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1.
Mov Disord ; 25(15): 2627-33, 2010 Nov 15.
Artículo en Inglés | MEDLINE | ID: mdl-20725914

RESUMEN

The relevance of the sensory system in the pathophysiology of cervical dystonia (CD) has been discussed since the description of sensory tricks associated with this disorder. Our objective was to locate changes in somatosensory processing of patients with CD responding in a passive sensory task of body regions that are not affected by dystonic symptoms. We used functional magnetic resonance imaging (fMRI) in 17 patients with CD and 17 healthy controls performing a strictly passive 30-degree forearm movement task with the left arm. TSUI and TWSTRS rating scales were used for clinical assessment. All patients were treated with botulinum neurotoxin type A (BoNT-A; Dysport®). Patients with CD showed BOLD-signal increase in the contralateral primary and secondary sensory cortex, the cingulate cortex and cerebellum bilaterally compared to healthy controls. We found a strong positive correlation of this activation with BoNT-A dosage in the supplementary motor area (SMA) and a negative correlation with the TWSTRS in that same region. The observed sensory overactivation suggests a general disinhibition of the somatosensory system in CD as it was not limited to the motor-system or the direct neuronal representation of the affected dystonic musculature alone.


Asunto(s)
Toxinas Botulínicas Tipo A/uso terapéutico , Corteza Motora/fisiopatología , Movimiento/fisiología , Corteza Somatosensorial/fisiopatología , Tortícolis/fisiopatología , Anciano , Mapeo Encefálico , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tortícolis/terapia
2.
Neuropsychobiology ; 62(3): 182-92, 2010 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-20664231

RESUMEN

BACKGROUND: There is evidence that patients with anorexia nervosa (AN) demonstrate specific cerebral activation patterns in response to visual food stimulation. We postulated that cerebral activation patterns could represent different perceptions of high-calorie images during hunger and satiety and could be determined by patients' subjective ratings. METHODS: After 6 h of starvation and also in a state of satiety, 12 female patients with AN and 12 normal-weight women were assessed by use of fMRI with high-calorie food images. All patients suffered from a restrictive type of AN. Heart rates, subjective ratings of satiety and valences of the visual stimuli were assessed. RESULTS: Food stimuli presented during a state of hunger were associated with significant activation of the anterior cingulate cortex and insula in the control group and of the prefrontal and central cortices and insula in the AN group. During the hunger state activation in AN of the dorsal posterior cingulate cortex was revealed compared to the controls. In the state of satiety, activation of the left insula was observed in the AN group. Use of the food valence judgment as a covariate confirmed the insula activation and revealed additional activation of the orbitofrontal, cingulate and medial temporal cortices. CONCLUSION: Our results indicate differences in cerebral activation patterns due to different perceptions of high-calorie food images, modulated by feelings of hunger or satiety, among AN patients with modulation by subjective ratings of food valence.


Asunto(s)
Anorexia Nerviosa/fisiopatología , Corteza Cerebral/fisiología , Giro del Cíngulo/fisiología , Estimulación Luminosa/métodos , Saciedad/fisiología , Percepción Visual/fisiología , Adolescente , Adulto , Anorexia Nerviosa/psicología , Mapeo Encefálico/métodos , Femenino , Alimentos , Frecuencia Cardíaca/fisiología , Humanos , Hambre/fisiología , Imagen por Resonancia Magnética/métodos , Persona de Mediana Edad
3.
Neuroimage ; 46(1): 193-200, 2009 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-19457385

RESUMEN

Temporal summation of nociceptive inputs in trigeminal networks can induce central sensitization and maintain chronic pain. We combined functional magnetic resonance imaging and electrically evoked pain-related potentials (PREP) in healthy human subjects to identify brain regions involved in temporal summation of nociceptive inputs. We stimulated the skin innervated by the ophthalmic division of the trigeminal nerve with trains of three, seven and eleven similar nociceptive pulses, while recording evoked hemodynamic or electrical brain responses. We found that PREP amplitudes and pain ratings increased in parallel with increasing train length. Strikingly, only hemodynamic responses in the posterior part of the anterior cingulate cortex (pACC) scaled with individual pain ratings on a verbal rating scale (VRS) and electrically evoked responses (i.e., PREP amplitudes for the three train lengths). These findings indicate that pACC codes temporal summation of trigeminal nociception and in this regard may be important for the development of central sensitization observed in chronic head and facial pain.


