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Functional Brain Imaging (functional + brain_imaging)
Selected AbstractsNo change in the structure of the brain in migraine: a voxel-based morphometric studyEUROPEAN JOURNAL OF NEUROLOGY, Issue 1 2003M. S. Matharu Migraine is a common, disabling form of primary neurovascular headache. For most of the twentieth century it was regarded as a vascular headache whose primary pathophysiology lay in the cranial vasculature. Functional brain imaging using positron emission tomography has demonstrated activation of the rostral brain stem in acute migraine. Voxel-based morphometry is a new fully automated whole brain technique that is sensitive to subtle macroscopic and mesoscopic structural differences between groups of subjects. In this study 11 patients suffering from migraine with aura (10 females, one male: 23,52 years, mean 31); 11 controls (10 females, one male: 23,52, mean 31); 17 patients with migraine without aura (16 females, one male: 24,57, mean 34); 17 controls (16 females, one male: 24,57, mean 34) were imaged with high resolution volumetric magnetic resonance imaging. There was no significant difference in global grey or white matter volumes between either patients with migraine and controls, or patients with aura and without aura. This study did not show any global or regional macroscopic structural difference between patients with migraine and controls, with migraine sufferers taken as homogenous groups. If structural changes are to be found, other methods of phenotyping migraine, such as by genotype or perhaps treatment response, may be required to resolve completely whether there is some subtle structural change in the brain of patients with migraine. [source] Functional brain imaging in pure akinesia with gait freezing: [18F] FDG PET and [18F] FP-CIT PET analyses,MOVEMENT DISORDERS, Issue 2 2009Hee K. Park MD Abstract Pure akinesia with gait freezing (PAGF) has characteristic features, including freezing of gait and prominent speech disturbance without rigidity or tremor. The purpose of this study was to investigate changes in brain glucose metabolism and presynaptic dopaminergic function in PAGF. By using [18F] fluorodeoxyglucose (FDG) PET, 11 patients with PAGF were compared with 14 patients with probable progressive supranuclear palsy (PSP), 13 patients with Parkinson's disease (PD), and 11 normal controls. [18F] N -(3-fluoropropyl)-2,-carbon ethoxy-3,-(4-iodophenyl) nortropane (FP-CIT) PET was performed in 11 patients with PAGF and with 10 normal controls. The PAGF patients showed decreased glucose metabolism in the midbrain when compared with normal controls. PSP patients showed a similar topographic distribution of glucose hypometabolism with additional areas, including the frontal cortex, when compared with normal controls. The FP-CIT PET findings in patients with PAGF revealed severely decreased uptake bilaterally in the basal ganglia. These findings suggest that both PAGF and PSP may be part of the same pathophysiologic spectrum of disease. However, the reason why PAGF manifests clinically in a different manner needs to be further elucidated. © 2008 Movement Disorder Society [source] Perfusion MR imaging with pulsed arterial spin-labeling: Basic principles and applications in functional brain imagingCONCEPTS IN MAGNETIC RESONANCE, Issue 5 2002Yihong Yang Abstract Basic principles of the arterial spin-labeling perfusion MRI are described, with focus on a brain perfusion model with pulsed labeling. A multislice perfusion imaging sequence with adiabatic inversion and spiral scanning is illustrated as an example. The mechanism of the perfusion measurement, the quantification of cerebral blood flow, and the suppression of potential artifacts are discussed. Applications of the perfusion imaging in brain activation studies, including simultaneous detection of blood flow and blood oxygenation, are demonstrated. Important issues associated with the applications such as sensitivity, quantification, and temporal resolution are discussed. © 2002 Wiley Periodicals, Inc. Concepts Magn Reson 14: 347,357, 2002 [source] Short-term plasticity visualized with flavoprotein autofluorescence in the somatosensory cortex of anaesthetized ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2004Hiroatsu Murakami Abstract In the present study, short-term plasticity of somatosensory neural responses was investigated using flavoprotein autofluorescence imaging in rats anaesthetized with urethane (1.5 g/kg, i.p.) Somatosensory neural activity was elicited by vibratory skin stimulation (50 Hz for 1 s) applied on the surface of the left plantar hindpaw. Changes in green autofluorescence (, = 500,550 