BOLD Changes Research Articles

Attenuation of the BOLD fMRI Signal and Changes in Functional Connectivity Affecting the Whole Brain in Presence of Brain Metastasis.

To date, there are almost no investigations addressing functional connectivity (FC) in patients with brain metastases (BM). In this retrospective study, we investigate the influence of BM on hemodynamic brain signals derived from functional magnetic resonance imaging (fMRI) and FC. Motor-fMRI data of 29 patients with BM and 29 matched healthy controls were analyzed to assess percent signal changes (PSC) in the ROIs motor cortex, premotor cortex, and supplementary motor cortex and FC in the sensorimotor, default mode, and salience networks using Statistical Parametric Mapping (SPM12) and marsbar and CONN toolboxes. In the PSC analysis, an attenuation of the BOLD signal in the metastases-affected hemisphere compared to the contralateral hemisphere was significant only in the supplementary motor cortex during hand movement. In the FC analysis, we found alterations in patients' FC compared to controls in all examined networks, also in the hemisphere contralateral to the metastasis. This indicates a qualitative attenuation of the BOLD signal in the affected hemisphere and also that FC is altered by the presence of BM, similarly to what is known for primary brain tumors. This transformation is not only visible in the infiltrated hemisphere, but also in the contralateral one, suggesting an influence of BM beyond local damage.

Behavioral variation among Fox Squirrel (Sciurus niger) populations in urban environments

Abstract Urbanization presents a myriad of challenges to wildlife, yet some individuals or species persist and even thrive in urban environments. Specific behavioral traits that have been proposed to enable animals to cope with challenges and frequently observed in urban wildlife populations across many taxonomic groups include changes in docility, activity, boldness, sociability, and aggression. We conducted a series of standardized behavioral assays to test the hypothesis that urbanization favors these traits in fox squirrels (Sciurus niger), a species that is widespread in urban areas. Based upon previous studies, we predicted that squirrels would exhibit higher levels of boldness, activity, and aggression and lower docility in urban areas with higher human density compared to their counterparts in areas with lower human density areas. We instead found a trend of higher sociability—but not aggression—in squirrels at higher human density sites over lower human density sites, and no differences in docility, boldness, or activity. Our results indicate that the behavior of fox squirrels does not vary dramatically on a fine scale of human density, apart from a trend in heightened sociability in higher human density urban environments.

Underlying Neural Mechanisms of Cognitive Improvement in Fronto-striatal Response Inhibition in People Living with HIV Switching Off Efavirenz: A Randomized Controlled BOLD fMRI Trial.

It is unclear whether neurotoxicity due to the antiretroviral drug efavirenz (EFV) results in neurocognitive impairment in people living with HIV (PLWH). Previously, we found that discontinuing EFV was associated with improved processing speed and attention on neuropsychological assessment. In this imaging study, we investigate potential neural mechanisms underlying this cognitive improvement using a BOLD fMRI task assessing cortical and subcortical functioning. Asymptomatic adult PLWH stable on emtricitabine/tenofovirdisoproxil/efavirenz were randomly (1:2) assigned to continue their regimen (n = 12) or to switch to emtricitabine/tenofovirdisoproxil/rilpivirine (n = 28). At baseline and after 12weeks, both groups performed the Stop-Signal Anticipation Task, which tests reactive and proactive inhibition (indicative of subcortical and cortical functioning, respectively), involving executive functioning, working memory, and attention. Behavior and BOLD fMRI activation levels related to processing speed and attention Z-scores were assessed in 17 pre-defined brain regions. Both groups had comparable patient and clinical characteristics. Reactive inhibition behavioral responses improved for both groups on week12, with other responses unchanged. Between-group activation did not differ significantly. For reactive inhibition, positive Pearson coefficients were observed for the change in BOLD fMRI activation levels and change in processing speed and attention Z-scores in all 17 regions in participants switched to emtricitabine/tenofovir disoproxil/rilpivirine, whereas in the control group, negative correlation coefficients were observed in 10/17 and 13/17 regions, respectively. No differential pattern was observed for proactive inhibition. Potential neural mechanisms underlying cognitive improvement after discontinuing EFV in PLWH were found in subcortical functioning, with our findings suggesting that EFV's effect on attention and processing speed is, at least partially, mediated by reactive inhibition. Clinicaltrials.gov identifier [NCT02308332].

Insights from social-ecological systems thinking for understanding and preventing famine.

