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PubMed2003

Neuroimaging in patients with head injury.

Head trauma affects thousands of people every year. Neuroimaging techniques provide some of the most important diagnostic, prognostic, and pathophysiological information in the management of brain injury. Anatomical imaging modalities can help assess intracranial hemorrhage, fractures, and other structural lesions. Functional imaging has been shown to be helpful in assessing the areas of the brain affected by the trauma as well as determining long term prognosis and rehabilitation potential. This article will review the current uses of neuroimaging techniques in head trauma and delineate future applications.

Brain Injuries↗
PubMed2000

Functional neuroimaging of cognition.

Neuroimaging has, in many respects, revolutionized the study of behavioral neurology and cognitive neuroscience. Early studies of brain-behavior relationships relied on a precise neurological examination as the basis for hypothesizing the site of brain damage that was responsible for a given behavioral syndrome. The advent of structural brain imaging, first with computed tomography (CT) and later with magnetic resonance imaging (MRI), paved the way for more precise anatomical localization of the cognitive deficits that are manifest after brain injury. In recent years, functional neuroimaging, broadly defined as techniques that provide measures of brain activity, has further increased our ability to study the neural basis of behavior. The modern era of functional brain imaging was introduced with the use of positron emission tomography (PET). In more recent years, functional magnetic resonance imaging (fMRI) has rapidly emerged as an extremely powerful technique with many advantages over PET for studying cognition. Thus, the principles underlying fMRI studies of cognition are the focus of this review.

Brain Injuries↗
PubMed2002

Neuroimaging of epilepsy.

Neuroimaging has an important role in the investigation and treatment of patients with epilepsy. Diagnosis of the underlying substrate in a given patient with epilepsy determines prognosis with higher accuracy than electroencephalography. Neuroimaging techniques include computed tomography (CT) and magnetic resonance imaging (MRI), although CT has a diminished role for diagnosis. MRI is the most appropriate imaging technique in the initial investigation of patients with epilepsy. MRI is the most sensitive technique for the diagnosis of hippocampal sclerosis, tumors, and malformations of cortical development. MRI is also critical for neurosurgical planning. Other imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography are reserved for patients with intractable epilepsy when surgery is contemplated. New developments such as MR spectroscopy, receptor PET, and magnetic source imaging are becoming clinical tools and have the promise of improving diagnosis.

Epilepsy↗
PubMed2004

[Depression and modern neuroimaging].

Modern neuroimaging like PET, SPECT, MR-Volumetry, functional MRI and MR-Spectroscopy has effectively advanced research on aetiology, pathogenesis and therapy options of depressive disorders. This review highlights the status of current research on this topic. Consistent with morphological findings, which report alterations in regions of emotionally relevant networks of the brain in depressive disorders, findings of functional studies point to changes in the basal ganglia, the frontal cortex and the limbic system involving the hippocampus and the amygdala. During processing of emotional cues depressive patients show different activation patterns in the regions of the frontal lobe and the amygdala. In our study of a subgroup we were also able to show deficits in processing cues independently from the emotional quality of the stimulus - especially in posterior-parietal and prefrontal areas. In healthy subjects affective modulation correlates with an ordered interaction of ventral-limbic and dorsal-neocortical regions of the brain, which become unbalanced in depressive disorders. In the future, modern neuroimaging will open promising fields of research, which aim at the identification of valid neurofunctional subgroups of the heterogeneous affective disorders and the development of more adjusted and efficient therapy strategies.

Animals↗
PubMed2005

Functional neuroimaging of sleep.

Sleep and sleep disorders have traditionally been viewed from a polysomnographic perspective. Although these methods provide information on the timing of various stages of sleep and wakefulness, they do not provide information regarding function in brain structures that have been implicated in the generation of sleep and that may be abnormal in different sleep disorders. Functional neuroimaging methods provide information regarding changes in brain function across the sleep-wake cycle that provides information for models of sleep dysregulation in a variety of sleep disorders. Early studies show reliable increases in function in limbic and anterior paralimbic cortex in rapid eye movement (REM) sleep and decreases in function in higher-order cortical regions in known thalamocortical networks during non-REM sleep. Although most of the early work in this area has been devoted to the study of normal sleep mechanisms, a collection of studies in diverse sleep disorders such as sleep deprivation, depression, insomnia, dyssomnias, narcolepsy, and sleep apnea suggest that functional neuroimaging methods have the potential to clarify the pathophysiology of sleep disorders and to guide treatment strategies.