nm) in blue light (, = 450,490 nm) were elicited in the right somatosensory cortex. The normalised maximal fluorescence responses (,F/F) was 2.0 ± 0.1% (n = 40). After tetanic cortical stimulation (TS), applied at a depth of 1.5,2.0 mm from the cortical surface, the responses elicited by peripheral stimulation were significantly potentiated in both peak amplitude and size of the responsive area (both P < 0.02; Wilcoxon signed rank test). This potentiation was clearly observed in the recording session started 5 min after the cessation of TS, and returned to the control level within 30 min. However, depression of the responses was observed after TS applied at a depth of 0.5 mm. TS-induced changes in supragranular field potentials in cortical slices showed a similar dependence on the depth of the stimulated sites. When TS was applied on the ipsilateral somatosensory cortex, marked potentiation of the ipsilateral responses and slight potentiation of the contralateral responses to peripheral stimulation were observed after TS, suggesting the involvement of commissural fibers in the changes in the somatosensory brain maps. The present study clearly demonstrates that functional brain imaging using flavoprotein autofluorescence is a useful technique for investigating neural plasticity in vivo. [source] Brain Imaging in Migraine ResearchHEADACHE, Issue 9 2010David Borsook MD Understanding the pathophysiology and pharmacology of migraine has been driven by astute clinical observations, elegant experimental medicine studies, and importantly by studying highly effective anti-migraine agents in the laboratory and the clinic. Significant progress has been made in the use of functional brain imaging to compliment observational studies of migraine phenotypes by highlighting pathways within the brain that may be involved in predisposition to migraine, modulating migraine pain or that could be sensitive to pharmacological or behavioral therapeutic intervention (Fig. 1). In drug discovery, molecular imaging approaches compliment functional neuroimaging by visualizing migraine drug targets within the brain. Molecular imaging enables the selection and evaluation of drug candidates by confirming that they engage their targets sufficiently at well tolerated doses to test our therapeutic hypotheses. Figure 1.,. Imaging and defining the migraine brain disease state: from anatomy to chemical entities (targets) to functional systems (function and pathways) (from Borsook et al31 with permission, Nature Publishing Group). Migraine is a progressive disorder. Developing our knowledge of where drugs act in the brain and of how the brain is altered in both episodic migraine (interictal state and ictal state) and chronic migraine are important steps to understanding why there is such differential responsiveness to therapeutics among migraine patients and to improving how they are evaluated and treated. [source] fMRI evidence for multisensory recruitment associated with rapid eye movements during sleepHUMAN BRAIN MAPPING, Issue 5 2009Charles Chong-Hwa Hong Abstract We studied the neural correlates of rapid eye movement during sleep (REM) by timing REMs from video recording and using rapid event-related functional MRI. Consistent with the hypothesis that REMs share the brain systems and mechanisms with waking eye movements and are visually-targeted saccades, we found REM-locked activation in the primary visual cortex, thalamic reticular nucleus (TRN), ,visual claustrum', retrosplenial cortex (RSC, only on the right hemisphere), fusiform gyrus, anterior cingulate cortex, and the oculomotor circuit that controls awake saccadic eye movements (and subserves awake visuospatial attention). Unexpectedly, robust activation also occurred in non-visual sensory cortices, motor cortex, language areas, and the ascending reticular activating system, including basal forebrain, the major source of cholinergic input to the entire cortex. REM-associated activation of these areas, especially non-visual primary sensory cortices, TRN and claustrum, parallels findings from waking studies on the interactions between multiple sensory data, and their ,binding' into a unified percept, suggesting that these mechanisms are also shared in waking and dreaming and that the sharing goes beyond the expected visual scanning mechanisms. Surprisingly, REMs were associated with a decrease in signal in specific periventricular subregions, matching the distribution of the serotonergic supraependymal plexus. REMs might serve as a useful task-free probe into major brain systems for functional brain imaging. Hum Brain Mapp 2009. © 2008 Wiley-Liss, Inc. [source] Antidepressants in clinical practice: limitations of