Brain scans reveal how emotions unfold over time

Most fMRI studies of emotion average brain activity across an entire time window, erasing precisely the information that matters most: how does activation shift from second to second as a feeling develops? The study, published in eLife, used time-resolved fMRI (functional magnetic resonance imaging, a method that tracks brain activity via blood flow) to follow participants as they watched emotionally evocative short film clips.

Four networks, four phases

The researchers identified four large-scale brain circuits that activate in sequence. The first network, active immediately upon viewing the clip, includes regions involved in perception and emotional evaluation. Networks for semantic interpretation and decision-making follow. Finally, activity emerges in the default mode network, typically associated with self-directed thought and reflection. The emotional content of the film clips influenced both which networks were active and the timing of that activity.

Relevance for cognitive aging

From a longevity perspective, the temporal profiles of emotional processing are known to change in psychiatric conditions. Disrupted emotion regulation is also a feature of cognitive decline and dementia. Understanding how healthy brain networks process emotions over time provides a baseline against which early deviations can be detected. The authors suggest that spatial and temporal markers of emotional processing may be useful for tracking changes in clinical populations. This remains preliminary and requires further research.

The study was conducted in healthy adults in a laboratory setting. Translating the findings to clinical applications or aging populations will require additional work.

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