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The ontogeny of linguistic functions in the human brain remains elusive. Although some auditory capacities are described before term, whether and how such immature cortical circuits might process speech are unknown. Here we used functional optical imaging to evaluate the cerebral responses to syllables at the earliest age at which cortical responses to external stimuli can be recorded in humans (28- to 32-wk gestational age). At this age, the cortical organization in layers is not completed. Many neurons are still located in the subplate and in the process of migrating to their final location. Nevertheless, we observed several points of similarity with the adult linguistic network. First, whereas syllables elicited larger right than left responses, the posterior temporal region escaped this general pattern, showing faster and more sustained responses over the left than over the right hemisphere. Second, discrimination responses to a change of phoneme (ba vs. ga) and a change of human voice (male vs. female) were already present and involved inferior frontal areas, even in the youngest infants (29-wk gestational age). Third, whereas both types of changes elicited responses in the right frontal region, the left frontal region only reacted to a change of phoneme. These results demonstrate a sophisticated organization of perisylvian areas at the very onset of cortical circuitry, 3 mo before term. They emphasize the influence of innate factors on regions involved in linguistic processing and social communication in humans.

In functional magnetic resonance imaging, the hemodynamic response function (HRF) is a stereotypical response to local changes in cerebral hemodynamics and oxygen metabolism due to briefly (< 4 s) evoked neural activity. Accordingly, the HRF is often used as an impulse response with the assumption of linearity in data analysis. In cognitive aging studies, it has been very common to interpret differences in brain activation as age‐related changes in neural activity. Contrary to this assumption, however, evidence has accrued that normal aging may also significantly affect the vasculature, thereby affecting cerebral hemodynamics and metabolism, confounding interpretation of fMRI cognitive aging studies. In this study, use was made of a multisensory task to evoke the HRF in ~87% of cerebral cortex in cognitively intact adults with ages ranging from 22 to 75 years. This widespread activation enabled us to investigate age trends in the spatial distributions of HRF characteristics within the majority of cortical gray matter, which we termed as global age trends. The task evoked both positive and negative HRFs, which were characterized using model‐free parameters in native‐space coordinates. We found significant global age trends in the distributions of HRF parameters in terms of both amplitudes (e.g., peak amplitude and contrast‐to‐noise ratio) and temporal dynamics (e.g., full‐width‐at‐half‐maximum). Our findings offer insight into how age‐dependent changes affect neurovascular coupling and show promise for use of HRF parameters as non‐invasive indicators for age‐related pathology. (A) The SAST (speeded audiovisual sequence‐following task) evokes an HRF (hemodynamic response function). (B) HRF parameters such as full‐width‐at‐half‐maximum (FWHM) are calculated. (C) Example HRF parameter maps on native‐space surfaces. (D) Corresponding HRF parameter distributions. (E) Parameter spatial means and standard deviations were correlated with age; R is correlation coefficient.

Interpretation of fMRI data depends on our ability to understand or model the shape of the hemodynamic response (HR) to a neural event. Although the HR has been studied almost since the beginning of fMRI, we are still far from having robust methods to account for the full range of known HR variation in typical fMRI analyses. This paper reviews how the authors and others contributed to our understanding of HR variation. We present an overview of studies that describe HR variation across voxels, healthy volunteers, populations, and dietary or pharmaceutical modulations. We also describe efforts to minimize the effects of HR variation in intrasubject, group, population, and connectivity analyses and the limits of these methods.

The study presents a recursive least-squares estimation method with an exponential forgetting factor for noise removal in functional near-infrared spectroscopy data and extraction of hemodynamic responses (HRs) from the measured data. The HR is modeled as a linear regression form in which the expected HR, the first and second derivatives of the expected HR, a short-separation measurement data, three physiological noises, and the baseline drift are included as components in the regression vector. The proposed method is applied to left-motor-cortex experiments on the right thumb and little finger movements in five healthy male participants. The algorithm is evaluated with respect to its performance improvement in terms of contrast-to-noise ratio in comparison with Kalman filter, low-pass filtering, and independent component method. The experimental results show that the proposed model achieves reductions of 77% and 99% in terms of the number of channels exhibiting higher contrast-to-noise ratios in oxy-hemoglobin and deoxy-hemoglobin, respectively. The approach is robust in obtaining consistent HR data. The proposed method is applied for both offline and online noise removal.

