Leading U.S. neuroscientists have identified a direct brain connection between fear and anxiety. Published in the prestigious journal NeuroImage, this research from the University of New Mexico and CalTech elucidates how acute fear responses evolve into persistent anxiety.
A pioneering study published in NeuroImage on May 28, 2020, offers crucial insights into how anxiety emerges from fear. Researchers from the University of New Mexico and the California Institute of Technology (CalTech) analyzed rodents using behavioral tests combined with advanced MRI scans.
The findings show that multiple brain regions activated by fear remain highly active long after the triggering event. To pinpoint these, scientists deactivated the SERT gene, which regulates serotonin receptors—a key neurotransmitter in the central nervous system, often dubbed the "happiness hormone."
SERT-KO mice, rendered more susceptible to fear and anxiety, underwent clearer MRI and behavioral assessments. Manganese injections further highlighted active neurons during scans. After a rest period to reduce stress, mice were exposed to TMT (2,3,5-trimethyl-3-thiazoline), a fox-derived odor that reliably triggers fear.
MRI scans conducted before, during, and after fear exposure detected 45 regions of elevated brain activity. Notably, some persisted for days post-event—in SERT-KO mice, up to 23 days, compared to 9 days in normal mice.
Lead researchers distinguish immediate fear processing from sustained anxiety, highlighting disrupted coordination in key areas like the striatum (motivation and survival) and pallidum (basal ganglia). A 2018 study had previously pinpointed anxiety's roots in the hippocampus.
Fear-induced anxiety also disrupts the brain's reward circuit, involving serotonin receptors. These insights from established institutions could enhance diagnosis and targeted therapies for anxiety disorders and post-traumatic stress in humans.
