15 research outputs found
Subthalamic beta band suppression reflects effective neuromodulation in chronic recordings
Background and purpose: Biomarkers for future adaptive deep brain stimulation still need evaluation in clinical routine. Here, we aimed to assess stimulation-induced modulation of beta-band activity and clinical symptoms in a Parkinson's disease patient during chronic neuronal sensing using a novel implantable pulse generator.
Methods: Subthalamic activity was recorded OFF and ON medication during a stepwise increase of stimulation amplitude. Off-line fast fourier transfom -based analysis of beta-band activity was correlated with motor performance rated from blinded videos.
Results: The stepwise increase of stimulation amplitude resulted in decreased beta oscillatory activity and improvement of bradykinesia. Mean low beta-band (13-20 Hz) activity correlated significantly with bradykinesia (ρ = 0.662, p < 0.01).
Conclusions: Motor improvement is reflected in reduced subthalamic beta-band activity in Parkinson's disease, supporting beta activity as a reliable biomarker. The novel PERCEPT neurostimulator enables chronic neuronal sensing in clinical routine. Our findings pave the way for a personalized precision-medicine approach to neurostimulation
Proteasome and autophagy-mediated impairment of late long-term potentiation (l-LTP) after traumatic brain injury in the somatosensory cortex of mice
Traumatic brain injury (TBI) can lead to impaired cognition and memory consolidation. The acute phase (24-48 h) after TBI is often characterized by neural dysfunction in the vicinity of the lesion, but also in remote areas like the contralateral hemisphere. Protein homeostasis is crucial for synaptic long-term plasticity including the protein degradation systems, proteasome and autophagy. Still, little is known about the acute effects of TBI on synaptic long-term plasticity and protein degradation. Thus, we investigated TBI in a controlled cortical impact (CCI) model in the motor and somatosensory cortex of mice ex vivo-in vitro. Late long-term potentiation (l-LTP) was induced by theta-burst stimulation in acute brain slices after survival times of 1-2 days. Protein levels for the plasticity related protein calcium/calmodulin-dependent protein kinase II (CaMKII) was quantified by Western blots, and the protein degradation activity by enzymatical assays. We observed missing maintenance of l-LTP in the ipsilateral hemisphere, however not in the contralateral hemisphere after TBI. Protein levels of CaMKII were not changed but, interestingly, the protein degradation revealed bidirectional changes with a reduced proteasome activity and an increased autophagic flux in the ipsilateral hemisphere. Finally, LTP recordings in the presence of pharmacologically modified protein degradation systems also led to an impaired synaptic plasticity: bath-applied MG132, a proteasome inhibitor, or rapamycin, an activator of autophagy, both administered during theta burst stimulation, blocked the induction of LTP. These data indicate that alterations in protein degradation pathways likely contribute to cognitive deficits in the acute phase after TBI, which could be interesting for future approaches towards neuroprotective treatments early after traumatic brain injury
The sensitivity of ECG contamination to surgical implantation site in brain computer interfaces.
BACKGROUND
Brain sensing devices are approved today for Parkinson's, essential tremor, and epilepsy therapies. Clinical decisions for implants are often influenced by the premise that patients will benefit from using sensing technology. However, artifacts, such as ECG contamination, can render such treatments unreliable. Therefore, clinicians need to understand how surgical decisions may affect artifact probability.
OBJECTIVES
Investigate neural signal contamination with ECG activity in sensing enabled neurostimulation systems, and in particular clinical choices such as implant location that impact signal fidelity.
METHODS
Electric field modeling and empirical signals from 85 patients were used to investigate the relationship between implant location and ECG contamination.
RESULTS
The impact on neural recordings depends on the difference between ECG signal and noise floor of the electrophysiological recording. Empirically, we demonstrate that severe ECG contamination was more than 3.2x higher in left-sided subclavicular implants (48.3%), when compared to right-sided implants (15.3%). Cranial implants did not show ECG contamination.
CONCLUSIONS
Given the relative frequency of corrupted neural signals, we conclude that implant location will impact the ability of brain sensing devices to be used for "closed-loop" algorithms. Clinical adjustments such as implant location can significantly affect signal integrity and need consideration
The zCOSMOS Survey. The dependence of clustering on luminosity and stellar mass at z=0.2-1
We study the dependence of galaxy clustering on luminosity and stellar mass
at redshifts z ~ [0.2-1] using the first zCOSMOS 10K sample.
We measure the redshift-space correlation functions xi(rp,pi) and its
projection wp(rp) for sub-samples covering different luminosity, mass and
redshift ranges. We quantify in detail the observational selection biases and
we check our covariance and error estimate techniques using ensembles of
semi-analytic mock catalogues. We finally compare our measurements to the
cosmological model predictions from the mock surveys.
At odds with other measurements, we find a weak dependence of galaxy
clustering on luminosity in all redshift bins explored. A mild dependence on
stellar mass is instead observed. At z~0.7, wp(rp) shows strong excess power on
large scales. We interpret this as produced by large-scale structure dominating
the survey volume and extending preferentially in direction perpendicular to
the line-of-sight. We do not see any significant evolution with redshift of the
amplitude of clustering for bright and/or massive galaxies.
