Neural correlate of spatial presence in an arousing and noninteractive virtual reality: an EEG and psychophysiology study

Using electroencephalography (EEG), psychophysiology, and psychometric measures, this is the first study which investigated the neurophysiological underpinnings of spatial presence. Spatial presence is considered a sense of being physically situated within a spatial environment portrayed by a medium (e.g., television, virtual reality). Twelve healthy children and 11 healthy adolescents were watching different virtual roller coaster scenarios. During a control session, the roller coaster cab drove through a horizontal roundabout track. The following realistic roller coaster rides consisted of spectacular ups, downs, and loops. Low-resolution brain electromagnetic tomography (LORETA) and event-related desynchronization (ERD) were used to analyze the EEG data. As expected, we found that, compared to the control condition, experiencing a virtual roller coaster ride evoked in both groups strong SP experiences, increased electrodermal reactions, and activations in parietal brain areas known to be involved in spatial navigation. In addition, brain areas that receive homeostatic afferents from somatic and visceral sensations of the body were strongly activated. Most interesting, children (as compared to adolescents) reported higher spatial presence experiences and demonstrated a different frontal activation pattern. While adolescents showed increased activation in prefrontal areas known to be involved in the control of executive functions, children demonstrated a decreased activity in these brain regions. Interestingly, recent neuroanatomical and neurophysiological studies have shown that the frontal brain continues to develop to adult status well into adolescence. Thus, the result of our study implies that the increased spatial presence experience in children may result from the not fully developed control functions of the frontal cortex.

Virtual reality and the role of the prefrontal cortex in adults and children

In this review, the neural underpinnings of the experience of presence are outlined. Firstly, it is shown that presence is associated with activation of a distributed network, which includes the dorsal and ventral visual stream, the parietal cortex, the premotor cortex, mesial temporal areas, the brainstem and the thalamus. Secondly, the dorsolateral prefrontal cortex (DLPFC) is identified as a key node of the network as it modulates the activity of the network and the associated experience of presence. Thirdly, children lack the strong modulatory influence of the DLPFC on the network due to their unmatured frontal cortex. Fourthly, it is shown that presence-related measures are influenced by manipulating the activation in the DLPFC using transcranial direct current stimulation (tDCS) while participants are exposed to the virtual roller coaster ride. Finally, the findings are discussed in the context of current models explaining the experience of presence, the rubber hand illusion, and out-of-body experiences.

Modulating presence and impulsiveness by external stimulation of the brain

BACKGROUND "The feeling of being there" is one possible way to describe the phenomenon of feeling present in a virtual environment and to act as if this environment is real. One brain area, which is hypothesized to be critically involved in modulating this feeling (also called presence) is the dorso-lateral prefrontal cortex (dlPFC), an area also associated with the control of impulsive behavior. METHODS In our experiment we applied transcranial direct current stimulation (tDCS) to the right dlPFC in order to modulate the experience of presence while watching a virtual roller coaster ride. During the ride we also registered electro-dermal activity. Subjects also performed a test measuring impulsiveness and answered a questionnaire about their presence feeling while they were exposed to the virtual roller coaster scenario. RESULTS Application of cathodal tDCS to the right dlPFC while subjects were exposed to a virtual roller coaster scenario modulates the electrodermal response to the virtual reality stimulus. In addition, measures reflecting impulsiveness were also modulated by application of cathodal tDCS to the right dlPFC. CONCLUSION Modulating the activation with the right dlPFC results in substantial changes in responses of the vegetative nervous system and changed impulsiveness. The effects can be explained by theories discussing the top-down influence of the right dlPFC on the "impulsive system".

European undergraduate curriculum in geriatric medicine developed using an international modified Delphi technique.

INTRODUCTION the rise in the number of older, frail adults necessitates that future doctors are adequately trained in the skills of geriatric medicine. Few countries have dedicated curricula in geriatric medicine at the undergraduate level. The aim of this project was to develop a consensus among geriatricians on a curriculum with the minimal requirements that a medical student should achieve by the end of medical school. METHODS a modified Delphi process was used. First, educational experts and geriatricians proposed a set of learning objectives based on a literature review. Second, three Delphi rounds involving a panel with 49 experts representing 29 countries affiliated to the European Union of Medical Specialists (UEMS) was used to gain consensus for a final curriculum. RESULTS the number of disagreements following Delphi Rounds 1 and 2 were 81 and 53, respectively. Complete agreement was reached following the third round. The final curriculum consisted of detailed objectives grouped under 10 overarching learning outcomes. DISCUSSION a consensus on the minimum requirements of geriatric learning objectives for medical students has been agreed by European geriatricians. Major efforts will be needed to implement these requirements, given the large variation in the quality of geriatric teaching in medical schools. This curriculum is a first step to help improve teaching of geriatrics in medical schools, and will also serve as a basis for advancing postgraduate training in geriatrics across Europe.

