99 research outputs found
Brief Mindfulness Meditation Improves Attention In Novices: Evidence From ERPs And Moderation By Neuroticism
Past research has found that mindfulness meditation training improves executive attention. Event-related potentials (ERPs) have indicated that this effect could be driven by more efficient allocation of resources on demanding attentional tasks, such as the Flanker Task and the Attention Network Test (ANT). However, it is not clear whether these changes depend on long-term practice. In two studies, we sought to investigate the effects of a brief, 10-min meditation session on attention in novice meditators, compared to a control activity. We also tested moderation by individual differences in neuroticism and the possible underlying neural mechanisms driving these effects, using ERPs. In Study 1, participants randomly assigned to listen to a 10-min meditation tape had better accuracy on incongruent trials on a Flanker task, with no detriment in reaction times (RTs), indicating better allocation of resources. In Study 2, those assigned to listen to a meditation tape performed an ANT more quickly than control participants, with no detriment in performance. Neuroticism moderated both of these effects, and ERPs showed that those individuals lower in neuroticism who meditated for 10 min exhibited a larger N2 to incongruent trials compared to those who listened to a control tape; whereas those individuals higher in neuroticism did not. Together, our results support the hypothesis that even brief meditation improves allocation of attentional resources in some novices
An ALMA Survey of faint disks in the Chamaeleon I star-forming region: Why are some Class II disks so faint?
ALMA surveys of nearby star-forming regions have shown that the dust mass in
the disk is correlated with the stellar mass, but with a large scatter. This
scatter could indicate either different evolutionary paths of disks or
different initial conditions within a single cluster. We present ALMA Cycle 3
follow-up observations for 14 Class II disks that were low S/N detections or
non-detections in our Cycle 2 survey of the Myr-old Chamaeleon I
star-forming region. With 5 times better sensitivity, we detect millimeter dust
continuum emission from six more sources and increase the detection rate to
94\% (51/54) for Chamaeleon I disks around stars earlier than M3. The
stellar-disk mass scaling relation reported in \citet{pascucci2016} is
confirmed with these updated measurements. Faint outliers in the
-- plane include three non-detections (CHXR71, CHXR30A, and T54)
with dust mass upper limits of 0.2 M and three very faint disks
(CHXR20, ISO91, and T51) with dust masses M. By
investigating the SED morphology, accretion property and stellar multiplicity,
we suggest for the three millimeter non-detections that tidal interaction by a
close companion (100 AU) and internal photoevaporation may play a role in
hastening the overall disk evolution. The presence of a disk around only the
secondary star in a binary system may explain the observed stellar SEDs and low
disk masses for some systems.Comment: ApJ accepte
An ALMA Survey of CO isotopologue emission from Protoplanetary Disks in Chamaeleon I
The mass of a protoplanetary disk limits the formation and future growth of
any planet. Masses of protoplanetary disks are usually calculated from
measurements of the dust continuum emission by assuming an interstellar
gas-to-dust ratio. To investigate the utility of CO as an alternate probe of
disk mass, we use ALMA to survey CO and CO J = line
emission from a sample of 93 protoplanetary disks around stars and brown dwarfs
with masses from 0.03 -- 2 M in the nearby Chamaeleon I star-forming
region. We detect CO emission from 17 sources and CO from only
one source. Gas masses for disks are then estimated by comparing the CO line
luminosities to results from published disk models that include CO freeze-out
and isotope-selective photodissociation. Under the assumption of a typical ISM
CO-to-H ratios of , the resulting gas masses are implausibly low,
with an average gas mass of 0.05 M as inferred from the average
