firstly defined as an isolated clinical entity, there is still a lack of appropriate cure and effective therapies to halt or slow the disease progression. While fundamental research has provided a better characterization of AD, much remains to be done for the development of new biological treatment strategies. It is now being debated whether functional neuroimaging (FNI) could help improve diagnostic accuracy and become a possible biomarker of AD. The primary purpose of this review was to determine whether data already published in the literature meet formal technology assessment standards for using regional cerebral blood flow (rCBF) or glucose metabolism (rCMRGlu) as a biomarker for AD. The secondary purpose was to identify any remaining gaps that might need to be systematically addressed before drug developers and regulators accept FNI as a biomarker for AD. The present paper reviews the literature regarding metabolic positron emission tomography (PET) and perfusion single photon emission computed tomography (SPECT) studies in AD. There is evidence that treatment with acetylcholinesterase inhibitors (AChEI) leads to changes in brain physiology within the brain regions critical to AD pathology, i.e. the temporal, parietal and frontal association cortex. However, a thorough analysis combining functional and neuropsychological data has not yet been attempted, and much research is needed to validate the role of FNI as a surrogate endpoint for AD clinical trials.

Alzheimer Disease↗
PubMed2000

Patients with acute stroke: recent developments in neuroimaging.

The authors discuss recent developments in neuroimaging and their role in the evaluation of patients with acute stroke from diagnostic, therapeutic, and prognostic points of view. New techniques permit a more detailed evaluation of the pathophysiology of stroke and therefore may lead to better management. This improvement is due to the increased sensitivity of the diagnostic tests in the acute phase of stroke to detect ischemic lesions and the ability to estimate tissue perfusion to determine vascular status.

Cerebrovascular Circulation↗
PubMed2004

Functional neuroimaging of primary headache disorders.

Until recently, primary headache disorders such as migraine and cluster headache were considered to be vascular in origin. However, advances in neuroimaging techniques, such as positron emission tomography, single photon emission computerized tomography, and functional magnetic resonance imaging, have augmented the growing clinical evidence that these headaches are primarily driven from the brain. This review covers functional imaging studies in migraine, cluster headache, rarer headache syndromes, and experimental head pain. Together with newer techniques, such as voxel-based morphometry and magnetic resonance spectrometry, functional imaging continues to play a role in elucidating and targeting the neural substrates in each of the primary headache syndromes.

Cerebrovascular Circulation↗
PubMed2006

Neuroimaging of sleep and sleep disorders.

Herein are presented the results of research in the area of sleep neuroimaging over the past year. Significant work has been performed to clarify the basic mechanisms of sleep in humans. New studies also extend prior observations regarding altered brain activation in response to sleep deprivation by adding information regarding vulnerability to sleep deprivation and regarding the influence of task difficulty on aberrant responses. Studies in sleep disorder medicine have yielded significant findings in insomnia, depression, and restless legs syndrome. Extensive advances have been made in the area of sleep apnea where physiologic challenges have been used to probe brain activity in the pathophysiology of sleep apnea syndrome.

Depressive Disorder↗
PubMed2005

Functional neuroimaging of primary headache disorders.

Until recently, primary headache disorders such as migraine and cluster headache were considered to be vascular in origin. However, advances in neuroimaging techniques, such as positron emission tomography, single photon emission computerized tomography, and functional magnetic resonance imaging, have augmented the growing clinical evidence that these headaches are primarily driven from the brain. This review covers functional imaging studies in migraine, cluster headache, rarer headache syndromes, and experimental head pain. Together with newer techniques, such as voxel-based morphometry and magnetic resonance spectrometry, functional imaging continues to play a role in elucidating and targeting the neural substrates in each of the primary headache syndromes.

Brain↗
PubMed2004

The molecular neuroimaging of anxiety disorders.

This paper reviews the molecular neuroimaging of anxiety disorders, and attempts to put recent advances in the context of previous findings. Knowledge of the metabolic correlates of symptom severity and treatment response in obsessive-compulsive disorder has been significantly extended, particularly response to selective serotonin reuptake inhibitor medication. However, the first neuroreceptor studies of serotonin transporter availability in obsessive-compulsive disorder have proved inconclusive, and further studies are anticipated. Reduced 5-HT1A receptor binding has been reported in panic disorder. Recent findings have extended the knowledge of hippocampal abnormalities in post-traumatic stress disorder, and have highlighted the complexity of the association between cortisol and the hippocampus in this disorder.

