2,129 research outputs found
Coding of visual object features and feature conjunctions in the human brain
Peer reviewedPublisher PD
Induced gamma band responses predict recognition delays during object identification
Peer reviewedPublisher PD
Induced gamma-band activity is related to the time point of object identification
Peer reviewedPostprin
Optical imaging of strain in two-dimensional crystals
Strain engineering is widely used in material science to tune the
(opto-)electronic properties of materials and enhance the performance of
devices. Two-dimensional atomic crystals are a versatile playground to study
the influence of strain, as they can sustain very large deformations without
breaking. Various optical techniques have been employed to probe strain in
two-dimensional materials, including micro-Raman and photoluminescence
spectroscopy. Here we demonstrate that optical second harmonic generation
constitutes an even more powerful technique, as it allows to extract the full
strain tensor with a spatial resolution below the optical diffraction limit.
Our method is based on the strain-induced modification of the nonlinear
susceptibility tensor due to a photoelastic effect. Using a two-point bending
technique, we determine the photoelastic tensor elements of molybdenum
disulfide. Once identified, these parameters allow us to spatially image the
two-dimensional strain field in an inhomogeneously strained sample.Comment: 13 pages, 4 figure
Color Transparent GPDs?
The relation between GPD's and color transparency is explored. The discovery
of color transparency in pionic diffractive dissociation reactions allows us to
make specific predictions for the behavior of the pion generalized parton
distribution, and provide a further test of any model of the pion form factor.Comment: 12 pages, 3 figure
Approximate Number Processing Skills Contribute to Decision Making Under Objective Risk: Interactions With Executive Functions and Objective Numeracy
Research on the cognitive abilities involved in decision making has shown that, under objective risk conditions (i.e., when explicit information about possible outcomes and risks is available), superior decisions are especially predicted by executive functions and exact number processing skills, also referred to as objective numeracy. So far, decision-making research has mainly focused on exact number processing skills, such as performing calculations or transformations of symbolic numbers. There is evidence that such exact numeric skills are based on approximate number processing (ANP) skills, which enable quick and accurate processing of non-symbolic numbers (e.g., Chen and Li, 2014). Very few studies, however, have investigated ANP skills in the context of risky decision making and have analyzed direct associations among the aforementioned sub functions. Possible interactions between the closely related skills have not been considered. The current study (N = 128) examines interactions of ANP skills with executive functions and objective numeracy, in predicting risky choice behavior. ANP skills are represented by the accuracy in a dot-comparison task. Decision making is measured by two versions of the Game of Dice Task (GDT), which place different emphases on the reflection of potential risks. The results show two-way as well as three-way interactions between the measures of ANP skills, executive functions, and objective numeracy in predicting risky decisions in both GDT versions. The riskiest decisions were most frequently made in case of low scores in all of the three competencies, while good performance in any one of them resulted in significant reductions of disadvantageous decisions. The findings indicate that high ANP skills can positively affect choice behavior in individuals who have weaknesses in reflectively attributed skills, namely executive functions and objective numeracy. Potential compensatory effects and mechanisms of ANP in decision making are discussed
Modulation of Somatosensory Alpha Rhythm by Transcranial Alternating Current Stimulation at Mu-Frequency
Introduction: Transcranial alternating current stimulation (tACS) is emerging
as an interventional tool to modulate different functions of the brain,
potentially by interacting with intrinsic ongoing neuronal oscillations.
Functionally different intrinsic alpha oscillations are found throughout the
cortex. Yet it remains unclear whether tACS is capable of specifically
modulating the somatosensory mu-rhythm in amplitude. Objectives: We used tACS
to modulate mu-alpha oscillations in amplitude. When compared to sham
stimulation we expected a modulation of mu-alpha oscillations but not visual
alpha oscillations by tACS. Methods: Individual mu-alpha frequencies were
determined in 25 participants. Subsequently, blocks of tACS with individual
mu-alpha frequency and sham stimulation were applied over primary
somatosensory cortex (SI). Electroencephalogram (EEG) was recorded before and
after either stimulation or sham. Modulations of mu-alpha and, for control,
visual alpha amplitudes were then compared between tACS and sham. Results:
Somatosensory mu-alpha oscillations decreased in amplitude after tACS was
applied at participants’ individual mu-alpha frequency. No changes in
amplitude were observed for sham stimulation. Furthermore, visual alpha
oscillations were not affected by tACS or sham, respectively. Conclusion: Our
results demonstrate the capability of tACS to specifically modulate the
targeted somatosensory mu-rhythm when the tACS frequency is tuned to the
individual endogenous rhythm and applied over somatosensory areas. Our results
are in contrast to previously reported amplitude increases of visual alpha
oscillations induced by tACS applied over visual cortex. Our results may point
to a specific interaction between our stimulation protocol and the functional
architecture of the somatosensory system
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