Statistical Mapping Research Articles

Increased Delta and Theta Power Density in Sickle Cell Disease Individuals with Chronic Pain Secondary to Hip Osteonecrosis: A Resting-State Eeg Study.

Identify the presence of a dysfunctional electroencephalographic (EEG) pattern in individuals with sickle cell disease (SCD) and hip osteonecrosis, and assess its potential associations with depression, anxiety, pain severity, and serum levels of brain-derived neurotrophic factor (BDNF). In this cross-sectional investigation, 24 SCD patients with hip osteonecrosis and chronic pain were matched by age and sex with 19 healthy controls. Resting-state EEG data were recorded using 32 electrodes for both groups. Power spectral density (PSD) and peak alpha frequency (PAF) were computed for each electrode across Delta, Theta, Alpha, and Beta frequency bands. Current Source Density (CSD) measures were performed utilizing the built-in Statistical nonparametric Mapping Method of the LORETA-KEY software. Our findings demonstrated that SCD individuals exhibited higher PSD in delta and theta frequency bands when compared to healthy controls. Moreover, SCD individuals displayed increased CSD in delta and theta frequencies, coupled with decreased CSD in the alpha frequency within brain regions linked to pain processing, motor function, emotion, and attention. In comparison to the control group, depression symptoms, and pain intensity during hip abduction were positively correlated with PSD and CSD in the delta frequency within the parietal region. Depression symptoms also exhibited a positive association with PSD and CSD in the theta frequency within the same region, while serum BDNF levels showed a negative correlation with CSD in the alpha frequency within the left insula. This study indicates that individuals with SCD experiencing hip osteonecrosis and chronic pain manifest a dysfunctional EEG pattern characterized by the persistence of low-frequency PSD during a resting state. This dysfunctional EEG pattern may be linked to clinical and biochemical outcomes, including depression symptoms, pain severity during movement, and serum BDNF levels.

Emissions of pesticides in the European Union: a new regional-level dataset

We present a European Union (EU)-wide dataset of estimated quantities of active substances of plant protection product applied on crops (also called “emissions”). Our estimates are derived from data reported by eight EU countries and extrapolated to encompass all EU regions using regression models. These models consider both climate and agricultural land use data. This allows us to spatially represent pesticide use at NUTS Level 3 of the European statistical mapping units, and within various agricultural land cover classes in each region. We compare our estimates with aggregated data provided by EUROSTAT and with independent, detailed data for the United Kingdom, highlighting an error typically within one order of magnitude. Our estimates can provide insights into the distribution and patterns of pesticide use in the EU around the year 2015. The estimate is most reliable for Western and Southern Europe. Outside these regions, data scarcity makes extrapolation more uncertain, potentially limiting the ability to accurate depict regional variations in pesticide use.

Genome- and Transcriptome-wide Association Studies to Discover Candidate Genes for Diverse Root Phenotypes in Cultivated Rice

Root system architecture plays a crucial role in nutrient and water absorption during rice production. Genetic improvement of the rice root system requires elucidating its genetic control. Genome-wide association studies (GWASs) have identified genomic regions responsible for rice root phenotypes. However, candidate gene prioritization around the peak region often suffers from low statistical power and resolution. Transcriptomics enables other statistical mappings, such as transcriptome-wide association study (TWAS) and expression GWAS (eGWAS), which improve candidate gene identification by leveraging the natural variation of the expression profiles. To explore the genes responsible for root phenotypes, we conducted GWAS, TWAS, and eGWAS for 12 root phenotypes in 57 rice accessions using 427,751 single nucleotide polymorphisms (SNPs) and the expression profiles of 16,901 genes expressed in the roots. The GWAS identified three significant peaks, of which the most significant peak responsible for seven root phenotypes (crown root length, crown root surface area, number of crown root tips, lateral root length, lateral root surface area, lateral root volume, and number of lateral root tips) was detected at 6,199,732 bp on chromosome 8. In the most significant GWAS peak region, OsENT1 was prioritized as the most plausible candidate gene because its expression profile was strongly negatively correlated with the seven root phenotypes. In addition to OsENT1, OsEXPA31, OsSPL14, OsDEP1, and OsDEC1 were identified as candidate genes responsible for root phenotypes using TWAS. Furthermore, a cis-eGWAS peak SNP was detected for OsDjA6, which showed the eighth strongest association with lateral root volume in the TWAS. The cis-eGWAS peak SNP for OsDjA6 was in strong linkage disequilibrium (LD) with a GWAS peak SNP on the same chromosome for lateral root volume and in perfect LD with another SNP variant in a putative cis-element at the 518 bp upstream of the gene. These candidate genes provide new insights into the molecular breeding of root system architecture.