Diagnostic Imaging↗
PubMed1997

Neuroimaging in presumed primary headache disorders.

As routine outpatient neuroimaging became available more than 20 years ago, controversy arose over appropriate selection of patients for computed tomography studies and subsequently magnetic resonance imaging studies. Nowhere is this more apparent than in headache. Because headache is a truly ubiquitous condition with a lifetime prevalence rate reaching 90%, it is clear we cannot scan all patients with headache. Review of the pertinent literature, expert consensus, and a Practice Parameter issued by the American Academy of Neurology all suggest that routine neuroimaging is not necessary in patients with migraine headaches as defined by the International Headache Society criteria. The literature would also support the belief that imaging is not necessary in patients with typical recurrent cluster headaches. However, patients with new-onset headaches, headaches with a progressive course, headaches with a significant change in pattern, headaches that never alternate sides, and headaches associated with any neurologic findings or seizures have a substantially higher likelihood of a secondary cause such as tumor, arteriovenous malformation, or other structural lesion. In these situations, imaging must be considered as part of the workup. Unfortunately, the literature does not provide enough data to make any statistically predictive observations in patients with headaches other than migraine or cluster headache with symptoms but no findings on neurologic examination.

Arteriovenous Malformations↗
PubMed1998

Neuroimaging analyses of human working memory.

We review a program of research that uses neuroimaging techniques to determine the functional and neural architecture of human working memory. A first set of studies indicates that verbal working memory includes a storage component, which is implemented neurally by areas in the left-hemisphere posterior parietal cortex, and a subvocal rehearsal component, which is implemented by left-hemisphere speech areas, including Broca's area as well as the premotor and supplementary motor areas. We provide a number of neuroimaging dissociations between the storage and rehearsal areas. A second set of studies focuses on spatial working memory and indicates that it is mediated by a network of predominantly right-hemisphere regions that include areas in posterior parietal, occipital, and frontal cortex. We provide some suggestive evidence that these areas, too, divide into storage and rehearsal regions, with right-hemisphere posterior parietal and premotor regions subserving spatial rehearsal. In a final set of studies, we turn to "executive processes," metaprocesses that regulate the processing of working-memory contents. We focus on the executive process of inhibition as it is used in verbal working memory. We provide evidence that such inhibition is mediated by the left-hemisphere prefrontal region and that it can be dissociated from verbal storage and rehearsal processes.

Brain↗
PubMed1998

Functional neuroimaging studies of encoding, priming, and explicit memory retrieval.

Human functional neuroimaging techniques provide a powerful means of linking neural level descriptions of brain function and cognition. The exploration of the functional anatomy underlying human memory comprises a prime example. Three highly reliable findings linking memory-related cognitive processes to brain activity are discussed. First, priming is accompanied by reductions in the amount of neural activation relative to naive or unprimed task performance. These reductions can be shown to be both anatomically and functionally specific and are found for both perceptual and conceptual task components. Second, verbal encoding, allowing subsequent conscious retrieval, is associated with activation of higher order brain regions including areas within the left inferior and dorsal prefrontal cortex. These areas also are activated by working memory and effortful word generation tasks, suggesting that these tasks, often discussed as separable, might rely on interdependent processes. Finally, explicit (intentional) retrieval shares much of the same functional anatomy as the encoding and word generation tasks but is associated with the recruitment of additional brain areas, including the anterior prefrontal cortex (right > left). These findings illustrate how neuroimaging techniques can be used to study memory processes and can both complement and extend data derived through other means. More recently developed methods, such as event-related functional MRI, will continue this progress and may provide additional new directions for research.

Amnesia↗
PubMed1986

Diagnostic neuroimaging in stroke. The complementary roles of referring physician and neuroradiologist.

