An Examination of the Association Between Subjective Distress and Functional Connectivity During Discarding Decisions in Hoarding Disorder.

BACKGROUND: Individuals with hoarding disorder (HD) demonstrate exaggerated subjective distress and hyperactivation of cingulate and insular cortex regions when discarding personal possessions. No prior study has sought to determine whether this subjective distress is associated with specific profiles of abnormal brain function in individuals with HD. METHODS: We used multimodal canonical correlation analysis plus joint independent component analysis to test whether five hoarding-relevant domains of subjective distress when deciding to discard possessions (anxiety, sadness, monetary value, importance, and sentimental attachment) are associated with functional magnetic resonance imaging-measured whole-brain functional connectivity in 72 participants with HD and 44 healthy controls. RESULTS: Three extracted components differed between HD participants and healthy control subjects. Each of these components depicted an abnormal profile of functional connectivity in HD participants relative to control subjects during discarding decisions, and a specific distress response profile. One component pair showed a relationship between anxiety ratings during discarding decisions and connectivity among the pallidum, perirhinal ectorhinal cortex, and dorsolateral prefrontal cortex. Another component comprised sadness ratings during discarding decisions and connectivity in the pallidum, nucleus accumbens, amygdala, and dorsolateral prefrontal cortex. The third component linked HD brain connectivity in several dorsolateral prefrontal cortex regions with perceived importance ratings during discarding decisions. CONCLUSIONS: The findings indicate that in patients with HD, the subjective intensity of anxiety, sadness, and perceived possession importance is related to abnormal functional connectivity in key frontal and emotional processing brain regions. The findings are discussed in terms of emerging neurobiological models of HD.

Effects of weather and season on human brain volume.

We present an exploratory cross-sectional analysis of the effect of season and weather on Freesurfer-derived brain volumes from a sample of 3,279 healthy individuals collected on two MRI scanners in Hartford, CT, USA over a 15 year period. Weather and seasonal effects were analyzed using a single linear regression model with age, sex, motion, scan sequence, time-of-day, month of the year, and the deviation from average barometric pressure, air temperature, and humidity, as covariates. FDR correction for multiple comparisons was applied to groups of non-overlapping ROIs. Significant negative relationships were found between the left- and right- cerebellum cortex and pressure (t = -2.25, p = 0.049; t = -2.771, p = 0.017). Significant positive relationships were found between left- and right- cerebellum cortex and white matter between the comparisons of January/June and January/September. Significant negative relationships were found between several subcortical ROIs for the summer months compared to January. An opposing effect was observed between the supra- and infra-tentorium, with opposite effect directions in winter and summer. Cohen's d effect sizes from monthly comparisons were similar to those reported in recent psychiatric big-data publications, raising the possibility that seasonal changes and weather may be confounds in large cohort studies. Additionally, changes in brain volume due to natural environmental variation have not been reported before and may have implications for weather-related and seasonal ailments.

Widespread hematite at high latitudes of the Moon.

Hematite (Fe2O3) is a common oxidization product on Earth, Mars, and some asteroids. Although oxidizing processes have been speculated to operate on the lunar surface and form ferric iron-bearing minerals, unambiguous detections of ferric minerals forming under highly reducing conditions on the Moon have remained elusive. Our analyses of the Moon Mineralogy Mapper data show that hematite, a ferric mineral, is present at high latitudes on the Moon, mostly associated with east- and equator-facing sides of topographic highs, and is more prevalent on the nearside than the farside. Oxygen delivered from Earth's upper atmosphere could be the major oxidant that forms lunar hematite. Hematite at craters of different ages may have preserved the oxygen isotopes of Earth's atmosphere in the past billions of years. Future oxygen isotope measurements can test our hypothesis and may help reveal the evolution of Earth's atmosphere.

Neural correlates of non-specific skin conductance responses during resting state fMRI.

