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Regional Brain Activity (regional + brain_activity)

Distribution by Scientific Domains

Medical Sciences	40%

Selected Abstracts

Differential amygdala responses to winning and losing: a functional magnetic resonance imaging study in humans

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2000
Tiziana Zalla
Abstract The amygdala has been shown to respond to many distinct types of affective stimuli, including reward and punishment feedback in animals. In humans, winning and losing situations can be considered as reward and punishment experiences, respectively. In this study, we used functional magnetic resonance imaging (fMRI) to measure regional brain activity when human subjects were given feedback on their performance during a simple response time task in a fictitious competitive tournament. Lexical stimuli were used to convey positive ,win' or negative ,lose' feedback. The frequency of positive and negative trials was parametrically varied by the experimenters independently from the subjects' actual performance and unbeknownst to them. The results showed that the parametric increase of winning was associated with left amygdala activation whereas the parametric increase of losing was associated with right amygdala activation. These findings provide functional evidence that the human amygdala differentially responds to changes in magnitude of positive or negative reinforcement conveyed by lexical stimuli. [source]

Specificity of regional brain activity in anxiety types during emotion processing

PSYCHOPHYSIOLOGY, Issue 3 2007
Anna S. Engels
Abstract The present study tested the hypothesis that anxious apprehension involves more left- than right-hemisphere activity and that anxious arousal is associated with the opposite pattern. Behavioral and fMRI responses to threat stimuli in an emotional Stroop task were examined in nonpatient groups reporting anxious apprehension, anxious arousal, or neither. Reaction times were longer for negative than for neutral words. As predicted, brain activation distinguished anxious groups in a left inferior frontal region associated with speech production and in a right-hemisphere inferior temporal area. Addressing a second hypothesis about left-frontal involvement in emotion, distinct left frontal regions were associated with anxious apprehension versus processing of positive information. Results support the proposed distinction between the two types of anxiety and resolve an inconsistency about the role of left-frontal activation in emotion and psychopathology. [source]

Electromagnetic brain activity evoked by affective stimuli in schizophrenia

PSYCHOPHYSIOLOGY, Issue 5 2006
Brigitte Rockstroh
Abstract Schizophrenia is typically associated with cognitive deficits, but symptoms also point to alterations in the processing of affective material, with potential impact on behavioral performance. This impact may unfold on multiple time scales, but initial processing of rapidly unfolding social cues may be particularly important. MEG-assessed regional brain activity associated with the capacity to process the emotional content of rapid visual stimuli (3/s) was examined in 12 individuals with schizophrenia and 12 matched controls. Patients showed less differentiation of emotional versus neutral stimuli 90,300 ms following picture onset. Together with group differences in the lateral topography of valence effects, these results are discussed as evidence of deficient automatic processing of emotionally potent stimuli in schizophrenia. [source]

Differential effects of cannabinoid receptor agonists on regional brain activity using pharmacological MRI

BRITISH JOURNAL OF PHARMACOLOGY, Issue 2 2008
C-L Chin
Background and purpose: Activation of cannabinoid CB1 and/or CB2 receptors mediates analgesic effects across a broad spectrum of preclinical pain models. Selective activation of CB2 receptors may produce analgesia without the undesirable psychotropic side effects associated with modulation of CB1 receptors. To address selectivity in vivo, we describe non-invasive, non-ionizing, functional data that distinguish CB1 from CB2 receptor neural activity using pharmacological MRI (phMRI) in awake rats. Experimental approach: Using a high field (7 T) MRI scanner, we examined and quantified the effects of non-selective CB1/CB2 (A-834735) and selective CB2 (AM1241) agonists on neural activity in awake rats. Pharmacological specificity was determined using selective CB1 (rimonabant) or CB2 (AM630) antagonists. Behavioural studies, plasma and brain exposures were used as benchmarks for activity in vivo. Key results: The non-selective CB1/CB2 agonist produced a dose-related, region-specific activation of brain structures that agrees well with published autoradiographic CB1 receptor density binding maps. Pretreatment with a CB1 antagonist but not with a CB2 antagonist, abolished these activation patterns, suggesting an effect mediated by CB1 receptors alone. In contrast, no significant changes in brain activity were found with relevant doses of the CB2 selective agonist. Conclusion and implications: These results provide the first clear evidence for quantifying in vivo functional selectivity between CB1 and CB2 receptors using phMRI. Further, as the presence of CB2 receptors in the brain remains controversial, our data suggest that if CB2 receptors are expressed, they are not functional under normal physiological conditions. British Journal of Pharmacology (2008) 153, 367,379; doi:10.1038/sj.bjp.0707506; published online 29 October 2007 [source]

Rehabilitation with dental prosthesis can increase cerebral regional blood volume

CLINICAL ORAL IMPLANTS RESEARCH, Issue 6 2005
Ikuya 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]