Associations of plasma GFAP, NfL, and p‐tau231 with early‐onset Alzheimer’s Disease pathology

AbstractBackgroundIncreased levels of glial fibrillary acidic protein (GFAP), neurofilament light (NfL), and phosphorylated tau 231 (p‐tau231) in plasma have been associated with late‐onset Alzheimer’s Disease (AD). The impact of these biomarkers in early‐onset AD (EOAD) is unclear and the novel plasma biomarker, p‐tau231, has not been studied in this population. We aimed to demonstrate the effect of each biomarker on EOAD pathology by investigating their associations with amyloid burden, tau burden, and gray matter density (GMD).Method183 EOAD participants from the Longitudinal EOAD study with available baseline plasma GFAP, NfL, p‐tau231, MRI, amyloid PET, and tau PET data were included (mean age = 58.7, 55.2% female, 54.1% APOE‐e4 carrier, mean MMSE = 21.9). Voxel‐wise multiple linear regression models of amyloid PET, tau PET, and T1‐weighted MRI images yielded statistical maps with GFAP, NfL, or p‐tau231 as predictors. Covariates were hierarchically added: Model 1: age, sex; Model 2: age, sex and APOE‐e4; Model 3: age, sex, APOE‐e4 and MMSE. All models are displayed at a family‐wise error adjustment of p<.05.ResultHigher levels of GFAP, NfL, and p‐tau231 were significantly associated with greater amyloid burden and tau burden. Higher levels of GFAP and NfL were also significantly associated with lower GMD. No significant associations were found for p‐tau231 and GMD (Figures 1, 2 & 3). When controlling for APOE‐e4 carrier status, the effect of GFAP on amyloid burden was no longer significant (Figure 1). After additionally controlling for MMSE, the effects of NfL and p‐tau231 on amyloid burden were no longer significant, while the effects of all three biomarkers on tau burden were reduced but remained significant. In terms in of GMD, the effect of NfL survived correction for dementia severity, while the effect of GFAP did not.ConclusionThese results suggest that all three plasma biomarkers show stronger associations with neurodegeneration (cortical atrophy and/or tau burden) than with amyloid burden. Furthermore, this study highlights the importance of plasma biomarkers for AD diagnosis and monitoring. Future work should investigate longitudinal associations and the mediational role of APOE‐e4 and dementia severity.

Females Derive Greater Neuroprotective Benefits from Social Connectedness than Males

AbstractBackgroundSocial connectedness is associated with better cognitive performance among older adults. Previously, we found that bridging (access to an expansive network of diverse and loosely connected individuals) and bonding (close and supportive relationships to familiar others) associated with preserved gray matter density (GMD). We sought to examine whether sex modulates these relationships in the Social Networks and Alzheimer’s Disease study (SNAD).MethodWe analyzed baseline data of 176 SNAD participants (58 male, 118 female; 117 cognitively‐unimpaired, 59 cognitively‐impaired; average age 68.57+/‐12.26 years). Bridging and bonding metrics were collected via in‐person interviews. We ran analyses in the pooled sample split by sex. Demographics and biomarkers between sexes were compared. Correlations between MRI regions of interest and bridging and bonding in males and females were performed. Voxel‐wise covaried for age, education, and intracranial volume in SPM12 yielded statistical maps for males and females which were corrected for family‐wise errors at p<0.01.ResultTable 1 shows demographic and biomarker comparisons between males and females. In females greater social bridging was significantly associated with (left p = 0.004, right p<0.001), as well as left frontal lobe thickness (p = 0.002), putamen (p = 0.011), and thalamus volumes (p = 0.002). No significant associations were observed for social bridging in males. Greater social bonding was significantly associated with preserved right frontal pole (p = 0.018) and caudal anterior cingulate thickness (p = 0.017) in females and greater right orbitofrontal thickness (p<0.001) in males (Figure 1).Our 3D voxel‐wise regression maps showed that in females greater social bridging was associated with preserved GMD of the frontal, temporal and parietooccipital lobes, while males showed no significant associations (Figure 2). In females greater social bonding was associated with preserved GMD in the lateral temporal and parietal lobes, while in males the associations were localized to the medial frontal and right orbitofrontal lobe (Figure 2).ConclusionWomen compared to men showed stronger effects of social enrichment on GMD and subcortical structures. Social bridging and bonding were associated to different brain regions in males and females. These results suggest that females may have a greater social‐based protection against neurodegeneration compared to their male counterparts.

