Transcutaneous auricular vagus nerve stimulation during a 3-back task: a high-density functional near-infrared...

Area of Science:

• Neuroscience
• Cognitive Science
• Biomedical Engineering

Background:

• Working memory deficits significantly impair individuals with neurological disorders.
• Transcutaneous vagus nerve stimulation (tVNS) is a potential non-invasive neuromodulatory technique to enhance cognitive functions, including working memory.
• High-density functional near-infrared spectroscopy (HD-fNIRS) offers a method to assess cortical hemodynamics during cognitive tasks.

Purpose of the Study:

• To investigate the effects of tVNS on working memory performance and prefrontal cortex activity using HD-fNIRS.
• To evaluate the feasibility and tolerability of simultaneous HD-fNIRS and tVNS during a working memory task.

Main Methods:

• Twenty-two healthy adults performed a 3-back task while undergoing HD-fNIRS monitoring of the prefrontal cortex.
• Active tVNS was applied to the tragus during the second task block, while sham tVNS was applied to the earlobe during the first block.
• Group-level statistical analyses examined task-related brain activity and differences between active and sham tVNS conditions.

Main Results:

• Task performance elicited robust activation in lateral frontal cortical areas under both active and sham tVNS conditions.
• No significant differences in cortical activity or behavioral performance were observed between active and sham tVNS.
• The study demonstrated the feasibility and tolerability of combining HD-fNIRS with tVNS.

Conclusions:

• While simultaneous HD-fNIRS and tVNS are feasible for studying working memory, the current stimulation parameters and fixed-order design did not yield significant differences.
• Future research should consider alternative designs to mitigate potential fatigue or habituation effects.
• HD-fNIRS shows promise for investigating neuromodulation effects on working memory in both healthy individuals and clinical populations.