The number and sophistication of neuroimaging methods for identifying location, size, type, and causes of stroke or stroke-like syndromes have expanded rapidly. In acute stroke, computed tomography is used to distinguish between nonhemorrhagic and hemorrhagic infarction and to eliminate several potential alternative diagnoses. Cerebral angiography can identify surgically treatable lesions in patients experiencing transient ischemic attacks and thus aid in preventing stroke. The superb sensitivity of magnetic resonance imaging has opened new vistas in the ongoing investigation of multiinfarct dementia and small infarcts in neurologically "noneloquent" regions of the brain. The more complete the referring physician's clinical and neurologic workup, the more able is the neuroradiologist to structure and coordinate the safest, fastest, and most cost-effective plan of neuroimaging to diagnose a patient's neurologic problem.

Cerebral Angiography↗
PubMed2005

What can functional neuroimaging tell the experimental psychologist?

I argue here that functional neuroimaging data--which I restrict to the haemodynamic techniques of fMRI and PET--can inform psychological theorizing, provided one assumes a "systematic" function-structure mapping in the brain. In this case, imaging data simply comprise another dependent variable, along with behavioural data, that can be used to test competing theories. In particular, I distinguish two types of inference: function-to-structure deduction and structure-to-function induction. With the former inference, a qualitatively different pattern of activity over the brain under two experimental conditions implies at least one different function associated with changes in the independent variable. With the second type of inference, activity of the same brain region(s) under two conditions implies a common function, possibly not predicted a priori. I illustrate these inferences with imaging studies of recognition memory, short-term memory, and repetition priming. I then consider in greater detail what is meant by a "systematic" function-structure mapping and argue that, particularly for structure-to-function induction, this entails a one-to-one mapping between functional and structural units, although the structural unit may be a network of interacting regions and care must be taken over the appropriate level of functional/structural abstraction. Nonetheless, the assumption of a systematic function-structure mapping is a "working hypothesis" that, in common with other scientific fields, cannot be proved on independent grounds and is probably best evaluated by the success of the enterprise as a whole. I also consider statistical issues such as the definition of a qualitative difference and methodological issues such as the relationship between imaging and behavioural data. I finish by reviewing various objections to neuroimaging, including neophrenology, functionalism, and equipotentiality, and by observing some criticisms of current practice in the imaging literature.

Arousal↗
PubMedDate not supplied

Functional neuroimaging correlates of functional amnesia.

Especially in the field of memory encoding and retrieval, the results of functional neuroimaging have provided new insights in anatomico-functional interactions. In particular this holds true for the role of the prefrontal cortex in mnestic information processing, for the contribution and participation of the two hemispheres in various processes of information transmission, and for views on disturbed information processing after organically obvious and so-called psychogenic forms of memory impairments. This report particularly stresses the insights obtained by functional neuroimaging for probably environmentally triggered deficiencies in memory processing and discusses possible subtle neuroanatomical correlates of functional amnesias. It is especially emphasised that stress conditions and depressive states may modify the release of steroids (glucocorticoids) and transmitter agonists at the brain level with the consequence of selective memory disturbances which may manifest as a "mnestic block syndrome".

Amnesia↗
PubMed2003

Neuroimaging in eating disorders.

Neuroanatomical and functional studies in the eating disorders (ED) are reviewed. Typically, anorexia nervosa (AN) is associated with cerebral spinal fluid spaces enlargement which generally recover as a function of re-feeding. However, specific cortical areas fail to correct in weight restored anorectic patients suggesting trait-related abnormalities. Functional changes in AN associated with starvation reverse with weight recovery, however, reduced 5-HT2A receptor binding may be fundamental to the pathophysiology of AN since this remains after long term weight restoration. Structural studies of bulimia nervosa (BN) provide evidence of brain atrophy, in the absence of significant weight loss but potentially related to chronic dietary restriction. Functional investigations reveal reduced thalamic and hypothalamic serotonin transporter availability in BN which increases with longer illness duration. Thus, BN is associated with substantial structural and functional alterations despite normal weight. Recent advances in neuroimaging techniques and their interpretation are increasing our understanding of normal processes in the control of food intake including neuroanatomical correlates of hunger and satiety. Taken together with the structural and functional changes observed in the ED, neuroimaging provides a powerful platform to identify the underlying trait-related pathophysiological mechanisms in the aetiology and maintenance of AN and BN.

Anorexia Nervosa↗
PubMed2003

Neuroimaging in amyotrophic lateral sclerosis.

