P3b reflects periodicity in linguistic sequences

Temporal predictability is thought to affect stimulus processing by facilitating the allocation of attentional resources. Recent studies have shown that periodicity of a tonal sequence results in a decreased peak latency and a larger amplitude of the P3b compared with temporally random, i.e., aperiodic sequences. We investigated whether this applies also to sequences of linguistic stimuli (syllables), although speech is usually aperiodic. We compared aperiodic syllable sequences with two temporally regular conditions. In one condition, the interval between syllable onset was fixed, whereas in a second condition the interval between the syllables’ perceptual center (p-center) was kept constant. Event-related potentials were assessed in 30 adults who were instructed to detect irregularities in the stimulus sequences. We found larger P3b amplitudes for both temporally predictable conditions as compared to the aperiodic condition and a shorter P3b latency in the p-center condition than in both other conditions. These findings demonstrate that even in acoustically more complex sequences such as syllable streams, temporal predictability facilitates the processing of deviant stimuli. Furthermore, we provide first electrophysiological evidence for the relevance of the p-center concept in linguistic stimulus processing

Zur Entwicklung und Irritation von Hörgewohnheiten

Bestimmte Songs sind so mit uns und unserem Leben verbunden, dass die Ablehnung dieser Songs durch andere emotional verletzend wirken kann. Auch wir selbst empfinden ungewohnte Hörerlebnisse oftmals als störend und abstoßend und sind nicht in der Lage, einen ästhetischen Zugang zu finden. Erwachsenenbildung kann hier Lernprozesse anregen und begleiten und im Ergebnis dazu führen, den Reiz eines mehr distanzierten Hörens gemeinsam zu entdecken

Time course of information processing in visual and haptic object classification

Peer reviewedPublisher PD

The influence of edge undulation on vortex formation for low-aspect-ratio propulsors

Experiments to study the effect of edge undulation on vortex formation have been conducted on impulsively accelerated plates. Abstractions of propulsors found in nature are produced by imprinting undulatory features with varying wavelengths onto the circumferential vortex-forming edge of circular plates. The effects of the small-scale disturbances introduced by these modifications are accessed by means of force measurements and time-resolved particle image velocimetry. Investigations of four different geometries at two different Reynolds numbers reveal an insensitivity of the flow towards length scales smaller than or similar to the thickness of the feeding shear layer. However, the instabilities in the shear layer and the coherence of the vortex wake are influenced when the wavelength of the undulation exceeds the shear-layer thickness by a significant margin. This results in a force augmentation due to enhanced entrainment into the turbulent vortex core, and thus an associated faster vortex growth rate. Yet, contrary to prior expectations, the time of vortex pinch-off remains constant for all edge modifications. The cause–effect relationship behind the stability of the vortex wake is further investigated. While for small edge undulations a turbulent transition of the vortex core results in vortex pinch-off, for larger edge undulations the turbulent vortex core is found to be fed constantly with additional circulation from the shear layer

Accurate Realizations of the Ionized Gas in Galaxy Clusters: Calibrating Feedback

Using the full, three-dimensional potential of galaxy cluster halos (drawn from an N-body simulation of the current, most favored cosmology), the distribution of the X-ray emitting gas is found by assuming a polytropic equation of state and hydrostatic equilibrium, with constraints from conservation of energy and pressure balance at the cluster boundary. The resulting properties of the gas for these simulated redshift zero clusters (the temperature distribution, mass-temperature and luminosity-temperature relations, and the gas fraction) are compared with observations in the X-ray of nearby clusters. The observed properties are reproduced only under the assumption that substantial energy injection from non-gravitational sources has occurred. Our model does not specify the source, but star formation and AGN may be capable of providing this energy, which amounts to 3 to 5 x10^{-5} of the rest mass in stars (assuming ten percent of the gas initially in the cluster forms stars). With the method described here it is possible to generate realistic X-ray and Sunyaev-Zel'dovich cluster maps and catalogs from N-body simulations, with the distributions of internal halo properties (and their trends with mass, location, and time) taken into account.Comment: Matches ApJ published version; 30 pages, 7 figure

Physical exercise during encoding improves vocabulary learning in young female adults

Acute physical activity has been repeatedly shown to improve various cognitive functions. However, there have been no investigations comparing the effects of exercise during verbal encoding versus exercise prior to encoding on long-term memory performance. In this current psychoneuroendocrinological study we aim to test whether light to moderate ergometric bicycling during vocabulary encoding enhances subsequent recall compared to encoding during physical rest and encoding after being physically active. Furthermore, we examined the kinetics of brain-derived neurotrophic factor (BDNF) in serum which has been previously shown to correlate with learning performance. We also controlled for the BDNF val66met polymorphism. We found better vocabulary test performance for subjects that were physically active during the encoding phase compared to sedentary subjects. Post-hoc tests revealed that this effect was particularly present in initially low performers. BDNF in serum and BDNF genotype failed to account for the current result. Our data indicates that light to moderate simultaneous physical activity during encoding, but not prior to encoding, is beneficial for subsequent recall of new items

Force estimates in turbulent vortex wakes of accelerating propulsors: The effects of edge undulation on vortex formation

The effects of edge undulation on separated flows and vortex formation are investigated with various geometries of accelerated, low aspect-ratio propulsors. In addition to force measurements, multi-camera planar particle image velocimetry (PIV) is applied for a large field of view of approximately 1.9 m × 0.3 m. Edge undulations with a wavelength λ, that is significantly larger than the thickness δ of the separated shear layer are identified to enhance the propulsion force during the stable vortex growth and before the vortex detaches. Edge undulation leads to a more turbulent vortex core and a faster vortex growth. The application of different approaches to recover the acting forces from PIV data lead to the conclusion, that the three-dimensionality of the turbulent vortex wake leads to both: a loss of out-of-plane vorticity and an underestimation of the kinetic energy in the vortex