assessment methods and drug responseHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 1 2001Sidney H Kennedy Abstract There is a recognized gap between knowledge derived from ,efficacy' data , based on usually brief randomized controlled trials and findings in natural practice ,effectiveness' studies. In considering the limitations of current antidepressants in clinical practice, we have selected three clinically important issues to examine in a natural practice data base that has been in existence for several years. These relate to: (1) Diagnostic heterogeneity and potential advances using functional brain imaging; (2) Variability of outcome measures during treatment and (3) Time to response and prediction of outcome. Copyright © 2001 John Wiley & Sons, Ltd. [source] Monocarboxylate transporters in the central nervous system: distribution, regulation and functionJOURNAL OF NEUROCHEMISTRY, Issue 1 2005Karin Pierre Abstract Monocarboxylate transporters (MCTs) are proton-linked membrane carriers involved in the transport of monocarboxylates such as lactate, pyruvate, as well as ketone bodies. They belong to a larger family of transporters composed of 14 members in mammals based on sequence homologies. MCTs are found in various tissues including the brain where three isoforms, MCT1, MCT2 and MCT4, have been described. Each of these isoforms exhibits a distinct regional and cellular distribution in rodent brain. At the cellular level, MCT1 is expressed by endothelial cells of microvessels, by ependymocytes as well as by astrocytes. MCT4 expression appears to be specific for astrocytes. By contrast, the predominant neuronal monocarboxylate transporter is MCT2. Interestingly, part of MCT2 immunoreactivity is located at postsynaptic sites, suggesting a particular role of monocarboxylates and their transporters in synaptic transmission. In addition to variation in expression during development and upon nutritional modifications, new data indicate that MCT expression is regulated at the translational level by neurotransmitters. Understanding how transport of monocarboxylates is regulated could be of particular importance not only for neuroenergetics but also for areas such as functional brain imaging, regulation of food intake and glucose homeostasis, or for central nervous system disorders such as ischaemia and neurodegenerative diseases. [source] Comparing Structural Equation Models That Use Different Measures of the Level of Response to AlcoholALCOHOLISM, Issue 5 2010Marc A. Schuckit Background:, The two measures of a low level of response (LR) to alcohol, an alcohol challenge and the retrospective Self-Report of the Effects of Alcohol questionnaire (SRE), each identify individuals at high risk for heavy drinking and alcohol problems. These measures also perform similarly in identifying subjects with unique functional brain imaging characteristics. However, few data are available regarding whether alcohol challenge-based and SRE-based LRs operate similarly in structural equation models (SEMs) that search for characteristics, which help to mediate how LR impacts alcohol outcomes. Methods:, Two hundred and ninety-four men from the San Diego Prospective Study were evaluated for their LR to alcohol using alcohol challenges at ,age 20. At ,age 35, the same subjects filled out the SRE regarding the number of drinks needed for effects 15 to 20 years earlier. The two different LR scores for these men were used in SEM analyses evaluating how LR relates to future heavy drinking and to drinking in peers (PEER), alcohol expectancies (EXPECT), and drinking to cope (COPE) as potential mediators of the LR to drinking pattern (ALCOUT) relationships. Results:, While the 2 LR measures that were determined 15 years apart related to each other at a modest level (r = 0.17, p < 0.01), the SEM results were similar regardless of the LR source. In both alcohol challenge-based and SRE-based LR models, LR related directly to ALCOUT, with partial mediation from PEER and COPE, but not through EXPECT in these 35-year-old men. Conclusions:, Consistent with the >60% overlap in prediction of outcomes for the 2 LR measures, and with results from functional brain imaging, alcohol challenge- and SRE-based LR values operated similarly in SEM models in these men. [source] BOLD contrast sensitivity enhancement and artifact reduction with multiecho EPI: Parallel-acquired inhomogeneity-desensitized fMRIMAGNETIC RESONANCE IN MEDICINE, Issue 6 2006Benedikt A. Poser Abstract Functional MRI (fMRI) generally employs gradient-echo echo-planar imaging (GE-EPI) to measure blood oxygen level-dependent (BOLD) signal changes that result from changes in tissue relaxation time T between activation