FMRI visualization of brain activity during a monetary incentive delay task

Comparative studies have implicated striatal and mesial forebrain circuitry in the generation of autonomic, endocrine, and behavioral responses for incentives. Using blood oxygen level-dependent functional magnetic resonance imaging, we sought to visualize functional activation of these regions in 12 normal volunteers as they anticipated and responded for monetary incentives. Both individual and group analyses of time-series data revealed significant activation of striatal and mesial forebrain structures (including insula, caudate, putamen, and mesial prefrontal cortex) during trials involving both monetary rewards and punishments. In addition to these areas, during trials involving punishment, group analysis revealed activation foci in the anterior cingulate and thalamus. These results corroborate comparative studies which implicate striatal and mesial forebrain circuitry in the elaboration of incentive-driven behavior. This report also introduces a new paradigm for probing the functional integrity of this circuitry in humans.     

Failing to deactivate: the association between brain activity during a working memory task and creativity

Working memory (WM) is an essential component for human higher order cognitive activities. Creativity has been essential to the development of human civilization. Previous studies from different fields have suggested creativity and capacity of WM have opposing characteristics possibly in terms of diffuse attention. However, despite a number of functional imaging studies on creativity, how creativity relates to brain activity during WM has never been investigated. In this functional magnetic resonance imaging (fMRI) study, we investigated this issue using an n-back WM paradigm and a psychometric measure of creativity (a divergent thinking test). A multiple regression analysis revealed that individual creativity was significantly and positively correlated with brain activity in the precuneus during the 2-back task (WM task), but not during the non-WM 0-back task. As the precuneus shows deactivation during cognitive tasks, our findings show that reduced task induced deactivation (TID) in the precuneus is associated with higher creativity measured by divergent thinking. The precuneus is included in the default mode network, which is deactivated during cognitive tasks. The magnitude of TID in the default mode network is considered to reflect the reallocation of cognitive resources from networks irrelevant to the performance of the task. Thus, our findings may indicate that individual creativity, as measured by the divergent thinking test, is related to the inefficient reallocation of attention, congruent with the idea that diffuse attention is associated with individual creativity.     

Statistical parametric network analysis of functional connectivity dynamics during a working memory task

Network analysis has become a tool of choice for the study of functional and structural Magnetic Resonance Imaging (MRI) data. Little research, however, has investigated connectivity dynamics in relation to varying cognitive load. In fMRI, correlations among slow (<0.1 Hz) fluctuations of blood oxygen level dependent (BOLD) signal can be used to construct functional connectivity networks. Using an anatomical parcellation scheme, we produced undirected weighted graphs linking 90 regions of the brain representing major cortical gyri and subcortical nuclei, in a population of healthy adults (n=43). Topological changes in these networks were investigated under different conditions of a classical working memory task - the N-back paradigm. A mass-univariate approach was adopted to construct statistical parametric networks (SPNs) that reflect significant modifications in functional connectivity between N-back conditions. Our proposed method allowed the extraction of 'lost' and 'gained' functional networks, providing concise graphical summaries of whole-brain network topological changes. Robust estimates of functional networks are obtained by pooling information about edges and vertices over subjects. Graph thresholding is therefore here supplanted by inference. The analysis proceeds by firstly considering changes in weighted cost (i.e. mean between-region correlation) over the different N-back conditions and secondly comparing small-world topological measures integrated over network cost, thereby controlling for differences in mean correlation between conditions. The results are threefold: (i) functional networks in the four conditions were all found to satisfy the small-world property and cost-integrated global and local efficiency levels were approximately preserved across the different experimental conditions; (ii) weighted cost considerably decreased as working memory load increased; and (iii) subject-specific weighted costs significantly predicted behavioral performances on the N-back task (Wald F=13.39,df(1)=1,df(2)=83,p<0.001), and therefore conferred predictive validity to functional connectivity strength, as measured by weighted cost. The results were found to be highly sensitive to the frequency band used for the computation of the between-region correlations, with the relationship between weighted cost and behavioral performance being most salient at very low frequencies (0.01-0.03 Hz). These findings are discussed in relation to the integration/specialization functional dichotomy. The pruning of functional networks under increasing cognitive load may permit greater modular specialization, thereby enhancing performance.     

