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Cortical Activation (cortical + activation)
Selected AbstractsOrexins/hypocretins and aminergic systemsACTA PHYSIOLOGICA, Issue 3 2010K. S. Eriksson Abstract Orexin/hypocretin neurones in the posterior hypothalamus are mutually connected with noradrenergic, serotonergic, dopaminergic, histaminergic, and cholinergic neurone systems. They activate these targets by direct post-synaptic and indirect pre-synaptic mechanisms and in turn receive inhibitory feedback and excitatory feed forward control. With respect to behavioural state control, orexin/hypocretin neurones are conducting the orchestra of biogenic amines. This review highlights the role of these players in the control of energy administration, sleep,wake architecture, cortical activation, plasticity, and memory functions in health and disease. [source] Reduced parietal and visual cortical activation during global processing in Williams syndromeDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 6 2007Dean Mobbs BSc Several lines of investigation suggest that individuals with Williams syndrome (WS), a neurodevelopmental disorder of well-characterized genetic etiology, have selective impairments in integrating local image elements into global configurations. We compared global processing abilities in 10 clinically and genetically diagnosed participants with WS (eight females, two males; mean age 31y 10mo [SD 9y 7mo], range 15y 5mo-48y 4mo) with a typically developed (TD) age- and sex-matched comparison group (seven females, one male; mean age 35y 2mo [SD 10y 10mo], range 24y-54y 7mo) using functional magnetic resonance imaging (fMRI). Behavioral data showed participants with WS to be significantly less accurate (p<0.042) together with a non-significant trend to be slower than the TD comparison group while performing the global processing task. fMRI data showed participants with WS to possess reduced activation in the visual and parietal cortices. Participants with WS also showed relatively normal activation in the ventral occipitotemporal cortex, but elevated activation in several posterior thalamic nuclei. These preliminary results largely confirm previous research findings and neural models implicating neurodevelopmental abnormalities in extended subcortical and cortical visual systems in WS, most notably dorsal-stream pathways. [source] Ankle dorsiflexion fMRI in children with cerebral palsy undergoing intensive body-weight-supported treadmill training: a pilot studyDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 1 2007John P Phillips MD This pilot study investigated the feasibility of using functional magnetic resonance imaging (fMRI) as a physiological marker of brain plasticity before and after an intensive body-weight-supported treadmill training (BWSTT) program in children with cerebral palsy (CP). Six ambulatory children (four males, two females; mean age 10y 6mo, age range 6,14y) with spastic CP (four hemiplegia, two asymmetric diplegia, all Gross Motor Function Classification System Level I) received BWSTT twice daily for 2 weeks. All children tolerated therapy; only one therapy session was aborted due to fatigue. With training, over ground mean walking speed increased from 1.47 to 1.66m/s (p=0.035). There was no change in distance walked for 6 minutes (pre-: 451m; post-: 458m;p 0.851). In three children, reliable fMRIs were taken of cortical activation pre- and post-intervention. Post-intervention increases in cortical activation during ankle dorsiflexion were observed in all three children. This study demonstrates that children with CP between 6 and 14 years of age can tolerate intensive locomotor training and, with appropriate modifications, can complete an fMRI series. This study supports further studies designed to investigate training-dependent plasticity in children with CP. [source] A shift from diffuse to focal cortical activity with developmentDEVELOPMENTAL SCIENCE, Issue 1 2006Sarah Durston Recent imaging studies have suggested that developmental changes may parallel aspects of adult learning in cortical activation becoming less diffuse and more focal over time. However, while adult learning studies examine changes within subjects, developmental findings have been based on cross-sectional samples and even comparisons across studies. Here, we used functional MRI in children to test directly for shifts in cortical activity during performance of a cognitive control task, in a combined longitudinal and cross-sectional study. Our longitudinal findings, relative to our cross-sectional ones, show attenuated activation in dorsolateral prefrontal cortical areas, paralleled by increased focal activation in ventral prefrontal regions related to task performance. [source] Functional MRI of the visual cortex and visual testing in patients with previous optic neuritisEUROPEAN JOURNAL OF NEUROLOGY, Issue 3 2002A. R. Langkilde The volume of cortical activation as detected by functional magnetic resonance imaging (fMRI) in the visual cortex has previously been shown to be reduced following optic neuritis (ON). In order to understand the cause of this change, we studied the cortical activation, both the size of the activated area and