What caught their attention was the brain’s “default mode network,” which Smith describes as “a lot of structures along the midline of the brain,” as well as parts of the parietal lobes above the backs of the ears. “The activity of these areas tend to fluctuate together, so we assume that they work together as a network,” Smith says. The default mode network is “most apparent” when a subject is awake and at rest, and is often associated with internal thoughts and mind wandering. In a scanner, the default mode network typically shows up as certain areas of the brain “lighting up” at the same time. But the brains of subjects who experienced ASMR looked different.
ASMR is usually precipitated by stimuli referred to as 'triggers'. ASMR triggers, which are most commonly auditory and visual, may be encountered through the interpersonal interactions of daily life. Additionally, ASMR is often triggered by exposure to specific audio and video. Such media may be specially made with the specific purpose of triggering ASMR or originally created for other purposes and later discovered to be effective as a trigger of the experience.