Hemodynamic Signals Research Articles

A model-based microfluidic feedback control system for replicating blood pressure and wall shear stress on the inner surface of common carotid artery induced by external counterpulsation

Replicating the hemodynamic signal of endothelial cells (ECs) induced by an external counterpulsation (ECP) using a microfluidic system is crucial for further studying EC mechanobiology associated with ECP theraphy. However, there is currently no suitable method to construct a microfluidic system that can accurately reproduce the hemodynamic signals including blood pressure (BP) and wall shear stress (WSS) on the inner surface of the common carotid artery following ECP intervention. In this study, we propose a model-based approach to build a microfluidic feedback control system (MFCS), which consists of a microfluidic chip and a pump system (PS) to resolve the above issue. An integrated transfer function (TF) model formed by the expression of the input impedance and the proportion integration differentiation (PID) controller is used to design the microfluidic chip and PS. The performance of the proposed MFCS for replicating the hemodynamic signals is evaluated by flow-field analysis, and calcium ion (Ca2+) response experiments are conducted to validate the functionality of the proposed MFCS for investigating mechanobiological mechanisms.

Association between autonomic dysfunction, 12-year mortality and 10-year incident cardiovascular disease

Abstract Background Standing from a supine position requires a co-ordinated response in peripheral and central haemodynamic signals to protect the brain and body from sudden drops in blood pressure (BP) and has previously been shown to be an important measure of neuro-cardiovascular health (1-3). Previous studies have found an association between BP and heart rate recovery (HRR) to standing with all-cause mortality, cardiovascular disease and other health outcomes (4-8). However, almost all of these studies have exclusively investigated the association of consensus-defined HR/BP phenotypes measured at specific timepoints during standing. Purpose We hypothesised that assessing information from the entire haemodynamic response to orthostasis - instead of discrete timepoints or consensus definitions - may uncover novel associations between BP/HR responses to active stand and neuro-cardiovascular health in older adults. This may afford better physiological understanding of the longitudinal relationships between the response to standing and both Cardiovascular Disease (CVD) and mortality. Methods We used functional Principal Components Analysis (FPCA) to examine the determinants of variability in the complete haemodynamic response to active stand and examine which components were related to mortality and incident CVD in >4500 community-dwelling adults aged 50+. Results Figure 1 shows the mean response curve according to mortality status and Figure 2 the mean curve for participants free of CVD at baseline who later have CVD vs those who remain CVD-free during 10 year follow-up. All-cause mortality was associated with functional principal components which discriminate higher baseline HR, blunted HR peak and impaired HRR up to ~25 seconds after standing. Components that discriminated high baseline and impaired recovery of SBP from the post-stand nadir to 60 seconds post stand were also associated with all-cause mortality. This association remained even after covariate adjustment. Interestingly, neither baseline SBP nor orthostatic hypotension (OH) were associated with mortality. Components which discriminate high baseline and blunted HR peak; elevated stroke volume index and impaired recovery of DBP from ~25 seconds post stand were associated with 10-year incident CVD. Conclusions To our knowledge this is the first study to incorporate data driven information over the entire trace of the haemodynamic response to standing to investigate associations with incident CVD and mortality. The fact that components which discriminated high BP and impaired recovery of BP were associated with 12-year mortality and 10-year incident CVD when traditional summary measures of OH and baseline BP were not; suggests that incorporating information across the entire response to standing allows for richer and more flexible associations with health outcomes to be uncovered and allows for a better understanding of the underlying physiology leading to such associations.Figure 1:Mean trace of Mortality StatusFigure 2:Mean Trace of CVD Status

Mitochondrial DNA Alterations in Glioblastoma and Current Therapeutic Targets.

Metabolic reprogramming within tumor cells involves a shift towards either glycolysis or mitochondrial respiration, depending on the stage of tumor progression. Consequently, irreversible dysfunction of the mitochondria is considered a crucial mechanism driving the progression mechanism. While numerous mutations in mitochondrial DNA (mtDNA) have been identified across various tumor types, including glioblastoma, many studies have been limited in the scope, focusing on small segments of mtDNA or utilizing sequencing methods with restricted sensitivity. As a result, several potentially significant mtDNA mutations may have been underestimated, along with their heteroplasmic states, which play a crucial role in determining the phenotypic impact of mtDNA mutation. Although both somatic and germline mtDNA mutations have been observed in different tumor types, research on the mtDNA mutations linked to glioblastoma remains scarce. The mitochondrial genome encodes thirteen protein-coding genes that are essential for the proper functioning of respiratory complex chains. Alterations in mitochondrial function manifest at various levels, including structural and functional changes, impacting mitogenic, hemodynamic, bioenergetic, and apoptotic signaling pathways. These alterations often signify a reduced efficiency of the oxidative phosphorylation system and energy production in tumor cells. As the crucial role of mitochondrial dysfunction in glioma development grows, mitochondria have emerged as promising targets for therapy aimed at overcoming chemoresistance and eliminating cancer cells. This brief review outlines the association between mtDNA alteration and glioblastoma, as well as the current advancements in therapeutic strategies targeting mtDNA alterations.