The risk of famine is rising in many countries today. Bold changes to famine information and response systems are urgently needed to improve capacities to prevent famine. To this end, the paper identifies six insights from social-ecological systems (SES) thinking for understanding and preventing famine. It argues that a state of famine emerges from human-environment interdependencies, complex causality, and non-linear system dynamics, shaped by history and context. The likelihood of famine can be reduced by strengthening resilience to the diverse stresses and shocks that drive destitution, food insecurity, undernutrition, morbidity, and mortality. SES thinking offers new opportunities to understand the dynamics of famine, diagnose lesser-known drivers, pinpoint new metrics, ascertain leverage points for intervention, and develop conceptual frameworks to inform policy. SES concepts and methods could also support the development of practical analytical tools to guide decisionmakers on how, where, and when to intervene most effectively and efficiently to strengthen resilience to the drivers of famine.

Rachmaninoff’s Preludes as a Cyclic Work

For over 18 years during the period 1892 to 1910, Sergei Rachmaninoff composed thePrelude, Op. 3, No. 2; 10 Preludes, Op. 23; and 13 Preludes, Op. 32. The key organization of Rachmaninoff’s 24 Preludes seems random at first glance, not based on any systematic order, as are the sets of Johann Sebastian Bach’s The Well-Tempered Clavier and Frédéric Chopin’s 24 Preludes, Op. 28. However, they consist of all the different major and minor keys and are uniquely integrated by cyclic manipulation of tonal relationships and thematic ideas. While they share numerous features, such as the use of common tones/chords, stepwise motion, chromatic lines, intervallic motives, and a certain rhythmic pattern, they also present divergent elements, such as bold key changes, irregular inclusion of relative- and parallel-key relationship, and effective contrasts in various aspects in many of consecutive preludes. The set of Rachmaninoff’s 24 Preludes is organized in his own unique, original, and meaningful system and conceptual design, which the author believes is highly successful as an integral, cyclic composition.

Designing a circular carbon and plastics economy for a sustainable future.

The linear production and consumption of plastics today is unsustainable. It creates large amounts of unnecessary and mismanaged waste, pollution and carbon dioxide emissions, undermining global climate targets and theSustainable Development Goals. This Perspective provides an integrated technological, economic and legal view on how to deliver a circular carbon and plastics economy that minimizes carbon dioxide emissions. Different pathways that maximize recirculation of carbon (dioxide) between plastics waste and feedstocks are outlined, including mechanical, chemical and biological recycling, and those involving the use of biomass and carbon dioxide. Four future scenarios are described, only one of which achieves sufficient greenhouse gas savings in line with global climate targets. Such a bold system change requires 50% reduction in future plastic demand, complete phase-out of fossil-derived plastics, 95% recycling rates of retrievable plastics and use of renewable energy. It is hard to overstate the challenge of achieving this goal. We therefore present a roadmap outlining the scale and timing of the economic and legal interventions that could possibly support this. Assessing the service lifespan and recoverability of plastic products, along with considerations of sufficiency and smart design, canmoreoverprovide design principles to guide future manufacturing, use and disposal of plastics.

Analyzing the hemodynamic basis of post-stroke epilepsy: impact of BOLD cerebrovascular reactivity changes and the role of STA-MCA bypass

Analyzing the hemodynamic basis of post-stroke epilepsy: impact of BOLD cerebrovascular reactivity changes and the role of STA-MCA bypass

