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Cerebral Glucose Metabolism (cerebral + glucose_metabolism)
Kinds of Cerebral Glucose Metabolism Selected AbstractsCortical control of thermoregulatory sympathetic activationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2010M. Fechir Abstract Thermoregulation enables adaptation to different ambient temperatures. A complex network of central autonomic centres may be involved. In contrast to the brainstem, the role of the cortex has not been clearly evaluated. This study was therefore designed to address cerebral function during a whole thermoregulatory cycle (cold, neutral and warm stimulation) using 18-fluordeoxyglucose-PET (FDG-PET). Sympathetic activation parameters were co-registered. Ten healthy male volunteers were examined three times on three different days in a water-perfused whole-body suit. After a baseline period (32°C), temperature was either decreased to 7°C (cold), increased to 50°C (warm) or kept constant (32°C, neutral), thereafter the PET examination was performed. Cerebral glucose metabolism was increased in infrapontine brainstem and cerebellar hemispheres during cooling and warming, each compared with neutral temperature. Simultaneously, FDG uptake decreased in the bilateral anterior/mid-cingulate cortex during warming, and in the right insula during cooling and warming. Conjunction analyses revealed that right insular deactivation and brainstem activation appeared both during cold and warm stimulation. Metabolic connectivity analyses revealed positive correlations between the cortical activations, and negative correlations between these cortical areas and brainstem/cerebellar regions. Heart rate changes negatively correlated with glucose metabolism in the anterior cingulate cortex and in the middle frontal gyrus/dorsolateral prefrontal cortex, and changes of sweating with glucose metabolism in the posterior cingulate cortex. In summary, these results suggest that the cerebral cortex exerts an inhibitory control on autonomic centres located in the brainstem or cerebellum. These findings may represent reasonable explanations for sympathetic hyperactivity, which occurs, for example, after hemispheric stroke. [source] The functional neuroanatomy of geriatric depressionINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 8 2009Gwenn S. Smith Abstract Objective Positron Emission Tomography (PET) studies of cerebral glucose metabolism have demonstrated sensitivity in evaluating the functional neuroanatomy of treatment response variability in depression, as well as in the early detection of functional changes associated with incipient cognitive decline. The evaluation of cerebral glucose metabolism in late life depression may have implications for understanding treatment response variability, as well as evaluating the neurobiological basis of depression in late life as a risk factor for dementia. Methods Sixteen patients with geriatric depression and 13 comparison subjects underwent resting PET studies of cerebral glucose metabolism, as well as magnetic resonance (MR) imaging scans to evaluate brain structure. Results Cerebral glucose metabolism was elevated in geriatric depressed patients relative to comparison subjects in anterior (right and left superior frontal gyrus) and posterior (precuneus, inferior parietal lobule) cortical regions. Cerebral atrophy (increased cerebrospinal fluid [CSF] and decreased grey and white matter volumes) were observed in some of these regions, as well. Regional cerebral metabolism was positively correlated with severity of depression and anxiety symptoms. Conclusions In contrast to decreased metabolism observed in normal aging and neurodegenerative conditions such as Alzheimer's disease, cortical glucose metabolism was increased in geriatric depressed patients relative to demographically matched controls, particularly in brain regions in which cerebral atrophy was observed, which may represent a compensatory response. Copyright © 2009 John Wiley & Sons, Ltd. [source] Regional cerebral brain metabolism correlates of neuroticism and extraversionDEPRESSION AND ANXIETY, Issue 3 2006Thilo Deckersbach Ph.D. Abstract Factor-analytic approaches to human personality have consistently identified several core personality traits, such as Extraversion/Introversion, Neuroticism, Agreeableness, Consciousness, and Openness. There is an increasing recognition that certain personality traits may render individuals vulnerable to psychiatric disorders, including anxiety disorders and depression. Our purpose in this study was to explore correlates between the personality dimensions neuroticism and extraversion as assessed by the NEO Five-Factor Inventory (NEO-FFI) and resting regional cerebral glucose metabolism (rCMRglu) in healthy control subjects. Based on the anxiety and depression literatures, we predicted correlations with a network of brain structures, including ventral and medial prefrontal cortex (encompassing anterior cingulate cortex and orbitofrontal cortex), insular cortex, anterior temporal pole, ventral striatum, and the amygdala. Twenty healthy women completed an 18FFDG (18F-fluorodeoxyglucose) positron emission tomography (PET) scan at rest and the NEO-FFI inventory. We investigated correlations between scores on NEO-FFI Neuroticism and Extraversion and rCMRglu using statistical parametric mapping (SPM99). Within a priori search territories, we found significant