Asunto(s)
Mapeo Encefálico , Encéfalo/fisiopatología , Dolor/fisiopatología , Nervio Trigémino/fisiología , Adulto , Encéfalo/irrigación sanguínea , Estimulación Eléctrica , Potenciales Evocados , Cara/inervación , Femenino , Giro del Cíngulo/irrigación sanguínea , Giro del Cíngulo/fisiopatología , Humanos , Interpretación de Imagen Asistida por Computador , Imagen por Resonancia Magnética , Masculino , Umbral del Dolor , Piel/inervación , Adulto Joven
4.
Radiology ; 249(3): 829-35, 2008 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18941165

RESUMEN

PURPOSE: To assess the visibility of small myocardial lesions at magnetic resonance (MR) imaging and to estimate how much myocardial damage is necessary to enable detection of late gadolinium enhancement (LGE) in vivo. MATERIALS AND METHODS: The study was approved by the local bioethics committee. Coronary microembolization was performed by injecting 300,000 microspheres into the distal portion of the left anterior descending artery in 18 anesthetized minipigs to create multifocal areas of myocardial damage. In vivo MR imaging was performed a mean of 6 hours after microembolization by using an inversion-recovery spoiled gradient-echo sequence (repetition time msec/echo time msec, 8/4; inversion time, 240-320 msec; flip angle, 20 degrees; spatial resolution, 1.3 x 1.7 x 5.0 mm(3)) after injection of 0.2 mmol gadopentetate dimeglumine per kilogram of body weight. High-spatial-resolution imaging of the explanted heart was performed by using the same sequence with a higher spatial resolution (0.5 x 0.5 x 2.0 mm(3)). Imaging results were verified with histologic examination. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of in vivo and ex vivo images were calculated, and a t test was used to analyze observed differences. RESULTS: Multifocal myocardial damage was successfully induced in all animals. Areas of LGE with low SNR (mean, 36.3 +/- 29.4 [standard deviation]) and CNR (23.7 +/- 19.8) were observed in vivo in 12 (67%) of 18 animals, whereas ex vivo imaging revealed spotted to streaky areas of LGE with higher SNR (91.4 +/- 27.8, P < .0001) and CNR (72.1 +/- 25.4, P < .0001) among normal-appearing myocardium in all cases (100%). Focal myocardial lesions exceeding 5% of myocardium per slice at histologic examination were detected in vivo with a sensitivity of 83%. CONCLUSION: Focal myocardial damage exceeding 5% of myocardium within the region of interest seems to be necessary for detection of LGE in vivo in an experimental model of coronary microembolization.


Asunto(s)
Gadolinio , Imagen por Resonancia Magnética , Miocardio/patología , Animales , Embolia/patología , Microesferas , Porcinos , Porcinos Enanos
5.
Methods Inf Med ; 57(S 01): e92-e105, 2018 07.
Artículo en Inglés | MEDLINE | ID: mdl-30016815

RESUMEN

INTRODUCTION: This article is part of the Focus Theme of Methods of Information in Medicine on the German Medical Informatics Initiative. "Smart Medical Information Technology for Healthcare (SMITH)" is one of four consortia funded by the German Medical Informatics Initiative (MI-I) to create an alliance of universities, university hospitals, research institutions and IT companies. SMITH's goals are to establish Data Integration Centers (DICs) at each SMITH partner hospital and to implement use cases which demonstrate the usefulness of the approach. OBJECTIVES: To give insight into architectural design issues underlying SMITH data integration and to introduce the use cases to be implemented. GOVERNANCE AND POLICIES: SMITH implements a federated approach as well for its governance structure as for its information system architecture. SMITH has designed a generic concept for its data integration centers. They share identical services and functionalities to take best advantage of the interoperability architectures and of the data use and access process planned. The DICs provide access to the local hospitals' Electronic Medical Records (EMR). This is based on data trustee and privacy management services. DIC staff will curate and amend EMR data in the Health Data Storage. METHODOLOGY AND ARCHITECTURAL FRAMEWORK: To share medical and research data, SMITH's information system is based on communication and storage standards. We use the Reference Model of the Open Archival Information System and will consistently implement profiles of Integrating the Health Care Enterprise (IHE) and Health Level Seven (HL7) standards. Standard terminologies will be applied. The SMITH Market Place will be used for devising agreements on data access and distribution. 3LGM2 for enterprise architecture modeling supports a consistent development process.The DIC reference architecture determines the services, applications and the standardsbased communication links needed for efficiently supporting the ingesting, data nourishing, trustee, privacy management and data transfer tasks of the SMITH DICs. The reference architecture is adopted at the local sites. Data sharing services and the market place enable interoperability. USE CASES: The methodological use case "Phenotype Pipeline" (PheP) constructs algorithms for annotations and analyses of patient-related phenotypes according to classification rules or statistical models based on structured data. Unstructured textual data will be subject to natural language processing to permit integration into the phenotyping algorithms. The clinical use case "Algorithmic Surveillance of ICU Patients" (ASIC) focusses on patients in Intensive Care Units (ICU) with the acute respiratory distress syndrome (ARDS). A model-based decision-support system will give advice for mechanical ventilation. The clinical use case HELP develops a "hospital-wide electronic medical record-based computerized decision support system to improve outcomes of patients with blood-stream infections" (HELP). ASIC and HELP use the PheP. The clinical benefit of the use cases ASIC and HELP will be demonstrated in a change of care clinical trial based on a step wedge design. DISCUSSION: SMITH's strength is the modular, reusable IT architecture based on interoperability standards, the integration of the hospitals' information management departments and the public-private partnership. The project aims at sustainability beyond the first 4-year funding period.