Females Derive Greater Neuroprotective Benefits from Social Connectedness than Males

AbstractBackgroundSocial connectedness is associated with better cognitive performance among older adults. Previously, we found that bridging (access to an expansive network of diverse and loosely connected individuals) and bonding (close and supportive relationships to familiar others) associated with preserved gray matter density (GMD). We sought to examine whether sex modulates these relationships in the Social Networks and Alzheimer’s Disease study (SNAD).MethodWe analyzed baseline data of 176 SNAD participants (58 male, 118 female; 117 cognitively‐unimpaired, 59 cognitively‐impaired; average age 68.57+/‐12.26 years). Bridging and bonding metrics were collected via in‐person interviews. We ran analyses in the pooled sample split by sex. Demographics and biomarkers between sexes were compared. Correlations between MRI regions of interest and bridging and bonding in males and females were performed. Voxel‐wise covaried for age, education, and intracranial volume in SPM12 yielded statistical maps for males and females which were corrected for family‐wise errors at p<0.01.ResultTable 1 shows demographic and biomarker comparisons between males and females. In females greater social bridging was significantly associated with (left p = 0.004, right p<0.001), as well as left frontal lobe thickness (p = 0.002), putamen (p = 0.011), and thalamus volumes (p = 0.002). No significant associations were observed for social bridging in males. Greater social bonding was significantly associated with preserved right frontal pole (p = 0.018) and caudal anterior cingulate thickness (p = 0.017) in females and greater right orbitofrontal thickness (p<0.001) in males (Figure 1). Our 3D voxel‐wise regression maps showed that in females greater social bridging was associated with preserved GMD of the frontal, temporal and parietooccipital lobes, while males showed no significant associations (Figure 2). In females greater social bonding was associated with preserved GMD in the lateral temporal and parietal lobes, while in males the associations were localized to the medial frontal and right orbitofrontal lobe (Figure 2).ConclusionWomen compared to men showed stronger effects of social enrichment on GMD and subcortical structures. Social bridging and bonding were associated to different brain regions in males and females. These results suggest that females may have a greater social‐based protection against neurodegeneration compared to their male counterparts.

Statistical Mapping of Magnetic Topology at Venus

AbstractDespite Venus having insignificant intrinsic magnetic fields, the magnetic connectivity between the solar wind and the Venus ionosphere, or magnetic topology, is not as simple as expected and is also important for characterizing the Venus space environment. This study provides a technique combining superthermal electron energy and pitch angle distributions to infer up to 6 subtypes of magnetic topology at Venus. This enables us to determine magnetic topology with automated procedures using the Venus Express (VEx) observations from May 2006 to November 2014. We find that the draped topology (both ends of a field line not connected to the collisional ionosphere) is the dominant topology in the near‐Venus space environment, >70%, except at low altitudes close to the ionosphere. The open (a field line connected to both the solar wind and the collisional ionosphere) and closed (a field line connected only to the collisional ionosphere) topologies make up 20%–30% on average of the magnetotail and up to 50% at low altitudes. This study provides the first characterization of the statistical distributions of different magnetic topologies at Venus.

EEG-Based Cortical Alterations in Individuals With Chronic Knee Pain Secondary to Osteoarthritis: A Cross-sectional Investigation

Chronic painful knee osteoarthritis (OA) is a disabling physical health condition. Alterations in brain responses to arthritic changes in the knee may explain persistent pain. This study investigated source localized, resting-state electroencephalography activity and functional connectivity in people with knee OA, compared to healthy controls. Adults aged 44 to 85 years with knee OA (n = 37) and healthy control (n = 39) were recruited. Resting-state electroencephalography was collected for 10 minutes and decomposed into infraslow frequency (ISF) to gamma frequency bands. Standard low-resolution electromagnetic brain tomography statistical nonparametric maps were conducted, current densities of regions of interest were compared between groups and correlation analyses were performed between electroencephalography (EEG) measures and clinical pain and functional outcomes in the knee OA group. Standard low-resolution electromagnetic brain tomography nonparametric maps revealed higher (P = .006) gamma band activity over the right insula (RIns) in the knee OA group. A significant (P < .0001) reduction in ISF band activity at the pregenual anterior cingulate cortex, whereas higher theta, alpha, beta, and gamma band activity at the dorsal anterior cingulate cortex, pregenual anterior cingulate cortex, the somatosensory cortex, and RIns in the knee OA group were identified. ISF activity of the dorsal anterior cingulate cortex was positively correlated with pain measures and psychological distress scores. Theta and alpha activity of RIns were negatively correlated with pain interference. In conclusion, aberrations in infraslow and faster frequency EEG oscillations at sensory discriminative, motivational-affective, and descending inhibitory cortical regions were demonstrated in people with chronic painful knee OA. Moreover, EEG oscillations were correlated with pain and functional outcome measures. PerspectiveThis study confirms alterations in the rsEEG oscillations and its relationship with pain experience in people with knee OA. The study provides potential cortical targets and the EEG frequency bands for neuromodulatory interventions for managing chronic pain experience in knee OA.