negative correlations between Neuroticism and rCMRglu in the insular cortex and positive correlations between Extraversion and rCMRglu in the orbitofrontal cortex. No significant correlations were found involving anterior cingulate, amygdala, or ventral striatum. Neuroticism and Extraversion are associated with activity in insular cortex and orbitofrontal cortex, respectively. Depression and Anxiety 23:133,138, 2006. © 2006 Wiley-Liss, Inc. [source] Epilepsy Patients Treated with Antiepileptic Drug Therapy Exhibit Compromised Ocular Perfusion CharacteristicsEPILEPSIA, Issue 11 2002Emma J. Roff Hilton Summary: ,Purpose: Reduced cerebral blood flow and decreased cerebral glucose metabolism have been identified in patients with epilepsy treated with antiepileptic drug (AED) therapy. The purpose of this study was to determine whether ocular haemodynamics are similarly reduced in patients with epilepsy treated with AEDs. Methods: Scanning laser Doppler flowmetry was used to measure retinal capillary microvascular flow, volume, and velocity in the temporal neuroretinal rim of 14 patients diagnosed with epilepsy (mean age, 42.0 ± 0.9 years). These values were compared with those of an age- and gender-matched normal subject group (n = 14; mean age, 41.7 ± 0.3 years). Student's unpaired two-tailed t tests were used to compare ocular blood-flow parameters between the epilepsy and normal subject groups (p < 0.05; Bonferroni corrected). Results: A significant reduction in retinal blood volume (p = 0.001), flow (p = 0.003), and velocity (p = 0.001) was observed in the epilepsy group (13.52 ± 3.75 AU, 219.14 ± 76.61 AU, and 0.77 ± 0.269 AU, respectively) compared with the normal subject group (19.02 ± 5.11 AU, 344.03 ± 93.03 AU, and 1.17 ± 0.301 AU, respectively). Overall, the percentage mean difference between the epilepsy and normal groups was 36.31% for flow, 28.92% for volume, and 34.19% for velocity. Conclusions: Patients with epilepsy exhibit reduced neuroretinal capillary blood flow, volume, and velocity compared with normal subjects. A reduction in ocular perfusion may have implications for visual function in people with epilepsy. [source] The correlation between cerebral glucose metabolism and benzodiazepine receptor density in the acute vegetative stateEUROPEAN JOURNAL OF NEUROLOGY, Issue 6 2002J. Rudolf This paper compares the results of parallel positron emission tomography (PET) studies of regional cerebral glucose metabolism with the radiotracer 18F-fluorodeoxyglucose (FDG) and benzodiazepine receptor (BZR) density by PET using the BZR ligand 11C-flumazenil (FMZ), a tracer of neuronal integrity, in nine patients with acute vegetative state (AVS, duration <1 month). Overall glucose utilization was significantly reduced in AVS in comparison with age-matched controls (global metabolic rate for glucose 26 ,mol/100 g/min in AVS vs. 31 ,mol/100 g/min in controls). FMZ-PET demonstrated a considerable reduction of BZR binding sites in all cortical regions that grossly corresponded to the extent of reduction of cerebral glucose metabolism assessed with FDG-PET, whilst the cerebellum was spared from neuronal loss. In controls, cortical relative flumazenil binding was not lower than five times the average white matter activity, whilst in AVS, nearly all values were below this threshold. There was no relevant overlap of the data of relative flumazenil binding between both groups. The comparison of FDG- and FMZ-PET findings in AVS demonstrates that alterations of cerebral glucose consumption do not represent mere functional inactivation, but irreversible structural brain damage. [source] Involvement of astroglial ceramide in palmitic acid-induced Alzheimer-like changes in primary neuronsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 8 2007Sachin Patil Abstract A high-fat diet has been shown to significantly increase the risk of the development of Alzheimer's disease (AD), a neurodegenerative disease histochemically characterized by the accumulation of amyloid beta (A,) protein in senile plaques and hyperphosphorylated tau in neurofibrillary tangles. Previously, we have shown that saturated free fatty acids (FFAs), palmitic and stearic acids, caused increased amyloidogenesis and tau hyperphosphorylaion in primary rat cortical neurons. These FFA-induced effects observed in neurons were found to be mediated by astroglial FFA metabolism. Therefore, in the present study we investigated the basic mechanism relating astroglial FFA metabolism and AD-like changes observed in neurons. We found that palmitic acid significantly increased de-novo synthesis of ceramide in astroglia, which in turn was involved in inducing both increased production of the A, protein and hyperphosphorylation of the tau protein. Increased amyloidogenesis and hyperphoshorylation of tau lead to formation of the two most important pathophysiological characteristics associated with AD, A, or senile plaques and neurofibrillary tangles, respectively. In addition to these pathophysiological changes, AD is also characterized by certain metabolic changes; abnormal cerebral glucose metabolism is one of the distinct characteristics of AD. In this context, we found that palmitic acid significantly decreased the levels of astroglial glucose transporter (GLUT1) and down-regulated glucose uptake and lactate release by astroglia. Our present data establish an underlying mechanism by which saturated fatty acids