Asunto(s)
Atención a la Salud , Tecnología de la Información , Algoritmos , Gestión Clínica , Comunicación , Sistemas de Apoyo a Decisiones Clínicas , Registros Electrónicos de Salud , Almacenamiento y Recuperación de la Información , Unidades de Cuidados Intensivos , Modelos Teóricos , Fenotipo , Políticas
6.
J Neurol ; 254(9): 1244-52, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-17694385

RESUMEN

Substantial disability in patients with hemianopia results from reduced visual perception. Several studies have shown that these patients have impaired saccades but may improve search strategies with appropriate training of saccades. We used fMRI to study the representation of saccades in patients with post-stroke hemianopia to the left. Brain activation during visually guided saccades was measured in 10 patients with a pure occipital cortical lesion causing homonymous hemianopia and in 10 healthy control subjects. Differences in activation between rest and saccades and between controls and patients were assessed with statistical parametric mapping (SPM'99). In normal subjects, significant activation was found in the frontal and parietal eye fields bilaterally and in the supplementary eye field. These areas were also activated in patients, however, to a lesser degree. In contrast, an area of increased activation in patients was found in the posterior parietal cortex of the (non-affected) left hemisphere. Visual field defects after striate lesions are associated with changes in the frontoparietal network underlying the cortical control of saccades.


Asunto(s)
Hemianopsia/fisiopatología , Lóbulo Occipital/fisiopatología , Movimientos Sacádicos , Accidente Cerebrovascular/fisiopatología , Campos Visuales , Anciano , Mapeo Encefálico , Electrooculografía , Femenino , Fijación Ocular , Lóbulo Frontal/fisiopatología , Lateralidad Funcional , Hemianopsia/etiología , Humanos , Imagen por Resonancia Magnética , Persona de Mediana Edad , Lóbulo Occipital/irrigación sanguínea , Lóbulo Parietal/fisiopatología , Valores de Referencia , Movimientos Sacádicos/fisiología , Accidente Cerebrovascular/complicaciones
7.
Neurosci Lett ; 426(1): 34-8, 2007 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-17881128

RESUMEN

Changes in neuronal activity of the visual cortex have been described in patients with hemianopia. The anatomical areas that are involved in neuroplastic changes have not been studied in a larger group of stroke patients with a homogenous structural pathology of the visual cortex. Brain activation was measured in 13 patients with a single ischemic lesion of the striate cortex and partially recovered hemianopia and in 13 age-matched control subjects using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI). Differences in activation between rest and visual hemifield stimulation were assessed with statistical parametric mapping using group and multi-group studies. In normal subjects, the most significant activation was found in the contralateral primary visual cortex (area 17) and bilaterally in the extrastriate cortex (areas 18 and 19). In patients, these areas were also activated when the intact hemifield was stimulated. During stimulation of the hemianopic side, bilateral activation was seen within the extrastriate cortex, stronger in the ipsilateral (contralesional) hemisphere. Stimulation of the hemianopic visual field is associated with ipsilateral activation of the extrastriate visual cortex. This pattern of activation suggests extensive neuronal plasticity within the visual cortex after postgeniculate ischemic lesions and may have implications for therapeutic interventions.