The hemodynamic response function (HRF) represents the transfer function linking neural activity with the functional MRI (fMRI) signal, modeling neurovascular coupling. Since HRF is influenced by non-neural factors, to date it has largely been considered as a confound or has been ignored in many analyses. However, underlying biophysics suggests that the HRF may contain meaningful correlates of neural activity, which might be unavailable through conventional fMRI metrics. Here, we estimated the HRF by performing deconvolution on resting-state fMRI data from a longitudinal sample of 25 healthy controls scanned twice and 44 adults with obsessive-compulsive disorder (OCD) before and after 4-weeks of intensive cognitive-behavioral therapy (CBT). HRF response height, time-to-peak and full-width at half-maximum (FWHM) in OCD were abnormal before treatment and normalized after treatment in regions including the caudate. Pre-treatment HRF predicted treatment outcome (OCD symptom reduction) with 86.4% accuracy, using machine learning. Pre-treatment HRF response height in the caudate head and time-to-peak in the caudate tail were top-predictors of treatment response. Time-to-peak in the caudate tail, a region not typically identified in OCD studies using conventional fMRI activation or connectivity measures, may carry novel importance. Additionally, pre-treatment response height in caudate head predicted post-treatment OCD severity (R = -0.48, P  = 0.001), and was associated with treatment-related OCD severity changes (R = -0.44, P  = 0.0028), underscoring its relevance. With HRF being a reliable marker sensitive to brain function, OCD pathology, and intervention-related changes, these results could guide future studies towards novel discoveries not possible through conventional fMRI approaches like standard BOLD activation or connectivity.

This study explored how the neural efficiency and proficiency worked in athletes with different skill levels from the perspective of effective connectivity brain network in resting state. The deconvolved conditioned Granger causality (GC) analysis was applied to functional magnetic resonance imaging (fMRI) data of 35 elite athletes (EAs) and 42 student‐athletes (SAs) of racket sports as well as 39 normal controls (NCs), to obtain the voxel‐wised hemodynamic response function (HRF) parameters representing the functional segregation and effective connectivity representing the functional integration. The results showed decreased time‐to‐peak of HRF in the visual attention brain regions in the two athlete groups compared with NC and decreased response height in the advanced motor control brain regions in EA comparing to the nonelite groups, suggesting the neural efficiency represented by the regional HRF was different in early and advanced skill levels. GC analysis demonstrated that the GC values within the middle occipital gyrus had a linear trend from negative to positive, suggesting a stepwise “neural proficiency” of the effective connectivity from NC to SA then to EA. The GC values of the inter‐lobe circuits in EA had the trend to regress to NC levels, in agreement with the neural efficiency of these circuits in EA. Further feature selection approach suggested the important role of the cerebral‐brainstem GC circuit for discriminating EA. Our findings gave new insight into the complementary neural mechanisms in brain functional segregation and integration, which was associated with early and advanced skill levels in athletes of racket sports. The neural efficiency represented by regional hemodynamic response function (HRF) was different in early and advanced stages of motor training. The Granger causality (GC) values within the middle occipital gyrus (MOG) had a linear trend from negative to positive, suggesting a stepwise “neural proficiency” of the effective connectivity from normal controls (NC) to student‐athletes (SA) then to elite athletes (EA). While the GC values of the fronto‐parietal and fronto‐occipital circuits in EA had the trend to regress to NC levels, in agreement with the neural efficiency of these circuits in EA. Complementary neural mechanisms in brain functional segregation and integration were associated with different levels of sports experience in fast‐ball athletes.

Objective: To determine the efficacy of intravenous Magnesium Sulphate in attenuating the hemodynamic response, Systolic Blood Pressure, in hypertensive patients undergoing laryngoscopy and endotracheal intubation compared with a Control Group. Study Design: Quasi-experimental study. Place and Duration of Study: Anesthesia Department, Pak Emirates Military Hospital, Rawalpindi Pakistan, from Apr to Oct 2018. Methodology: A total of 110 diagnosed patients of hypertension, taking anti-hypertensive medication, between 30–65 years of age, belonging to either gender, and undergoing elective surgery were enrolled. Patients were given intravenous Magnesium Sulphate (30 mg/kg) in 20 ml normal saline over a period of 03 minutes before induction of general anesthesia while control Group was given 20 ml of normal saline (placebo). Systolic Blood Pressure for both Groups was recorded on a performa by an observer two minutes after intubation. Results: The mean age of patients in treatment Group was 43.95±8.39 years and in control Group, 43.84±8.36 years. Out of 110 patients, 41(37.27%) were males and 69(62.73%) were females. The efficacy of MgSO4 was 16(29.09%) and in control Group, it was 04(7.27%) with p-value of 0.003(<0.05). Conclusion: Intravenous Magnesium Sulphate is efficacious in attenuating hemodynamic response to laryngoscopy and intubation in hypertensive patients.