Effects of normal aging on event-related potentials and oscillatory brain activity during a haptic repetition priming task

This study reports neural repetition effects in young and older adults while performing a haptic repetition priming task consisting in the detection of the bilateral symmetry of familiar objects. To examine changes in event-related potentials (ERPs) and induced brain oscillations of object repetition priming with aging, we recorded EEGs of healthy groups of young (n=14; mean age=29.93 years) and older adults (n=15; mean age=66.4). Both groups exhibited similar behavioral haptic priming across repetitions, although young adults responded faster than the older group. Young and older adults showed ERP repetition enhancement at the 500-900 ms time window. In contrast, only the young participants showed ERP repetition suppression at the 1200-1500 ms segment. The results from the induced oscillations showed more positive amplitudes in young than in older adults at theta, alpha and beta frequencies (4-30 Hz). In addition, we found amplitude modulation related to stimulus repetition in the upper alpha and low beta sub-bands only in young adults (1250-1750 ms).The results suggest that although behavioral priming is spared with age, normal aging affects ERPs and oscillatory responses when performing an incidental priming symmetry detection task with haptically explored objects.     

The activity of nonspecific inflammation in hypertensive patients

AIM: To study the indices of nonspecific inflammation (C-reactive protein--CRP, interleukine 6--IL-6) in patients with essential hypertension (EH) as compared to a circadian profile of blood pressure (BP); changes of CRP in the course of therapy with indapamide-retard and ACE inhibitor perindopril. MATERIAL AND METHODS: The trial enrolled 81 patients with hypertension of stage I-II, moderate and high risk, aged 45.1 +/- 1.3 years, free of chronic inflammatory disease exacerbation, 2 months and more after acute respiratory diseases and 2-week absence of antihypertensive therapy. CRP was estimated by turbidimetry, IL-6--by ELISA, circadian BP monitoring was made using TM 2421 device. Seventeen patients were randomized to receive ariphon retard (Servier), twenty patients--prestarium. The data were processed with STATISTICA 6 programs. RESULTS: CRP level in the patients was 7.0 +/- 1.6 mg/l; an elevated CRP concentration (> 3 mg/l) was registered in 55% patients. These patients demonstrated a positive correlation of CRP concentration with the data of 24-h systolic BP (r = 0.37, p < 0.05) and 24-h diastolic BP (r = 0.43, p = 0.003) monitoring, abnormal circadian rhythm of BP (nondippers). IL-6 in the examinees was 6.7 +/- 1.3 pg/ml. An elevated IL-6 concentration was detected in 30%. In such patients a positive correlation was found between IL-6 and 24-h systolic and diastolic BP (r = 0.88; p < 0.05 and r = 0.97; p < 0.01, respectively). CONCLUSION: A positive correlation between CRP, IL-6 and BP may evidence for involvement of nonspecific inflammation in the course of EH. Patients with elevated CRP responded to ariphon retard with positive CRP dynamics. This can be explained by a relief of chronic hemodynamic stress. A positive CRP dynamics in response to prestarium can be mediated by block of angiotensin II.     

Frontostriatal system in planning complexity: a parametric functional magnetic resonance version of Tower of London task

In the present study, we sought to investigate which brain structures are recruited in planning tasks of increasing complexity. For this purpose, a parametric self-paced pseudo-randomized event-related functional MRI version of the Tower of London task was designed. We tested 22 healthy subjects, enabling assessment of imaging results at a second (random effects) level of analysis. Compared with baseline, planning activity was correlated with increased blood oxygenation level-dependent (BOLD) signal in the dorsolateral prefrontal cortex, striatum, premotor cortex, supplementary motor area, and visuospatial system (precuneus and inferior parietal cortex). Task load was associated with increased activity in these same regions. In addition, increasing task complexity was correlated with activity in the left anterior prefrontal cortex, a region supposed to be specifically involved in third-order higher cognitive functioning.     

Brain activity in patients with deficiency versus excess patterns of major depression: A task fMRI study