Changes in brain connectivity and neurovascular dynamics during dexmedetomidine-induced loss of consciousness.

Elucidating the neurophysiological changes underlying loss and recovery of consciousness is a fundamental question in neuroscience. Here, we analyze magnetic resonance imaging data collected across multiple time-points to characterize how the human brain's connectivity and neurovascular dynamics change as it transitions from wakefulness to dexmedetomidine-induced unconsciousness, and early-stage recovery of consciousness. During hypnosis, brain regions become less functionally synchronized to each other; they attain a smaller number of functional configurations compared to wakefulness, and display functional connectivity patterns that are more similar to the underlying structural connectivity. Furthermore, cerebral blood flow significantly decreases across the whole brain, and less metabolically demanding low frequency fluctuations in the hemodynamic signal become more prominent. Collectively, loss of consciousness is accompanied by widespread connectivity and neurovascular changes in the brain, characteristic of less metabolically demanding dynamics.

A novel non-invasive method for measuring the spatial kinematic behavior of cardiomyocytes regulated by mechanical cues

The intact heart undergoes complex and multiscale mechanical remodeling processes. Measuring rhythmic spatial contraction of the myocardium is crucial for assessing mechanical durability and the ability to mount coordinated responses to pressure, electrical, and hemodynamic signals. However, current cardiomyocyte measurement platforms typically focus on action potentials and XY-plane contractions. Therefore, effective evaluation methods for studying the influence of mechanical cues on the spatial dynamic contraction of cardiomyocytes are still lacking. In this study, we developed a topographic guiding combined with an optical spatial motion tracking method to provide controllable mechanical stimulation for inducing directed contraction of cardiomyocytes and obtaining spatial motion information in vitro. We first performed a detailed investigation of cell connections and cytoskeleton orientations by combining the proposed method with immunofluorescence. Next, spatial constrictive modes, features, and key parameters of microgroove-guided cardiomyocytes were studied. Finally, the three-dimensional (3D) motions of the cardiomyocytes at different positions on the structure were compared. We found that the XY-plane contraction of cardiomyocytes typically has only one direction and shows a significant phase delay compared to the axial motion. In addition, cardiomyocytes located near the edges of the microgrooves were restricted by stronger mechanical forces, resulting in a significant height change reduction. These results provide new perspectives for structural and functional research on cardiomyocytes under long-term mechanical regulation. Overall, this study provides a highly precise and convenient method for evaluating the 3D cardiomyocyte motion under mechanical induction. This method is expected to enhance understanding of cardiomyocyte development and be useful for research on cardiac mechanics and functions.

Change of Cerebral Hemodynamic Signals during the Process of Swallowing Water, Acetic Acid Solution and Salt Solution in Healthy Adults: An fNIRS Study.

The aim of this preliminary study was to investigate the similarities and differences in cortical activation patterns during the swallowing of water, acetic acid solution and salt solution in healthy adults using functional near-infrared spectroscopy (fNIRS). Eighteen right-handed healthy adults were recruited and fNIRS was used to measure changes in concentrations of oxygenated hemoglobin (HbO2) and deoxygenated hemoglobin (HbR) in 35 channels during the swallowing of water, acetic acid solution and salt solution. The task-based experiment used a block-design in which participants alternated between resting blocks of 30 s and task blocks (swallowing water, acetic acid solution, or salt solution) of 30 s, repeated six times. Participants remained still during the resting blocks and performed a swallowing action every 6 s during the task blocks. Data preprocessing was conducted using NirSpark software and statistical analyses were performed using either one-sample or paired t-tests to compare differences in cortical activation in healthy participants between swallowing a water and acetic acid solution, as well as swallowing a water and salt solution. Compared to the resting state, nine brain regions, including primary somatosensory cortex (S1), primary motor cortex (M1), dorsolateral prefrontal cortex (DLPFC), Wernicke's area, premotor cortex (PMC), supplementary motor area (SMA), inferior frontal cortex (IFC), orbitofrontal cortex (OFC) and frontopolar area, were commonly activated during the process of swallowing water, acetic acid solution, and salt solution. The DLPFC, Broca's area, PMC and SMA showed higher activation levels during the swallowing of acetic acid solution when compared to swallowing water, with statistically significant differences (p < 0.05). The frontopolar area and OFC exhibited higher activation during the swallowing of salt solution when compared to water, also with statistically significant differences (p < 0.05). Multiple brain regions were activated during the swallowing of water, acetic acid solution and salt solution in healthy adults. Moreover, swallowing acetic acid solution leads to stronger activation of DLPFC, Broca's area, PMC and SMA, while swallowing salt solution leads to stronger activation of the frontopolar area and OFC.