and rest. Since T strongly varies across the brain and BOLD contrast is maximal only where the echo time (TE) equals the local T, imaging at a single TE is a compromise in terms of overall sensitivity. Furthermore, the long echo train makes EPI very sensitive to main field inhomogeneities, causing strong image distortion. A method is presented that uses accelerated parallel imaging to reduce image artifacts and acquire images at multiple TEs following a single excitation, with no need to increase TR. Sensitivity gains from the broadened T coverage are optimized by pixelwise weighted echo summation based on local T or contrast-to-noise ratio (CNR) measurements. The method was evaluated using an approach that allows differential BOLD CNR to be calculated without stimulation, as well as with a Stroop experiment. Results obtained at 3 T showed that BOLD sensitivity improved by 11% or more in all brain regions, with larger gains in areas typically affected by strong susceptibility artifacts. The use of parallel imaging markedly reduces image distortion, and hence the method should find widespread application in functional brain imaging. Magn Reson Med, 2006. © 2006 Wiley-Liss, Inc. [source] On the timing characteristics of the apparent diffusion coefficient contrast in fMRIMAGNETIC RESONANCE IN MEDICINE, Issue 2 2002Stacey L. Gangstead Abstract For the past 10 years, functional MRI (fMRI) has seen rapid progress in both clinical and basic science research. Most of the imaging techniques are based on the blood oxygenation level-dependent (BOLD) contrast which arises from the field perturbation of the paramagnetic deoxyhemoglobin due to the mismatch between the local oxygen demand and delivery. Because the changes of oxygenation level take place mostly in the veins, the dominant signal sources of the BOLD signal are intra- and extravascular proton pools of the veins. Perfusion imaging methods, developed parallel to the BOLD technique, seek to quantify the blood flow and perfusion. Recently, perfusion imaging using arterial spin tagging methods have been used to study brain function by investigating the changes of the blood flow and perfusion during brain activation, thereby generating an alternative contrast mechanism to the functional brain imaging. Since most of these methods require tagging pulse and wait time for blood to be delivered to the imaged slice, the temporal resolution may not be optimal. Dynamic intravoxel incoherent motion (IVIM) weighting schemes using apparent diffusion coefficient (ADC) contrast were suggested to image the relative changes of the in-plane blood flow during brain function. In this report, it was demonstrated that, in addition to the spatial discrepancies of the activated areas, the time course based on the ADC contrast consistently precedes that from the BOLD contrast with timing offset on the order of 1 sec. Since arterial networks would have different spatial locations and preceding temporal characters, the findings in this report are indicative that the ADC contrast is sensitive to the arterial blood flow changes. Magn Reson Med 48:385,388, 2002. © 2002 Wiley-Liss, Inc. [source] A decade of functional brain imaging applied to bladder controlNEUROUROLOGY AND URODYNAMICS, Issue 1 2010Clare J. Fowler Abstract Over the last 10 years functional brain imaging has emerged as the most powerful technique for studying human brain function. Although the literature is now vast, including studies of every imaginable aspect of cortical function, the number of studies that have been carried out examining brain control of bladder function is relatively limited. Nevertheless those that have been reported have transformed our thinking. This article reviews that development in the context of emerging ideas of interoception and a working model of brain activity during bladder filling and emptying is proposed. Some studies have also been carried out using functional imaging methods to examine pathophysiological bladder conditions or the effect of treatments and these are reviewed and future work anticipated. Neurourol. Urodynam. 