Several neuroimaging modalities have been used with varying success to aid the clinical process of establishing the diagnosis of amyotrophic lateral sclerosis (ALS). By demonstrating evidence of occult upper motor neuron degeneration in vivo, a speedier and more definitive diagnosis in suspected cases could lead to earlier treatment and earlier enrollment in clinical trials. Findings compatible with ALS on routine MRI are not consistently found and are non-specific. Thus, routine anatomic imaging is useful in ruling out diseases that mimic ALS, but not in classification of new cases. Functional imaging techniques, such as PET and fMRI, have provided fascinating insights into the cortical functional reorganization that accompanies muscular weakness. PET and SPECT have revealed involvement of regions of the brain beyond the motor cortex, something not well appreciated by pathological examination. Of great need is a surrogate marker of therapeutic efficacy to make drug evaluation more efficient; neuroimaging, and magnetic resonance spectroscopy in particular, holds great promise in this regard in addition to helping us better understand the of neurodegeneration.

Amyotrophic Lateral Sclerosis↗
PubMed2003

Neuroimaging communality between schizophrenia and obsessive compulsive disorder: a putative basis for schizo-obsessive disorder?

Four major brain regions have been repeatedly implicated in the pathophysiology of obsessive compulsive disorder (OCD) in in vivo neuroimaging studies: the caudate nucleus, the orbitofrontal cortex, the anterior cingulate gyrus and the mediodorsal thalamic nucleus. The present review describes the neuroimaging studies on schizophrenia, pertaining to these brain regions. Our working hypothesis is that such common brain regions, if dysfunctional in schizophrenic patients, would be candidates for a neural network subserving the newly emerging syndrome of schizo-obsessive disorder. Findings, though, are controversial. We conclude that further studies, aimed at specific monitoring of these brain regions, in patients suffering from the schizo-obsessive syndrome are warranted.

Brain↗
PubMedDate not supplied

Functional neuroimaging in acute stroke.

To the present day, the first and most widespread diagnostic approach in the assessment of acute stroke remains CT scan. Its sensitivity is very high (nearly 100%) in detecting intracerebral hemorrhage in the acute period, but its capability of revealing ischemic injury in the very first hours from symptom onset is relatively poor. Since the efficacy of thrombolytic treatment in acute stroke has been suggested by the ECASS and NINDS rt-PA trials, functional neuroimaging able to distinguish potentially salvageable tissue from irreversibly injured areas has acquired primary importance. The possibility to correctly identify the tissue of the ischemic penumbra within the first hours from symptom onset is essential for correct patient selection for thrombolitic treatment. Different imaging strategies are available for the definition of perfusion deficits within the acute time window; among these are positron emission tomography (PET), single photon emission computed tomography (SPECT), Xenon CT (XeCT), dynamic CT perfusion imaging (CTP), diffusion weighted magnetic resonance imaging (DW-MRI), and perfusion weighted magnetic resonance imaging (PW-MRI). Though each technique has its advantages and limitations to present day functional MRI remains the most widespread imaging technique in the assessment of acute stroke being more accessible than both SPECT and PET, and capable of giving information on both perfusion and tissue functional status in a single imaging session. In this paper we discuss the role of functional neuroimaging in acute stroke.

Brain Ischemia↗
PubMed2026

BriGHT: transcriptome-regularized multimodal neuroimaging for brain disorder prediction.

MOTIVATION: Hypergraph-based models for brain disorder prediction mainly adopt imaging-derived hypergraphs as propagation backbones. However, the entanglement of topology construction and feature propagation leaves regional representations weakly constrained by underlying biological organization, making them vulnerable to subject-specific variation and noise, particularly in heterogeneous multimodal settings. RESULTS: We present BriGHT, a Brain transcriptome-reGularized Hypergraph framework for mulTimodal disorder prediction. BriGHT employs a transcriptome-derived structural reference as a soft anchoring prior to regularize neuroimaging ROI embeddings, stabilizing representation geometry while preserving disease-relevant subject-specific variation. BriGHT further incorporates a reliability-aware fusion module to estimate subject-specific modality reliability from prediction confidence, cross-modal consistency, and decision certainty, enabling adaptive integration under heterogeneous modality quality. Experiments on three neuroimaging cohorts (ADNI, ADHD-200, REST-meta-MDD) and four modalities (VBM, fMRI, FDG, AV45) demonstrate that BriGHT consistently outperforms competing graph/hypergraph learning methods across six brain disorder prediction tasks. Perturbation analyses show that BriGHT benefits from the spatial correspondence between transcriptomic modules and imaging ROIs, rather than from arbitrary hypergraph regularization alone. Ablation and meta-analytic interpretability analyses support the contribution of transcriptomic anchoring and adaptive fusion to robust and biologically meaningful brain disorder prediction. AVAILABILITY: The software is publicly available at: https://github.com/Yaolab-fantastic/BriGHT. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Journal Article↗
PubMed2003

