6,224 research outputs found
An interoceptive predictive coding model of conscious presence
We describe a theoretical model of the neurocognitive mechanisms underlying conscious presence and its disturbances. The model is based on interoceptive prediction error and is informed by predictive models of agency, general models of hierarchical predictive coding and dopaminergic signaling in cortex, the role of the anterior insular cortex (AIC) in interoception and emotion, and cognitive neuroscience evidence from studies of virtual reality and of psychiatric disorders of presence, specifically depersonalization/derealization disorder. The model associates presence with successful suppression by top-down predictions of informative interoceptive signals evoked by autonomic control signals and, indirectly, by visceral responses to afferent sensory signals. The model connects presence to agency by allowing that predicted interoceptive signals will depend on whether afferent sensory signals are determined, by a parallel predictive-coding mechanism, to be self-generated or externally caused. Anatomically, we identify the AIC as the likely locus of key neural comparator mechanisms. Our model integrates a broad range of previously disparate evidence, makes predictions for conjoint manipulations of agency and presence, offers a new view of emotion as interoceptive inference, and represents a step toward a mechanistic account of a fundamental phenomenological property of consciousness
Growth, Characterization, Vortex Pinning and Vortex Flow Properties of Single Crystals of Iron Chalcogenide Superconductor FeCrSe
We report the growth and characterization of single crystals of iron
chalcogenide superconductor FeCrSe. There is an enhancement of the
superconducting transition temperature (T) as compared to the T of the single crystals of the parent compound FeSe by about 25%.
The superconducting parameters such as the critical fields, coherence length,
penetration depth and the Ginzburg-Landau parameter have been estimated for
these single crystals. Analysis of the critical current data suggests a
fluctuation in electronic mean free path induced () pinning mechanism
in this material. Thermally activated transport across the superconducting
transition in the presence of external magnetic fields suggests a crossover
from a single vortex pinning regime at low fields to a collective flux creep
regime at higher magnetic fields. The nature of charge carriers in the normal
state estimated from the Hall effect and thermal transport measurements could
provide crucial information on the mechanism of superconductivity in Fe-based
materials.Comment: 2 additional figures, additional discussion on nature of charge
carrier
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