•By modifying FSCV components, simultaneous fMRI data can be acquired with minimal imaging artifacts.•We detect and quantify evoked dopamine and/or tissue oxygen changes using FSCV during BOLD fMRI.•FSCV-fMRI is used to derive a neurotransmitter-inclusive hemodynamic response function (HRF).•Dopamine-derived HRFs can identify brain regions that encode dopamine release amplitude. The vascular contributions of neurotransmitters to the hemodynamic response are gaining more attention in neuroimaging studies, as many neurotransmitters are vasomodulatory. To date, well-established electrochemical techniques that detect neurotransmission in high magnetic field environments are limited. Here, we propose an experimental setting enabling simultaneous fast-scan cyclic voltammetry (FSCV) and blood oxygenation level-dependent functional magnetic imaging (BOLD fMRI) to measure both local tissue oxygen and dopamine responses, and global BOLD changes, respectively. By using MR-compatible materials and the proposed data acquisition schemes, FSCV detected physiological analyte concentrations with high temporal resolution and spatial specificity inside of a 9.4 T MRI bore. We found that tissue oxygen and BOLD correlate strongly, and brain regions that encode dopamine amplitude differences can be identified via modeling simultaneously acquired dopamine FSCV and BOLD fMRI time-courses. This technique provides complementary neurochemical and hemodynamic information and expands the scope of studying the influence of local neurotransmitter release over the entire brain.

The theoretical foundation of brain-computer interface partly lies in the neural mechanism of motor function plasticity. There has been extensive research on the functional neuroplasticity induced by motor skill training in the human cerebral cortex; however, less is known about the specifics within the cerebellum. The present study employed resting-state functional magnetic resonance imaging (fMRI) data from athletes and matched non-athlete controls to investigate the adaptation of cerebellar functional segregation and integration in athletes who require rapid visual-motor coordination. First, this study utilized a data-driven blind-deconvolution hemodynamic response functions (HRF) retrieval technique to estimate voxel-wise HRF that represent local functional segregation. Second, the study quantified effective connectivity using conditional Granger causality (CGC) analysis as a means of characterizing directed functional integration. Lastly, the logistic regression classification model was applied to evaluating the importance of those significant features in two groups’ comparison. The athletes exhibited greater HRF response heights in the visual-spatial cognitive regions, but lower excitatory/inhibitory effects between these regions and the motor execution areas in the cerebellum when compared to the control group. These findings suggested that there was improved local functional segregation within the visual-spatial cognitive regions, as well as reduced functional integration between these regions and the motor execution areas in the cerebellum among athletes. Our results suggested the antagonistic alterations of cerebellar functional segregation and integration induced by motor skill training, and consequently to accelerate the reaction, movement planning, and execution in athletes who required fast demands of visual-motor coordination. Our findings shed new light on how motor skill training drove neuroplasticity within the cerebellum and offered a deeper understanding of the complementary hypotheses of neural efficiency and neural proficiency that underlay optimal athletic performance.

PurposeCardiac resynchronization therapy (CRT) devices have multiple programmable pacing parameters. The purpose of this study was to determine the best pacing mode, i.e., associated with the greatest acute hemodynamic response, in each patient.MethodsPatients in sinus rhythm and intact atrioventricular conduction were included within 3 months of implantation of devices featuring SyncAV and multipoint pacing (MPP) algorithms. The effect of nominal biventricular pacing using the latest activated electrode (BiV-Late), optimized atrioventricular delay (AVD), nominal and optimized SyncAV, and anatomical MPP was determined by non-invasive measurement of systolic blood pressure (SBP). CRT response was defined as SBP increase > 10% relative to baseline.ResultsThirty patients with left bundle branch block (LBBB) were included. BiV-Late increased SBP compared to intrinsic rhythm (128 ± 21 mmHg vs. 121 ± 22 mmHg, p = 0.0002). The best pacing mode further increased SBP to 140 ± 19 mmHg (p < 0.0001 vs. BiV-Late). The proportion of CRT responders increased from 40% with BiV-Late to 80% with the best pacing mode (p = 0.0005). Compared to BiV-Late, optimized AVD and optimized SyncAV increased SBP (to 134 ± 21 mmHg, p = 0.004, and 133 ± 20 mmHg, p = 0.0003, respectively), but nominal SyncAV and MPP did not. The best pacing mode was variable between patients and was different from nominal BiV-Late in 28 (93%) patients. Optimized AVD was the most frequent best mode, in 14 (47%) patients.ConclusionIn patients with LBBB, the best pacing mode was patient-specific and doubled the magnitude of acute hemodynamic response and the proportion of acute CRT responders compared to nominal BiV-Late pacing.Trial registrationClinicalTrials.gov: NCT03779802