Objective:Patients with major depressive disorder (MDD) may experience a series of emotional and mental problems accompanied by characteristic clinical symptoms. Depressive patients often have emotional recognition disorders, but the reasons remain unclear. Though a great many functional abnormalities have been observed in the brains of depressed patients, such abnormalities are not often related to clinical symptoms. Currently in Traditional Chinese Medicine (TCM), syndrome differentiation for the MDD mainly consists of excess pattern (EP), and deficiency pattern (DP). EP and DP emphasize balance-regulation thought processes, and are widely used in diagnosis of diseases including depression, anxiety, insomnia, and other emotional disorders. We hope that syndrome differentiation in TCM can combine clinical symptoms and brain function more effectively. The present study investigated altered patterns and different association of brain activation in MDD patients with EP and DP during a facial emotion discrimination task with fMRI.Methods:A total of 45 patients (20 with EP and 25 with DP) and 18 normal controls participated in this study. Whole-brain functional scans were collected for each subject. Different patterns of brain activation and association during the facial emotion discrimination task were analyzed statistically.Results:Comparing all the MDD patients with the normal controls, there were no significant differences for sad vs. neutral condition or for happy vs. neutral condition (corrected p > 0.05). One-way ANCOVA showed significant differences in the left inferior frontal gyrus, the left insula, and the left caudate for sad vs. neutral condition across the DP, EP and NC groups (corrected p < 0.05). The whole brain activation comparison for sad vs. neutral condition between the EP MDD subtype and the DP MDD subtype further verified these differences in the left insula and left inferior frontal gyrus, discovering that these regions showed increased activation in EP MDD subtype compared with the DP MDD subtype (corrected p < 0.05). There were no significant differences in brain activation between each MDD subtype and the normal controls.Conclusion:Disparities in sad face processing exist between MDD patients with different TCM syndrome types, suggesting that TCM syndrome differentiation may provide a biological basis for negativity bias in depression, and may determine both symptom formation and social dysfunction.     

Specific and nonspecific enzymes involved in the catabolism of mononucleoside and dinucleoside polyphosphates

This review concerns enzymes that can degrade nucleoside 5'-tetra- and pentaphosphates (p(4)N and p(5)N) and those that can degrade various dinucleoside polyphosphates (Np(3-6)N'). Most of these enzymes are hydrolases, and they occur in all types of organisms. Certain fungi and protozoa also possess specific Np(n)N' phosphorylases. Specific p(4)N hydrolases have been demonstrated in mammals and in plants. In yeast, p(4)N and p(5)N are hydrolyzed by exopolyphosphatases. Among other hydrolases that can degrade these minor mononucleotides are phosphatases, apyrase, and (asymmetrical) Np(4)N' hydrolase, as well as the nonspecific adenylate deaminase. Np(n)N's are good substrates for Type I phosphodiesterases and nucleotide pyrophosphatases, and diadenosine polyphosphates are easily deaminated to diinosine polyphosphates by nonspecific adenylate deaminases. Specific Np(3)N' hydrolases occur in both prokaryotes and eukaryotes. Interestingly, the human fragile histidine triad (Fhit) tumor suppressor protein appears to be a typical Np(3)N' hydrolase. Among the specific Np(4)N' hydrolases are asymmetrically cleaving ones, which are typical of higher eukaryotes, and symmetrically cleaving enzymes found in Physarum polycephalum and in many bacteria. An enzyme that hydrolyzes both diadenosine tetraphosphate and diadenosine triphosphate has been found in the fission yeast Schizosaccharomyces pombe. Its amino acid sequence is similar to that of the human Fhit/Np(3)N' hydrolase. Very recently, a typical (asymmetrical) Np(4)N' hydrolase has been demonstrated for the first time in a bacterium-the pathogenic Bartonella bacilliformis. Another novelty is the discovery of diadenosine 5', 5"'-P(1),P 6-hexaphosphate hydrolases in budding and fission yeasts and in mammalian cells. These enzymes and the (asymmetrical) Np(4)N' hydrolases have the amino acid motif typical of the MutT (or Nudix hydrolase) family. In contrast, the Schizosaccharomyces pombe Ap(4)A/Ap(3)A hydrolase, the human Fhit protein, and the yeast Np(n)N' phosphorylases belong to a superfamily GAFH, which includes the histidine triad proteins.     

A comparison of performance measures of an added-purpose task versus a single-purpose task for upper extremities.

Occupational therapists often employ multidimensional tasks. These tasks, referred to as added-purpose tasks, provide a person with necessary exercise, yet direct the focus of attention toward another objective or outcome. The assumption is that the additional purpose will result in improved task performance, provided it is sufficiently distracting or meaningful to the person. The present study examined the effects of an added-purpose task compared with a single-purpose task on performance, as measured by the number of repetitions, task duration, and exercise heart rate. Thirty subjects performed either the added-purpose task or the single-purpose task three times during a 2-week period. Each session was terminated when the subject reported that he or she was exercising at a "very hard" rate on a measure of perceived exertion. A multiple analysis of variance for repeated measures indicated no significant difference between the performance of the subjects in the added-purpose versus the single-purpose task group on any of the dependent measures. Solicitation of patients' assessment of the value and meaningfulness of the rehabilitative task has practical importance.     

Effectiveness of graded activity versus physiotherapy in patients with chronic nonspecific low back pain: midterm follow up results of a randomized controlled trial

Background

Low back pain (LBP) is a major health and economic problem worldwide. Graded activity and physiotherapy are commonly used interventions for nonspecific low back pain. However, there is currently little evidence to support the use of one intervention over the other in the medium-term.