Benefits of a mosaic approach for assessing cortical atrophy in individual multiple sclerosis patients.

Cortical gray matter (GM) atrophy plays a central role in multiple sclerosis (MS) pathology. However, it is not commonly assessed in clinical routine partly because a number of methodological problems hamper the development of a robust biomarker to quantify GM atrophy. In previous work, we have demonstrated the clinical utility of the "mosaic approach" (MAP) to assess individual GM atrophy in the motor neuron disease spectrum and frontotemporal dementia. In this study, we investigated the clinical utility of MAP in MS, comparing this novel biomarker to existing methods for computing GM atrophy in single patients. We contrasted the strategies based on correlations with established biomarkers reflecting MS disease burden. We analyzed T1-weighted MPRAGE magnetic resonance imaging data from 465 relapsing-remitting MS patients and 89 healthy controls. We inspected how variations of existing strategies to estimate individual GM atrophy ("standard approaches") as well as variations of MAP (i.e., different parcellation schemes) impact downstream analysis results, both on a group and an individual level. We interpreted individual cortical disease burden as single metric reflecting the fraction of significantly atrophic data points with respect to the control group. In addition, we evaluated the correlations to lesion volume (LV) and Expanded Disability Status Scale (EDSS). We found that the MAP method yielded highest correlations with both LV and EDSS as compared to all other strategies. Although the parcellation resolution played a minor role in terms of absolute correlations with clinical variables, higher resolutions provided more clearly defined statistical brain maps which may facilitate clinical interpretability. This study provides evidence that MAP yields high potential for a clinically relevant biomarker in MS, outperforming existing methods to compute cortical disease burden in single patients. Of note, MAP outputs brain maps illustrating individual cortical disease burden which can be directly interpreted in daily clinical routine.

9 Interoceptive Attentiveness: Evidence for Neurofunctional Correlates from an EEG Source Localization Study

Objective:Since seminal work by Sherrington, the term interoception refers to the ability to sense modifications of internal bodily states as opposed to the ability to sense stimuli coming from outside the body itself. Despite conceptual changes regarding the afferent signals subserving this type of inner perception, the core of this definition is still valid and widely accepted. The critical contribution of internal state perception to self-regulation as well as higher-order cognitive processes has led to the development of psychometric and observational measures trying to capture individual interoceptive skills, focusing especially on the ability to orient attention to internal sensations. Nonetheless, despite growing interest in interoceptive attention (IAtt), little is known about neurofunctional correlates of our ability to redirect attention to internal sensations and consciously process them, as well as on potential objective biomarkers of IAtt performance.Participants and Methods:This study included 36 volunteers who were asked to complete a heart-beat counting task (HCT), a common IAtt task. During both resting-state and HCT, central electrophysiological (EEG, 32 electrodes) and cardiovascular activity (ECG, I lead) were recorded. eLORETA was used to estimate both task-related and resting-state intracortical sources of EEG signals. Statistical non-parametric mapping (SnPM) was used to draw and investigate contrast statistical maps between rest- and task-related cortical current density.Results:Contrast analyses comparing HCT and resting revealed higher Alpha frequency current density estimates during the task, with primary cortical seed in the right parahippocampal gyrus. Regression analyses of the relationship between IAtt scores and task-related changes in intracortical current density during HCT revealed a positive relationship for the Beta frequency bands with primary cortical seeds in the cingulate gyrus and insula. Conclusions:Findings add to available literature by further specifying the electrophysiological signature of interoceptive attentiveness, and suggest specific electrophysiological markers as objective measures of individual IAtt skills.