불경 본생담 아난다 서사의 문학치료적 독해

This paper explores the therapeutic potential within the past life stories of Ananda from the Buddhist sutra Jataka, applying the literary therapy theories and methods of the Society of Korean Literary Therapy.Literary therapeutics regards humans as literary beings, and its main task is to reflect on and adjust the story-in-depth inherent in life through the story-in-depth inherent in works. Using Ananda's narratives as a reflective tool, this study aims to examine the mindsets and behaviors that modern individuals should adopt when pursuing religious practices and the path of sainthood. In the Jataka, Ananda, alongside Devadatta, emerges as the second most frequently depicted character after Buddha. Often depicted as someone living a worldly life, Ananda symbolizes the juncture between the paths of Buddha and Devadatta. Many stories vividly portray his journey, showcasing a qualitative transformation from worldly entanglements to becoming an authentic companion of the Buddha. This process offers profound insights for contemporary individuals ensnared by greed and ignorance, illustrating how to break free, undergo existential transformation, and progress towards enlightenment.
 Through a narrative analysis of various Jataka materials, this study identifies six conditions contributing to Ananda's transition from a worldly existence to a saintly one. Firstly, an open-minded approach to truth, embracing immediate acceptance devoid of prejudice. Secondly, the willingness to let go without remorse, embracing bold changes in direction. Thirdly, embodying humility, sincere honesty, and selflessness in actions. Fourthly, the capacity for cool-headed discernment and practical problem-solving. Fifthly, unwavering faith and resilience during crises. Sixthly, fostering a humanity of respect and engaging in practical acts of compassion. These aspects interconnect rather than stand alone, portraying a human existence passionately lived not only through thoughts but also actions. Ananda's portrayal in the Jataka stories can be seen as a literary representation of the ideal Buddhist figure, serving as inspiration for Buddhism followers.
 Ananda's portrayal in the Jataka stories can be seen as a literary representation of the ideal Buddhist figure, serving as inspiration for Buddhism followers. The findings of this analysis hold significance in the realm of Buddhist counseling. Ananda's narrative provides rich material for healing conversations between counselors and clients, each characteristic of Ananda offering potential as a therapeutic focus. Employing 'story-making,' a hallmark technique in literary therapy, where clients reconstruct Ananda stories and reflect upon them, could introduce a novel approach to Buddhist counseling. Moreover, incorporating Ananda stories into established Buddhist counseling methods, such as ascetic meditation healing, could diversify and enhance the counseling experience. Leveraging various literary works, including folk tales, could serve as a valuable avenue to enrich Buddhist counseling methodologies.

Personality Affects Zebrafish Response to Sertraline.

Sertraline is widely prescribed to treat anxiety and depression. Sertraline acts by blocking serotonin, norepinephrine, and dopamine transporters systems and has been detected in surface waters globally, where it may impact fish behavior. We classified zebrafish personality on three behavioral axes, boldness, anxiety, and sociability, assigning fish as either high or low in each category. The fish were exposed to nominal concentrations of 0, 5, 50, 500, or 5000 ng/L sertraline (measured concentrations: <10, 21.3, 370, and 2200 ng/L, respectively) to assess changes in boldness, anxiety, and sociability after 7 and 28 days. We also measured shoaling behavior and response to an alarm cue, and determined the gut microbiome of a subset of fish. After 7 days there was no overall effect of sertraline on boldness, but there was an interaction between initial personality and sex, with a stronger impact on females classified as low-boldness personality. Sertraline reduced sociability in all treatments compared with the control, but there was again an interaction between sertraline and initial personality. Fish that were classified as low-sociability responded more strongly to sertraline. After 7 days, fish exposed to a nominal concentration of 5000 ng/L (2200 ng/L measured) showed higher anxiety than controls, with the overall pattern of initial behavior retained. After 28 days, similar patterns were observed, but with higher variation. There was only a weak association between the gut microbiome and personality. Overall, the study highlights the importance of considering initial behavior, which can affect response to pollutants. Our results may also be applicable to human studies and provide a mechanism to explain why different individuals respond differently to the drug. Environ Toxicol Chem 2024;43:132-146. © 2023 SETAC.

Investigating zero transmission of HIV in the MSM population: a UK modelling case study

BackgroundUNAIDS 90-90-90 goals for HIV have been surpassed in the UK, with focus now moving to ending transmission by 2030. The concept of zero transmission is complex and many factors can influence transmission. We aimed to investigate how the target of zero transmission might be reached in the UK.MethodsWe developed a de novo Markov state transition open cohort model of HIV with a 50-year time horizon, which models six key screening, treatment and prevention parameters, including treatment-as-prevention (TasP) and pre-exposure prophylaxis (PrEP). We studied the anticipated HIV epidemic trajectory over time in men who have sex with men (MSM), with and without changing the six key parameters, defining zero transmission as a 60% reduction in incidence compared with 2010 incidence.ResultsZero transmission in the MSM population was not achieved within the model’s time horizon in our base case scenario, when the six key parameters were set to their 2019 values. Several future scenarios were explored, including a combination approach to preventing HIV transmission through increasing five key parameter values and considering three different TasP values; zero transmission was achieved by 2030 in the scenario where TasP was increased from its current level of 97–99%, avoiding 48,969 new HIV cases over the time horizon and reducing the lifetime risk of acquiring HIV for HIV-negative MSM not using PrEP from 13.65 to 7.53%.ConclusionsZero transmission in the UK MSM population can be reached by the target year of 2030 with bold changes to HIV policy. A combination approach such as the UK Government’s ‘Towards Zero’ Action plan, impacting multiple policies and including an increase in TasP, has the potential to achieve meaningful reductions in HIV transmission and meet this ambitious goal.