Anxiety Disorders↗
PubMed2001

The neuropsychology of multiple sclerosis: contributions of neuroimaging research.

Multiple sclerosis (MS) is often associated with cognitive and emotional changes that affect daily activities and quality of life. Deficits in memory, executive function, processing speed, and other cognitive domains are frequently reported. In addition, mood disturbances and fatigue are common. In this article, the authors highlight research on individual differences in the neuropsychology of MS, and emphasize neuroimaging studies that help elucidate the basis of the deficits.

Brain↗
PubMed2001

Neuroimaging techniques in the diagnostic work-up of patients with the antiphospholipid syndrome.

The detection of multisystemic involvement often leads to a correct diagnosis of the antiphospholipid syndrome (APS), even in cases with predominant neurologic manifestations. However, when central nervous system deficits are isolated and have a relapsing-remitting or a progressive course, other conditions must be carefully considered. In this context, the diagnostic accuracy of conventional magnetic resonance imaging (MRI) is hampered by its limited pathologic specificity, which is one of the reasons why no or only modest correlations have been found between the burden of MRI-visible lesions and other clinical or laboratory measures of disease severity in patients with APS. Neuroimaging techniques with a higher pathologic specificity than conventional MRI show promise in achieving diagnostic confidence earlier in the course of APS and in better monitoring the efficacy of therapeutic interventions.

Antibodies, Antiphospholipid↗
PubMed1996

Neuroimaging in anorexia nervosa.

Neuroimaging in anorexia nervosa has revealed morphological and functional alterations, most of which are currently interpreted as consequences of the anorectic state that are reversible, at least partially, after weight gain. Enlargement of CSF spaces, mainly of cortical sulci, is evident on CT and MRI. This reversible shrinkage of brain tissue ("pseudoatrophy") also affects the pituitary gland. A functional imaging study with positron emission tomography (PET) revealed caudate hyperactivity during the anorectic state, and several mild right-left asymmetries possibly related to alterations of mental state (vigilance, depression, etc.) have also been reported in bulimia nervosa. New aspects may be added, when techniques to image functional brain activation during specific tasks and regional receptor binding capacities are used to study anorexia nervosa.

Anorexia Nervosa↗
PubMed1995

CBA--an atlas-based software tool used to facilitate the interpretation of neuroimaging data.

CBA, a software tool used to improve quantification and evaluation of neuroimaging data has been developed. It uses a detailed 3-dimensional brain atlas that can be adapted to fit the brain of an individual patient represented by a series of displayed images. Anatomical information from the atlas can then be introduced into the images. If the patient has been imaged in different modalities, adaptation of the atlas to the different images will provide the transformation that brings the images into registration. CBA can thus be used as a tool for fusing multimodality information from the same patient. Furthermore, by applying the inverse atlas transformation, images from a patient can be transformed to conform to the anatomy of the atlas brain. This anatomical standardization, where the atlas brain itself serves as the anatomy standard, brings data from different individuals into a compatible form providing possibilities to perform individual-group and group-by-group comparisons between patients and normal controls.

Animals↗
PubMedDate not supplied

Hemimegalencephaly: clinical, EEG, neuroimaging, and IMP-SPECT correlation.

Iofetamine-single photon emission computed tomography (IMP-SPECT) was performed on 2 girls (5 1/2 and 6 years of age) with histories of intractable seizures, developmental delay, and unilateral hemiparesis secondary to hemimegalencephaly. Electroencephalography (EEG) revealed frequent focal discharges in 1 patient, while a nearly continuous burst suppression pattern over the malformed hemisphere was recorded in the other. IMP-SPECT demonstrated a good correlation with neuroimaging studies. In spite of the different EEG patterns, which had been proposed to predict contrasting clinical outcomes, both IMP-SPECT scans disclosed a similar decrease in tracer uptake in the malformed hemisphere. These results are consistent with the pattern of decreased tracer uptake found in other interictal studies of focal seizures without cerebral malformations. In view of recent recommendations for hemispherectomy in these patients, we suggest that the IMP-SPECT scan be used to compliment EEG as a method to define the extent of abnormality which may be more relevant to long-term prognosis than EEG alone.

Amphetamines↗