58 Right Anterior Temporal Lobe Atrophy is Associated with Informant-Reported Socioemotional Dysfunction in Patients with Frontotemporal and Early Onset Alzheimer's Dementia

Objective:Abnormalities in social and emotional behavior are the major diagnostic criteria for behavioral variant frontotemporal dementia (bvFTD). Investigators have attributed their behavioral disturbances to disease in mesial prefrontal and related networks, such as the salience network. This study examined the main neural correlates of informant-reported socioemotional dysfunction among patients with bvFTD compared to those with early-onset (before age 65) Alzheimer's Disease (EOAD).Participants and Methods:Participants included 13 patients with bvFTD and their caregivers and 18 patients with EOAD and their caregivers. The caregivers consisted of a spouse, family member, or other informant who resided with the patient. They completed the informant-based Socioemotional Dysfunction Scale (SDS), a 40-item scale which rates common disturbances in social and emotional behavior on a five-point Likert scale (1-5). The patients underwent magnetic resonance imaging (MRI) with tensor-based morphometry (TBM) analysis of the 3D T1-weighted MRI scans. Computations of mean Jacobian values within select regions of interest (ROIs) in frontal and temporal lobes generated numerical summaries of regional volumes, and voxel-wise regressions created 3D statistical maps of the association between tissue volume and SDS total scores. Statistical analyses included independent samples t-tests group differences in ROIs and SDS scores, Pearson correlations between SDS scores and brain volumes, and multiple regression of ROIs with SDS scores and group as predictor variables.Results:Compared to the EOAD group, the bvFTD group had significantly higher SDS scores (p &lt; .001; d = 2.24), smaller frontal lobe volumes (specifically dorsolateral-prefrontal cortex, p = .003; d = 1.24), and larger temporal lobe volumes (specifically hippocampus, p = .014; d = 0.979). Within the bvFTD group, higher SDS scores were associated with a smaller right anterior temporal lobe (ATL; p = .005; r = -.729), especially the lateral ATLs (p = .002; r = -.776), and a smaller bilateral orbitofrontal cortex (OFC; p = .016; r = -.650). In contrast, within the EOAD group, higher SDS scores were associated with a smaller right parietal cortex (p = .030; r = .542). In the entire sample (both bvFTD and EOAD), higher SDS scores was associated with a smaller lateral ATL volumes (p = .019; r = -.431). Regression analyses confirmed that SDS score predicted lateral ATL volume (p = .041; b = -.262) after controlling for diagnosis (p &lt; .001; b = -.692).Conclusions:These findings are consistent with greater socioemotional dysfunction, smaller frontal, and larger mesial temporal regions in bvFTD, when compared to EOAD. The findings, however, suggest that positively disturbed socioemotional behavior in bvFTD, as reported by caregivers, results from involvement of the right temporal lobe and the lateral temporal region, with further contribution from disease in OFC. The association of SDS scores and ATL volume across diagnostic groups suggests that this region is instrumental in socioemotional functioning and that the SDS may have diagnostic value in distinguishing the "right-temporal variant" of bvFTD.

Clinical application of a fixed reference line in the ultrasound quantitative diagnosis of female pelvic organ prolapse

ObjectiveThis study explored using an improved ultrasound (US) for quantitative evaluation of the degree of pelvic organ prolapse(POP).DesignA transluminal probe was used to standardize ultrasound imaging of pelvic floor organ displacements. A US reference line was fixed between the lower edge of the pubic symphysis and the central axis of the pubic symphysis at a 30°counterclockwise angle.MethodPoints Aa, Ba, C and Bp on pelvic organ prolapse quantification (POP-Q) were then compared with the points on pelvic floor ultrasound (PFUS).ResultsOne hundred thirteen patients were included in the analysis of the standard US plane. Correlations were good in the anterior and middle compartments (PBN:Aa, ICC = 0.922; PBB:Ba, ICC = 0.923; and PC:C, ICC = 0.925), and Bland-Altman statistical maps corresponding to the average difference around the 30°horizontal line were close to 0. Correlations were poor in the posterior compartment (PRA:Bp, ICC = 0.444). However, eight (7.1%) cases of intestinal hernia and 21 (18.6%) cases of rectocele were diagnosed.ConclusionsIntroital PFUS using an intracavitary probe, which is gently placed at the introitus of the urethra and the vagina, may be accurately used to evaluate organ displacement. The application of a 30°horizontal line may improve the repeatability of the US diagnosis of POP.

Group analysis and classification of working memory task conditions using electroencephalogram cortical currents during an n-back task.