the signal change following ON, and compared the results with results of neuroophthalmological testing. We studied nine patients with previous acute ON and 10 healthy persons served as controls using fMRI with visual stimulation. In addition to a reduced activated volume, patients showed a reduced blood oxygenation level dependent (BOLD) signal increase and a greater asymmetry in the visual cortex, compared with controls. The volume of visual cortical activation was significantly correlated to the result of the contrast sensitivity test. The BOLD signal increase correlated significantly to both the results of the contrast sensitivity test and to the Snellen visual acuity. Our results indicate that fMRI is a useful method for the study of ON, even in cases where the visual acuity is severely impaired. The reduction in activated volume could be explained as a reduced neuronal input; however, the greater asymmetry might point to a cortical reorganization as a consequence of neuronal damage. Future fMRI studies in ON will add to the understanding of the neural adaptive behaviour following ON. [source] Differential patterns of cortical activation as a function of fluid reasoning complexityHUMAN BRAIN MAPPING, Issue 2 2009Bernardo Perfetti Abstract Fluid intelligence (gf) refers to abstract reasoning and problem solving abilities. It is considered a human higher cognitive factor central to general intelligence (g). The regions of the cortex supporting gf have been revealed by recent bioimaging studies and valuable hypothesis on the neural correlates of individual differences have been proposed. However, little is known about the interaction between individual variability in gf and variation in cortical activity following task complexity increase. To further investigate this, two samples of participants (high-IQ, N = 8; low-IQ, N = 10) with significant differences in gf underwent two reasoning (moderate and complex) tasks and a control task adapted from the Raven progressive matrices. Functional magnetic resonance was used and the recorded signal analyzed between and within the groups. The present study revealed two opposite patterns of neural activity variation which were probably a reflection of the overall differences in cognitive resource modulation: when complexity increased, high-IQ subjects showed a signal enhancement in some frontal and parietal regions, whereas low-IQ subjects revealed a decreased activity in the same areas. Moreover, a direct comparison between the groups' activation patterns revealed a greater neural activity in the low-IQ sample when conducting moderate task, with a strong involvement of medial and lateral frontal regions thus suggesting that the recruitment of executive functioning might be different between the groups. This study provides evidence for neural differences in facing reasoning complexity among subjects with different gf level that are mediated by specific patterns of activation of the underlying fronto-parietal network. Hum Brain Mapp, 2009. © 2007 Wiley-Liss, Inc. [source] Simultaneous measurements of cerebral oxygenation changes during brain activation by near-infrared spectroscopy and functional magnetic resonance imaging in healthy young and elderly subjectsHUMAN BRAIN MAPPING, Issue 1 2002D. Jannet Mehagnoul-Schipper Abstract Near infrared spectroscopy (NIRS) and functional magnetic resonance imaging (fMRI) both allow non-invasive monitoring of cerebral cortical oxygenation responses to various stimuli. To compare these methods in elderly subjects and to determine the effect of age on cortical oxygenation responses, we determined motor-task-related changes in deoxyhemoglobin concentration ([HHb]) over the left motor cortex in six healthy young subjects (age 35 ± 9 years, mean ± SD) and five healthy elderly subjects (age 73 ± 3 years) by NIRS and blood-oxygen-level-dependent (BOLD) fMRI simultaneously. The motor-task consisted of seven cycles of 20-sec periods of contralateral finger-tapping at a rate as fast as possible alternated with 40-sec periods of rest. Time-locked averages over the seven cycles were used for further analysis. Task-related decreases in [HHb] over the motor cortex were measured by NIRS, with maximum changes of ,0.83 ± 0.38 ,mol/L (P < 0.01) for the young and ,0.32 ± 0.17 ,mol/L (P < 0.05) for the elderly subjects. The BOLD-fMRI signal increased over the cortex volume under investigation with NIRS, with maximum changes of 2.11 ± 0.72% (P < 0.01) for the young and 1.75 ± 0.71% (P < 0.01) for the elderly subjects. NIRS and BOLD-fMRI measurements showed good correlation in the young (r = ,0.70, r2 = 0.48, P < 0.001) and elderly subjects (r = ,0.82, r2 = 0.67, P < 0.001). Additionally, NIRS measurements demonstrated age-dependent decreases in task-related cerebral oxygenation responses (P < 0.05), whereas fMRI measurements demonstrated smaller areas of cortical activation in the elderly subjects (P < 0.05). These findings demonstrate that NIRS and fMRI similarly assess cortical oxygenation changes in young subjects and also in elderly subjects. In addition, cortical oxygenation responses to brain activation alter with aging. Hum. Brain Mapping 16:14,23, 2002. © 2002 Wiley-Liss, Inc. [source] Reduced