Skin conductance responses (SCRs) reliably occur in the absence of external stimulation. However, the neural correlates of these non-specific SCRs have been less explored than brain activity associated with stimulus-elicited SCRs. This study modeled spontaneous skin conductance responses observed during an unstructured resting state fMRI scan in 58 adolescents. A Finite Impulse Response (FIR) fMRI model was used to detect any type of hemodynamic response shape time-locked to non-specific SCRs; the shape of these responses was then carefully characterized. The strongest evidence for signal change was found in several sub-regions of sensorimotor cortex. There also was evidence for engagement of discrete areas within the lateral surfaces of the parietal lobe, cingulate cortex, fronto-insular operculum, and both visual and auditory primary processing areas. The hemodynamic profile measured by FIR modeling clearly resembled an event-related response. However, it was a complex response, best explained by two quickly successive, but opposing neuronal impulses across all brain regions - a brief positive response that begins several seconds prior to the SCR with a much longer negative neuronal impulse beginning shortly after the SCR onset. Post hoc exploratory analyses linked these two hemodynamic response phases to different emotion-related individual differences. In conclusion, this study shows the neural correlates of non-specific SCRs are a widespread, cortical network of brain regions engaged in a complex, seemingly biphasic fashion. This bimodal response profile should be considered in replication studies that attempt to directly link brain activity to possible homeostatic mechanisms or seek evidence for alternative mechanisms.

Reflected Protons in the Lunar Wake and Their Effects on Wake Potentials.

The refilling of the lunar wake is facilitated by the wake ambipolar electric potential arising from the electron pressure gradient. Incident solar wind protons can be reflected by the lunar crustal magnetic fields and the lunar surface on the dayside and repicked up, entering the lunar wake due to their large gyroradii. This burst of positive charges can cause the lunar wake potential to be reduced by hundreds of volts. We utilize over 7 years of ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) measurements to systematically investigate how the reflected protons affect the lunar wake potential structure when the Moon is immersed in the solar wind. RPs have a peak occurrence rate of ~20% for downstream distances from the Moon at N × 2πR g and a preference of high occurrence rates and high densities in the direction of the motional electric field of the solar wind. We show that reflected protons in the lunar wake can significantly change the electrostatic ambipolar potentials in the wake, leading in turn to the formation of field-aligned, accelerated electron beams. Our case study also suggests a nonmonotonic field-aligned potential structure in the presence of reflected protons in the wake. Lastly, our results show that when the reflected proton density is larger than ~30% of the local proton density from refilling solar wind protons, the wake potential scales as the logarithmic density of reflected protons, which can be explained by the Boltzmann relation.

A preliminary study of association between adolescent estradiol level and dorsolateral prefrontal cortex activity during emotion regulation.

Non-human primate models have been useful in clarifying estradiol's role in cognitive processing. These animal studies indicate estradiol impacts cognitive processes supported by regions within dorsolateral prefrontal cortex (DLPFC). Although human functional neuroimaging studies have begun to find similar relationships between estradiol in women for some forms of 'cold' cognitive control, to date no studies have examined the relationship between estradiol and DLPFC function in the context of active attempts to regulate one's emotions. Here, we asked whether peripheral 17-beta estradiol levels in adolescent girls in different pubertal developmental stages (age = 14.9 years ± 1.74) were related to engagement of DLPFC regions during the use of a cognitive strategy for regulating emotion known as reappraisal using functional Magnetic Resonance Imaging. Findings indicated that higher estradiol levels predicted greater DLPFC activity during the down-regulation of negative emotion using reappraisal. This is the first report of an association between estradiol level and DLPFC activity during cognitive reappraisal of negative emotion. The study suggests a possibility that estradiol might positively contribute to regulatory function of a cortical system important for emotional experiences.

Mapping the Lunar Wake Potential Structure With ARTEMIS Data.

The refilling of the lunar wake is relatively well explained by the theory of 1-D plasma expansion into a vacuum; however, the field-aligned wake potential is not a directly measured quantity, and thus, a statistical analysis of wake potentials at high altitudes has not been previously performed. In this study, we obtain the wake potential by comparing the field-aligned electron distributions inside and outside of the lunar wake measured by the two probes of the Acceleration, Reconnection, Turbulence, and Electrodynamics of Moon's Interaction with the Sun (ARTEMIS) mission. The derived potentials from ARTEMIS data vary with solar wind electron temperature and bulk flow velocity as the theory predicts. We also expand the 1-D plasma theory to 2-D in the plane of the interplanetary magnetic field and the solar wind velocity to examine how a tilted interplanetary magnetic field affects the wake potential structure. As the expansion time for the two sides of the wake differs, a wake potential asymmetry is developed in our model. This asymmetry is confirmed by the data-derived wake potentials. Moreover, ambipolar electric fields are obtained from both the modeled and data-derived wake potentials and show good agreement. Lastly, we examine the effects of the solar wind strahl-electron population on the wake potential structure, which appears to cause a net potential difference across the lunar shadow. This may imply that the disturbance of the wake plasma expansion extends farther outside the wake than previous plasma-expansion theories have predicted.