Electroencephalographic studies of working memory have demonstrated cortical activity and oscillatory representations without clarifying how the stored information is retained in the brain. To address this gap, we measured scalp electroencephalography data, while participants performed a modified n-back working memory task. We calculated the current intensities from the estimated cortical currents by introducing a statistical map generated using Neurosynth as prior information. Group analysis of the cortical current level revealed that the current amplitudes and power spectra were significantly different between the modified n-back and delayed match-to-sample conditions. Additionally, we classified information on the working memory task conditions using the amplitudes and power spectra of the currents during the encoding and retention periods. Our results indicate that the representation of executive control over memory retention may be mediated through both persistent neural activity and oscillatory representations in the beta and gamma bands over multiple cortical regions that contribute to visual working memory functions.

Dynamics of pesticides in surface water bodies by applying data mining to spatiotemporal big data. A case study for the Puglia Region

Surface water pollution by pesticides is a primary concern in many parts of the world. Therefore, an effective monitoring program is essential to assess the environmental state of aquatic ecosystems and evaluate mitigation strategies.In the Puglia Region (southern Italy), a complex seasonal monitoring program for detecting pesticide residues in water was initiated in 2018 and is still underway (over four years). The program was based on site-specific assessments and identified 170 Plant Protection Products (PPPs) to identify residues in the surface water bodies of Puglia.In this context, the present work aims to analyse pesticide data obtained from the regional monitoring of rivers over four years using a multidisciplinary approach, which includes statistical methods, data mining, and mapping tools to extract as much information as possible.To this end, data mining was applied to identify the prevalent mixtures of pesticide residues found at the monitoring stations and correlate these results with possible causative factors. The results showed that surface water bodies are subject to different pressures derived from the massive use of PPPs, and several seasonal and territorial-related factors were identified to be strictly correlated with pesticide concentration results. Nine main PPPs mixtures have been identified in the Puglia River. Glyphosate, AMPA, imidacloprid, and azoxystrobin represent the main residues detected in the surface aquatic environments regarding the amount and frequency revealed.The methodological approach proposed in the present work can represent a good “model study” to be used by researchers to interpret water quality trends and data variability from long-term monitoring studies. Moreover, our results can significantly support the decision-making process and implementation of environmental mitigation measures by optimising the results of complex monitoring programs.

Should perception of emotions be classified according to threat detection rather than emotional valence? An updated meta-analysis for a whole-brain atlas of emotional faces processing.

Human navigation of social interactions relies on the processing of emotion on faces. This meta-analysis aimed to produce an updated brain atlas of emotional face processing from whole-brain studies based on a single emotional face-viewing paradigm (PROSPERO CRD42022251548). We conducted a systematic literature search of Embase, MEDLINE and PsycINFO from May 2008 to October 2021. We used seed-based d mapping with permutation of subject images to conduct a quantitative meta-analysis of functional neuroimaging contrasts between emotional (e.g., angry, happy) and neutral faces. We conducted agglomerative hierarchical clustering of meta-analytic map contrasts of emotional faces relative to neutral faces. We investigated lateralization of emotional face processing. From 5549 studies identified, 55 data sets (1489 healthy participants) met our inclusion criteria. Relative to neutral faces, we found extensive activation clusters by fearful faces in the right inferior temporal gyrus, right fusiform area, left putamen and amygdala, right parahippocampalgyrus and cerebellum; we found smaller activation clusters by angry faces in the right cerebellum and right middle temporal gyrus (MTG) and by disgusted faces in the left MTG. Happy and sad faces did not reach statistical significance. Clustering analyses showed similar activation patterns of fearful and angry faces; activation patterns of happy and sad faces showed the least correlation with other emotional faces. Emotional face processing was predominantly left-lateralized in the amygdala and anterior insula, and right-lateralized in the ventromedial prefrontal cortex. Reliance on discretized effect sizes based on peak coordinate location instead of statistical brain maps, and the varying level of statistical threshold reporting from original studies, could lead to underdetection of smaller clusters of activation. Processing of emotional faces appeared to be oriented toward identifying threats on faces, from highest (i.e., angry or fearful faces) to lowest level (i.e., happy or sad faces), with a more complex lateralization pattern than previously theorized. Emotional faces may be processed in latent grouping but organized by threat content rather than emotional valence.