Asunto(s)
Hemianopsia/diagnóstico , Hemianopsia/fisiopatología , Accidente Cerebrovascular/complicaciones , Corteza Visual/fisiopatología , Vías Visuales/fisiopatología , Adulto , Anciano , Mapeo Encefálico , Circulación Cerebrovascular/fisiología , Potenciales Evocados Visuales/fisiología , Femenino , Lateralidad Funcional/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Plasticidad Neuronal/fisiología , Lóbulo Parietal/anatomía & histología , Lóbulo Parietal/fisiopatología , Reconocimiento Visual de Modelos/fisiología , Estimulación Luminosa , Recuperación de la Función/fisiología , Accidente Cerebrovascular/fisiopatología , Corteza Visual/anatomía & histología , Campos Visuales/fisiología , Vías Visuales/anatomía & histología , Percepción Visual/fisiología
8.
Res Vet Sci ; 82(3): 281-6, 2007 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-17064742

RESUMEN

Minipigs are widely used to examine physiologic mechanisms under experimental settings. The purpose of our study was to localize the visual cortex of minipigs using visual stimulation in functional magnetic resonance imaging (fMRI). Five male Göttinger minipigs were studied with fMRI during visual stimulation with series of light impulses conducted into the MR cabin via fibre optical wave guides (EPI sequences, block design, 1.5 T clinical routine MR-scanner). Statistics were performed using SPM'99. All minipigs showed activation of the visual cortex due to light stimulation. The activation could be superimposed to T2-weighted structural images with good spatial resolution revealing the exact location of the visual cortex. We were able to localize the visual cortex in minipigs for the first time utilizing fMRI on a routine scanner. However, this may be useful for precise positioning of electrodes or implants or be used as a further uncomplicated non-invasive method in physiologic experiments.


Asunto(s)
Imagen por Resonancia Magnética/veterinaria , Porcinos Enanos/anatomía & histología , Corteza Visual/anatomía & histología , Corteza Visual/fisiología , Animales , Humanos , Imagen por Resonancia Magnética/métodos , Porcinos , Porcinos Enanos/fisiología
9.
Schizophr Res ; 83(2-3): 121-30, 2006 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-16497485

RESUMEN

Successful and unsuccessful intention to learn words was assessed by means of event-related functional MRI. Eighteen patients with schizophrenia and 15 healthy control participants were scanned while being given two word lists to read and another seven to learn with immediate recall. Neural activation patterns were segregated according to whether words were subsequently recalled or forgotten and these conditions were contrasted with each other and reading. Compared to controls, patients with schizophrenia showed deficits with regard to neural recruitment of right hippocampus and of cerebellar structures during successful verbal learning. Furthermore, a reversal of activated structures was evident in the two groups: Controls showed activation of right frontal and left middle temporal structures during the unsuccessful intention to learn. During successful learning, there was additional activation of right superior parietal lobule. In contrast, patients showed activation of right superior parietal lobule during unsuccessful and successful intention to learn. There were additional frontal and left middle temporal lobe activations during successful learning. We conclude that increased parietal activity may reflect a mechanism which compensates for the lack of hippocampal and cerebellar contributions to verbal learning in schizophrenia.


Asunto(s)
Mapeo Encefálico , Encéfalo/fisiopatología , Recuerdo Mental/fisiología , Esquizofrenia/fisiopatología , Aprendizaje Verbal/fisiología , Adulto , Análisis de Varianza , Encéfalo/irrigación sanguínea , Estudios de Casos y Controles , Femenino , Lateralidad Funcional , Humanos , Procesamiento de Imagen Asistido por Computador/métodos , Imagen por Resonancia Magnética/métodos , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Oxígeno/sangre
10.
J Neurosci ; 23(9): 3790-5, 2003 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-12736349

RESUMEN

In rodents, cyclically fluctuating levels of gonadal steroid hormones modulate neural plasticity by altering synaptic transmission and synaptogenesis. Alterations of mood and cognition observed during the menstrual cycle suggest that steroid-related plasticity also occurs in humans. Cycle phase-dependent differences in cognitive performance have almost exclusively been found in tasks probing lateralized neuronal domains, i.e., cognitive domains such as language, which are predominantly executed by one hemisphere. To search for neural correlates of hormonally mediated neural plasticity in humans, we thus conducted a functional magnetic resonance imaging study measuring brain activity related to a semantic decision task in the language domain. This was contrasted with a letter-matching task in the perceptual domain, in which we expected no steroid hormone-mediated effect. We investigated 12 young healthy women in a counterbalanced repeated-measure design during low-steroid menstruation and high-steroid midluteal phase. Steroid serum levels correlated with the volume and lateralization of particular brain activations related to the semantic task but not with brain activity related to the perceptual task. More specifically, bilateral superior temporal recruitment correlated positively with progesterone and medial superior frontal recruitment with both progesterone and estradiol serum levels, whereas activations in inferior and middle frontal cortex were unaffected by steroid levels. In contrast to these specific interactions, testosterone levels correlated nonselectively with overall activation levels by neural and/or vascular factor(s). In conclusion, our data demonstrate steroid hormone responsivity in the adult human brain by revealing neural plasticity in the language domain, which appears hormone, task, and region specific.


