A brief breath-counting mindfulness exercise can improve how people learn to distinguish dangerous from safe cues during fear conditioning. In a discriminative fear conditioning experiment, participants who practiced breath counting gave lower shock-expectancy ratings to a safety signal (CS−) than those who read freely, indicating less overgeneralization of fear to safe stimuli. The mindfulness group also showed reduced skin conductance responses overall, yet the groups did not differ in their overall fear acquisition effect. The findings suggest that breath-counting tasks enhance sensitivity to conditioned fear acquisition by reducing exaggerated fear responses to safety signals, offering insights for preventing anxiety disorders.
Depression often accompanies liver cirrhosis, but the underlying reasons are unclear. In mice with cirrhosis induced by common bile duct ligation (CBDL), depression-like behaviors, inflammation, reduced synaptic proteins in the prefrontal cortex, gut microbiota imbalance, and altered blood metabolites were observed. These changes were reversed by severing the subdiaphragmatic vagus nerve, and a single injection of arketamine improved the depression-like behaviors. The findings suggest that the gut-liver-brain axis, via the vagus nerve, mediates depression in cirrhosis, and arketamine may offer a new treatment.
Mice with hepatic ischemia/reperfusion (HI/R) injury showed depression-like behaviors, splenomegaly, systemic inflammation, reduced synaptic proteins in the prefrontal cortex, altered gut microbiota, and changed blood metabolites and lipids. Cutting the subdiaphragmatic vagus nerve blocked these changes, suggesting the gut-microbiota-liver-brain axis via the vagus nerve underlies the link between liver injury and depression. A single injection of arketamine alleviated the depression-like phenotypes in these mice, indicating potential for treating depression in chronic liver disease patients.