People who have experienced psychological trauma often suffer from dissociation - a feeling of detachment from their own body or the surrounding world. Conventional therapy requires painful immersion in traumatic memories, and many patients abandon treatment. Psychologists are looking for ways to help them "ground" in the present moment by training interoception - the ability of the nervous system to perceive signals from inside the body, such as heartbeat or breathing. Mindfulness meditation develops such sensitivity, but beginners and anxious people find it difficult to hold attention.
Researchers from Emory University School of Medicine, led by Negar Fani, Alexa Kondas and Timothy McDermott, decided to test whether adding a physical external anchor to meditation would help. They used a small device on the sternum that sends a low-frequency vibration to the skin. The vibration either synchronizes with breathing or pulses at regular intervals. Such buzzing serves as a constant bodily reminder and helps return attention to the body without great mental effort.
The clinical trial involved 116 adults with traumatic experience and elevated levels of dissociation. They were randomly assigned to groups: all completed eight short mindfulness meditation sessions over several weeks, but about half meditated with vibration on the chest, and the other half without the device. Before and after the course, participants underwent a special type of MRI that measures the microscopic structure of the brain's white matter. White matter is the "wiring" of nerve cell processes connecting different parts. The scientists assessed the density of these processes: its growth usually reflects strengthening or formation of new connections, that is, neuroplasticity - the brain's ability to reorganize under the influence of experience.
The scanning showed: in the vibration group, the density of nerve fibers increased in the corticospinal tract - a large bundle of nerve pathways transmitting motor and sensory signals between the brain and the body. Those who meditated without vibration showed no such changes. An additional analysis with three-dimensional reconstruction of the tract confirmed the result.
Participants also filled out questionnaires after each session, rating how connected they felt to their body. Over eight sessions, the vibration group reported significantly greater improvement in body awareness than the standard meditation group. A reduction in the feeling of dissociation was observed in both groups approximately equally.
The most interesting finding emerged when comparing scans and questionnaires: in the vibration group, the increase in nerve fiber density in the corticospinal tract was directly linked to a decrease in dissociation. The more the white matter structure changed, the greater the clinical improvement. In the group without vibration, no such link was found. This is a correlation - a statistical relationship that by itself does not prove that changes in the brain caused the improvement in symptoms.
The authors suggest that the device stimulates the sensory nerves of the chest, and the constant rhythmic signal makes the brain build denser connections in the corticospinal tract to process this information. In turn, the strengthened biological "wiring" facilitates perception of one's own body at rest, over time weakening dissociation. However, the exact mechanisms remain hypothetical: MRI shows structure but not microscopic chemical processes. In addition, this is an interim analysis of an ongoing trial, so it is unknown whether the changes will persist after months or years. Psychological improvements were measured by participants' self-reports, that is, subjectively.
The study "Good vibrations: Sternal vibration enhances white matter density and interoceptive awareness" was published in the journal Neuropsychopharmacology.