Widespread Autonomic Physiological Coupling Across the Brain-Body Axis.

The brain is closely attuned to visceral signals from the body's internal environment, as evidenced by the numerous associations between neural, hemodynamic, and peripheral physiological signals. We show that these brain-body co-fluctuations can be captured by a single spatiotemporal pattern. Across several independent samples, as well as single-echo and multi-echo fMRI data acquisition sequences, we identify widespread co-fluctuations in the low-frequency range (0.01 - 0.1 Hz) between resting-state global fMRI signals, neural activity, and a host of autonomic signals spanning cardiovascular, pulmonary, exocrine and smooth muscle systems. The same brain-body co-fluctuations observed at rest are elicited by arousal induced by cued deep breathing and intermittent sensory stimuli, as well as spontaneous phasic EEG events during sleep. Further, we show that the spatial structure of global fMRI signals is maintained under experimental suppression of end-tidal carbon dioxide (PETCO2) variations, suggesting that respiratory-driven fluctuations in arterial CO2 accompanying arousal cannot explain the origin of these signals in the brain. These findings establish the global fMRI signal as a significant component of the arousal response governed by the autonomic nervous system.

Statistical Complexity Analysis of Neurovascular Coupling with Cognitive Stimulation in Healthy Participants.

Neurovascular coupling (NVC) is the tight relationship between changes in cerebral blood flow and neural activation. NVC can be evaluated non-invasively using transcranial Doppler ultrasound (TCD)-measured changes in brain activation (cerebral blood velocity [CBv]) using different cognitive tasks and stimuli. This study used a novel approach to analyzing CBv changes occurring in response to 20 tasks from the Addenbrooke's Cognitive Examination III in 40 healthy individuals. The novel approach compared various information entropy families (permutation, Tsallis, and Rényi entropy) and statistical complexity measures based on disequilibrium. Using this approach, we found the majority of the attention, visuospatial, and memory tasks from the Addenbrooke's Cognitive Examination III that showed lower statistical complexity values when compared with the resting state. On the entropy-complexity (HC) plane, a receiver operating characteristic curve was used to distinguish between baseline and cognitive tasks using the area under the curve. Best area under the curve values were 0.91 ± 0.04, p = .001, to distinguish between resting and cognitively active states. Our findings show that brain hemodynamic signals captured with TCD can be used to distinguish between resting state (baseline) and cognitive effort (stimulation paradigms) using entropy and statistical complexity as an alternative method to traditional techniques such as coherent averaging of CBv signals. Further work should directly compare these analysis methods to identify the optimal method for analyzing TCD-measured changes in NVC.

Cortical and subcortical brain networks predict prevailing heart rate.

Resting heart rate may confer risk for cardiovascular disease (CVD) and other adverse cardiovascular events. While the brainstem's autonomic control over heart rate is well established, less is known about the regulatory role of higher level cortical and subcortical brain regions, especially in humans. This study sought to characterize the brain networks that predict variation in prevailing heart rate in otherwise healthy adults. We used machine learning approaches designed for complex, high-dimensional data sets, to predict variation in instantaneous heart period (the inter-heartbeat-interval) from whole-brain hemodynamic signals measured by fMRI. Task-based and resting-state fMRI, as well as peripheral physiological recordings, were taken from two data sets that included extensive repeated measurements within individuals. Our models reliably predicted instantaneous heart period from whole-brain fMRI data both within and across individuals, with prediction accuracies being highest when measured within-participants. We found that a network of cortical and subcortical brain regions, many linked to visceral motor and visceral sensory processes, were reliable predictors of variation in heart period. This adds to evidence on brain-heart interactions and constitutes an incremental step toward developing clinically applicable biomarkers of brain contributions to CVD risk.