Normal fMRI brain activation patterns in children performing a verb generation task

Although much is known concerning brain-language relations in adults, little is known about how these functions might be represented during the developmental period. We report results from 17 normal children, ages 7-18 years, who have successfully completed a word fluency paradigm during functional magnetic resonance imaging at 3 Tesla. Regions of activation replicate those reported for adult subjects. However, a statistically significant association between hemispheric lateralization of activation and age was found in the children. Specifically, although most subjects at all ages showed left hemisphere dominance for this task, the degree of lateralization increased with age. This study demonstrates that fMRI can reveal developmental shifts in the pattern of brain activation associated with semantic language function.     

Specific versus Nonspecific Brain Activity in a Parametric N-Back Task

In this study functional magnetic resonance imaging (fMRI) was used to examine cerebral activity patterns in relation to increasing mental load of a working memory task. Aim of the experiment was to distinguish nonspecific task-related processes from specific workload processes analytically. Twelve healthy volunteers engaged in a spatial n-back task with four levels. FMRI data were acquired with the 3D-PRESTO pulse sequence. Analysis entailed a two-step multiple regression algorithm, which was specifically designed to measure and separate load-sensitive and load-insensitive activity simultaneously, while preserving the original high spatial resolution of the fMRI signal. Load-sensitive and load-insensitive activity was found in both dorsolateral-prefrontal and parietal cortex, predominantly bilaterally, and in the anterior cingulate. As expected, the left primary sensorimotor cortex showed predominantly load-insensitive activity. Load-sensitive activity reflects specific working memory functions, such as temporary retention and manipulation of information, while load-insensitive activity reflects supportive functions, such as visual orientation, perception, encoding, and response selection and execution. Good performance was correlated with a large area of load-sensitive activity in anterior cingulate, and with a small area of load-insensitive activity in the right parietal cortex. The findings indicate that nonspecific and specific working memory processes colocalize and are represented in multiple frontal and parietal regions. Implication of this analytical strategy for application in research on psychiatric disorders is discussed.     

Specific alterations of cerebral hemodynamics during a planning task: a transcranial Doppler sonography study

Planning plays an important role in daily activities, and several experimental paradigms have been investigated with brain imaging methods showing activity in putative brain regions such as dorsolateral prefrontal cortex and other frontal and non-frontal regions. The Stockings of Cambridge (SOC), a related procedure to the Tower of London task, was introduced to 21 healthy subjects while they underwent bilateral transcranial Doppler sonography (TCD) of the middle (MCA) and anterior (ACA) cerebral arteries. Different levels of difficulty were applied during continuous registration of peak mean cerebral blood flow velocity (CBFV). A specific test procedure allowed separating the actual planning from the execution phase. There was also a similar control task, which did not involve planning. CBFV differed among the planning, execution, and control conditions (MCA: P < 0.01; ACA: P < 0.001), but did not show a significant difference between the MCA and ACA (P > 0.1). Easy tasks yielded a more rapid increase of CBFV in the MCA compared to difficult problems during planning (P < 0.05). In conclusion, our findings of specific CBFV patterns support the idea of different cognitive challenges for planning and control and between easy and difficult conditions.     

Spatio-temporal brain activity related to rotation method during a mental rotation task of three-dimensional objects: an MEG study

During mental rotation tasks, subjects perform mental simulation to solve tasks. However, detailed neural mechanisms underlying mental rotation of three-dimensional (3D) objects, particularly, whether higher motor areas related to mental simulation are activated, remain unknown. We hypothesized that environmental monitoring-a process based on environmental information and is included in motor execution-is as a key factor affecting the utilization of higher motor areas. Therefore, using magnetoencephalography (MEG), we measured spatio-temporal brain activities during two types (two-dimensional (2D) and 3D rotation tasks) of mental rotation of 3D objects. Only the 3D rotation tasks required subjects to mentally rotate objects in a depth plane with visualization of hidden parts of the visual stimuli by acquiring and retrieving 3D information. In cases showing significant differences in the averaged activities at 100-ms intervals between the two rotations, the activities were located in the right dorsal premotor (PMd) at approximately 500 ms. In these cases, averaged activities during 3D rotation were greater than those during 2D rotation, implying that the right PMd activities are related to environmental monitoring. During 3D rotation, higher activities were observed from 200 to 300 ms in the left PMd and from 400 to 700 ms in the right PMd. It is considered that the left PMd is related to primary motor control, whereas the right PMd plays a supplementary role during mental simulation. Further, during 3D rotation, late higher activities related to mental simulation are observed in the right superior parietal lobule (SPL), which is connected to PMd.     

