Acetylcholine, a neurotransmitter involved in cognition and REM sleep regulation, may play a role in lucid dreaming—a state where metacognitive awareness returns during sleep. Recent studies using acetylcholinesterase inhibitors suggest a link, but the causal mechanisms remain unknown. This review examines theories connecting acetylcholine and metacognition across wakefulness and sleep, analyzing the phenomenon at microscopic, mesoscopic, and macroscopic levels. It develops exploratory hypotheses to guide future research on how acetylcholine receptor activity affects metacognition.
Meditation training produces beneficial effects on health, cognition, emotion, and social behavior. Sociologists have shown that individual-level traits and outcomes can spread through social networks across three or more degrees of connection. This article proposes that meditation-induced changes may similarly propagate through practitioners' social networks by positively influencing others via prosocial actions, improved cognitive functioning, and increased positive affect. Positive affective states and their physiological correlates may also be shared directly. The authors argue that such spreading could form the basis for collective responses to societal challenges and call for future research to examine this phenomenon.
A three-month mental training module focused on socio-affective skills like compassion (the Affect module) reduced negative feelings when viewing images of human suffering and increased brain activity in the right supramarginal gyrus. Two other three-month modules—one cultivating attention and interoceptive awareness (Presence) and another cultivating socio-cognitive skills like theory of mind (Perspective)—did not produce these effects. The findings suggest that compassion-based mental training specifically improves emotion regulation when facing adversity, whereas attention- or meta-cognitive training does not.