The Effects of Acute Stress on Evoked-cortical Connectivity through Wide-field Optical Mapping of Neural and Hemodynamic Signals.

A single exposure to stress can induce functional changes in neurons, potentially leading to acute stress disorder or post-traumatic stress disorder. In this study, we used in vivo wide-field optical mapping to simultaneously measure neural calcium signals and hemodynamic responses over the whole cortical area. We found that cortical mapping to whisker stimuli was altered under acute stress conditions. In particular, callosal projections in the anterior cortex (primary/secondary motor, somatosensory forelimb cortex) relative to barrel field (S1BF) of somatosensory cortex were weakened. On the contrary, the projections in posterior cortex relative to S1BF were mostly unchanged or were only occasionally strengthened. In addition, changes in intra-cortical connection were opposite to those in inter-cortical connection. Thus, the S1BF connections to the anterior cortex were strengthened while those to the posterior cortex were weakened. This suggests that the well-known barrel cortex projection route was enhanced. In summary, our in vivo wide-field optical mapping study indicates that a single acute stress can impact whole-brain networks, affecting both neural and hemodynamic responses.

On the influence of the vascular architecture on Gradient Echo and Spin Echo BOLD fMRI signals across cortical depth: a simulation approach based on realistic 3D vascular networks.

GE-BOLD contrast stands out as the predominant technique in functional MRI experiments for its high sensitivity and straightforward implementation. GE-BOLD exhibits rather similar sensitivity to vessels independent of their size at submillimeter resolution studies like those examining cortical columns and laminae. However, the presence of nonspecific macrovascular contributions poses a challenge to accurately isolate neuronal activity. SE-BOLD increases specificity towards small vessels, thereby enhancing its specificity to neuronal activity, due to the effective suppression of extravascular contributions caused by macrovessels with its refocusing pulse. However, even SE-BOLD measurements may not completely remove these macrovascular contributions. By simulating hemodynamic signals across cortical depth, we gain insights into vascular contributions to the laminar BOLD signal. In this study, we employed four realistic 3D vascular models to simulate oxygen saturation states in various vascular compartments, aiming to characterize both intravascular and extravascular contributions to GE and SE signals, and corresponding BOLD signal changes, across cortical depth at 7T. Simulations suggest that SE-BOLD cannot completely reduce the macrovascular contribution near the pial surface. Simulations also show that both the specificity and signal amplitude of BOLD signals at 7T depend on the spatial arrangement of large vessels throughout cortical depth and on the pial surface.

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.

Two-photon imaging of excitatory and inhibitory neural response to infrared neural stimulation.

Pulsed infrared neural stimulation (INS, 1875nm) is an emerging neurostimulation technology that delivers focal pulsed heat to activate functionally specific mesoscale networks and holds promise for clinical application. However, little is known about its effect on excitatory and inhibitory cell types in cerebral cortex. Estimates of summed population neuronal response time courses provide a potential basis for neural and hemodynamic signals described in other studies. Using two-photon calcium imaging in mouse somatosensory cortex, we have examined the effect of INS pulse train application on hSyn neurons and mDlx neurons tagged with GCaMP6s. We find that, in anesthetized mice, each INS pulse train reliably induces robust response in hSyn neurons exhibiting positive going responses. Surprisingly, mDlx neurons exhibit negative going responses. Quantification using the index of correlation illustrates responses are reproducible, intensity-dependent, and focal. Also, a contralateral activation is observed when INS applied. In sum, the population of neurons stimulated by INS includes both hSyn and mDlx neurons; within a range of stimulation intensities, this leads to overall excitation in the stimulated population, leading to the previously observed activations at distant post-synaptic sites.

