Sleep spindles are related to sleep‐dependent memory consolidation and general cognitive abilities. However, they undergo drastic maturational changes during adolescence. Here we used a longitudinal ...approach (across 7 years) to explore whether developmental changes in sleep spindle density can explain individual differences in sleep‐dependent memory consolidation and general cognitive abilities. Ambulatory polysomnography was recorded during four nights in 34 healthy subjects (24 female) with two nights (baseline and experimental) at initial recording (age range 8–11 years) and two nights at follow‐up recording (age range 14–18 years). For declarative learning, participants encoded word pairs with a subsequent recall before and after sleep. General cognitive abilities were measured by the Wechsler Intelligence Scale. Higher slow (11–13 Hz) than fast (13–15 Hz) spindle density at frontal, central, and parietal sites during initial recordings, followed by a shift to higher fast than slow spindle density at central and parietal sites during follow‐up recordings, suggest that mature spindle topography develops throughout adolescence. Fast spindle density increases from baseline to experimental night were positively related to sleep‐dependent memory consolidation. In addition, we found that the development of fast spindles predicted the improvement in memory consolidation across the two longitudinal measurements, a finding that underlines a crucial role for mature fast spindles for sleep‐dependent memory consolidation. Furthermore, slow spindle changes across adolescence were related to general cognitive abilities, a relationship that could indicate the maturation of frontal networks relevant for efficient cognitive processing. A video of this article can be viewed at: https://www.youtube.com/watch?v=7NXJzm8HbIw and https://www.youtube.com/watch?v=iuMQY1OIJ0s
Our results demonstrate that the typical mature spindle topography with slow spindles dominating frontal areas and fast spindles centro‐parietal areas develops throughout adolescence (a). Slow spindle development appears to contribute to the generation of frontal brain networks relevant for efficient cognitive processing (b), whereas fast spindles seem to be crucial for sleep‐dependent memory consolidation as their maturation is related to more efficient sleep‐dependent memory consolidation (c).
Functional interactions between sleep spindle activity, declarative memory consolidation, and general cognitive abilities in school-aged children.
Healthy, prepubertal children (n = 63; mean age 9.56 ...± 0.76 y); ambulatory all-night polysomnography (2 nights); investigating the effect of prior learning (word pair association task; experimental night) versus nonlearning (baseline night) on sleep spindle activity; general cognitive abilities assessed using the Wechsler Intelligence Scale for Children-IV (WISC-IV).
Analysis of spindle activity during nonrapid eye movement sleep (N2 and N3) evidenced predominant peaks in the slow (11-13 Hz) but not in the fast (13-15 Hz) sleep spindle frequency range (baseline and experimental night). Analyses were restricted to slow sleep spindles. Changes in spindle activity from the baseline to the experimental night were not associated with the overnight change in the number of recalled words reflecting declarative memory consolidation. Children with higher sleep spindle activity as measured at frontal, central, parietal, and occipital sites during both baseline and experimental nights exhibited higher general cognitive abilities (WISC-IV) and declarative learning efficiency (i.e., number of recalled words before and after sleep).
Slow sleep spindles (11-13 Hz) in children age 8-11 y are associated with inter-individual differences in general cognitive abilities and learning efficiency.
The origin of the transmission damage in PWO crystals is discussed. It is shown that both electron and hole centers created on the basis of structural defects in PbWO4 crystals contributed to the ...induced absorption of the crystals. The different aspects of the suppression of the recharge processes in PWO scintillation crystals are also discussed.
Improved light yield of lead tungstate scintillators Annenkov, A; Borisevitch, A; Hofstaetter, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
08/2000, Letnik:
450, Številka:
1
Journal Article
Recenzirano
The application at medium and low energies of lead tungstate scintillators, so far optimized for the ECAL calorimeter of CMS for the future LHC, is strongly limited by their poor light yield. ...Suitable dopants like molybdenum and terbium can help to overcome this problem. Concepts, results, advantages and drawbacks of this approach are discussed.
A previously reported structure proposal for Pb-deficient PbWO4 (Pb7W8O32−x, space group P4/nnc) could be rejected based on neutron powder diffraction data. A new model in agreement with X-ray and ...neutron diffraction data is proposed (tetragonal, tP48, space group P-4-h10g2dcba, a=7.7208(1), c=12.0417(2) Å). It is a superstructure of the scheelite type with partial vacancies on a one-fold lead site, leading to the composition Pb7.5W8O32.
A facility for the test of large-area muon chambers at high rates Agosteo, S; Altieri, S; Belli, G ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2000, Letnik:
452, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Operation of large-area muon detectors at the future Large Hadron Collider (LHC) will be characterized by large sustained hit rates over the whole area, reaching the range of
kHz
cm
−2
. We describe ...a dedicated test zone built at CERN to test the performance and the aging of the muon chambers currently under development. A radioactive source delivers photons causing the sustained rate of random hits, while a narrow beam of high-energy muons is used to directly calibrate the detector performance. A system of remotely controlled lead filters serves to vary the rate of photons over four orders of magnitude, to allow the study of performance as a function of rate.
A coupled channel analysis of the centrally produced
K
+
K
−and
π
+
π
−final states has been performed in
pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ...ratios to
ππ and
K
K
of the
f
0(980),
f
0(1370),
f
0(1500) and
f
0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the
π
+
π
−and
K
+
K
−channels has been performed.
Human brain activity is intrinsically organized into resting-state networks (RSNs) that transiently activate or deactivate at the sub-second timescale. Few neuroimaging studies have addressed how ...Alzheimer's disease (AD) affects these fast temporal brain dynamics, and how they relate to the cognitive, structural and metabolic abnormalities characterizing AD. We aimed at closing this gap by investigating both brain structure and function using magnetoencephalography (MEG) and hybrid positron emission tomography-magnetic resonance (PET/MR) in 10 healthy elders, 10 patients with subjective cognitive decline (SCD), 10 patients with amnestic mild cognitive impairment (aMCI) and 10 patients with typical Alzheimer's disease with dementia (AD). The fast activation/deactivation state dynamics of RSNs were assessed using hidden Markov modeling (HMM) of power envelope fluctuations at rest measured with MEG. Correlations were sought between temporal properties of HMM states and participants' cognitive test scores, whole hippocampal grey matter volume and regional brain glucose metabolism. The posterior default-mode network (DMN) was less often activated and for shorter durations in AD patients than matched healthy elders. No significant difference was found in patients with SCD or aMCI. The time spent by participants in the activated posterior DMN state did not correlate significantly with cognitive scores, nor with the whole hippocampal volume. However, it correlated positively with the regional glucose consumption in the right dorsolateral prefrontal cortex (DLPFC). AD patients present alterations of posterior DMN power activation dynamics at rest that identify an additional electrophysiological correlate of AD-related synaptic and neural dysfunction. The right DLPFC may play a causal role in the activation of the posterior DMN, possibly linked to the occurrence of mind wandering episodes. As such, these data might suggest a neural correlate of the decrease in mind wandering episodes reported in pathological aging.
The reaction pp -> pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), ...f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.
The results of studies on the spectroscopic properties and the origin of luminescent radiation centers in PbWO4 single crystals are presented in this paper. Investigation of the excitation spectra of ...luminescence bands and polarization measurements confirm the previously observed two green bands and establish a connection of these bands with transitions within centers based on the WO3 group. The energy level scheme for radiation centers is proposed.
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