Serotonin in the brain can be understood as an extension of the gut's serotonergic system, which controls digestion. Central serotonin activity mimics a digestion/satiety circuit, where low serotonergic tone facilitates cognitive automaticity and higher tone helps identify flexible solutions when initial responses fail. This perspective explains serotonin's roles in reward processing, exploration, and psychedelic experiences, and clarifies links between serotonergic dysfunction and psychiatric symptoms.
MDMA (100 mg) reduces functional connectivity between the right insula and the salience network in the brain, indicating a disintegration of this network. This decrease in connectivity correlates with higher baseline trait anxiety and more intense acute experiences of altered bodily sensations under the drug. The findings suggest that insular disintegration is a neurobiological signature of the MDMA experience, linking the drug's effects on brain activity to individual differences in anxiety and bodily awareness.
A pilot randomized-controlled trial tested whether Kundalini yoga could protect the aging brain. Eleven healthy older adults who had never meditated were randomly assigned to either a Kundalini yoga program or a psychoeducation comparison. Brain scans taken before and after 12 weeks showed a significant increase in right hippocampal gray matter volume only in the yoga group. The finding suggests that Kundalini yoga may have neuroprotective effects for older adults, though the small sample limits generalizability.