flux of stacked CO lines. The low gas masses and gas-to-dust ratios for
Cha I disks are both consistent with similar results from disks in the Lupus
star-forming region. The faint CO line emission may instead be explained if
disks have much higher gas masses, but freeze-out of CO or complex C-bearing
molecules is underestimated in disk models. The conversion of CO flux to CO gas
mass also suffers from uncertainties in disk structures, which could affect gas
temperatures. CO emission lines will only be a good tracer of the disk mass
when models for C and CO depletion are confirmed to be accurate.Comment: accepted for publication in Ap
Brief Mindfulness Meditation Improves Attention in Novices: Evidence From ERPs and Moderation by Neuroticism
Past research has found that mindfulness meditation training improves executive attention. Event-related potentials (ERPs) have indicated that this effect could be driven by more efficient allocation of resources on demanding attentional tasks, such as the Flanker Task and the Attention Network Test (ANT). However, it is not clear whether these changes depend on long-term practice. In two studies, we sought to investigate the effects of a brief, 10-min meditation session on attention in novice meditators, compared to a control activity. We also tested moderation by individual differences in neuroticism and the possible underlying neural mechanisms driving these effects, using ERPs. In Study 1, participants randomly assigned to listen to a 10-min meditation tape had better accuracy on incongruent trials on a Flanker task, with no detriment in reaction times (RTs), indicating better allocation of resources. In Study 2, those assigned to listen to a meditation tape performed an ANT more quickly than control participants, with no detriment in performance. Neuroticism moderated both of these effects, and ERPs showed that those individuals lower in neuroticism who meditated for 10 min exhibited a larger N2 to incongruent trials compared to those who listened to a control tape; whereas those individuals higher in neuroticism did not. Together, our results support the hypothesis that even brief meditation improves allocation of attentional resources in some novices
Corrigendum: Brief Mindfulness Meditation Improves Attention in Novices: Evidence From ERPs and Moderation by Neuroticism
Amygdala-related electrical fingerprint is modulated with neurofeedback training and correlates with deep-brain activation: proof-of-concept in borderline personality disorder
Background: The modulation of brain circuits of emotion is a promising pathway to treat borderline personality disorder (BPD). Precise and scalable approaches have yet to be established. Two studies investigating the amygdala-related electrical fingerprint (Amyg-EFP) in BPD are presented: one study addressing the deep-brain correlates of Amyg-EFP, and a second study investigating neurofeedback (NF) as a means to improve brain self-regulation.
Methods: Study 1 combined electroencephalography (EEG) and simultaneous functional magnetic resonance imaging to investigate the replicability of Amyg-EFP-related brain activation found in the reference dataset (N = 24 healthy subjects, 8 female; re-analysis of published data) in the replication dataset (N = 16 female individuals with BPD). In the replication dataset, we additionally explored how the Amyg-EFP would map to neural circuits defined by the research domain criteria. Study 2 investigated a 10-session Amyg-EFP NF training in parallel to a 12-weeks residential dialectical behavior therapy (DBT) program. Fifteen patients with BPD completed the training, N = 15 matched patients served as DBT-only controls.
Results: Study 1 replicated previous findings and showed significant amygdala blood oxygenation level dependent activation in a whole-brain regression analysis with the Amyg-EFP. Neurocircuitry activation (negative affect, salience, and cognitive control) was correlated with the Amyg-EFP signal. Study 2 showed Amyg-EFP modulation with NF training, but patients received reversed feedback for technical reasons, which limited interpretation of results.