induce AD-associated pathophysiological as well as metabolic changes, placing ,astroglial fatty acid metabolism' at the center of the pathogenic cascade in AD. [source] The functional neuroanatomy of geriatric depressionINTERNATIONAL JOURNAL OF GERIATRIC PSYCHIATRY, Issue 8 2009Gwenn S. Smith Abstract Objective Positron Emission Tomography (PET) studies of cerebral glucose metabolism have demonstrated sensitivity in evaluating the functional neuroanatomy of treatment response variability in depression, as well as in the early detection of functional changes associated with incipient cognitive decline. The evaluation of cerebral glucose metabolism in late life depression may have implications for understanding treatment response variability, as well as evaluating the neurobiological basis of depression in late life as a risk factor for dementia. Methods Sixteen patients with geriatric depression and 13 comparison subjects underwent resting PET studies of cerebral glucose metabolism, as well as magnetic resonance (MR) imaging scans to evaluate brain structure. Results Cerebral glucose metabolism was elevated in geriatric depressed patients relative to comparison subjects in anterior (right and left superior frontal gyrus) and posterior (precuneus, inferior parietal lobule) cortical regions. Cerebral atrophy (increased cerebrospinal fluid [CSF] and decreased grey and white matter volumes) were observed in some of these regions, as well. Regional cerebral metabolism was positively correlated with severity of depression and anxiety symptoms. Conclusions In contrast to decreased metabolism observed in normal aging and neurodegenerative conditions such as Alzheimer's disease, cortical glucose metabolism was increased in geriatric depressed patients relative to demographically matched controls, particularly in brain regions in which cerebral atrophy was observed, which may represent a compensatory response. Copyright © 2009 John Wiley & Sons, Ltd. [source] Regional cerebral glucose metabolism during sevoflurane anaesthesia in healthy subjects studied with positron emission tomographyACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2010L. SCHLÜNZEN Background: The precise mechanism by which sevoflurane exerts its effects in the human brain remains unknown. In the present study, we quantified the effects of sevoflurane on regional cerebral glucose metabolism (rGMR) in the human brain measured with positron emission tomography. Methods: Eight volunteers underwent two dynamic 18F-fluorodeoxyglucose positron emission tomography (PET) scans. One scan assessed conscious-baseline metabolism and the other scan assessed metabolism during 1 minimum alveolar concentration (MAC) sevoflurane anaesthesia. Cardiovascular and respiratory parameters were monitored and bispectral index responses were registered. Statistical parametric maps and conventional regions of interest analysis were used to determine rGMR differences. Results: All subjects were unconsciousness at 1.0 MAC sevoflurane. Cardiovascular and respiratory parameters were constant over time. In the awake state, rGMR ranged from 0.24 to 0.35 ,mol/g/min in the selected regions. Compared with the conscious state, total GMR decreased 56% in sevoflurane anaesthesia. In white and grey matter, GMR was averaged 42% and 58% of normal, respectively. Sevoflurane reduced the absolute rGMR in all selected areas by 48,71% of the baseline (P,0.01), with the most significant reductions in the lingual gyrus (71%), occipital lobe in general (68%) and thalamus (63%). No increases in rGMR were observed. Conclusions: Sevoflurane caused a global whole-brain metabolic reduction of GMR in all regions of the human brain, with the most marked metabolic suppression in the lingual gyrus, thalamus and occipital lobe. [source] Neuroimaging in bipolar disorderBIPOLAR DISORDERS, Issue 3 2000Stephen M Strakowski Objective: The authors reviewed neuroimaging studies of bipolar disorder in order to evaluate how this literature contributes to the current understanding of the neurophysiology of the illness. Method: Papers were reviewed as identified, using the NIMH PubMed literature search systems that reported results of neuroimaging studies involving a minimum of five bipolar disorder patients compared with healthy comparison subjects. Results: Structural neuroimaging studies report mixed results for lateral and third ventriculomegaly. Recent studies suggest subcortical structural abnormalities in the striatum and amygdala, as well as the prefrontal cortex. Proton spectroscopic studies suggest that abnormalities in choline metabolism exist in bipolar disorder, particularly in the basal ganglia. Additionally, phosphorous MRS suggests that there may be abnormalities in frontal phospholipid metabolism in bipolar disorder. Functional studies have identified affective state-related changes in cerebral glucose metabolism and blood flow, particularly in the prefrontal cortex during depression, but no clear abnormalities specific to bipolar disorder have been consistently observed. Conclusions: The current literature examining the neurophysiology of bipolar disorder using neuroimaging is limited. Nonetheless, abnormalities in specific frontal-subcortical brain circuits seem likely. Additional targeted studies are needed to capitalize on this burgeoning technology to advance our understanding of the neurophysiology of bipolar disorder. [source] | |||||||||||||||||||