Transcranial direct current stimulation of the motor cortex in waking resting state induces motor imagery

This study investigates if anodal and cathodal transcranial direct current stimulation (tDCS) of areas above the motor cortex (C3) influences spontaneous motor imagery experienced in the waking resting state. A randomized triple-blinded design was used, combining neurophysiological techniques with tools of quantitative mentation report analysis from cognitive linguistics. The results indicate that while spontaneous motor imagery rarely occurs under sham stimulation, general and athletic motor imagery (classified as athletic disciplines), is induced by anodal tDCS. This insight may have implications beyond basic consciousness research. Motor imagery and corresponding motor cortical activation have been shown to benefit later motor performance. Electrophysiological manipulations of motor imagery could in the long run be used for rehabilitative tDCS protocols benefitting temporarily immobile clinical patients who cannot perform specific motor imagery tasks – such as dementia patients, infants with developmental and motor disorders, and coma patients.<br/

Psychophysiology of False Memories in a Deese-Roediger-McDermott Paradigm with Visual Scenes

Remembering something that has not in fact been experienced is commonly referred to as false memory. The Deese-Roediger-McDermott (DRM) paradigm is a well-elaborated approach to this phenomenon. This study attempts to investigate the peripheral physiology of false memories induced in a visual DRM paradigm. The main research question is whether false recognition is different from true recognition in terms of accompanying physiological responses

Learning Trivializing Gradient Flows for Lattice Gauge Theories

We propose a unifying approach that starts from the perturbative construction of trivializing maps by L\"uscher and then improves on it by learning. The resulting continuous normalizing flow model can be implemented using common tools of lattice field theory and requires several orders of magnitude fewer parameters than any existing machine learning approach. Specifically, our model can achieve competitive performance with as few as 14 parameters while existing deep-learning models have around 1 million parameters for $SU(3)$ Yang--Mills theory on a $16^2$ lattice. This has obvious consequences for training speed and interpretability. It also provides a plausible path for scaling machine-learning approaches toward realistic theories.Comment: 10 pages, 4 figures, 1 tabl

Acute changes in social composition and agonistic behavior in male vervet monkeys ( Cercopithecus aethiops sabaeus )

Among nonhuman primates the composition of social groups influences the interactions of group members. We assessed the effects of acute changes in social composition on behavior among 15 adult male vervet monkeys ( Cercopithecus aethiops sabaeus ). Subjects were observed in their basal social groups which comprised 3 adult males, 2–4 adult females, and offspring; and in two subgroups consisting of either two or three adult males. Agonism and vigilance increased in smaller groups relative to basal conditions, while subjects in two-male groups displayed more aggression than those in three-male groups. These findings suggest that, among male vervet monkeys, acute disruption of stable social groups increases aggressive behavior, and that the amount of agonism is influenced by the composition of the consequent subgroups. © 1992 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/38426/1/1350270307_ftp.pd

›Nahtoderfahrungen‹. Ein wissenschaftliches Mysterienspiel heute: Interview mit Dieter Vaitl vom 11. November 2017

Dieter Vaitl geht davon aus, dass es sich bei ›Nahtoderfahrungen‹ (NTE) um eine sehr heterogene, begrifflich schwer zu fassende Ansammlung von Phänomenen handelt, die keinesfalls nur in Todesnähe auftreten. Sie sollten deswegen besser innerhalb des wesentlich breiteren Spektrums veränderter Bewusstseinszustände denn als isoliertes Phänomen beschrieben werden. Ihre Komplexität ist vor allem methodologisch eine Herausforderung für die Forschung, die sich dem Thema daher am besten über mehrdimensional angelegte Ansätze widmen sollte. Dieses Potential wurde bislang jedoch noch gar nicht ausgeschöpft. Vaitl sieht daher keinen Grund, aus den bestehenden Erklärungsschwierigkeiten ›Beweisspektakel‹ zugunsten eines Glaubens an jenseitige Wirklichkeiten abzuleiten.In this interview, Dieter Vaitl assumes that ›Near-Death Experience‹ (NDE) is a very heterogeneous collection of phenomena that are difficult to conceptualize and that by no means only occur near death. NDE are therefore better described within the much broader spectrum of altered states of consciousness, rather than as an isolated phenomenon. Their complexity is above all a methodological challenge for research, which should therefore best address the topic using multidimensional approaches. However, this potential has not yet been fully exploited. Vaitl therefore sees no reason to derive from the existing difficulties in explanation an ›evidence spectacle‹ in favor of a belief in otherworldly realities