Asunto(s)
Encéfalo/fisiología , Hormonas/sangre , Ciclo Menstrual/fisiología , Plasticidad Neuronal/fisiología , Conducta Verbal/fisiología , Adulto , Conducta/fisiología , Encéfalo/anatomía & histología , Mapeo Encefálico , Dominancia Cerebral/fisiología , Estradiol/sangre , Femenino , Hormona Folículo Estimulante/sangre , Humanos , Modelos Lineales , Fase Luteínica/fisiología , Imagen por Resonancia Magnética , Ciclo Menstrual/sangre , Menstruación/fisiología , Estimulación Luminosa , Progesterona/sangre , Tiempo de Reacción/fisiología , Valores de Referencia , Testosterona/sangre
11.
Brain Res Cogn Brain Res ; 25(3): 884-90, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16260123

RESUMEN

Cross-modal plasticity in deaf subjects is still discussed controversial. We tried to figure out whether the plasticity is dependent on the extent of hearing loss. Three groups of volunteers, comprising twelve individuals each, were investigated. They were characterized by three distinctive features, one had normal hearing, the other one lost hearing and the third had only minimal residual hearing ability. All participants, except those of group one, were capable of using German Sign Language (GSL). The groups were studied with functional MRI in a standard block design during individuals' watching sign language videos alternating with black frame. During sign language conditions, deaf subjects revealed a significant activation of the auditory cortex in both hemispheres comprising Brodmann areas (BA) 42 and 22 corresponding to the secondary associative auditory areas. Additionally, activation of the angular and supramarginal gyrus was seen. Activation of the primary auditory cortex was revealed in deaf subjects with total hearing loss during sign language tasks but not in subjects with residual hearing ability. In conclusion our results indicate a cortical reorganization of the auditory cortex comprising primary auditory fields only present in subjects with total hearing loss.


Asunto(s)
Corteza Cerebral/fisiopatología , Sordera/fisiopatología , Pérdida Auditiva/psicología , Plasticidad Neuronal/fisiología , Adolescente , Adulto , Edad de Inicio , Corteza Auditiva/fisiología , Interpretación Estadística de Datos , Sordera/congénito , Femenino , Lateralidad Funcional/fisiología , Humanos , Masculino , Persona de Mediana Edad , Lectura , Lengua de Signos
12.
Brain Res Cogn Brain Res ; 25(3): 760-76, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16337110

RESUMEN

Concepts of higher attention functions distinguish focused and divided attention. The present study investigated whether these mental abilities are mediated by common or distinct neural substrates. In a first experiment, 19 healthy subjects were examined with functional brain imaging (fMRI) while they attended to either one or both of two simultaneously presented visual information streams and responded to repetitive stimuli. This experiment resembled a typical examination of these mental functions with the single task demanding focused and the dual task conditions requiring divided attention. Both conditions activated a widespread, mainly right-sided network including dorso- and ventrolateral prefrontal structures, superior and inferior parietal cortex, and anterior cingulate gyrus. Under higher cognitive demands of divided attention, activity in these structures was enhanced and left-sided homologues were recruited. In a second experiment investigating another 17 subjects with almost the same paradigm, it was accounted for that in most dual task investigations of focused and divided attention the single tasks are easier to process than their combined presentation. Therefore, the task difficulty of focused attention tasks was increased. Almost the same activity pattern observed during division of attention was now found during focusing attention. Comparing both attentional states matched for task difficulty, differences were found in visual but not in prefrontal or parietal cortex areas. Our results suggest that focused and divided attention depend on largely overlapping neuronal substrates. Differences in activation patterns, especially in prefrontal and parietal areas, may result from unequal demands on executive control due to disparate processing requirements in typical tasks of focused and divided attention: Easier conditions begin with mainly right-sided activity within the attention network. As conditions become more difficult, left-lateralized homologue areas activate.