The clustering measured in the zCOSMOS data at 0.5<z<1 for galaxies with
log(M/M_\odot)>=10 is only marginally consistent with predictions from the mock
surveys. On scales larger than ~2 h^-1 Mpc, the observed clustering amplitude
is compatible only with ~1% of the mocks. Thus, if the power spectrum of matter
is LCDM with standard normalization and the bias has no unnatural
scale-dependence, this result indicates that COSMOS has picked up a
particularly rare, ~2-3 sigma positive fluctuation in a volume of ~10^6 h^-1
Mpc^3. These findings underline the need for larger surveys of the z~1 Universe
to appropriately characterize the level of structure at this epoch.Comment: 18 pages, 21 figures, accepted for publication in Astronomy and
Astrophysic
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
The Belle II Physics Book
We present the physics program of the Belle II experiment, located on the
intensity frontier SuperKEKB collider. Belle II collected its first
collisions in 2018, and is expected to operate for the next decade. It is
anticipated to collect 50/ab of collision data over its lifetime. This book is
the outcome of a joint effort of Belle II collaborators and theorists through
the Belle II theory interface platform (B2TiP), an effort that commenced in
2014. The aim of B2TiP was to elucidate the potential impacts of the Belle II
program, which includes a wide scope of physics topics: B physics, charm, tau,
quarkonium, electroweak precision measurements and dark sector searches. It is
composed of nine working groups (WGs), which are coordinated by teams of
theorist and experimentalists conveners: Semileptonic and leptonic B decays,
Radiative and Electroweak penguins, phi_1 and phi_2 (time-dependent CP
violation) measurements, phi_3 measurements, Charmless hadronic B decay, Charm,
Quarkonium(like), tau and low-multiplicity processes, new physics and global
fit analyses. This book highlights "golden- and silver-channels", i.e. those
that would have the highest potential impact in the field. Theorists
scrutinised the role of those measurements and estimated the respective
theoretical uncertainties, achievable now as well as prospects for the future.
Experimentalists investigated the expected improvements with the large dataset
expected from Belle II, taking into account improved performance from the
upgraded detector.Comment: 689 page
Subthalamic beta band suppression reflects effective neuromodulation in chronic recordings
Background and purpose: Biomarkers for future adaptive deep brain stimulation still need evaluation in clinical routine. Here, we aimed to assess stimulation-induced modulation of beta-band activity and clinical symptoms in a Parkinson's disease patient during chronic neuronal sensing using a novel implantable pulse generator.
Methods: Subthalamic activity was recorded OFF and ON medication during a stepwise increase of stimulation amplitude. Off-line fast fourier transfom -based analysis of beta-band activity was correlated with motor performance rated from blinded videos.
Results: The stepwise increase of stimulation amplitude resulted in decreased beta oscillatory activity and improvement of bradykinesia. Mean low beta-band (13-20 Hz) activity correlated significantly with bradykinesia (ρ = 0.662, p < 0.01).
Conclusions: Motor improvement is reflected in reduced subthalamic beta-band activity in Parkinson's disease, supporting beta activity as a reliable biomarker. The novel PERCEPT neurostimulator enables chronic neuronal sensing in clinical routine. Our findings pave the way for a personalized precision-medicine approach to neurostimulation
Proteasome and Autophagy-Mediated Impairment of Late Long-Term Potentiation (l-LTP) after Traumatic Brain Injury in the Somatosensory Cortex of Mice
Traumatic brain injury (TBI) can lead to impaired cognition and memory consolidation. The acute phase (24–48 h) after TBI is often characterized by neural dysfunction in the vicinity of the lesion, but also in remote areas like the contralateral hemisphere. Protein homeostasis is crucial for synaptic long-term plasticity including the protein degradation systems, proteasome and autophagy. Still, little is known about the acute effects of TBI on synaptic long-term plasticity and protein degradation. Thus, we investigated TBI in a controlled cortical impact (CCI) model in the motor and somatosensory cortex of mice ex vivo-in vitro. Late long-term potentiation (l-LTP) was induced by theta-burst stimulation in acute brain slices after survival times of 1–2 days. Protein levels for the plasticity related protein calcium/calmodulin-dependent protein kinase II (CaMKII) was quantified by Western blots, and the protein degradation activity by enzymatical assays. We observed missing maintenance of l-LTP in the ipsilateral hemisphere, however not in the contralateral hemisphere after TBI. Protein levels of CaMKII were not changed but, interestingly, the protein degradation revealed bidirectional changes with a reduced proteasome activity and an increased autophagic flux in the ipsilateral hemisphere. Finally, LTP recordings in the presence of pharmacologically modified protein degradation systems also led to an impaired synaptic plasticity: bath-applied MG132, a proteasome inhibitor, or rapamycin, an activator of autophagy, both administered during theta burst stimulation, blocked the induction of LTP. These data indicate that alterations in protein degradation pathways likely contribute to cognitive deficits in the acute phase after TBI, which could be interesting for future approaches towards neuroprotective treatments early after traumatic brain injury
Identifying robust subspaces for dynamically consistent reduced-order models
Nonlinear models for large/complex structures are hard to simulate for parametric studies of long-time dynamical behaviors. Reduced order models (ROMs) provide tools that both allow long-time dynamical simulations and reduce data storage requirements. In data-based model reduction, there is usually no consistent way to determine if the obtained ROM is robust to the variations in system parameters. Here, we use two concepts of dynamical consistency and subspace robustness to evaluate ROMs validity for parametric studies. The application of these concepts is demonstrated by reducing a nonlinear finite element model of a cantilever beam in a two well potential field. The resulting procedure can be used for developing and evaluating ROMs that are robust to the variations in the parameters or operating conditions. © The Society for Experimental Mechanics, Inc. 2014