Influence of contingency awareness on neural, electrodermal and evaluative responses during fear conditioning

In an fMRI study, effects of contingency awareness on conditioned responses were assessed in three groups comprising 118 subjects. A differential fear-conditioning paradigm with visual conditioned stimuli, an electrical unconditioned stimulus and two distractors was applied. The instructed aware group was informed about the contingencies, whereas the distractors prevented contingency detection in the unaware group. The third group (learned aware) was not informed about the contingencies, but learned them despite the distractors. Main effects of contingency awareness on conditioned responses emerged in several brain structures. Post hoc tests revealed differential dorsal anterior cingulate, insula and ventral striatum responses in aware conditioning only, whereas the amygdala was activated independent of contingency awareness. Differential responses of the hippocampus were specifically observed in learned aware subjects, indicating a role in the development of contingency awareness. The orbitofrontal cortex showed varying response patterns: lateral structures showed higher responses in instructed aware than unaware subjects, the opposite was true for medial parts. Conditioned subjective and electrodermal responses emerged only in the two aware groups. These results confirm the independence of conditioned amygdala responses from contingency awareness and indicate specific neural circuits for different aspects of fear acquisition in unaware, learned aware and instructed aware subjects

Influence of Body Position on Cortical Pain-Related Somatosensory Processing: An ERP Study

Background: Despite the consistent information available on the physiological changes induced by head down bed rest, a condition which simulates space microgravity, our knowledge on the possible perceptual-cortical alterations is still poor. The present study investigated the effects of 2-h head-down bed rest on subjective and cortical responses elicited by electrical, pain-related somatosensory stimulation. Methodology/Principal Findings: Twenty male subjects were randomly assigned to two groups, head-down bed rest (BR) or sitting control condition. Starting from individual electrical thresholds, Somatosensory Evoked Potentials were elicited by electrical stimuli administered randomly to the left wrist and divided into four conditions: control painless condition, electrical pain threshold, 30 % above pain threshold, 30 % below pain threshold. Subjective pain ratings collected during the EEG session showed significantly reduced pain perception in BR compared to Control group. Statistical analysis on four electrode clusters and sLORETA source analysis revealed, in sitting controls, a P1 component (40–50 ms) in the right somatosensory cortex, whereas it was bilateral and differently located in BR group. Controls ’ N1 (80–90 ms) had widespread right hemisphere activation, involving also anterior cingulate, whereas BR group showed primary somatosensory cortex activation. The P2 (190–220 ms) was larger in left-central locations of Controls compared with BR group. Conclusions/Significance: Head-down bed rest was associated to an overall decrease of pain sensitivity and an altered pai

Differential activation of the lateral premotor cortex during action observation

<p>Abstract</p> <p>Background</p> <p>Action observation leads to neural activation of the human premotor cortex. This study examined how the level of motor expertise (expert vs. novice) in ballroom dancing and the visual viewpoint (internal vs. external viewpoint) influence this activation within different parts of this area of the brain.</p> <p>Results</p> <p>Sixteen dance experts and 16 novices observed ballroom dance videos from internal or external viewpoints while lying in a functional magnetic resonance imaging scanner. A conjunction analysis of all observation conditions showed that action observation activated distinct networks of premotor, parietal, and cerebellar structures. Experts revealed increased activation in the ventral premotor cortex compared to novices. An internal viewpoint led to higher activation of the dorsal premotor cortex.</p> <p>Conclusions</p> <p>The present results suggest that the ventral and dorsal premotor cortex adopt differential roles during action observation depending on the level of motor expertise and the viewpoint.</p