Multiparametric MR Evaluation of the Photoperiodic Regulation of Hypothalamic Structures in Sheep

Most organisms on earth, humans included, have developed strategies to cope with environmental day-night and seasonal cycles to survive. For most of them, their physiological and behavioral functions, including the reproductive function, are synchronized with the annual changes of day length, to ensure winter survival and subsequent reproductive success in the following spring.Sheep are sensitive to photoperiod, which also regulates natural adult neurogenesis in their hypothalamus. We postulate that the ovine model represents a good alternative to study the functional and metabolic changes occurring in response to photoperiodic changes in hypothalamic structures of the brain.Here, the impact of the photoperiod on the neurovascular coupling and the metabolism of the hypothalamic structures was investigated at 3T using BOLD fMRI, perfusion-MRI and proton magnetic resonance spectroscopy (1H-MRS). A longitudinal study involving 8 ewes was conducted during long days (LD) and short days (SD) revealing significant BOLD, rCBV and metabolic changes in hypothalamic structures of the ewe brain between LD and SD. More specifically, the transition between LD and SD revealed negative BOLD responses to hypercapnia at the beginning of SD period followed by significant increases in BOLD, rCBV, Glx and tNAA concentrations towards the end of the SD period. These observations suggest longitudinal mechanisms promoting the proliferation and differentiation of neural stem cells within the hypothalamic niche of breeding ewes.We conclude that multiparametric MRI studies including 1H-MRS could be promising non-invasive translational techniques to investigate the existence of natural adult neurogenesis in-vivo in gyrencephalic brains.

Associations of patient‐specific resting state variability with CSF and clinical biomarkers: Data from Alzheimer’s disease clinical trials

AbstractBackgroundChanges of brain functional connectivity assessed using MRI in patients with Alzheimer’s disease (AD) have been previously reported. However, factors contributing to the variability among patients have not been sufficiently investigated. Here, we investigated the association of patient‐specific resting state parameters with CSF markers and clinical measures.MethodWe analyzed the baseline rs‐fMRI of 158 patients (87 female, age 50‐89) with mild AD collected in the Marguerite RoAD trial of gantenerumab in mild AD (NCT02051608) and 132 cognitively unimpaired adults (88 female, age 56‐90) from ADNI. We investigated the within‐ and between‐subjects’ variability in five brain networks (Sensory Motor, Cerebellar, Visual, Default Mode and Cognitive Control), inferred from the two groups using a Bayesian probabilistic model (PROFUMO, Harrison‐Smith‐2015; Harrison‐Woolrich‐2020). We computed spatial maps, BOLD amplitude changes, and spatial (temporal) functional connectivity between‐ and within‐networks for each subject. Those metrics were compared between groups using T‐tests. In AD patients we used linear models to investigate associations of the extracted metrics with CSF markers (Amyloid Beta 42, p‐Tau217, pTAU/Abeta 1‐42 ratio and Neurogranin) and cognitive scores (ADAS‐Cog 13, MMSE and ADCS‐ADL), while controlling for age, sex and MRI‐scanner type. All results were corrected for multiplicity using FDR.ResultOn average the signal amplitude was lower in the Cognitive Control and the Sensory Motor (p &lt; 0.0001) networks in AD patients compared to cognitively unimpaired adults. Interestingly, in AD patients the lower amplitude observed in the cognitive control network was associated with cognitive decline (β = 0.02, p = 0.01). Moreover, significant associations were observed in AD patients between lower signal amplitude and higher CSF levels of ABeta 42 (β = ‐0.02, p = 0.036) and cognitive decline (β = 0.02, p = 0.008) (Fig.2). AD group showed on average reduced functional connectivity compared to the healthy one. Furthermore, the within‐AD patients’ analysis showed weak between‐ and strong within‐networks connectivity (T‐test, q &lt; 0.05, Fig.1).ConclusionIn patients with mild AD, the signal amplitude and connectivity in the cognitive control and DMN networks were associated with both CSF level of ABeta42 and cognitive scores.

Reproducibility of cerebral perfusion measurements using BOLD delay.