Neuroimaging of animal models of brain disease.

The main aim of this review is to describe some of the many animal models that have proved to be valuable from a neuroimaging perspective. This paper complements other articles in this volume, with a focus on animal models of the pathology of human brain disorders for investigations with modern non-invasive neuroimaging techniques. The use of animal model systems forms a fundamental part of neuroscience research efforts to improve the prevention, diagnosis, understanding and treatment of neurological conditions. Without such models it would be impossible to investigate such topics as the underlying mechanisms of neuronal cell damage and death, or to screen compounds for possible anticonvulsant properties. The adequacy of any one particular model depends on the suitability of information gained during experimental conditions. It is important, therefore, to understand the various types of animal model available and choose an appropriate model for the research question.

Animals↗
PubMed1995

Abnormalities of gyration, heterotopias, tuberous sclerosis, focal cortical dysplasia, microdysgenesis, dysembryoplastic neuroepithelial tumour and dysgenesis of the archicortex in epilepsy. Clinical, EEG and neuroimaging features in 100 adult patients.

Cerebral cortical dysgenesis (CD) is a heterogeneous disorder of cortical development and organization commonly associated with epilepsy, with a variety of subtypes. We reviewed the clinical, EEG and neuroimaging features in 100 adult patients with CD. There were 39 men and 61 women with a median age of 27 years (range 15-63 years). All patients were referred because of medically refractory epilepsy. Median age at seizure onset was 10 years (range 3 weeks to 39 years); in 30 patients, onset was in adulthood. The epilepsy was classified as generalized in 16 patients and localization-related in 84. Of the latter, the epileptic syndromes in decreasing frequency were frontal (32%), temporal (31%), parietal (14%) and occipital (7%). Only 15% of patients had a history of status epilepticus. Prenatal/perinatal problems were reported in 32 patients but these were severe in only four: exposure to drugs (three) and infection (one) during the first trimester. Delayed developmental milestones were seen in 10%, mental retardation in 9%, additional congenital abnormalities in 4% and neurological deficits in 14% of patients. Diagnosis of CD was based on neuroimaging in 70, pathology in four and both methods in the remaining 26. The following subcategories were identified: agyria/diffuse macrogyria (four patients), focal macrogyria (16), focal polymicrogyria (one), focal macrogyria/polymicrogyria associated with a cleft (11), minor gyral abnormalities (seven), subependymal grey matter heterotopia (20), bilateral subcortical laminar grey matter heterotopia (eight), tuberous sclerosis (five), focal cortical dysplasia/microdysgenesis (seven) and dysembryoplastic neuroepithelial tumours (DNT) (21). Sixty-eight percent of patients had normal CT and 19 out of 36 patients had normal previous conventional MRI. MRI-based hippocampal volume measurements in 47 patients revealed ratios (smaller: larger hippocampus) of < 0.90 in 16, 0.90-0.94 in 14 and > or = 0.95 in 17 patients. EEGs were normal in only five patients. Alpha rhythm was preserved in 78 patients, including one patient with bilateral posterior macrogyria. Localized polymorphic slow activity was present in 43 patients. Five of 68 patients with focal/unilateral CD had only bilateral independent/synchronous spiking and 14 out of 32 with diffuse/bilateral CD only focal/unilateral spiking. In 60 patients with nondiffuse CD or with abnormal gyration or DNT, the epileptiform abnormalities were less extensive than coextensive with the lesion in 28, more extensive than and overlapped the lesion in 18 and remote from the lesion in five; nine patients did not have epileptiform abnormalities. There was poor correlation between the epileptic syndromes and EEG abnormalities and the location/extent of CD as defined by MRI and pathology.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