Non-invasive detection of cardiac arrhythmias using photoplethysmography signals

Abstract Cardiac arrhythmias (CAs) are associated with critical heart-related complications such as stroke or heart failure. Because of the intermittent and asymptomatic presentation of some CAs in their early stages, the screening remains limited using traditional methods based on ECG. Recent advances in photoplethysmography (PPG) have revealed substantial potential for wearable devices to detect CAs within large populations. Although PPG has demonstrated efficiency in discriminating atrial fibrillation (AF) from normal sinus rhythm, it remains unclear whether AF detection methods remains effective in the presence of CAs other than AF. In this study, we applied a recurrent neural network on a dataset containing eight different types of CAs (Table 1). The classifier processes sequences of interbeat intervals (IBIs) as input and discriminates between normal and abnormal rhythms. The algorithm was evaluated on 64 patients (45 males and 19 females , with a mean age of 55.9 ± 16.0) undergoing a diagnostic or therapeutic electrophysiological procedure. This dataset includes simultaneous recordings of PPG signals from a wrist-bracelet and 12-lead ECG, with the latter used as the gold-standard for annotating cardiac rhythms. The classifier achieved 84% accuracy, 77% sensitivity and 88% specificity in detecting abnormal rhythms. Table 1 shows that AF (99.6%), atrial tachycardia (100%) and AVRT (96.4%) were well classified as abnormal rhythm, whereas the reliability of the detection decreased for atrial flutter (65.4%), atrial or ventricular bigeminy (72.4%) and ventricular tachycardia (80.2%). Undetected abnormal rhythms were often characterized by a rather regular rhythm (illustrated by VT in Figure 1) and CAs for which PPG heartbeat detection was initially not optimal (Bigeminy in Figure 1). In conclusion, this study shows the capability of PPG-based technology to detect various CAs extending beyond AF. It highlights the merits and limitations of IBI-based detection of abnormal rhythms, highlighting the need for a better comprehension of the peripheral hemodynamic signature of CAs.

Structural and Functional Characteristics of the Dorsolateral Prefrontal Cortex in Schizophrenia Spectrum Disorders and Their Associations with Onset Age

Background: the dorsolateral prefrontal cortex (DLPFC) is one of the latest brain structures to mature during the ontogeny, and its structural and functional abnormalities play an important role in the pathogenesis of schizophrenia. As schizophrenia spectrum disorders usually start before the complete brain maturation and their earlier onset is coupled with worse prognosis, we suggested that earlier illness onset is related to more pronounced aberrations of the DLPFC. The aim of study was to analyze the associations of the onset age of schizophrenia spectrum disorders with structural and functional characteristics of the DLPFC that differentiated patients with schizophrenia spectrum disorders from healthy controls. Patients and methods: male patients with a diagnosis of schizophrenia spectrum disorders (n = 82) and healthy controls (n = 86) underwent structural MRI and functional resting-state fMRI. Cortical thickness and whole-brain functional connectivity of the DLPFC as well as local coherence and amplitude of low-frequency fluctuations of haemodynamic signal in the DLPFC were analyzed. Results: patients demonstrated a decreased gray matter thickness in the DLPFC bilaterally along with aberrant (predominantly decreased) functional connectivity of the DLPFC with other brain structures in each hemisphere. These measures were not associated with the age of illness onset. Conclusions: structural and functional abnormalities revealed in this study coincide with conventional view on the DLPFC as one of the key regions in schizophrenia spectrum disorders pathogenesis, however, these aberrations were not related to the age of psychosis onset. Possible interpretations of our results and limitations of the study are discussed in the article.

Changes in the visual areas of the cerebral cortex in children with left-sided anisometropic amblyopia according to structural MRI and resting-state fMRI

Thanks to the development of structural and functional magnetic resonance imaging (MRI) methods, in recent decades there has been a lot of research aimed at elucidating brain abnormalities caused by amblyopia. In the cases of this prevalent visual disorder, the anomalies causing decreased visual acuity and other visual disabilities cannot be determined by standard ophthalmologic examination. Since there are several types of this disorder that are fundamentally different in etiology, it is natural to suggest the presence of different types of corresponding brain abnormalities. In this regard, before obtaining a general picture of the pathogenesis of amblyopia, studies conducted on groups of specially selected similar patients are very important. This paper presents the results of a study of school-age children with left-sided anisometropic amblyopia. In the patients investigated, MRI data revealed interhemispheric differences in the thickness of the lateral occipital cortex, and resting-state fMRI revealed interhemispheric differences in the local coherence of the hemodynamic signal within 17 Brodmann area and in the functional connectivity between 17 and 18+19 Brodmann areas. The data obtained contribute to the creation of a general MRI database on the pathophysiology of amblyopia, help clarify some controversial issues and indicate the advisability of using resting-state fMRI in ophthalmology.

Cortical Networks Relating to Arousal Are Differentially Coupled to Neural Activity and Hemodynamics.