A psychophysiology practical as part of the medical psychology course

Die Vermittlung der Zusammenhänge zwischen psychologischen Funktionen und körperlichen Veränderungen sowie deren Relevanz für die Entstehung und Aufrechterhaltung von Krankheiten stellt ein zentrales Ziel der Ausbildung in Medizinischer Psychologie dar. Zur Veranschaulichung dieser Zusammenhänge führten wir ein Psychophysiologie-Praktikum im ersten vorklinischen Semester ein. Die Studierenden führten in Vierergruppen mit Hilfe ausführlicher schriftlicher Instruktionen jeweils ca. 30 Minuten andauernde praktische Übungen durch, die die folgenden Themen behandelten: (1) Stress (abhängige Variable: Herzrate), (2) "Lügendetektor" (abhängige Variable: Hautleitwertsreaktionen), (3) Biofeedback (abhängige Variable: Hauttemperatur) und (4) Elektroenzephalogramm (abhängige Variable: Amplituden der vier klassischen Frequenzbänder). Die praktischen Übungen wurden durch theoretische Gruppenarbeiten und einen Termin zur Zusammenfassung der Ergebnisse der Übungen ergänzt. Die studentische Evaluation des Praktikums war durchweg positiv. So wurde das Praktikum als Bereicherung des Kurses angesehen, und der selbstbeurteilte Kenntnisstand auf dem Gebiet der Psychophysiologie zeigte eine signifikante Verbesserung. Diese Ergebnisse sowie unsere Eindrücke während des Praktikums bekräftigten unseren Entschluss, ein Psychophysiologie-Praktikum als Teil des Kurses der Medizinischen Psychologie und Medizinischen Soziologie fest zu etablieren.Teaching in medical psychology aims at establishing an understanding of the relationships between psychological functions and bodily reactions and of the relevance of these interactions for the development and maintenance of diseases. To illustrate these relationships, a psychophysiology practical was introduced in the first semester. Students performed practical 30-minute exercises in groups of four on the basis of comprehensive written instructions. The following topics were covered: (1) stress (dependent variable: heart rate), (2) "lie detection" (dependent variable: skin conductance response), (3) biofeedback (dependent variable: skin temperature), and (4) electroencephalogram (dependent variable: amplitude in the four classical frequency bands). The practical exercises were complemented by theoretical group work and a summary of the results of the exercises. Students evaluated the practical positively. It was considered a benefit to the course, and the self-rated knowledge in the area of psychophysiology increased significantly. These results, as well as our experiences during the practical, have reinforced our decision to establish a psychophysiology practical as part of the medical psychology/medical sociology course

Vom neuronalen Einzelfahrschein zur kortikalen Netzkarte : audio-visuelle Objekterkennung in der Großhirnrinde

Die Wahrnehmung von Objekten gelingt uns jeden Tag unzählige Male – zumeist rasend schnell und problemlos. Obwohl fast immer mehrere unserer Sinne gleichzeitig bei ihrer Wahrnehmung angesprochen werden, erscheinen uns diese Objekte dennoch als ganzheitlich und geschlossen. Für die neuronale Verarbeitung eines bellenden Hundes zum Beispiel empfängt die Großhirnrinde zumindest Eingangsdaten des Seh- und des Hörsystems. Sie werden auf getrennten Pfaden und in spezialisierten Arealen mit aufsteigender Komplexität analysiert. Dieses Funktionsprinzip der parallel verteilten Verarbeitung stellt die Wissenschaftler aber auch vor das so genannte »Bindungsproblem«: Wo und wie werden die Details wieder zu einem Ganzen – zu einer neuronalen Repräsentation – zusammengefügt? Am Institut für medizinische Psychologie der Universitätsklinik Frankfurt untersuchen Neurokognitionsforscher die crossmodale Objekterkennung mit einer Kombination modernster Verfahren der Hirnforschung und kommen dabei den Ver - arbeitungspfaden in der Großhirnrinde auf die Spur

Improving audio-visual temporal perception through training enhances beta-band activity

Multisensory integration strongly depends on the temporal proximity between two inputs. In the audio-visual domain, stimulus pairs with delays up to a few hundred milliseconds can be perceived as simultaneous and integrated into a unified percept. Previous research has shown that the size of this temporal window of integration can be narrowed by feedback-guided training on an audio-visual simultaneity judgment task. Yet, it has remained uncertain how the neural network that processes audio-visual asynchronies is affected by the training. In the present study, participants were trained on a 2-interval forced choice audio-visual simultaneity judgment task. We recorded their neural activity with magnetoencephalography in response to three different stimulus onset asynchronies (0 ms, each participant’s individual binding window, 300 ms) before, and one day following training. The Individual Window stimulus onset asynchrony condition was derived by assessing each participant’s point of subjective simultaneity. Training improved performance in both asynchronous stimulus onset conditions (300 ms, Individual Window). Furthermore, beta-band amplitude (12–30 Hz) increased from pre-compared to post-training sessions. This increase moved across central, parietal, and temporal sensors during the time window of 80–410 ms post-stimulus onset. Considering the putative role of beta oscillations in carrying feedback from higher to lower cortical areas, these findings suggest that enhanced top-down modulation of sensory processing is responsible for the improved temporal acuity after training. As beta oscillations can be assumed to also preferentially support neural communication over longer conduction delays, the widespread topography of our effect could indicate that training modulates not only processing within primary sensory cortex, but rather the communication within a large-scale network