Asunto(s)
Atención/fisiología , Encéfalo/fisiología , Adulto , Corteza Cerebral/fisiología , Circulación Cerebrovascular , Cognición/fisiología , Femenino , Fijación Ocular/fisiología , Giro del Cíngulo/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Memoria a Corto Plazo/fisiología , Red Nerviosa/fisiología , Lóbulo Parietal/fisiología , Corteza Prefrontal/fisiología , Desempeño Psicomotor/fisiología , Tiempo de Reacción/fisiología , Percepción Visual/fisiología
13.
Stroke ; 33(5): 1286-93, 2002 May.
Artículo en Inglés | MEDLINE | ID: mdl-11988605

RESUMEN

BACKGROUND AND PURPOSE: Plasticity in extended, parallel, or reciprocal operating networks is well recognized. Changes in neuronal activity after lesions to distinct localized structures, such as the primary visual cortex, are less well characterized. We investigated the cortical reorganization in patients with poststroke visual field defects using blood oxygen level-dependent functional MRI. METHODS: Brain activation was measured in 7 patients with a single occipital cortical lesion and partially recovered hemianopia and in 7 age-matched control subjects. Differences in activation between rest and visual hemifield stimulation were assessed with statistical parametric mapping (SPM'99). RESULTS: In normal subjects, significant activation was found in the contralateral primary visual cortex and bilaterally in the extrastriate cortex. During hemifield stimulation of the unaffected side of stroke patients, a similar pattern was found compared with that seen in control subjects. During stimulation of the hemianopic side, bilateral activation was seen within the extrastriate cortex, stronger in the ipsilateral hemisphere. The primary visual cortex was not significantly activated in either hemisphere during stimulation of the hemianopic side. CONCLUSIONS: Visual field defects after stroke are associated with bilateral activation of the extrastriate visual cortex. This pattern of activation indicates altered neuronal activity in the visual system. Further investigation is necessary to determine the relationship between functional reorganization and recovery of lost visual function after poststroke hemianopia.


Asunto(s)
Encéfalo/irrigación sanguínea , Encéfalo/fisiopatología , Hemianopsia/diagnóstico , Hemianopsia/fisiopatología , Accidente Cerebrovascular/diagnóstico , Adulto , Anciano , Velocidad del Flujo Sanguíneo , Mapeo Encefálico , Circulación Cerebrovascular , Presentación de Datos , Femenino , Fijación Ocular , Lateralidad Funcional , Hemianopsia/etiología , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Lóbulo Occipital/irrigación sanguínea , Lóbulo Occipital/fisiopatología , Estimulación Luminosa/instrumentación , Estimulación Luminosa/métodos , Valores de Referencia , Descanso , Accidente Cerebrovascular/complicaciones
14.
Brain Res Cogn Brain Res ; 20(2): 242-55, 2004 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-15183395

RESUMEN

Our event-related functional MRI (efMRI) study investigates whether visual advance information (AI) affects rather perceptual or central response-related processing areas. Twelve subjects were required to make a go/no-go decision to a conjunction of a specific color and motion direction. The stimuli were preceded by a cue, providing 100% valid advance information about motion direction. Partial and full advance information (PAI and FAI) predicted possible targets, respectively, certain nontargets, neutral cues (NAI) gave no prediction. The time between cue and stimulus (stimulus onset asynchrony, SOA) was varied. A response benefit was found after PAI as compared with NAI. The benefit was small with a short SOA (150 ms), increased with intermediate SOA (450 ms) and sustained with long SOA (750 ms). Perceptual and central processing areas were more active with increasing SOA, but only central response-related processing areas were selectively modulated by cue information. In particular, supplementary motor area and bilateral inferior parietal lobe were more active with PAI than with NAI. If comparing NAI with FAI, more errors were made and activity was larger in central processing areas. Our results suggest that, depending on the processing time, cues providing perceptual information modulate central response-related processes.


Asunto(s)
Potenciales Evocados Visuales/fisiología , Imagen por Resonancia Magnética , Percepción de Movimiento/fisiología , Adulto , Corteza Cerebral/fisiología , Cognición/fisiología , Color , Femenino , Humanos , Masculino , Tiempo de Reacción/fisiología
15.
Neurosci Lett ; 371(2-3): 220-5, 2004 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-15519761