Lernzielkatalog für die studentische Lehre im Fachbereich „Geriatrie“ an Fakultäten für Humanmedizin.

Zusammenfassung Die Betreuung geriatrischer Patientinnen und Patienten setzt, nebst einer entsprechenden Haltung, fundierte Kenntnisse in Diagnostik und Behandlung praktisch aller medizinischen Fachgebiete voraus. Daher ist es wichtig, dass die Kompetenz von Studierenden der Humanmedizin im Bereich Geriatrie entsprechend gefördert wird. Bis heute hat jedoch die studentische Ausbildung im Fach Geriatrie an vielen europäischen Universitäten einen unklaren oder untergeordneten Stellenwert. Als ersten Schritt zur Förderung der Lehre in der Geriatrie hat die Europäische Facharztvereinigung Geriatrie (UEMS-GMS) in einem Delphi-Prozess einen Lernzielkatalog entwickelt. Dieser Katalog enthält die Mindestanforderungen mit spezifischen Lernzielen (Wissen, Fertigkeiten und Haltungen), welche die Studierenden der Humanmedizin bezüglich Geriatrie bis zum Abschluss des Medizinstudiums erwerben sollen. Zur Förderung der Implementierung dieses neuen, kompetenzbasierten Lernzielkatalogs an den deutschsprachigen Universitäten wurde eine an den Sprachgebrauch des „DACH-Raums“ (Deutschland, Österreich und Schweiz) angepasste deutsche Version erstellt. Im vorliegenden Beitrag wird diese Übersetzung vorgestellt. Die Fachgesellschaften für Geriatrie aus Deutschland, Österreich und der Schweiz empfehlen den medizinischen Fakultäten der jeweiligen Länder, diesen Katalog umzusetzen.

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Rastrojo de arroz (Oryza sativa L.) en sistemas de siembra directa : alternativas de manejo

Los objetivos principales del presente trabajo fueron: a) Estudiar cuál es el uso adecuado de las distintas herramientas para mejorar la mineralización del rastrojo de la cosecha de arroz (Oryza sativa L.) bajo siembra directa y b) Determinar, para períodos cortos, la cantidad de rastrojo depositado superficialmente y su tiempo de mineralización al utilizar las distintas técnicas de manejo del mismo. Los tratamientos fueron: cosechadora con desparramador deflector (T1DD), cosechadora sin desparramador triturador (T2SDT), cosechadora con desparramador centrífugo de caucho (T3DC) y cosechadora con desparramador metálico (T4DM). Alternativas implementadas: a) desmalezado b) rolo cuchilla y c) quemado de rastrojo. En las primeras dos alternativas, se aplicaron tres dosis de urea. Los resultados principales fueron: a) La T2SDT produjo, una mayor deposición de material en el centro de la máquina (21680 kg ha-1), b) la distribución de rastrojo de la (T3DC) fue más uniforme que para los otros tratamientos. Las principales conclusiones fueron: 1) Los desparramadores centrífugos de caucho y metálico produjeron mejor distribución del material, 2) El uso de desmalezadora o rolo cuchilla sobre rastrojo de los tratamientos T3DC y T4DM aceleró la mineralización de los mismos. 3) Las dosis de urea causó poco incremento en la mineralización del rastrojo.

Carbon, boron and oxygen isotope ratios of sediments from the Moresby Seamount

We report results from boron, carbon and oxygen stable isotope analyses of faulted and veined rocks recovered by scientific ocean drilling during ODP Leg 180 in the western Woodlark Basin, off Papua New Guinea. In this area of active continental extension, crustal break-up and incipient seafloor spreading, a shallow-dipping, seismically active detachment fault accommodates strain, defining a zone of mylonites and cataclasites, vein formation and fluid infiltration. Syntectonic microstructures and vein-fill mineralogy suggest frictional heating during slip during extension and exhumation of Moresby Seamount. Low carbon and oxygen isotope ratios of calcite veins indicate precipitation from hydrothermal fluids (delta13C PDB down to -17?; delta18O PDB down to -22?) formed by both dehydration and decarbonation. Boron contents are low (<7 ppm), indicating high-grade metamorphic source rock for the fluids. Some of the delta11B signatures (17-35?; parent solutions to calcite vein fills) are low when compared to deep-seated waters in other tectonic environments, likely reflecting preferential loss of 11B during low-grade metamorphism at depth. Pervasive devolatilization and flux of CO2-rich fluids are evident from similar vein cement geochemistry in the detachment fault zone and splays further updip. Multiple rupture-and-healing history of the veins suggests that precipitation may be an important player in fluid pressure evolution and, hence, seismogenic fault movement.