BOLD delay is an emerging, noninvasive method for assessing cerebral perfusion that does not require the use of intravenous contrast agents and is thus particularly suited for longitudinal monitoring. In this study, we assess the reproducibility of BOLD delay using data from 136 subjects with normal cerebral perfusion scanned on two separate occasions with scanners, sequence parameters, and intervals between scans varying between subjects. The effects of various factors on the reproducibility of BOLD delay, defined here as the differences in BOLD delay values between the scanning sessions, were investigated using a linear mixed model. Reproducibility was additionally assessed using the intraclass correlation coefficient of BOLD delay between sessions. Reproducibility was highest in the posterior cerebral artery territory. The mean BOLD delay test-retest difference after accounting for the aforementioned factors was 1.2 s (95% CI=1.0 to 1.4s). Overall, BOLD delay shows good reproducibility, but care should be taken when interpreting longitudinal BOLD delay changes that are either very small or are located in certain brain regions.

重复垂钓对鲫幼鱼易钓性和能量代谢及个性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 重复垂钓对鲫幼鱼易钓性和能量代谢及个性的影响 DOI: 10.5846/stxb202106201635 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31300341);重庆市自然科学基金项目(cstc2021jcyj-msxm0498);重庆市教委科学技术研究项目(KJQN201900540, KJQN202000539) Effects of repeated angling on vulnerability to angling, energy metabolism and personality of juvenile crucian carp (Carassius auratus) Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:先捕后放是一种重要的鱼类资源保护策略和渔业管理手段。经历先捕后放的被钓鱼类个体的生理与行为会发生变化。当这些个体再次面对人工垂钓诱饵时,可能会呈现更加谨慎的摄饵或鱼钩回避行为。为考察重复垂钓对鱼类易钓性、能量代谢和个性的影响,本研究以鲤科鱼类鲫(Carassius auratus)幼鱼为实验对象,在(25.3±0.1)℃水温条件下对垂钓组和对照组进行3次的能量代谢(标准代谢率,SMR;最大代谢,MMR)和个性(勇敢性、活跃性)测定。其中,垂钓组需进行垂钓实验,而对照组不进行任何垂钓操作。研究发现:(1)重复垂钓显著降低鲫幼鱼的垂钓率,但明显增加单尾平均垂钓时间和整体死亡率。(2)重复垂钓降低鲫幼鱼的体重、肥满度、SMR、MMR、代谢空间(AS)和相对代谢空间(FAS),但整体上不影响勇敢性和活跃性。(3)在测定Ⅰ中,高易钓性个体的体长和开阔区运动时间比大于低易钓性个体,但前者的肥满度小于后者。然而,在测定Ⅱ和Ⅲ中,高易钓性个体的形态参数、能量代谢、个性(勇敢性和活跃性)与低易钓性个体并无差异。研究表明:重复垂钓明显降低鲫幼鱼的易钓性,并且种内个体易钓性的变化方向不尽相同;重复垂钓对鲫幼鱼的形态和有氧代谢能力产生负面影响,可能降低了其用于运动、生长和消化等生理功能的代谢潜能。 Abstract:Catch and release is very popular as fish conservation strategy and fisheries management. The individuals who experience catch and release will have substantial changes in their physiology and behavior. When these individuals are faced with artificial bait again, they may show more cautious bait-taking or hook avoidance behavior. In order to investigate the effects of the repeated angling on vulnerability to angling, energy metabolism and personality of the Cyprinidae, juvenile crucian carp (Carassius auratus) was used for the animal model in our study. The morphology, metabolic rate (e.g., standard metabolic rate, SMR; the maximum metabolic rate, MMR) and personality (e.g., activity and boldness) of both the angling and control group were measured three times at (25.3±0.1) ℃. The individuals of the angling group were subjected to an angling experiment at each trial while fish in the control group did not experience any angling operation. The results show that the angling rate decreased significantly and the average individual angling time increased significantly as the increased of angling times. Repeated angling resulted in a higher death rate in the angling group compared to the control group. The body mass, condition factor, SMR, MMR, aerobic scope, and factorial aerobic scope were significantly decreased by the repeated angling in the angling group compared to the control group, but there were no changes in boldness and activity after the repeated angling. During the first test, high vulnerability to angling phenotype (HVA) had larger body length and movement time in open area, lower condition factor compared to low vulnerability to angling phenotype (LVA). However, during the second and third test, no difference in morphology parameters, energy metabolism, and personality (e.g., boldness, activity) could be detected between the HVA and LVA. Our study suggests that the repeated angling reduces the vulnerability to angling in juvenile crucian carp, and the change direction in vulnerability to angling are different among groupmates with the angling group. Repeated angling decreases aerobic scope of the juvenile crucian fish, which may reduce potential metabolic scope for physiological functions such as exercise, growth and digestion, and ultimately reduce the survival fitness of the individual. 参考文献 相似文献 引证文献

Urbanization increases fluctuating asymmetry and affects behavioral traits of a common grasshopper.

