83 research outputs found
Inhibitory neurons exhibit high controlling ability in the cortical microconnectome
脳が安定して活動を続けられるメカニズムの一端を解明 --新皮質で、抑制性細胞は他細胞を制御しやすいトポロジカルな位置取りをする--. 京都大学プレスリリース. 2021-04-09.The brain is a network system in which excitatory and inhibitory neurons keep activity balanced in the highly non-random connectivity pattern of the microconnectome. It is well known that the relative percentage of inhibitory neurons is much smaller than excitatory neurons in the cortex. So, in general, how inhibitory neurons can keep the balance with the surrounding excitatory neurons is an important question. There is much accumulated knowledge about this fundamental question. This study quantitatively evaluated the relatively higher functional contribution of inhibitory neurons in terms of not only properties of individual neurons, such as firing rate, but also in terms of topological mechanisms and controlling ability on other excitatory neurons. We combined simultaneous electrical recording (~2.5 hours) of ~1000 neurons in vitro, and quantitative evaluation of neuronal interactions including excitatory-inhibitory categorization. This study accurately defined recording brain anatomical targets, such as brain regions and cortical layers, by inter-referring MRI and immunostaining recordings. The interaction networks enabled us to quantify topological influence of individual neurons, in terms of controlling ability to other neurons. Especially, the result indicated that highly influential inhibitory neurons show higher controlling ability of other neurons than excitatory neurons, and are relatively often distributed in deeper layers of the cortex. Furthermore, the neurons having high controlling ability are more effectively limited in number than central nodes of k-cores, and these neurons also participate in more clustered motifs. In summary, this study suggested that the high controlling ability of inhibitory neurons is a key mechanism to keep balance with a large number of other excitatory neurons beyond simple higher firing rate. Application of the selection method of limited important neurons would be also applicable for the ability to effectively and selectively stimulate E/I imbalanced disease states
The relationship between attention and avoidance coping in anorexia nervosa: functional magnetic resonance imaging study
[Background] Numerous studies have demonstrated attentional control difficulties and high avoidance coping in patients with anorexia nervosa. Attention is a critical coping resource because it enables individuals to demonstrate self-control and complete goal-directed behaviours. [Aims] We aimed to examine whether attentional control difficulty is related to high avoidance coping, and investigate the neural underpinnings of attentional control difficulties in individuals with anorexia nervosa. [Method] Twenty-three patients with anorexia nervosa and 17 healthy controls completed questionnaires that assessed attention and coping, and underwent functional magnetic resonance imaging while performing a go/no-go task. [Results] Patients with anorexia nervosa showed weaker attentional control, higher omission error rates and higher avoidance coping compared with healthy controls. Attentional control difficulty was associated with higher avoidance coping in both groups. Functional magnetic resonance imaging analysis showed less deactivation in regions representing internal mental processing, such as the praecuneus, cuneus and left lingual gyrus, during the no-go condition. Moreover, weakened deactivation of the left lingual gyrus was associated with higher commission error rate in the anorexia nervosa group. [Conclusions] Our results suggest that patients with anorexia nervosa may have difficulty in maintaining attention to external ongoing events because of disturbance from internal self-related thought, and support the notion that attentional control difficulties underlie the frequent use of avoidance coping in anorexia nervosa
Neural correlates of a mindfulness-based intervention in anorexia nervosa
