Stanford study maps how brief stimuli can sustain emotions, revealing a shared brain timing signature in humans and mice

New research from Stanford Medicine offers a clearer look at how fleeting sensory events can set off emotional states that linger well beyond the trigger. The findings, reported in Science, point to a conserved brainwide timing pattern seen in both humans and mice.

To create a safe, precisely timed negative experience across species, the team used brief air puffs to the eye, similar to a common eye exam test. Participants described the sensation as annoying or uncomfortable, and repeated puffs led to a longer-lasting feeling of irritation.

A two-phase brainwide response

In hospitalized epilepsy patients who already had intracranial electrodes implanted for clinical monitoring, researchers recorded widespread neural activity during the eye-puff task. They observed a fast burst of activity within about 200 milliseconds, followed by a slower phase lasting roughly 700 milliseconds that involved emotion-linked circuits.

When the same task was run in mice, the brain response showed a comparable two-phase pattern. Repeated puffs also produced a more persistent negative state, reflected in reduced reward-seeking behavior after the stimulus ended.

Ketamine hints at a mechanism

The team then tested ketamine, a drug known to blunt typical emotional reactions at certain doses while leaving basic sensory awareness intact. In both humans and mice, ketamine preserved the reflexive blink but reduced longer, self-protective eye closure between puffs.

Neural recordings suggested why: ketamine selectively shortened the slower, sustained phase of activity without eliminating the initial rapid sensory broadcast. By compressing this integrative window, the drug appeared to limit the brain’s ability to maintain an emotional state from a brief event.

Why timing may matter clinically

Researchers say these measurable timing properties could help explain emotional symptoms that are either too persistent or too fleeting across psychiatric conditions. They also argue that brainwide synchrony and the duration of integrative activity may be key variables for future diagnostics and treatment research.

The work builds on a cross-species approach designed to isolate fundamental, evolutionarily conserved principles of emotional processing. While the study focused on mildly aversive input, the authors say similar timing rules may also apply to positive experiences, an area they are continuing to investigate.