29: 49,55, 2010. © 2009 Wiley-Liss, Inc. [source] Bladder control, urgency, and urge incontinence: Evidence from functional brain imaging,NEUROUROLOGY AND URODYNAMICS, Issue 6 2008Derek Griffiths Abstract Aim To review brain imaging studies of bladder control in subjects with normal control and urge incontinence; to define a simple model of supraspinal bladder control; and to propose a neural correlate of urgency and possible origins of urge incontinence. Methods Review of published reports of brain imaging relevant to urine storage, and secondary analyses of our own recent observations. Results In a simple model of normal urine storage, bladder and urethral afferents received in the periaqueductal gray (PAG) are mapped in the insula, forming the basis of sensation; the anterior cingulate gyrus (ACG) provides monitoring and control; the prefrontal cortex makes voiding decisions. The net result, as the bladder fills, is inhibition of the pontine micturition center (PMC) and of voiding, together with gradual increase in insular response, corresponding to increasing desire to void. In urge-incontinent subjects, brain responses differ. At large bladder volumes and strong sensation, but without detrusor overactivity (DO), most cortical responses become exaggerated, especially in ACG. This may be both a learned reaction to previous incontinence episodes and the neural correlate of urgency. The neural signature of DO itself seems to be prefrontal deactivation. Possible causes of urge incontinence include dysfunction of prefrontal cortex or limbic system, suggested by weak responses and/or deactivation, as well as abnormal afferent signals or re-emergence of infantile reflexes. Conclusions Bladder control depends on an extensive network of brain regions. Dysfunction in various parts may contribute to urge incontinence, suggesting that there are different phenotypes requiring different treatments. Neurourol. Urodynam. 27:466,474, 2008. © 2007 Wiley-Liss, Inc. [source] Anatomical and functional brain imaging using high-resolution echo-planar spectroscopic imaging at 1.5 TeslaNMR IN BIOMEDICINE, Issue 4 2005Weiliang Du Abstract High-resolution echo-planar spectroscopic imaging (EPSI) of water resonance (i.e. without water suppression) is proposed for anatomic and functional imaging of the human brain at 1.5,T. Water spectra with a resolution of 2.6,Hz and a bandwidth of 333,Hz were obtained in small voxels (1.7,×,1.7,×,3,mm3) across a single slice. Although water spectra appeared Lorentzian in most of the voxels in the brain, non-Lorentzian broadening of the water resonance was observed in voxels containing blood vessels. In functional experiments with a motor task, robust activation in motor cortices was observed in high-resolution T maps generated from the EPSI data. Shift of the water resonance frequency occurred during neuronal activation in motor cortices. The activation areas appeared to be more localized after excluding the voxels in which the lineshape of the water resonance had elevated T and became more non-Lorentzian during the motor task. These preliminary results suggest that high-resolution EPSI is a promising tool to study susceptibility-related effects, such as BOLD contrast, for improved anatomical and functional imaging of the brain. Copyright © 2005 John Wiley & Sons, Ltd. [source] Preoperative Functional Assessment of Auditory Cortex in Adult Cochlear Implant Users,,THE LARYNGOSCOPE, Issue 1 2001Peter S. Roland MD Abstract Objectives To e-plore functional neuroanatomical responses to auditory stimulation before and after implantation. Study Design A prospective study of three cochlear implant candidates (pure-tone averages of 90 dB HL or greater bilaterally and hearing in noise test [HINT] performances of <40%) in which regional cerebral blood flow (rCBF) was assessed using single photon emission computed tomography (SPECT). Methods Candidates watched a 15-minute videotaped story under four conditions: audio presented monaurally in the right and left ears (aided), audio presented binaurally (aided), and visual-only presentation of the story. Five minutes into each story, 20 to 25 mCi of technetium 99m (99mTc) hexamethyl-propyleneamine-oxime (HMPAO) (Ceratec; Nycomed Amersham, Princeton, NJ, U.S.A.) was injected over a 30-second period to ensure that subjects were unaware of tracer administration. Subjects were scanned for 20 minutes using a PRISM 3000 gamma camera (Picker International, Cleveland, OH, U.S.A.). Data were normalized and co-registered, and subtraction images were compiled. Subtraction images contrasted activation patterns generated under the visual-only control condition to the auditory activation states acquired monaurally and binaurally. Results Right and left ear monaural stimulation in normal hearing subjects resulted in significant bilateral activation of Brodmann areas 41, 42, 21, 22, and 38. Although substantial intersubject response variability was noted, subjects generally failed to bilaterally activate these areas under monaural hearing aid presentations; however, bilateral activation of areas 41 and 22 was noted under binaural presentations. Conclusions Despite relatively similar hearing losses in each ear, significant differences in preoperative auditory corte- activation were observed between ears. These