Conclusions: Recorded via scalp EEG, the Amyg-EFP picks up brain activation of high relevance for emotion. Administering Amyg-EFP NF in addition to standardized BPD treatment was shown to be feasible. Clinical utility remains to be investigated
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Neural traces of stress: cortisol related sustained enhancement of amygdala-hippocampal functional connectivity
Stressful experiences modulate neuro-circuitry function, and the temporal trajectory of these alterations, elapsing from early disturbances to late recovery, heavily influences resilience and vulnerability to stress. Such effects of stress may depend on processes that are engaged during resting-state, through active recollection of past experiences and anticipation of future events, all known to involve the default mode network (DMN). By inducing social stress and acquiring resting-state functional magnetic resonance imaging (fMRI) before stress, immediately following it, and 2 h later, we expanded the time-window for examining the trajectory of the stress response. Throughout the study repeated cortisol samplings and self-reports of stress levels were obtained from 51 healthy young males. Post-stress alterations were investigated by whole brain resting-state functional connectivity (rsFC) of two central hubs of the DMN: the posterior cingulate cortex (PCC) and hippocampus. Results indicate a ’recovery’ pattern of DMN connectivity, in which all alterations, ascribed to the intervening stress, returned to pre-stress levels. The only exception to this pattern was a stress-induced rise in amygdala-hippocampal connectivity, which was sustained for as long as 2 h following stress induction. Furthermore, this sustained enhancement of limbic connectivity was inversely correlated to individual stress-induced cortisol responsiveness (AUCi) and characterized only the group lacking such increased cortisol (i.e., non-responders). Our observations provide evidence of a prolonged post-stress response profile, characterized by both the comprehensive balance of most DMN functional connections and the distinct time and cortisol dependent ascent of intra-limbic connectivity. These novel insights into neuro-endocrine relations are another milestone in the ongoing search for individual markers in stress-related psychopathologies
Dual-Wavelength ALMA Observations of Dust Rings in Protoplanetary Disks
We present new Atacama Large Millimeter/submillimeter Array (ALMA)
observations for three protoplanetary disks in Taurus at 2.9\,mm and
comparisons with previous 1.3\,mm data both at an angular resolution of
(15\,au for the distance of Taurus). In the single-ring disk DS
Tau, double-ring disk GO Tau, and multiple-ring disk DL Tau, the same rings are
detected at both wavelengths, with radial locations spanning from 50 to
120\,au. To quantify the dust emission morphology, the observed visibilities
are modeled with a parametric prescription for the radial intensity profile.
The disk outer radii, taken as 95\% of the total flux encircled in the model
intensity profiles, are consistent at both wavelengths for the three disks.
Dust evolution models show that dust trapping in local pressure maxima in the
outer disk could explain the observed patterns. Dust rings are mostly
unresolved. The marginally resolved ring in DS Tau shows a tentatively narrower
ring at the longer wavelength, an observational feature expected from efficient
dust trapping. The spectral index () increases outward and
exhibits local minima that correspond to the peaks of dust rings, indicative of
the changes in grain properties across the disks. The low optical depths
(0.1--0.2 at 2.9\,mm and 0.2--0.4 at 1.3\,mm) in the dust rings
suggest that grains in the rings may have grown to millimeter sizes. The
ubiquitous dust rings in protoplanetary disks modify the overall dynamics and
evolution of dust grains, likely paving the way towards the new generation of
planet formation.Comment: accepted for publication in Ap
Gaps and Rings in an ALMA Survey of Disks in the Taurus Star-forming Region
Rings are the most frequently revealed substructure in ALMA dust observations of protoplanetary disks, but their origin is still hotly debated. In this paper, we identify dust substructures in 12 disks and measure their properties to investigate how they form. This subsample of disks is selected from a high-resolution () ALMA 1.33 mm survey of 32 disks in the Taurus star-forming region, which was designed to cover a wide range of sub-mm brightness and to be unbiased to previously known substructures. While axisymmetric rings and gaps are common within our sample, spiral patterns and high contrast azimuthal asymmetries are not detected. Fits of disk models to the visibilities lead to estimates of the location and shape of gaps and rings, the flux in each disk component, and the size of the disk. The dust substructures occur across a wide range of stellar mass and disk brightness. Disks with multiple rings tend to be more massive and more extended. The correlation between gap locations and widths, the intensity contrast between rings and gaps, and the separations of rings and gaps could all be explained if most gaps are opened by low-mass planets (super-Earths and Neptunes) in the condition of low disk turbulence (). The gap locations are not well correlated with the expected locations of CO and N ice lines, so
condensation fronts are unlikely to be a universal mechanism to create gaps and rings, though they may play a role in some cases.Several ERC grants
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