RESUMEN

In the present study, we used fMRI to investigate whether event-related preparatory processes of self-initiated and externally triggered movements differ. Twenty subjects were examined with 1000 T2*-weighted images in two consecutive sessions. During the first session subjects performed self-initiated abductions of the right index finger. For the second session subjects were instructed to perform the movements in response to visual cues. Number and timing of movements were matched between conditions. For statistical inference on multisubject level, random effects analyses were performed. Significantly enhanced activity during self-initiated compared to externally triggered movements was found within the left SMA, the left pre- and sensorimotor cortex, the right putamen, the left anterior cingulate gyrus, and the left inferior parietal lobe. The significantly increased activity during self-initiated in comparison to externally triggered movements might represent differential demands of the two conditions on the neuronal motor net during movement preparation, reflecting utilization of precise knowledge when to move in self-initiated movements. Our results emphasize a possible role of the primary motor cortex for movement preparation as observed in electrophysiological studies, but do not support a specific involvement of the dorsolateral prefrontal cortex as suggested by former block design studies.


Asunto(s)
Potenciales Evocados/fisiología , Imagen por Resonancia Magnética/métodos , Movimiento/fisiología , Desempeño Psicomotor/fisiología , Adulto , Análisis de Varianza , Femenino , Humanos , Masculino , Estimulación Luminosa/métodos
16.
Epilepsy Res ; 51(3): 269-78, 2002 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-12399077

RESUMEN

Hyperventilation (HV) can be used to provoke epileptiform activity and occasionally seizures in generalised and in focal epilepsies. Based on the hypothesis that HV might alter brain diffusion in the epileptogenic areas of patients with temporal lobe epilepsy (TLE), we examined these alterations using quantitative diffusion MR imaging (DI) in four patients with TLE and unilateral hippocampal sclerosis (TLE-HS) and six patients with TLE without hippocampal sclerosis (TLE-pure), and in 10 healthy volunteers. Brain diffusion was measured at baseline and immediately after 4 min of HV. In all patients with TLE HV was repeated two times, 4 min each, followed by subsequent DI. The apparent diffusion coefficient (ADC) was quantified in predefined regions of interest. In controls, the ADC did not differ between baseline and HV and between right and left side. Compared to controls TLE-HS patients showed significantly higher ADC at baseline in the hippocampus of the ictogenic side (111+/-13 vs. 87.5+/-4.26 x 10(-5) mm(2)/s, P=0.029). During HV ADC decreased significantly in the ictogenic hippocampus compared to controls (-17.3+/-7.1 vs. -3.34+/-8.7, P=0.004). In TLE-pure patients ADC of the ictogenic hippocampus was higher than in normals (99.3+/-14.2 vs. 87.5+/-4.26 x 10(-5) mm(2)/s, P=0.031) but there was no significant decrease during HV. Serial HV did not further enhance this decrease. No significant HV-induced changes were seen in other brain areas. In conclusion, our results show that HV can induce dynamic changes of brain diffusion in patients with sclerotic hippocampi but not in non-sclerotic hippocampi. These findings may be utilized for lateralisation of the epileptogenic hippocampus during presurgical evaluation of TLE.


Asunto(s)
Encéfalo/diagnóstico por imagen , Imagen de Difusión por Resonancia Magnética/métodos , Epilepsia del Lóbulo Temporal/diagnóstico por imagen , Hiperventilación/complicaciones , Adulto , Epilepsia del Lóbulo Temporal/etiología , Femenino , Hipocampo/diagnóstico por imagen , Hipocampo/patología , Humanos , Masculino , Persona de Mediana Edad , Radiografía , Esclerosis , Estadísticas no Paramétricas
17.
Acad Radiol ; 18(1): 113-9, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20947388

RESUMEN

RATIONALE AND OBJECTIVES: The purpose of this study was to perform high-resolution contrast-enhanced peripheral multistation magnetic resonance angiography using a new blood-pool contrast agent (gadofosveset trisodium; Vasovist) while suppressing venous signal by using an acquisition scheme with k-space segmentation. MATERIALS AND METHODS: Multistation peripheral magnetic resonance angiography with Vasovist was performed in 20 patients with known peripheral arterial occlusive disease. The k-space of the three-dimensional data sets was segmented such that the central parts were acquired during the first pass of the blood-pool agent, while the peripheral parts were acquired in the steady state. A third magnetic resonance angiographic data set acquired using the conventional technique served as comparison for venous overlay. Two radiologists blindly compared vessel sharpness, conspicuity, and venous contamination. Furthermore, a semiautomatic program to compare edge sharpness was used. Results were compared by means of Wilcoxon's signed rank sum test. RESULTS: Comparison of vessel sharpness revealed statistically significant differences in favor of the fused data sets in all three stations. Arteries were depicted more sharply in the fused images and over longer parts, while veins were almost completely suppressed. CONCLUSIONS: Peripheral contrast-enhanced magnetic resonance angiography with first-pass and steady-state k-space segmentation using a blood-pool contrast agent proved feasible and provided high-resolution data with sharp delineation of the arteries while reducing venous contamination.