Statistical distribution of mirror-mode-like structures in the magnetosheaths of unmagnetized planets – Part 2: Venus as observed by the Venus Express spacecraft

Abstract. In this series of papers, we present statistical maps of mirror-mode-like (MM) structures in the magnetosheaths of Mars and Venus and calculate the probability of detecting them in spacecraft data. We aim to study and compare them with the same tools and a similar payload at both planets. We consider their dependence on extreme ultraviolet (EUV) solar flux levels (high and low). The detection of these structures is done through magnetic-field-only criteria, and ambiguous determinations are checked further. In line with many previous studies at Earth, this technique has the advantage of using one instrument (a magnetometer) with good time resolution, facilitating comparisons between planetary and cometary environments. Applied to the magnetometer data of the Venus Express (VEX) spacecraft from May 2006 to November 2014, we detect structures closely resembling MMs lasting in total more than 93 000 s, corresponding to about 0.6 % of VEX's total time spent in Venus's plasma environment. We calculate MM-like occurrences normalized to the spacecraft's residence time during the course of the mission. Detection probabilities are about 10 % at most for any given controlling parameter. In general, MM-like structures appear in two main regions: one behind the shock and the other close to the induced magnetospheric boundary, as expected from theory. For solar maximum, the active region behind the bow shock is further inside the magnetosheath, near the solar minimum bow shock location. The ratios of the observations during solar minimum and maximum are slightly dependent on the depth ΔB/B of the structures; deeper structures are more prevalent at solar maximum. A dependence on solar EUV (F10.7) flux is also present, where at higher F10.7 flux the events occur at higher values than the daily-average value of the flux. The main dependence of the MM-like structures is on the condition of the bow shock: for quasi-perpendicular conditions, the MM occurrence rate is higher than for quasi-parallel conditions. However, when the shock becomes “too perpendicular” the chance of observing MM-like structures reduces again. Combining the plasma data from the Ion Mass Analyser (IMA on board Venus Express) with the magnetometer data shows that the instability criterion for MMs is reduced in the two main regions where the structures are measured, whereas it is still enhanced in the region between these two regions, implying that the generation of MMs is transferring energy from the particles to the field. With the addition of the Electron Spectrometer (ELS on board Venus Express) data, it is possible to show that there is an anti-phase between the magnetic field strength and the density for the MM-like structures. This study is Part 2 of a series of papers on the magnetosheaths of Mars and Venus.

Region-specific changes in brain activity and memory after continuous positive airway pressure therapy in obstructive sleep apnea: a pilot high-density electroencephalography study.

Limited channel electroencephalography (EEG) investigations in obstructive sleep apnea (OSA) have revealed deficits in slow wave activity (SWA) and spindles during sleep and increased EEG slowing during resting wakefulness. High-density EEG (Hd-EEG) has also detected local parietal deficits in SWA (delta power) during NREM. It is unclear whether effective continuous positive airway pressure (CPAP) treatment reverses regional SWA deficits, and other regional sleep and wake EEG abnormalities, and whether any recovery relates to improved overnight memory consolidation. A clinical sample of men with moderate-severe OSA underwent sleep and resting wake recordings with 256-channel Hd-EEG before and after 3 months of CPAP. Declarative and procedural memory tasks were administered pre- and post-sleep. Topographical spectral power maps and differences between baseline and treatment were compared using t-tests and statistical nonparametric mapping (SnPM). In 11 compliant CPAP users (5.2 ± 1.1 hours/night), total sleep time did not differ after CPAP but N1 and N2 sleep were lower and N3 was higher. Centro-parietal gamma power during N3 increased and fronto-central slow spindle activity during N2 decreased (SnPM < 0.05). No other significant differences in EEG power were observed. When averaged specifically within the parietal region, N3 delta power increased after CPAP (p = 0.0029) and was correlated with the change in overnight procedural memory consolidation (rho = 0.79, p = 0.03). During resting wakefulness, there were trends for reduced delta and theta power. Effective CPAP treatment of OSA may correct regional EEG abnormalities, and regional recovery of SWA may relate to procedural memory improvements in the short term.