data suggest that functional brain imaging provides a useful tool for e-ploring the responsiveness of the auditory corte- in cochlear implant candidates. [source] Rehabilitation with dental prosthesis can increase cerebral regional blood volumeCLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2005Ikuya Miyamoto Abstract: Treatment with denture for edentulous people is highly important for maintaining quality of life. However, its effect on the brain is unknown. In this experimental study, we hypothesized that dental prosthesis can recover not only the physical condition of mastication system but also the regional brain activity. We evaluated functional brain imaging of edentulous subjects fixed by dental implant prosthesis with clenching tasks by multi-channel near-infrared optical topography. Results revealed a significantly (P<0.001; paired t -test) increased cerebral regional blood volume during maximum voluntary clenching task by implant-retained prosthesis. There were no statistically significant differences between patients with and without prosthesis in the latency to the maximum regional blood volume after the task. Conclusively, clenching can be effective for increasing cerebral blood volume; accordingly maintenance of normal chewing might prevent the brain from degenerating. Résumé Le traitement par prothèses des édentés est extrêmement important pour garder la qualité de vie. Cependant, son effet sur le cerveau est inconnu. Dans cette étude expérimentale, l'hypothèse qui a étéémise concernait les prothèses dentaires et leur aptitude à rétablir non seulement la condition physique du système masticatoire mais également l'activité cérébrale régionale. L'imagerie du cerveau fonctionnel de l'édenté avec des prothèses sur implants avec travail de serrage par topographie optique près de l'infrarouge à multiple canaux. Les résultats ont révélé une augmentation significative (P<0.001/test-t par paires) de la circulation sanguine régionale cérébrale durant la force de serrage volontaire maximale par les prothèses retenues sur implants. Il n'y avait aucune différence significative entre les avec et sans prothèses dans le temps de latence jusqu'à la circulation sanguine régionale maximale après le serrage. Le serrage peut être efficace pour augmenter la circulation sanguine cérébrale et donc le maintien d'une mastication normale pourrait prévenir toute dégénérescence cérébrale. Zusammenfassung Die Versorgung mit Prothesen bei zahnlosen Patienten ist sehr wichtig, um die Lebensqualität zu erhalten. Der Einfluss auf das Gehirn ist jedoch nicht bekannt. In dieser experimentellen Studie stellten wir die Hypothese auf, dass eine dentale Prothese nicht nur den physischen Zustand des Kausystems wieder herstellen kann, sondern auch die regionale Hirnaktivität beeinflusst. Wie untersuchten funktionelle Gehirnbilder von zahnlosen Subjekten mit auf Implantaten befestigten Prothesen, welche Aufgaben beim Zusammenbeissen erledigen mussten, mittels multi-kanal optischer Topographie nahe am Infrarotbereich. Die Resultate zeigten einen signifikanten (P<0.001; gepaarter t -Test) Anstieg in der regionalen cerebralen Durchblutung während des Maximums beim freiwilligen Zusammenbeissen mit der auf Implantaten befestigten Prothese. Es bestanden keine statistisch signifikanten Unterschiede in der Latenzzeit bis zur maximalen regionalen Durchblutung nach Erfüllung der Aufgabe mit oder ohne Prothese. Es wird die Schlussfolgerung gezogen, dass das Zusammenbeissen zu einem Ansteigen der cerebralen Durchblutung führen kann. Daher könnte der Erhalt einer normalen Kaufunktion einer Degeneration des Gehirn entgegenwirken. Resumen El tratamiento con dentaduras para personas edéntulas es altamente importante para conservar la calidad de vida. En este estudio experimental, hemos hipotizado que las prótesis dentales pueden recuperar no solo las condiciones físicas del sistema masticatorio sino también la actividad cerebral regional. Hemos evaluado las imágenes funcionales del cerebro de pacientes edéntulos rehabilitados por prótesis implantosoportadas con tareas de apretado por medio de topografía óptica casi-infrarroja multicanal. Los resultados revelaron un flujo sanguíneo cerebral regional significativamente (P<0.001; t -test pareado) aumentado durante la mordida máxima voluntaria con prótesis implantosoportada. No hubo diferencias estadísticamente significativas entre con o sin prótesis en la latencia al flujo sanguíneo regional tras la tarea. En conclusión, el apretado puede ser efectivo para incrementar el flujo sanguíneo cerebral; en consecuencia, el mantenimiento de una masticación normal puede prevenir la degeneración cerebral. [source] | ||||||||||||||||||||||