Even in the absence of specific sensory input or a behavioral task, the brain produces structured patterns of activity. This organized activity is modulated by changes in arousal. Here, we use wide-field voltage imaging to establish how arousal relates to cortical network voltage and hemodynamic activity in spontaneously behaving head-fixed male and female mice expressing the voltage-sensitive fluorescent FRET sensor Butterfly 1.2. We find that global voltage and hemodynamic signals are both positively correlated with changes in arousal with a maximum correlation of 0.5 and 0.25, respectively, at a time lag of 0 s. We next show that arousal influences distinct cortical regions for both voltage and hemodynamic signals. These include a broad positive correlation across most sensory-motor cortices extending posteriorly to the primary visual cortex observed in both signals. In contrast, activity in the prefrontal cortex is positively correlated to changes in arousal for the voltage signal while it is a slight net negative correlation observed in the hemodynamic signal. Additionally, we show that coherence between voltage and hemodynamic signals relative to arousal is strongest for slow frequencies below 0.15 Hz and is near zero for frequencies >1 Hz. We finally show that coupling patterns are dependent on the behavioral state of the animal with correlations being driven by periods of increased orofacial movement. Our results indicate that while hemodynamic signals show strong relations to behavior and arousal, these relations are distinct from those observed by voltage activity.

Imaging bioluminescence by detecting localized haemodynamic contrast from photosensitized vasculature.

Bioluminescent probes are widely used to monitor biomedically relevant processes and cellular targets in living animals. However, the absorption and scattering of visible light by tissue drastically limit the depth and resolution of the detection of luminescence. Here we show that bioluminescent sources can be detected with magnetic resonance imaging by leveraging the light-mediated activation of vascular cells expressing a photosensitive bacterial enzyme that causes the conversion of bioluminescent emission into local changes in haemodynamic contrast. In the brains of rats with photosensitized vasculature, we used magnetic resonance imaging to volumetrically map bioluminescent xenografts and cell populations virally transduced to express luciferase. Detecting bioluminescence-induced haemodynamic signals from photosensitized vasculature will extend the applications of bioluminescent probes.

Charitable crowdfunding donation-intention estimation depending on emotional project images using fNIRS-based functional connectivity.

Charitable fundraising increasingly relies on online crowdfunding platforms. Project images of charitable crowdfunding use emotional appeals to promote helping behavior. Negative emotions are commonly used to motivate helping behavior because the image of a happy child may not motivate donors to donate as willingly. However, some research has found that happy images can be more beneficial. These contradictory results suggest that the emotional valence of project imagery and how fundraisers frame project images effectively remain debatable. Thus, we compared and analyzed brain activation differences in the prefrontal cortex governing human emotions depending on donation decisions using functional near-infrared spectroscopy, a neuroimaging device. We advance existing theory on charitable behavior by demonstrating that little correlation exists in donation intentions and brain activity between negative and positive project images, which is consistent with survey results on donation intentions by victim image. We also discovered quantitative brain hemodynamic signal variations between donors and nondonors, which can predict and detect donor mental brain functioning using functional connectivity, that is, the statistical dependence between the time series of electrophysiological activity and oxygenated hemodynamic levels in the prefrontal cortex. These findings are critical in developing future marketing strategies for online charitable crowdfunding platforms, especially project images.

PVN predisposes microglia to be susceptible to hemodynamic signals and promote sympathetic excitation in hypertension

Hypertension is usually accompanied with an elevated sympathetic tonicity, but how sympathetic hyperactivity is triggered is not fully understood. Recent advances reveal that microglia-centered neuroinflammation contributes to sympathetic excitation in hypertension. In this study, we performed a temporospatial analysis of microglia at both morphological and transcriptomic levels, and found that microglia in the hypothalamic paraventricular nucleus (PVN) were early responders to hypertensive challenges. PVN is the central hub for maintaining cardiovascular function via regulation of fluid balance and sympathetic outflow. Comprehensive vasculature analyses unveiled that PVN was characterized by high capillary density, thin vessel diameter, and complex vascular topology among brain regions. As such, PVN is susceptible to the penetration of ATP released from the vasculature in response to hemodynamic disturbance after blood pressure increase. ATP ligation to microglial P2Y12 receptor is responsible for the microglial accumulation and activation in the PVN. Both pharmacological blockade and genetic ablation of microglial P2Y12 could substantially restrain blood pressure increase under hypertensive challenge. Together, these findings disclose that a unique vasculature pattern results in the vulnerability of PVN pre-sympathetic neurons to hypertension-associated inflammatory insults, which is mediated by microglia. NSFC82170441. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.