Nonuniform high-gamma (60-500 Hz) power changes dissociate cognitive task and anatomy in human cortex

High-gamma-band (\u3e60 Hz) power changes in cortical electrophysiology are a reliable indicator of focal, event-related cortical activity. Despite discoveries of oscillatory subthreshold and synchronous suprathreshold activity at the cellular level, there is an increasingly popular view that high-gamma-band amplitude changes recorded from cellular ensembles are the result of asynchronous firing activity that yields wideband and uniform power increases. Others have demonstrated independence of power changes in the low- and high-gamma bands, but to date, no studies have shown evidence of any such independence above 60 Hz. Based on nonuniformities in time-frequency analyses of electrocorticographic (ECoG) signals, we hypothesized that induced high-gamma-band (60-500 Hz) power changes are more heterogeneous than currently understood. Using single-word repetition tasks in six human subjects, we showed that functional responsiveness of different ECoG high-gamma sub-bands can discriminate cognitive task (e.g., hearing, reading, speaking) and cortical locations. Power changes in these sub-bands of the high-gamma range are consistently present within single trials and have statistically different time courses within the trial structure. Moreover, when consolidated across all subjects within three task-relevant anatomic regions (sensorimotor, Broca\u27s area, and superior temporal gyrus), these behavior- and location-dependent power changes evidenced nonuniform trends across the population. Together, the independence and nonuniformity of power changes across a broad range of frequencies suggest that a new approach to evaluating high-gamma-band cortical activity is necessary. These findings show that in addition to time and location, frequency is another fundamental dimension of high-gamma dynamics

Hexamethylcyclopentadiene: time-resolved photoelectron spectroscopy and ab initio multiple spawning simulations

Progress in our understanding of ultrafast light-induced processes in molecules is best achieved through a close combination of experimental and theoretical approaches. Direct comparison is obtained if theory is able to directly reproduce experimental observables. Here, we present a joint approach comparing time-resolved photoelectron spectroscopy (TRPES) with ab initio multiple spawning (AIMS) simulations on the MS-MR-CASPT2 level of theory. We disentangle the relationship between two phenomena that dominate the immediate molecular response upon light absorption: a spectrally dependent delay of the photoelectron signal and an induction time prior to excited state depopulation in dynamics simulations. As a benchmark molecule, we have chosen hexamethylcyclopentadiene, which shows an unprecedentedly large spectral delay of (310 \ub1 20) fs in TRPES experiments. For the dynamics simulations, methyl groups were replaced by "hydrogen atoms" having mass 15 and TRPES spectra were calculated. These showed an induction time of (108 \ub1 10) fs which could directly be assigned to progress along a torsional mode leading to the intersection seam with the molecular ground state. In a stepladder-type approach, the close connection between the two phenomena could be elucidated, allowing for a comparison with other polyenes and supporting the general validity of this finding for their excited state dynamics. Thus, the combination of TRPES and AIMS proves to be a powerful tool for a thorough understanding of ultrafast excited state dynamics in polyenes.Peer reviewed: YesNRC publication: Ye

How is participation related to well-being of homeless people?:An explorative qualitative study in a Dutch homeless shelter facility

The majority of homeless people is socially excluded which negatively affects their well-being. Therefore, participation-based programs are needed. The current research is conducted within a Dutch homeless shelter facility that offers educational, recreational, and labor activities to clients in an environment which is designed to feel safe (an enabling niche). The main aim of these activities is to facilitate social participation. We conducted two qualitative studies consisting of 16 semi-structured interviews, to explore clients’ experiences with participation in activities in relation to their well-being. The findings showed that clients experienced that participation had led to an improvement of physical, social, and mental well-being. In general, clients reported that due to participation in activities they have strengthened their social support network, improved their (mental and physical) health, self-esteem and personal growth. We concluded that in order to facilitate long-term positive outcomes of participation in practice, it is necessary to focus on group cohesion, and on the social worker’s behavior and attitud

De totstandkoming van meetinstrumenten van empowerment onder de loep:Instrumentontwikkeling volgens de kwaliteitsstandaarden, een kritische beschouwing

