339 research outputs found
Correlation between amygdala BOLD activity and frontal EEG asymmetry during real-time fMRI neurofeedback training in patients with depression
Real-time fMRI neurofeedback (rtfMRI-nf) is an emerging approach for studies
and novel treatments of major depressive disorder (MDD). EEG performed
simultaneously with an rtfMRI-nf procedure allows an independent evaluation of
rtfMRI-nf brain modulation effects. Frontal EEG asymmetry in the alpha band is
a widely used measure of emotion and motivation that shows profound changes in
depression. However, it has never been directly related to simultaneously
acquired fMRI data. We report the first study investigating
electrophysiological correlates of the rtfMRI-nf procedure, by combining
rtfMRI-nf with simultaneous and passive EEG recordings. In this pilot study,
MDD patients in the experimental group (n=13) learned to upregulate BOLD
activity of the left amygdala using an rtfMRI-nf during a happy emotion
induction task. MDD patients in the control group (n=11) were provided with a
sham rtfMRI-nf. Correlations between frontal EEG asymmetry in the upper alpha
band and BOLD activity across the brain were examined. Average individual
changes in frontal EEG asymmetry during the rtfMRI-nf task for the experimental
group showed a significant positive correlation with the MDD patients'
depression severity ratings, consistent with an inverse correlation between the
depression severity and frontal EEG asymmetry at rest. Temporal correlations
between frontal EEG asymmetry and BOLD activity were significantly enhanced,
during the rtfMRI-nf task, for the amygdala and many regions associated with
emotion regulation. Our findings demonstrate an important link between amygdala
BOLD activity and frontal EEG asymmetry. Our EEG asymmetry results suggest that
the rtfMRI-nf training targeting the amygdala is beneficial to MDD patients,
and that alpha-asymmetry EEG-nf would be compatible with the amygdala
rtfMRI-nf. Combination of the two could enhance emotion regulation training and
benefit MDD patients.Comment: 28 pages, 16 figures, to appear in NeuroImage: Clinica
Hydrogen Fluoride in High-Mass Star-forming Regions
Hydrogen fluoride has been established to be an excellent tracer of molecular
hydrogen in diffuse clouds. In denser environments, however, the HF abundance
has been shown to be approximately two orders of magnitude lower. We present
Herschel/HIFI observations of HF J=1-0 toward two high-mass star formation
sites, NGC6334 I and AFGL 2591. In NGC6334 I the HF line is seen in absorption
in foreground clouds and the source itself, while in AFGL 2591 HF is partially
in emission. We find an HF abundance with respect to H2 of 1.5e-8 in the
diffuse foreground clouds, whereas in the denser parts of NGC6334 I, we derive
a lower limit on the HF abundance of 5e-10. Lower HF abundances in dense clouds
are most likely caused by freeze out of HF molecules onto dust grains in
high-density gas. In AFGL 2591, the view of the hot core is obstructed by
absorption in the massive outflow, in which HF is also very abundant 3.6e-8)
due to the desorption by sputtering. These observations provide further
evidence that the chemistry of interstellar fluorine is controlled by freeze
out onto gas grains.Comment: accepted in Ap
Real-time fMRI neurofeedback training of the amygdala activity with simultaneous EEG in veterans with combat-related PTSD
Posttraumatic stress disorder (PTSD) is a chronic and disabling
neuropsychiatric disorder characterized by insufficient top-down modulation of
the amygdala activity by the prefrontal cortex. Real-time fMRI neurofeedback
(rtfMRI-nf) is an emerging method with potential for modifying the
amygdala-prefrontal interactions. We report the first controlled emotion
self-regulation study in veterans with combat-related PTSD utilizing rtfMRI-nf
of the amygdala activity. PTSD patients in the experimental group (EG, n=20)
learned to upregulate BOLD activity of the left amygdala (LA) using rtfMRI-nf
during a happy emotion induction task. PTSD patients in the control group (CG,
n=11) were provided with a sham rtfMRI-nf. The study included three rtfMRI-nf
training sessions, and EEG recordings were performed simultaneously with fMRI.
PTSD severity was assessed using the Clinician-Administered PTSD Scale (CAPS).
The EG participants showed a significant reduction in total CAPS ratings,
including significant reductions in avoidance and hyperarousal symptoms.
Overall, 80% of the EG participants demonstrated clinically meaningful
reductions in CAPS ratings, compared to 38% in the CG. During the first
session, fMRI connectivity of the LA with the orbitofrontal cortex and the
dorsolateral prefrontal cortex (DLPFC) was progressively enhanced, and this
enhancement significantly and positively correlated with initial CAPS ratings.
Left-lateralized enhancement in upper alpha EEG coherence also exhibited a
significant positive correlation with the initial CAPS. Reduction in PTSD
severity between the first and last rtfMRI-nf sessions significantly correlated
with enhancement in functional connectivity between the LA and the left DLPFC.