Urbanization has a major impact on biodiversity. For many organisms, the urbanization process means environmental stress caused by fragmentation and increased temperatures in cities and atmospheric, soil, light, and noise pollution. Such environmental stress can influence both the morphology and behavior of animals. Hence, individuals might be selected for survival-facilitating traits under high pressures in urban areas. The specific impact of urbanization on insect behavior is still largely unexplored. We studied the impact of urbanization on one of the most common grasshopper species in Germany, Chorthippus biguttulus, by comparing morphological and behavioral traits of individuals sampled from grasslands with low, medium, and high urbanization levels. We first investigated whether urbanization as a stressor affected body size and fluctuating asymmetry in the locomotor organs. Next, we examined whether urbanization induced changes in the individuals' boldness and activity. Our results showed that fluctuating asymmetry of grasshoppers' locomotory organs increased more than twofold with urbanization level. Further, individuals' boldness and walking activity increased from areas with low to high urbanization levels. Our results indicate strong responses of grasshoppers in terms of morphology and behavior to the urban environment. To compensate for urbanization effects on arthropod populations, management strategies need to be developed that maintain ecological processes and reduce environmental stress in urban areas.

A modeling framework for determining modulation of neural-level tuning from non-invasive human fMRI data

Many neuroscience theories assume that tuning modulation of individual neurons underlies changes in human cognition. However, non-invasive fMRI lacks sufficient resolution to visualize this modulation. To address this limitation, we developed an analysis framework called Inferring Neural Tuning Modulation (INTM) for “peering inside” voxels. Precise specification of neural tuning from the BOLD signal is not possible. Instead, INTM compares theoretical alternatives for the form of neural tuning modulation that might underlie changes in BOLD across experimental conditions. The most likely form is identified via formal model comparison, with assumed parametric Normal tuning functions, followed by a non-parametric check of conclusions. We validated the framework by successfully identifying a well-established form of modulation: visual contrast-induced multiplicative gain for orientation tuned neurons. INTM can be applied to any experimental paradigm testing several points along a continuous feature dimension (e.g., direction of motion, isoluminant hue) across two conditions (e.g., with/without attention, before/after learning).

The End of Ambition: The United States and the Third World in the Vietnam Era

The End of Ambition: The United States and the Third World in the Vietnam Era

DIFFERENCES IN BOLD MRI SIGNAL INTENSITY BETWEEN HYPERTENSIVE PATIENTS AND HEALTHY VOLUNTEERS

Objective: An increased sympathetic tone is associated with the initiation and maintenance of most forms of arterial hypertension. Background activity of a core network of neurons in the brain and brainstem is supposed to be important for long-term blood pressure control. Imaging techniques such as blood oxygen level dependant magnetic resonance imaging (BOLD MRI) are now capable of detecting changes in oxygenation within the brain using blood oxygen levels. So far, the BOLD fMRI signal intensity changes provoked by a cold pressor test (CPT) have not been compared between hypertensive patients (HT) and normotensive subjects (NT). The primary objective was to compare the signal intensity changes in HT and NT participants. Design and method: This was a prospective case-controlled study. A 7 tesla MRI was used for fMRI acquisition. BOLD MRI signal intensity changes during a cold pressure test and during rest were analyzed using statistical parametric mapping (SPM) for whole brain analysis. The connectivity CONN toolbox was used to analyze functional networks. Results: 30 NT subjects (age 34 ± 10 (mean ± SD), BMI 23 ± 2 kg/m2, systolic blood pressure (SBP) 117 ± 10 mm Hg and diastolic blood pressure (DBP) 71 ± 9 mm Hg) and 16 HT patients (age 46.5 ± 13, BMI 27 ± 3 kg/m2, SBP 148 ± 11 mm Hg and DBP 92 ± 6 mm Hg) were enrolled. The CPT increased the SBP by 21 ± 20 (median ± SD) and 25 ± 24 mm Hg in NT and HT, respectively, and the DBP by 20 ± 19 (NT) and 19 ± 17 (HT) mm Hg. BOLD fMRI signal intensity increased significantly in NT but not in HT. The pattern of resting state connectivity was different between NT and HT, with a decreased global connectivity in HT. Conclusions: BOLD fMRI signal intensity responses to CPT test were less pronounced in HTA patients compared to NT. The different response to stress may be secondary to different neuronal activity pattern during the resting state between the two groups as suggested by connectivity analysis.