right hemisphere activation in severely abused violent offenders during a working memory task: An fMRI studyAGGRESSIVE BEHAVIOR, Issue 2 2001Adrian Raine Abstract This study uses functional magnetic resonance imaging (fMRI) to address two important gaps in our knowledge of brain functioning and violence: (1) What are the brain correlates of adults in the community who have suffered severe physical abuse early in life and who go on to perpetrate serious violence in adulthood? (2) What characterizes those who experience severe physical abuse but who refrain from serious violence? Four groups of participants recruited from the community (controls, severe physical child abuse only, serious violence only, and severely abused, seriously violent offenders) underwent fMRI while performing a visual/verbal working memory task. Violent offenders who had suffered severe child abuse show reduced right hemisphere functioning, particularly in the right temporal cortex. Abused individuals who refrain from serious violence showed relatively lower left, but higher right, activation of the superior temporal gyrus. Abused individuals, irrespective of violence status, showed reduced cortical activation during the working memory task, especially in the left hemisphere. Brain deficits were independent of IQ, history of head injury, task performance, cognitive strategy, and mental activity during the control task. Findings constitute the first fMRI study of brain dysfunction in violent offenders, and indicate that initial right hemisphere dysfunction, when combined with the effects of severe early physical abuse, predisposes to serious violence but that relatively good right hemisphere functioning protects against violence in physically abused children. Aggr. Behav. 27:111,129, 2001. © 2001 Wiley-Liss, Inc. [source] Functional changes of the cortical motor system in hereditary spastic paraparesisACTA NEUROLOGICA SCANDINAVICA, Issue 3 2009B. Koritnik Background,,, Hereditary spastic paraparesis (HSP) is a heterogeneous group of disorders characterized by progressive bilateral lower limb spasticity. Functional imaging studies in patients with corticospinal tract involvement have shown reorganization of motor circuitry. Our study investigates functional changes in sensorimotor brain areas in patients with HSP. Methods,,, Twelve subjects with HSP and 12 healthy subjects were studied. Functional magnetic resonance imaging (fMRI) was used to measure brain activation during right-hand finger tapping. Image analysis was performed using general linear model and regions of interest (ROI)-based approach. Weighted laterality indices (wLI) and anterior/posterior indicies (wAI and wPI) were calculated for predefined ROIs. Results and discussion,,, Comparing patients and controls at the same finger-tapping rate (1.8 Hz), there was increased fMRI activation in patients' bilateral posterior parietal cortex and left primary sensorimotor cortex. No differences were found when comparing patients and controls at 80% of their individual maximum tapping rates. wLI of the primary sensorimotor cortex was significantly lower in patients. Subjects with HSP also showed a relative increase in the activation of the posterior parietal and premotor areas compared with that of the primary sensorimotor cortex. Our findings demonstrate an altered pattern of cortical activation in subjects with HSP during motor task. The increased activation probably reflects reorganization of the cortical motor system. [source] Temperament, Tympanum, and Temperature: Four Provisional Studies of the Biobehavioral Correlates of Tympanic Membrane Temperature AsymmetriesCHILD DEVELOPMENT, Issue 3 2002W. Thomas Boyce Previous research in both humans and nonhuman primates suggests that subtle asymmetries in tympanic membrane (TM) temperatures may be related to aspects of cognition and socioaffective behavior. Such associations could plausibly reflect lateralities in cerebral blood flow that support side-to-side differences in regional cortical activation. Asymmetries in activation of the left and right frontal cortex, for example, are correlates of temperamental differences in child behavior and markers of risk status for affective and anxiety disorders. Tympanic membrane temperatures might thus reflect the neural asymmetries that subserve individual differences in temperament and behavior. This report merged findings from four geographically and demographically distinctive studies, which utilized identical thermometry methods to examine associations between TM temperature asymmetries and biobehavioral attributes of 4- to 8-year-old children (N= 468). The four studies produced shared patterns of associations that linked TM temperature lateralities to individual differences in behavior and socioaffective difficulties. Warmer left TMs were associated with "surgent," affectively positive behaviors, whereas warmer right TMs were related to problematic, affectively negative behaviors. Taken together, these findings suggest that asymmetries in TM temperatures could be associated with behavior problems that signal risk for developmental psychopathology. [source] Cortical 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] | ||||||||||||||||