Virtual reality training of lucid dreaming.

Metacognitive reflections on one's current state of mind are largely absent during dreaming. Lucid dreaming as the exception to this rule is a rare phenomenon; however, its occurrence can be facilitated through cognitive training. A central idea of respective training strategies is to regularly question one's phenomenal experience: is the currently experienced world real, or just a dream? Here, we tested if such lucid dreaming training can be enhanced with dream-like virtual reality (VR): over the course of four weeks, volunteers underwent lucid dreaming training in VR scenarios comprising dream-like elements, classical lucid dreaming training or no training. We found that VR-assisted training led to significantly stronger increases in lucid dreaming compared to the no-training condition. Eye signal-verified lucid dreams during polysomnography supported behavioural results. We discuss the potential mechanisms underlying these findings, in particular the role of synthetic dream-like experiences, incorporation of VR content in dream imagery serving as memory cues, and extended dissociative effects of VR session on subsequent experiences that might amplify lucid dreaming training during wakefulness. This article is part of the theme issue 'Offline perception: voluntary and spontaneous perceptual experiences without matching external stimulation'.

Tumor carcinoide primario de ovario que se presenta como enfermedad cardiaca carcinoide / Primary carcinoid tumor of the ovary presenting with carcinoid heart disease / Primary carcinoid tumor of the ovary presenting with carcinoid heart disease

RESUMEN El tumor carcinoide primario de ovario es una entidad poco frecuente que se caracteriza por la producción de sustancias vasoactivas que pasan directamente al torrente circulatorio y producen el llamado síndrome carcinoide. Estas sustancias también son las causantes de la formación de placas de fibrosis en las válvulas cardiacas, principalmente las derechas. Presentamos un caso de tumor carcinoide primario de ovario con afectación de la válvula tricúspide, que fue diagnosticado a partir de la lesión cardiaca. En la literatura están descritos casos clínicos aislados y revisiones de casos que nos pueden ayudar en el diagnóstico y en la toma de decisiones terapéuticas. Debemos conocer la existencia de estos tumores; la clínica debe alertarnos sobre su presencia. Es primordial un manejo multidisciplinar junto con endocrinólogos, cardiólogos, oncólogos, anatomo-patólogos, anestesistas, ginecólogos y cirujanos cardiacos, para ofrecer un tratamiento completo.

ABSTRACT Primary ovarian carcinoid tumor is a rare neoplasm characterized by the production of vasoactive substances that enter the bloodstream and give rise to the so-called carcinoid syndrome. These substances may also cause fibrotic plaques in the heart valves, mainly those in the right cardiac chambers. We describe the case of a primary ovarian carcinoid tumor with tricuspid valve involvement in which the diagnosis was prompted by identification of cardiac involvement. Knowledge of the clinical manifestations of neuroendocrine tumors is important in diagnosis and patient management. Recognition of typical clinical features may help suggest the correct diagnosis. Multidisciplinary discussion allows the formulation of a comprehensive management strategy involving endocrinologists, cardiologists, oncologists, pathologists, anaesthesiologists, gynaecologists and heart surgeons.