Improved weight bearing during gait at 6 weeks post-surgery with an angle stable locking system after distal tibial fracture

BackgroundFunctional recovery after intramedullary nailing of distal tibial fractures can be monitored using ipsilateral vertical ground reaction forces (vGRF), giving insight into recovery of patients’ gait symmetry. Previous work compared patient cohorts to healthy controls, but it remains unclear if these metrics can identify treatment-based differences in return to function post-surgery. Research questionIs treatment of a distal tibial fracture with intramedullary nailing with an angle stable locking system (ASLS) associated with higher ipsilateral vGRF and improved symmetry compared to conventional intramedullary nailing at an early time point? MethodsThirty-nine patients treated with ASLS intramedullary nailing were retrospectively compared to thirty-nine patients with conventional locking. vGRFs were collected at 1, 6, 12, 26, and 52 weeks post-surgery during standing and gait. Discrete metrics of ipsilateral vGRF (maximal force, impulse) and asymmetry were compared between treatments at each time point. Time-scale comparisons of ipsilateral vGRF and lower limb asymmetry were additionally performed for gait trials. Mann-Whitney Test or a two-way analysis of variance tested discrete comparisons; statistical non-parametric mapping tested time-scale data between treatment groups. ResultsDuring gait, ASLS-treated patients applied more load on the operated limb (17–38% stance, p = 0.015) and consequently loaded limbs more symmetrically (8–37% stance, p = 0.008) during the loading response at 6 weeks post-surgery compared to conventional IM treatment. Discrete measures of symmetry at the same time point identified treatment-based differences in maximal force (p = 0.039) and impulse (p = 0.012), with ASLS-treated patients exhibiting more symmetry. No differences were identified in gait trials at later time points nor from all standing trials. SignificanceDuring the initial loading response of gait, increased ipsilateral vGRF and improved weightbearing symmetry were identified in ASLS patients at 6 weeks post-surgery compared to conventional IM nailing. Early and objective metrics of dynamic movement are suggested to identify treatment-based differences in functional recovery.

Independent component analysis: a reliable alternative to general linear model for task-based fMRI.

Functional magnetic resonance imaging (fMRI) is a valuable tool for the presurgical evaluation of patients undergoing neurosurgeries. Although many pre-processing steps have been modified according to advances in recent years, statistical analysis has remained largely the same since the first days of fMRI. In this study, we examined the ability of Independent Component Analysis (ICA) to separate the activation of a language task in fMRI, and we compared it with the results of the General Lineal Model (GLM). Sixty patients undergoing evaluation for brain surgery due to various brain lesions and/or epilepsy and 20 control subjects completed an fMRI language mapping protocol that included three tasks, resulting in 259 fMRI scans. Depending on brain lesion characteristics, patients were allocated to (1) static/chronic not-expanding lesions (Group 1) and (2) progressive/expanding lesions (Group 2). GLM and ICA statistical maps were evaluated by fMRI experts to assess the performance of each technique. In the control group, ICA and GLM maps were similar without any superiority of either technique. In Group 1 and Group 2, ICA performed statistically better than GLM, with a p-value of < 0.01801 and < 0.0237, respectively. This indicated that ICA performs as well as GLM when the subjects are able to cooperate well (less movement, good task performance), but ICA could outperform GLM in the patient groups. When both techniques were combined, 240 out of 259 scans produced reliable results, showing that the sensitivity of task-based fMRI can be increased when both techniques are integrated with the clinical setup. ICA may be slightly more advantageous, compared to GLM, in patients with brain lesions, across the range of pathologies included in our population and independent of symptoms chronicity. Our findings suggest that GLM analysis may be more susceptible to brain activity perturbations induced by a variety of lesions or scanner-induced artifacts due to motion or other factors. In our research, we demonstrated that ICA is able to provide fMRI results that can be used in surgery, taking into account patient and task-wise aspects that differ from those when fMRI is used in research.

Coherent-Error Threshold for Surface Codes from Majorana Delocalization.

Statistical mechanics mappings provide key insights on quantum error correction. However, existing mappings assume incoherent noise, thus ignoring coherent errors due to, e.g., spurious gate rotations. We map the surface code with coherent errors, taken as X or Z rotations (replacing bit or phase flips), to a two-dimensional (2D) Ising model with complex couplings, and further to a 2D Majorana scattering network. Our mappings reveal both commonalities and qualitative differences in correcting coherent and incoherent errors. For both, the error-correcting phase maps, as we explicitly show by linking 2D networks to 1D fermions, to a Z_{2}-nontrivial 2D insulator. However, beyond a rotation angle ϕ_{th}, instead of a Z_{2}-trivial insulator as for incoherent errors, coherent errors map to a Majorana metal. This ϕ_{th} is the theoretically achievable storage threshold. We numerically find ϕ_{th}≈0.14π. The corresponding bit-flip rate sin^{2}(ϕ_{th})≈0.18 exceeds the known incoherent threshold p_{th}≈0.11.