Measurement of the cosmic optical background using the long range reconnaissance imager on New Horizons.

The cosmic optical background is an important observable that constrains energy production in stars and more exotic physical processes in the universe, and provides a crucial cosmological benchmark against which to judge theories of structure formation. Measurement of the absolute brightness of this background is complicated by local foregrounds like the Earth's atmosphere and sunlight reflected from local interplanetary dust, and large discrepancies in the inferred brightness of the optical background have resulted. Observations from probes far from the Earth are not affected by these bright foregrounds. Here we analyse the data from the Long Range Reconnaissance Imager (LORRI) instrument on NASA's New Horizons mission acquired during cruise phase outside the orbit of Jupiter, and find a statistical upper limit on the optical background's brightness similar to the integrated light from galaxies. We conclude that a carefully performed survey with LORRI could yield uncertainties comparable to those from galaxy counting measurements.

Dust Ablation on the Giant Planets: Consequences for Stratospheric Photochemistry.

Ablation of interplanetary dust supplies oxygen to the upper atmospheres of Jupiter, Saturn, Uranus, and Neptune. Using recent dynamical model predictions for the dust influx rates to the giant planets (Poppe, A.R. et al. [2016], Icarus 264, 369), we calculate the ablation profiles and investigate the subsequent coupled oxygen-hydrocarbon neutral photochemistry in the stratospheres of these planets. We find that dust grains from the Edgeworth-Kuiper Belt, Jupiter-family comets, and Oort-cloud comets supply an effective oxygen influx rate of 1.0 - 0.7 + 2.2 × 10 7 O atoms cm-2 s-1 to Jupiter, 7.4 - 5.1 + 16 × 10 4 cm-2 s-1 to Saturn, 8.9 - 6.1 + 19 × 10 4 cm-2 s-1 to Uranus, and 7.5 - 5.1 + 16 × 10 5 cm-2 s-1 to Neptune. The fate of the ablated oxygen depends in part on the molecular/atomic form of the initially delivered products, and on the altitude at which it was deposited. The dominant stratospheric products are CO, H2O, and CO2, which are relatively stable photochemically. Model-data comparisons suggest that interplanetary dust grains deliver an important component of the external oxygen to Jupiter and Uranus but fall far short of the amount needed to explain the CO abundance currently seen in the middle stratospheres of Saturn and Neptune. Our results are consistent with the theory that all of the giant planets have experienced large cometary impacts within the last few hundred years. Our results also suggest that the low background H2O abundance in Jupiter's stratosphere is indicative of effective conversion of meteoric oxygen to CO during or immediately after the ablation process - photochemistry alone cannot efficiently convert the H2O into CO on the giant planets.

Reduced Frontoparietal Activity in Schizophrenia Is Linked to a Specific Deficit in Goal Maintenance: A Multisite Functional Imaging Study.

Patients with schizophrenia (SZ) previously demonstrated specific deficits in an executive function known as goal maintenance, associated with reduced middle frontal gyrus (MFG) activity. This study aimed to validate a new tool-the Dot Pattern Expectancy (DPX) task-developed to facilitate multisite imaging studies of goal maintenance deficits in SZ or other disorders. Additionally, it sought to arrive at recommendations for scan length for future studies using the DPX. Forty-seven SZ and 56 healthy controls (HC) performed the DPX in 3-Tesla functional magnetic resonance imaging (fMRI) scanners at 5 sites. Group differences in DPX-related activity were examined with whole brain voxelwise analyses. SZs showed the hypothesized specific performance deficits with as little as 1 block of data. Reduced activity in SZ compared with HC was observed in bilateral frontal pole/MFG, as well as left posterior parietal lobe. Efficiency analyses found significant group differences in activity using 18 minutes of scan data but not 12 minutes. Several behavioral and imaging findings from the goal maintenance literature were robustly replicated despite the use of different scanners at different sites. We did not replicate a previous correlation with disorganization symptoms among patients. Results were consistent with an executive/attention network dysfunction in the higher levels of a cascading executive system responsible for goal maintenance. Finally, efficiency analyses found that 18 minutes of scanning during the DPX task is sufficient to detect group differences with a similar sample size.