神経性やせ症患者の不安に対するマインドフルネス瞑想の効果 --脳活動の変化を明らかに--. 京都大学プレスリリース. 2023-02-02.Accepting anxiety for peace of mind. 京都大学プレスリリース. 2023-02-08.We examined the neural underpinnings of the effects of mindfulness on anxiety in anorexia nervosa using functional magnetic resonance imaging in 21 anorexia patients. We used a functional magnetic resonance imaging task designed to induce weight-related anxiety and asked participants to regulate their anxiety either using or not using an acceptance strategy. Our results showed reduced activity in the amygdala, anterior cingulate cortex, putamen, caudate, orbital gyrus, middle frontal gyrus, posterior cingulate cortex and precuneus following a mindfulness-based intervention. The present study provides new insight regarding the neural mechanisms underlying the effect of mindfulness-based intervention in ameliorating anorexia nervosa
Dusty ERO Search behind Two Massive Clusters
We performed deep K'-band imaging observations of 2 massive clusters, MS
0451.6-0305 at z = 0.55 and MS 0440.5+0204 at z = 0.19, for searching
counterparts of the faint sub-mm sources behind these clusters, which would
provide one of the deepest extremely red object(ERO) samples. Comparing our
near-infrared images with optical images taken by the Hubble Space Telescope
and by the Subaru Telescope, we identified 13 EROs in these fields. The sky
distributions of EROs are consistent with the previous results, that there is a
sign of strong clustering among detected EROs. Also, the surface density with
corrected lensing amplification factors in both clusters are in good agreement
with that derived from previous surveys. We found 7 EROs and 3 additional very
red objects in a small area (\sim 0.6 arcmin^2) of the MS 0451.6-0305 field
around an extended SCUBA source. Many of their optical and near-infrared colors
are consistent with dusty star-forming galaxies at high redshifts(z \sim
1.0-4.0), and they may be constituting a cluster of dusty starburst galaxies
and/or lensed star-forming galaxies at high redshift. Their red J-K' colors and
faint optical magnitudes suggest they are relatively old massive stellar
systems with ages(>300 Mega years) suffering from dust obscuration. We also
found a surface-density enhancement of EROs around the SCUBA source in the MS
0440.5+0204 field.Comment: 19 pages, 11 figures, Latex(using pasj00.cls). To be published in
PASJ vol 55, No. 4(Aug 2003
Subaru Spectroscopy of the Gravitational Lens HST 14176+5226: Implications for a Large Cosmological Constan
We present new optical spectroscopy of the lens elliptical galax in the
``Einstein Cross'' lens system HST 14176+5226, using the Faint Object Camera
and Spectrograph (FOCAS) of the Subaru t Our spectroscopic observations are
aimed at measuring the stella dispersion of the lens galaxy, located at high
redshift of z_L= as an important component to lens models. We have measured
this 230 +- 14 km s^{-1} (1 sigma) inside 0.35 effective radi based on the
comparison between the observed galaxy spectrum and templates of three G-K
giants by means of the Fourier cross-corr To extract the significance of this
information on the geometry universe which also affects the lensing of the
background image, to fit three different lens models to the available data of
the Provided that the lens galaxy has the structural and dynamical p (i.e., its
radial density profile, core radius, and velocity ani similar to those of local
elliptical galaxies, we calculate the function for the simultaneous
reproduction of both the observed and newly measured velocity dispersion of the
lens. Although the interval depends rather sensitively on the adopted lens
models o parameters, our experiments suggest the larger likelihood for a
cosmological constant, Omega_Lambda: formal 1 sigma lower Omega_Lambda in the
flat universe ranges 0.73 to 0.97, where lower limit is basically unavailable.
This method for determinin model is thus dependent on lens models but is
insensitive to oth ambiguities, such as the dust absorption or the evolutionary
eff galaxies. Exploring spectroscopic observations of more lens gala redshift
may minimize the model uncertainties and thus place a m constraint on
Omega_Lambda.Comment: 23 pages, 5 figures, accepted for publication in The Astronomical
Journa
Gamma rays from a reverse shock with turbulent magnetic fields in GRB 180720B
Gamma-ray bursts (GRBs) are the most electromagnetically luminous cosmic
explosions. They are powered by collimated streams of plasma (jets) ejected by
a newborn stellar-mass black hole or neutron star at relativistic velocities
(near the speed of light). Their short-lived (typically tens of seconds) prompt
-ray emission from within the ejecta is followed by long-lived
multi-wavelength afterglow emission from the ultra-relativistic forward shock.
