Structural differences between non-lucid dreams, lucid dreams and out-of-body experience reports assessed by graph analysis.

Dreaming is a complex phenomenon that occurs during sleep, involving various conscious dream experiences. Lucid dreams (LDs) involve heightened awareness within the dream environment, while out-of-body experiences (OBEs) involve the sensation of being outside one's physical body. OBEs occur during sleep paralysis (SP), where voluntary movements are inhibited during sleep/wake transitions while remaining aware of the surroundings. The relationship between LDs and OBEs is debated, with some viewing them as distinct phenomena and others considering them different manifestations of the same underlying experience. This study aimed to characterize non-lucid dreams, LDs, and OBEs by analyzing dream reports' structural properties. OBE reports displayed a condensed and interconnected network structure compared to non-lucid dreams and LDs. Additionally, OBE reports exhibited a specialized network structure, with specific nodes playing a more central role. These findings suggest that OBE dreams may have a more coherent and unified narrative, with certain nodes being pivotal in the network structure.

Spontaneous and induced out-of-body experiences during sleep paralysis: Emotions, "AURA" recognition, and clinical implications.

Sleep paralysis is characterized by the incapacity to perform voluntary movements during sleep/wake transitions, and could bring great discomfort. During sleep paralysis, out-of-body experiences can occur. Out-of-body experiences refers to the sensation of being outside of the physical body and perceiving the world from this outside perspective; however, they are pleasant in comparison with other sleep paralysis hallucinations. Lucid dreams are dreams in which a subject becomes aware of being dreaming while the dream occurs. Here, we designed an online survey to study the predominant and specific emotions during sleep paralysis and/or out-of-body experience events as well as the somatosensory perceptions that preceded their occurrence. The sample (N = 329) was divided into experimental groups depending on the presence/absence of out-of-body experiences, capacity to induce (or not) out-of-body experiences, and perception/no-perception of the sleep paralysis. We showed that more positive emotions were associated with out-of-body experiences and more negative emotions were associated with sleep paralysis episodes, and for those who claim the ability to induce out-of-body experiences, positive emotions were more frequent in their episodes. We found that subjects perceived auditory, tactile and visual sensations before sleep paralysis episodes, and we proposed that these could be an "aura" of sleep paralysis. Furthermore, subjects that had out-of-body experiences but had never felt the sleep paralysis, perceived tactile and visual sensations to the same extent as subjects with out-of-body experiences that felt the sleep paralysis. Therefore, we proposed that the "aura" recognition could be used under controlled conditions for out-of-body experiences induction in patients with sleep paralysis to diminish the negative symptoms associated with sleep paralysis episodes.

Immediate Early Genes, Memory and Psychiatric Disorders: Focus on c-Fos, Egr1 and Arc.

Many psychiatric disorders, despite their specific characteristics, share deficits in the cognitive domain including executive functions, emotional control and memory. However, memory deficits have been in many cases undervalued compared with other characteristics. The expression of Immediate Early Genes (IEGs) such as, c-fos, Egr1 and arc are selectively and promptly upregulated in learning and memory among neuronal subpopulations in regions associated with these processes. Changes in expression in these genes have been observed in recognition, working and fear related memories across the brain. Despite the enormous amount of data supporting changes in their expression during learning and memory and the importance of those cognitive processes in psychiatric conditions, there are very few studies analyzing the direct implication of the IEGs in mental illnesses. In this review, we discuss the role of some of the most relevant IEGs in relation with memory processes affected in psychiatric conditions.

Simvastatin pretreatment prevents ambient particle-induced lung injury in mice.

Air particulate pollution negatively affects the health of the population exposed, being the lung the main target organ. Simvastatin (SV) is widely used for the prevention and risk reduction of coronary disease. Its pleiotropic effects may provide benefit for lung diseases. Here, we investigated the preventive effect of simvastatin pretreatment on acute intranasal exposure to ROFA (Residual Oil Fly Ash), and UAP (Urban Air Particle from Buenos Aires). Male BALB/c mice were randomized in two groups to receive either saline (control, C) solution or SV (1 mg/kg bw /day; ip) for 14 days. After SV treatment, ROFA or UAP (1 mg/kg bw) or saline were intranasally delivered for 24 hours generating 4 subgroups for the ROFA experiment (C, SV, ROFA and SV+ROFA) and 3 subgroups for the UAP experiment (C, SV, UAP and SV+UAP). Biomarkers of lung injury were examined in BAL cells evaluating total cell number (TCN), cell differential (CD) and superoxide anion generation (O2-), in lung homogenates assessing superoxide dismutase activity (SOD) and tumor necrosis factor α (TNFα); and in blood samples determining interleukin 6 (IL-6) production. ROFA and UAP produced an acute pulmonary injury, characterized by an increase in BAL, TCN and neutrophilic inflammatory influx, a rise in O2- generation, and production of the proinflammatory TNFα cytokine. SV pretreatment had no significant effect per se on any of these biomarkers but prevented the pulmonary cytotoxicity and inflammation induced by ROFA and UAP. Our results encourage further studies to determine the preventive effects on lung injury induced by air pollutants.