Granulocyte metabolic activity in chronic nonspecific lung diseases]

Biochemiluminescent (BCL) investigation of oxidative metabolism in patients suffering from chronic nonspecific lung diseases (CNLD) has shown activation of granulocyte metabolism measured by zymosan-dependent luminol-amplified chemiluminescence and the intensification of lipid peroxidation estimated by spontaneous serum BCL. At the same time H2O2-induced BCL was decreased, attesting to the abatement of antioxidative activity. The revealed imbalance of oxidative and antioxidative processes may be the pathogenic factor in CNLD development.     

Brain activity preceding a 2D manual catching task

We investigated the event-related desynchronization (ERD) and synchronization (ERS) properties of cortical EEG rhythms in regions of interest (ROI) during the preparation of a 2D task for manual catching of a moving object. EEG signals were recorded through a 32-channel system in eleven healthy subjects during the interception task consisting of 2D catching with the right hand of a handle moving at constant velocity (1.5 m/s) on a predefined straight trajectory. The first session of catching movements (CATCHING_PRE) was compared with a second session after 1 h with identical characteristics (CATCHING_POST) and with other two conditions, where the subjects had to reach and grasp the handle fixed in the medium of platform (REACHING) and they looked at the object moving without catching it (GAZE TRACKING). Changes of cortical rhythms were correlated with dynamic and kinematic indexes of motor performance in both catching sessions.Movements requiring different strategies (predictive versus prospective) are supported by specific changes of cortical EEG rhythms: in the CATCHING condition a more evident power decrease (ERD) in alpha 2 and beta band in the sensorimotor region contralateral to the catching hand was observed, while in the REACHING one a bilateral ERD in beta band was found. Motor learning and movement automatization were characterized by a significant reduction of theta ERS in the anterior cingulate cortex (ACC), a ROI linked to focused attention, and with a shift of neuronal activation in alpha 2 band from the bilateral superior parietal areas to the homologous area of the left hemisphere. Finally, our EEG findings are consistent with the role of supplementary motor (SMA), premotor and prefrontal areas in motor planning and preparation. In particular, theta ERS in left SMA significantly correlated with an improvement of motor performance, as evidenced by its correlation with the training-related reduction of interception time (IT).     

健康青少年视觉注意作业的功能性磁共振成像初步研究

目的：应用功能性磁共振成像（fMRI）探讨视觉注意作业时健康青少年脑功能定位。方法：使用美国GE 1.5T Signa Horizon LX超导型磁共振仪，对19名健康青少年进行视觉注意作业的fMRI检查，采用梯度回波-平面回波成像序列采集数据，经工作站处理后获功能图像。同时进行氢谱分析。结果：健康青少年视觉注意作业测验激活脑区的范围较广泛，不同脑区的激活计数不同，9岁—12岁和13岁—15岁两个年龄段比较，结果无显著性差异（P>0.05）。本研究健康青少年双侧苍白球1H MRS结果（峰下面积比值）：左侧，NAA/Cr3.24±1.27、cho/Cr0.71±0.15、ml/Cr0.66±0.17、a-Glx/Cr0.84±0.18；右侧，NAA/Cr3.17±1.12、cho/Cr0.66±0.19、ml/Cr0.60±0.16、a-Glx/Cr0.71±0.28。经Fisher精确检验法，健康青少年双侧额上回、双侧额中回和左侧额下回的激活脑区计数与理想激活脑区计数的差异均无显著性，其余脑区激活计数的差异均有显著性。结论：本组健康青少年脑区激活计数及氢谱分析可供临床参考。视觉注意作业主要涉及记忆信息的提取速度和注意能量，双侧额叶可能参与其过程。     

Widespread dorsal stream activation during a parametric mental rotation task, revealed with functional magnetic resonance imaging

Following a parametrically modulated mental rotation task, in which 10 healthy subjects were instructed to determine whether alphanumeric characters were normal or mirror-reversed, bilateral dorsal stream activations culminating in the intraparietal region were revealed with functional magnetic resonance imaging. Although the parietal activations were bilateral, we observed a right hemispheric dominance for the task, consistent with our previous findings (I. M. Harris et al., 2000). By studying individual activation maps in response to the paradigm, we discerned parcellation of the intraparietal region into discrete subdivisions. In this paper, we address the involvement of structures surrounding the intraparietal sulcus in mental rotation, as well as describing a wider visuospatial attentional network, encompassing neural substrates within the dorsal stream.