Empowerment is een centraal begrip binnen het sociaal werk in Nederland en Vlaanderen. Er is behoefte aan meetinstrumenten die de empowerende effecten van hulpaanbod blootleggen. De wijze waarop meetinstrumenten ontwikkeld worden, lijkt echter invloed te hebben op de kwaliteit van de instrumenten (Steenssens, Van Regenmortel & Schalk, 2017). Een vijftal kwaliteitsstandaarden is ontwikkeld, waarmee uitspraken gedaan kunnen worden over de kwaliteit van de totstandkoming van dergelijke meetinstrumenten. Om zicht te krijgen op de waarde van deze kwaliteitsstandaarden wordt in dit artikel de wijze waarop een drietal empowerment meetinstrumenten ontwikkeld zijn, kritisch beschouwd vanuit deze standaarden. Dit is gedaan door semigestructureerde interviews met ontwikkelaars te combineren met analyses van bestaand materiaal over de instrumenten. De kwaliteitsstandaarden blijken een kader te bieden met richtlijnen voor instrumentontwikkeling. Het blijkt van belang om goed af te bakenen wat gemeten wordt, zodat een volledig beeld van empowerment verkregen wordt. Verder is goede afstemming tussen contextspecifieke elementen en meer generieke elementen in itemopbouw nodig en is betrokkenheid van de doelgroep bij instrumentontwikkeling noodzakelijk

Three-dimensional magnetic resonance tomography with sub-10 nanometer resolution

We demonstrate three-dimensional magnetic resonance tomography with a resolution down to 5.99 +- 0.07 nm. Our measurements use lithographically fabricated microwires as a source of three-dimensional magnetic field gradients, which we use to image NV centers in a densely doped diamond by Fourier-accelerated magnetic resonance tomography. We also present a compressed sensing scheme for imaging of a spatially localized ensemble from undersampled data, which allows for a direct visual interpretation without numerical optimization. The resolution achieved in our work approaches the positioning accuracy of site-directed spin labeling, paving the way to three-dimensional structure analysis by magnetic-gradient based tomography

Unexpected sound omissions are signaled in human posterior superior temporal gyrus: An intracranial study

Context modulates sensory neural activations enhancing perceptual and behavioral performance and reducing prediction errors. However, the mechanism of when and where these high-level expectations act on sensory processing is unclear. Here, we isolate the effect of expectation absent of any auditory evoked activity by assessing the response to omitted expected sounds. Electrocorticographic signals were recorded directly from subdural electrode grids placed over the superior temporal gyrus (STG). Subjects listened to a predictable sequence of syllables, with some infrequently omitted. We found high-frequency band activity (HFA, 70-170 Hz) in response to omissions, which overlapped with a posterior subset of auditory-active electrodes in STG. Heard syllables could be distinguishable reliably from STG, but not the identity of the omitted stimulus. Both omission- and target-detection responses were also observed in the prefrontal cortex. We propose that the posterior STG is central for implementing predictions in the auditory environment. HFA omission responses in this region appear to index mismatch-signaling or salience detection processes

Assessing dynamics, spatial scale, and uncertainty in task-related brain network analyses

This is the publisher's version, also available electronically from http://journal.frontiersin.org/Journal/10.3389/fncom.2014.00031/abstractThe brain is a complex network of interconnected elements, whose interactions evolve dynamically in time to cooperatively perform specific functions. A common technique to probe these interactions involves multi-sensor recordings of brain activity during a repeated task. Many techniques exist to characterize the resulting task-related activity, including establishing functional networks, which represent the statistical associations between brain areas. Although functional network inference is commonly employed to analyze neural time series data, techniques to assess the uncertainty—both in the functional network edges and the corresponding aggregate measures of network topology—are lacking. To address this, we describe a statistically principled approach for computing uncertainty in functional networks and aggregate network measures in task-related data. The approach is based on a resampling procedure that utilizes the trial structure common in experimental recordings. We show in simulations that this approach successfully identifies functional networks and associated measures of confidence emergent during a task in a variety of scenarios, including dynamically evolving networks. In addition, we describe a principled technique for establishing functional networks based on predetermined regions of interest using canonical correlation. Doing so provides additional robustness to the functional network inference. Finally, we illustrate the use of these methods on example invasive brain voltage recordings collected during an overt speech task. The general strategy described here—appropriate for static and dynamic network inference and different statistical measures of coupling—permits the evaluation of confidence in network measures in a variety of settings common to neuroscience

Universal behavior of localization of residue fluctuations in globular proteins

Localization properties of residue fluctuations in globular proteins are studied theoretically by using the Gaussian network model. Participation ratio for each residue fluctuation mode is calculated. It is found that the relationship between participation ratio and frequency is similar for all globular proteins, indicating a universal behavior in spite of their different size, shape, and architecture.Comment: 4 pages, 3 figures. To appear in Phys. Rev.