This shock is driven into the circumburst medium by the GRB ejecta that are in
turn decelerated by a mildly-relativistic reverse shock. Forward shock emission
was recently detected up to teraelectronvolt-energy -rays, and such
very-high-energy emission was also predicted from the reverse shock. Here we
report the detection of optical and gigaelectronvolt-energy -ray
emission from GRB 180720B during the first few hundred seconds, which is
explained by synchrotron and inverse-Compton emission from the reverse shock
propagating into the ejecta, implying a low-magnetization ejecta. Our optical
measurements show a clear transition from the reverse shock to the forward
shock driven into the circumburst medium, accompanied by a 90-degree change in
the mean polarization angle and fluctuations in the polarization degree and
angle. This indicates turbulence with large-scale toroidal and
radially-stretched magnetic field structures in the reverse and forward shocks,
respectively, which tightly couple to the physics of relativistic shocks and
GRB jets -- launching, composition, dissipation and particle acceleration.Comment: 5 pages, 4 figures (main) plus Methods and Supplementary Methods,
accepted for publicatio
Spectropolarimetry of Extremely Luminous Type Ia Supernova 2009dc: Nearly Spherical Explosion of Super-Chandrasekhar Mass White Dwarf
We present the first spectropolarimetric observations of a candidate of
super-Chandrasekhar mass Type Ia supernova (SN): SN 2009dc. The observations
were performed at 5.6 and 89.5 days after the B-band maximum. The data taken at
the later epoch are used to determine the interstellar polarization. Continuum
polarization is found to be small (<0.3 %), indicating that the explosion is
nearly spherically symmetric. This fact suggests that a very aspherical
explosion is not a likely scenario for SN 2009dc. Polarization at the Si II and
Ca II lines clearly shows a loop in the Q-U plane, indicating a
non-axisymmetric, clumpy distribution of intermediate-mass elements. The degree
of line polarization at the Si and Ca line is moderate (0.5% +- 0.1% and 0.7%
+- 0.1%, respectively), but it is higher than expected from the trend of other
Type Ia SNe. This may suggest that there are thick enough, clumpy Si-rich
layers above the thick 56Ni-rich layers (>~ 1.2 Msun). The observed
spectropolarimetric properties, combined with the photometric and spectroscopic
properties, suggest that the progenitor of SN 2009dc has a super-Chandrasekhar
mass, and that the explosion geometry is globally spherically symmetric, with
clumpy distribution of intermediate-mass elements.Comment: 9 pages, 6 figures, The Astrophysical Journal, in pres
On the Origin of Lyman- Blobs at High Redshift: Kinematic Evidence for a Hyperwind Galaxy at z = 3.1
We present deep optical spectroscopy of an extended Ly emission-line
blob located in an over-dense region at redshift ; `blob 1' of
Steidel et al. (2000). The origin of such Ly blobs has been debated for
some time; two of the most plausible models are (1) that it comes from a
dust-enshrouded, extreme starburst galaxy with a large-scale galactic outflow
(superwind/hyperwind) or (2) that it is the cooling radiation of proto-galaxies
in dark matter halos. Examination of the kinematic properties of the Ly
emission-line gas should allow us to determine its nature. With this
motivation, we performed optical spectroscopy of `blob 1' using the Subaru
Telescope, and found that its kinematic properties can be well explained in
terms of superwind activity.Comment: 12 pages, including 4 figures, accepted for publication in ApJ
The Type Ic Hypernova SN 2002ap
Photometric and spectroscopic data of the energetic Type Ic supernova (SN)
2002ap are presented, and the properties of the SN are investigated through
models of its spectral evolution and its light curve. The SN is
spectroscopically similar to the "hypernova" SN 1997ef. However, its kinetic
energy [ erg] and the mass ejected (2.5-5
) are smaller, resulting in a faster-evolving light curve. The SN
synthesized of Ni, and its peak luminosity was
similar to that of normal SNe. Brightness alone should not be used to define a
hypernova, whose defining character, namely very broad spectral features, is
the result of a high kinetic energy. The likely main-sequence mass of the
progenitor star was 20-25 , which is also lower than that of both
hypernovae SNe 1997ef and 1998bw. SN 2002ap appears to lie at the low-energy
and low-mass end of the hypernova sequence as it is known so far. Observations
of the nebular spectrum, which is expected to dominate by summer 2002, are
necessary to confirm these values.Comment: 10 pages, 4 figures, accepted for publication in ApJL, 30 April 2002
(minor changes to match the accepted version, with figures being colored
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