Measurement of CSF pulsation from EPI-based human fMRI

It is recently discovered that the glymphatic system and meningeal lymphatic system are the primary routes for the clearance of brain waste products. The CSF flow is part of these systems, facilitating the clearance procedure. Nonetheless, the relationship between CSF flow and brain functional activity has been underexplored. To investigate CSF dynamics and functional brain activity simultaneously, recent studies have proposed a CSF inflow index measured on edge slices (CSFedge) of echo-planar imaging (EPI) based functional magnetic resonance imaging (fMRI), however, it lacks the quantitative aspect of the CSF pulsation. We proposed a new method for quantifying CSF pulsation (CSFpulse) based on an interslice CSF pulsation model in the 4th ventricle of EPI-based fMRI. The proposed CSFpulse successfully detected the higher CSF flow during the resting state than the typical task states (visual and motor) (p<.05), which is consistent with previous studies based on phase contrast (PC) MRI and CSF volume MRI, while it was not detected in CSFedge based indices or baseline CSF signals in various regions of interest (ROIs). Moreover, CSFpulse demonstrated dynamic functional changes in CSF pulsation: it decreased during the activation-on blocks while it increased during the activation-off blocks. CSFpulse significantly correlated with stroke volume measured using PC MRI, a standard method for CSF pulsation quantification, under the same functional state, while CSFedge based indices or CSF ROIs showed no correlation with the PC MRI stroke volume. Lastly, the correlation of CSFpulse with global BOLD was weaker than that of CSFedge, suggesting that CSFpulse may reflect distinct CSF physiological information that is less affected by global BOLD effects. Based on these results, the proposed CSFpulse provides CSF pulsatility information more accurately in a quantitative manner than CSFedge based indices from the recent CSF studies or the conventional ROI-based analysis. In addition to the high correlation with PC MRI, CSFpulse is much faster than PC MRI and provides information of functional brain activations simultaneously, advantageous over PC MRI or CSF volume MRI. Accordingly, the suggested CSFpulse can be used for investigating intra-subject functional changes in BOLD and CSF pulsation simultaneously and inter-subject CSF pulsation variations based on conventional EPI-based fMRI, which warrants further investigation.

Tracking the Temporal Footprint Effect of Thermonociception and Denervation on the Brain's Pain Matrix: fMRI and BOLD Study in Rats.

ObjectivePain constitutes an essential alarm for preserving the organism’s integrity. Damage to the nervous system produces a pathological condition known as neuropathic pain.PurposeBlood oxygenation level-dependent (BOLD) and functional magnetic resonance imaging (fMRI) have been widely used to map neuroanatomy and the active regions of interest (ROI) of nociceptive processing. Our study explored the brain’s BOLD response in rats after thermal noxious stimulation, immediately after sciatic nerve damage and during 75 minutes after surgical lesion of the sciatic nerve.MethodsNine male Wistar rats were tested; the experiments were performed on a 7-Tesla /21-cm Varian Agilent system. This approach allowed, for the first time, to measure in vivo the BOLD changes in brain regions involved with the pain process: cingulated (ACC), somatosensory (S1), and insular cortices (IC), as well as thalamus (Th) and ventral tegmental area (VTA) related with acute thermal pain and during the early stages of sciatic denervation that produce neuropathic pain.ResultsDuring thermonociception scan, all subjects showed BOLD activation in the ROIs determined as ACC, S1, Th, IC and VTA. After denervation, these regions continued to show activation with a slow decrement in intensity for the duration of the experiment. The results suggest that these brain structures are overactive during the genesis of neuropathic pain.ConclusionThe study shows for the first time continuous activation of the pain matrix following an acute thermal nociceptive stimulus followed by neuropathic damage. These results have given insight into the early stages of the development of neuropathic pain in vivo.