Asunto(s)
Medios de Contraste , Gadolinio , Angiografía por Resonancia Magnética/métodos , Compuestos Organometálicos , Enfermedades Vasculares Periféricas/diagnóstico , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Aumento de la Imagen/métodos , Imagenología Tridimensional/métodos , Masculino , Persona de Mediana Edad , Variaciones Dependientes del Observador
18.
Eye Brain ; 2: 57-62, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-28539763

RESUMEN

PURPOSE: Recent functional magnetic resonance imaging (fMRI) studies have described reorganized activation of the oculomotor and visual cortex after focal brain lesions. These studies are based on comparison with healthy individuals who may have a very heterogenous refractive error. The influence of refractive error on the cortical control of an oculomotor task such as a prosaccade trial, however, is unknown. METHODS: To investigate the influence of visual acuity on changes of cortical oculomotor control, we studied the representation of visually guided prosaccades in nine subjects with refractive error and 11 normally sighted subjects using fMRI. Correction of refractive error was not allowed during fMRI. Differences in activation between rest and saccades as well as between subjects with refractive error vs subjects with normal vision were assessed with statistical parametric mapping. RESULTS: In both groups, activation of a frontoparietal network was observed. Subjects with refractive errors showed increased activation compared to normally sighted subjects, with overactivation in bilateral frontal and parietal eye fields, supplementary eye fields, as well as in the bilateral extrastriate cortex. CONCLUSIONS: This group of subjects with refractive error showed increased activation in an extended oculomotor and visual network to maintain performance during simple prosaccades. This observation underlines the importance of using appropriate control groups in fMRI-studies after brain lesions.

19.
Int J Clin Exp Hypn ; 58(4): 444-56, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20799123

RESUMEN

Cerebral activation patterns during the first three auto-suggestive phases of autogenic training (AT) were investigated in relation to perceived experiences. Nineteen volunteers trained in AT and 19 controls were studied with fMRI during the first steps of autogenic training. FMRI revealed activation of the left postcentral areas during AT in those with experience in AT, which also correlated with the level of AT experience. Activation of prefrontal and insular cortex was significantly higher in the group with experience in AT while insular activation was correlated with number years of simple relaxation exercises. Specific activation in subjects experienced in AT may represent a training effect. Furthermore, the correlation of insular activation suggests that these subjects are different from untrained subjects in emotional processing or self-awareness.


Asunto(s)
Autosugestión , Corteza Cerebral/fisiología , Imagen por Resonancia Magnética , Adulto , Atención/fisiología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Corteza Prefrontal/fisiología , Relajación/fisiología , Adulto Joven
20.
Clin Neurol Neurosurg ; 112(6): 490-5, 2010 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-20444537

RESUMEN

OBJECTIVE: Previous fMRI studies on activation of working memory in multiple sclerosis (MS) patients presented heterogeneous results. Patients were reported to have altered brain activation patterns either in typical working memory circuits or in other brain regions even if they did not have any cognitive impairment according to the test batteries. We hypothesized that brain activation patterns in patients at a very early stage of the disease at very low EDSS-Score would not differ from healthy subjects. METHODS: We examined 13 patients at an early stage of MS matched with 13 healthy controls with a detailed psychometric test battery and an fMRI working memory paradigm. RESULTS: Patients and healthy controls did not differ in psychometric test batteries. In both groups those cortex areas typically involved in working memory processes like dorso-lateral prefrontal (DLPFC), ventro-lateral-prefrontal (VLPFC), fronto-medial and parietal cortex areas (Brodmann 6, 7, 8, 9, 10, 32, 40, 45, 46, 47) were equally activated. CONCLUSION: In contrast to former studies we found no differences in activation patterns in the fMRI scanning measuring working memory tasks between psychometrically tested homogenous groups of patients in early stages of MS and control subjects.


Asunto(s)
Memoria a Corto Plazo/fisiología , Esclerosis Múltiple/patología , Esclerosis Múltiple/psicología , Adulto , Atención/fisiología , Encéfalo/patología , Encéfalo/fisiología , Trastornos del Conocimiento/patología , Trastornos del Conocimiento/psicología , Evaluación de la Discapacidad , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Red Nerviosa/patología , Pruebas Neuropsicológicas , Adulto Joven
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