New Delhi: Watching short-form videos on platforms such as TikTok or Instagram may reduce activity in brain regions responsible for cognitive control and self-regulation, a new study has found. It also linked this effect to the levels of glutamate, an excitatory neurotransmitter, in the brain.
Published in the journal NeuroImage and led by Yuzheng Hu at Zhejiang University in China, the study scanned the brains of 56 young adults with functional magnetic resonance imaging (fMRI) while they freely watched short videos. The researchers used proton magnetic resonance spectroscopy (H-MRS) to measure resting levels of glutamate and γ-aminobutyric acid (GABA) in the dorsal anterior cingulate cortex (dACC), a frontal brain region.
When participants watched videos they preferred and finished, activity dropped noticeably in both the dACC and the dorsolateral prefrontal cortex (dlPFC)—core hubs of the cognitive control network. Videos that were quickly skipped produced far less of this effect. Visual cortex areas, by contrast, were activated normally regardless of preference.
“Immersive viewing of preferred short videos deactivates the cognitive control network and individual differences in this deactivation are linked to glutamate metabolism,” the researchers wrote.
Not a failure of cognitive control
Higher resting glutamate in the dACC was associated with less deactivation in both regions. On the other hand, GABA levels showed no clear relationship. Functional connectivity between the dACC and dlPFC increased during video watching, more strongly for preferred clips.
The authors stress that this deactivation should not be interpreted as a failure of cognitive control. Rather, it likely reflects the low conflict inherent to passive viewing, allowing the brain to settle into a more automatic, absorbed state similar to “flow”.
The brain’s monitoring systems may ease off when content is highly engaging, making it easier to keep watching. Individual differences in glutamate may help explain why some people find it harder to stop scrolling than others.
The study was preregistered and used a naturalistic setup in which participants could freely skip videos. Its limitations include the relatively small, mostly young-adult sample, the use of completion (rather than explicit ratings) to define “liked” videos, and the absence of measures of participants’ habitual short-video use.
The findings add to evidence that highly engaging digital media can reconfigure the balance between reward-driven and control-related brain systems, and they highlight a possible neurochemical factor in vulnerability to excessive consumption.
(Edited by Prasanna Bachchhav)
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