Our results demonstrate that the rtfMRI-nf of the amygdala activity has the
potential to correct the amygdala-prefrontal functional connectivity
deficiencies specific to PTSD.Comment: 26 pages, 16 figures, to appear in NeuroImage: Clinica
Herschel observations of EXtraordinary Sources: Analysis of the full Herschel/HIFI molecular line survey of Sagittarius B2(N)
A sensitive broadband molecular line survey of the Sagittarius B2(N)
star-forming region has been obtained with the HIFI instrument on the Herschel
Space Observatory, offering the first high-spectral resolution look at this
well-studied source in a wavelength region largely inaccessible from the ground
(625-157 um). From the roughly 8,000 spectral features in the survey, a total
of 72 isotopologues arising from 44 different molecules have been identified,
ranging from light hydrides to complex organics, and arising from a variety of
environments from cold and diffuse to hot and dense gas. We present an LTE
model to the spectral signatures of each molecule, constraining the source
sizes for hot core species with complementary SMA interferometric observations,
and assuming that molecules with related functional group composition are
cospatial. For each molecule, a single model is given to fit all of the
emission and absorption features of that species across the entire 480-1910 GHz
spectral range, accounting for multiple temperature and velocity components
when needed to describe the spectrum. As with other HIFI surveys toward massive
star forming regions, methanol is found to contribute more integrated line
intensity to the spectrum than any other species. We discuss the molecular
abundances derived for the hot core, where the local thermodynamic equilibrium
approximation is generally found to describe the spectrum well, in comparison
to abundances derived for the same molecules in the Orion KL region from a
similar HIFI survey.Comment: Accepted to ApJ. 64 pages, 14 figures. Truncated abstrac
Integration of Simultaneous Resting-State EEG, fMRI, and Eye Tracker Methods to Determine and Verify EEG Vigilance Measure
Resting-state functional magnetic resonance imaging (rsfMRI) has been widely
used for studying the (presumably) awake and alert human brain. Although rsfMRI
scans are typically collected while individuals are instructed to focus their
eyes on a fixation cross, objective and verified experimental measures to
quantify degree of alertness (e.g., vigilance) are not readily available.
Concurrent electroencephalography and fMRI (EEG-fMRI) measurements are also
widely used to study human brain with high spatial/temporal resolution. EEG is
the modality extensively used for estimating vigilance during eyes-closed
resting state. On the other hand, pupil size measured using an eye-tracker
device could provide an indirect index of vigilance. In this study, we
investigated whether simultaneous multimodal EEG-fMRI combined with eye-tracker
measurements can be used to determine EEG signal feature associated with pupil
size changes (e.g., vigilance measure) in healthy human subjects (n=10) during
brain rest with eyes open. We found that EEG frontal and occipital beta power
(FOBP) correlates with pupil size changes, an indirect index for locus
coeruleus activity implicated in vigilance regulation (r=0.306, p<0.001).
Moreover, FOBP also correlated with heart rate (r=0.255, p<0.001), as well as
several brain regions in the anti-correlated network, including the bilateral
insula and inferior parietal lobule. These results support the conclusion that
FOBP is an objective measure of vigilance in healthy human subjects
Herschel observations of interstellar chloronium
Using the Herschel Space Observatory's Heterodyne Instrument for the
Far-Infrared (HIFI), we have observed para-chloronium (H2Cl+) toward six
sources in the Galaxy. We detected interstellar chloronium absorption in
foreground molecular clouds along the sight-lines to the bright submillimeter
continuum sources Sgr A (+50 km/s cloud) and W31C. Both the para-H2-35Cl+ and
para-H2-37Cl+ isotopologues were detected, through observations of their
1(11)-0(00) transitions at rest frequencies of 485.42 and 484.23 GHz,
respectively. For an assumed ortho-to-para ratio of 3, the observed optical
depths imply that chloronium accounts for ~ 4 - 12% of chlorine nuclei in the
gas phase. We detected interstellar chloronium emission from two sources in the
Orion Molecular Cloud 1: the Orion Bar photodissociation region and the Orion
South condensation. For an assumed ortho-to-para ratio of 3 for chloronium, the
observed emission line fluxes imply total beam-averaged column densities of ~
2.0E+13 cm-2 and ~ 1.2E+13 cm-2, respectively, for chloronium in these two
sources. We obtained upper limits on the para-H2-35Cl+ line strengths toward H2
Peak 1 in the Orion Molecular cloud and toward the massive young star AFGL
2591. The chloronium abundances inferred in this study are typically at least a
factor ~10 larger than the predictions of steady-state theoretical models for
the chemistry of interstellar molecules containing chlorine. Several
explanations for this discrepancy were investigated, but none has proven
satisfactory, and thus the large observed abundances of chloronium remain
puzzling.Comment: Accepted for publication in the Astrophysical Journa
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