Year: 2025
Type: article
Abstract: BACKGROUND: The locus coeruleus-norepinephrine (LC-NE) system is a well-established regulator of behavior, yet its precise role remains unclear. Animal studies predominantly support a "gain" hypothesis, suggesting that the LC-NE system enhances sensory processing. In contrast, human studies have proposed an alternative "urgency" hypothesis, postulating that LC-NE primarily accelerates responses. METHOD: To address this discrepancy, we administered transcutaneous vagus nerve stimulation (tVNS) in two experiments. In the first experiment (n = 22), we showed that 4-s tVNS trains reliably induced greater pupil dilation compared to SHAM condition, indicating increased LC-NE activity. In the second experiment (n = 21), we applied tVNS during a random dot motion task to assess its impact on perceptual decision-making. RESULT: tVNS improved accuracy without affecting reaction times, which appears inconsistent with the "urgency" hypothesis. Exploratory drift-diffusion model analyses further support the "gain" hypothesis, revealing that tVNS increased the drift rate, indicative of enhanced evidence accumulation. Both accuracy and drift-rate improvements were most prominent following errors and especially pronounced in participants who exhibited post-error declines in these measures under SHAM. CONCLUSION: Our findings align with the "gain" hypothesis, with tentative evidence suggesting that the impact of LC-NE activity adapts to task demands. Accordingly, tVNS showed the strongest effects in contexts prone to accuracy declines, possibly reflecting attentional disengagement, which points to a role of LC in mitigating lapses of attention.
Source: Brain stimulation
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $4,430
Award: G6462978238
OpenAlex ID: W4409918805