Task-based functional connectivity as an indicator of genetic liability to schizophrenia.

Impaired functional connectivity has been hypothesized as a potential source of the cognitive deficits routinely observed in patients with schizophrenia. Additionally, these deficits may be manifestations of the genetic liability to schizophrenia and present in the non-psychotic first-degree relatives of that group. However, no study has examined task-based functional connectivity in schizophrenia relatives using independent component analysis (ICA). We employed group ICA to test the hypothesis that the unexpressed genetic liability to schizophrenia is reflected in the functional connectivity between brain regions during a task measuring context processing. We compared 20 schizophrenia patients and 32 patients' first-degree relatives to 22 controls demographically matched to the patients and 28 controls' relatives, respectively. The group ICA showed differential connectivity between patients and controls in a task-related network constituting right middle frontal gyrus (MFG) and right posterior parietal lobe. A network constituting left MFG and left posterior parietal, which was also related to the context processing task, did not differ between groups. These findings demonstrate that connectivity abnormalities associated with the genetic liability to schizophrenia are most strongly expressed in a right lateralized executive fronto-parietal network, and that these abnormalities are linked to context processing impairments.

Toward a neurometric foundation for probabilistic independent component analysis of fMRI data.

Improved fMRI data analysis methods hold promise for breakthroughs in cognitive and affective neuroscience. Group probabilistic independent component analysis (pICA), such as that implemented by MELODIC (Beckmann & Smith IEEE Transactions on Medical Imaging 23:137-152, 2004), is one popular technique that typifies this development. Recently pICA has been proposed to be a reliable method for studying connectivity networks (Zuo et al. NeuroImage 49:2163-2177, 2010); however, there is no "standard" way to complete a pICA, and the full impact of the options on neurometric properties of resulting components is unknown. In the present study, we sought to assess the robustness, reproducibility, and within-subject test-retest reliability of ICA in two data sets: The first included 30 subjects imaged 3 weeks apart while completing a cognitive control task, and the second included 27 subjects imaged 9 months apart during rest. In addition to examining the impact of analytic parameters on the neurometrics, this study was the first to simultaneously investigate within-subject reliability of ICA-derived components from rest and task fMRI data. Results suggested that for both task and rest, meta-level analyses using 25 subject orders optimized robustness of the components. The impact of dimensionality and voxel threshold for components was subsequently examined regarding properties of reproducibility and within-subject retest reliability. Component thresholds between 0.2 and 0.6 of the maximum value optimized reproducibility across multiple dimensionalities and produced generally fair to moderate reliability estimates (Cicchetti & Sparrow American Journal of Mental Deficiency 86:127-137, 1981). These guidelines strengthen the foundation for this data-driven approach to fMRI analysis by providing prescriptive findings and a descriptive set of neurometrics for resting-state and task fMRI.

Optimization of a goal maintenance task for use in clinical applications.

BACKGROUND: We sought to develop a Dot Pattern Expectancy task (DPX) to assess goal maintenance for use in clinical trials. Altering the standard task created 5 versions of the DPX to compare-a standard version and 4 others. Alterations in the interstimulus interval (ISI) length and the strength of a learned prepotent response distinguished the different tasks. These adjustments were designed to decrease administration time and/or improve reliability of the data. METHODS: We determined participant eligibility in an initial session (the first of 3) using clinical interviewing tools. The initial session also included a demographic assessment and assessments of community functioning and symptom severity. All versions of the DPX were administered, across 3 sessions. Specific deficits on the context processing compared with difficulty control condition were evaluated using mixed-effects logistic regression within a hierarchical linear model. RESULTS: We analyzed the data from 136 control participants and 138 participants with schizophrenia. Relative to a difficulty control condition, patients performed worse than controls on context processing conditions that required goal maintenance. ISI did not predict errors. Stronger prepotency was associated with increased errors in the difficulty control relative to context processing condition for controls, which improved the interpretability of findings for patients. Reliability was acceptable for a version of the task with a 10-minute running time. CONCLUSIONS: The best compromise between task duration and interpretability occurred on a version with a short ISI and a strong prepotency.