Transcutaneous Auricular Vagus Nerve Stimulation Improves Spatial Working Memory in Healthy Young Adults

Abstract

Working memory (WM) is one of the core components of higher cognitive functions. There exists debate regarding the extent to which current techniques can enhance human WM capacity. Here, we examined the WM modulation effects of a previously less studied technique, transcutaneous auricular vagus nerve stimulation (taVNS). In experiment 1, a within-subject study, we aimed to investigate whether and which stimulation protocols of taVNS can modulate spatial WM performance in healthy adults. Forty-eight participants performed baseline spatial n-back tasks (1, 3-back) and then received online taVNS, offline taVNS, or sham stimulation before or during (online group) the posttest of spatial n-back tasks in random order. Results showed that offline taVNS could significantly increase hits in spatial 3-back task, whereas no effect was found in online taVNS or sham group. No significant taVNS effects were found on correct rejections or reaction time of accurate trials (aRT) in both online and offline protocols. To replicate the results found in experiment 1 and further investigate the generalization effect of offline taVNS, we carried out experiment 2. Sixty participants were recruited and received offline taVNS or offline earlobe stimulation in random order between baseline and posttests of behavioral tests (spatial/digit 3-back tasks). Results replicated the findings; offline taVNS could improve hits but not correct rejections or aRT in spatial WM performance, which were found in experiment 1. However, there were no significant stimulation effects on digit 3-back task. Overall, the findings suggest that offline taVNS has potential on modulating WM performance.

Assessing the Effect of Simultaneous Combining of Transcranial Direct Current Stimulation and Transcutaneous Auricular Vagus Nerve Stimulation on the Improvement of Working Memory Performance in Healthy Individuals

“…Thus, we employed anodal left-DLPFC tDCS in the first experiment. In the standard taVNS protocol, electrodes were placed in the left cymba conchae with the anode outside (Neuser et al, 2020 ; Sun et al, 2021a ), and the same protocol was employed in the present study.…”

“…To test the facilitation of tDCS over the left DLPFC and its combined effects with taVNS, we employed a within-subjects design in this experiment, with each participant completing three separate sessions, which had different stimulation conditions, such as L-DLPFC tDCS, taVNS, and SJS-L. Every two sessions were separated by a period of 3 days, such that participants completed three different sessions at the first, fourth, and seventh days (Sun et al, 2021a ). The stimulation orders were balanced between the participants.…”

“…The anode and cathode of taVNS were both placed in the left cymba conchae, with the anode outside and 0.5 cm apart from the cathode. The electrical stimulation waveform was a single-phase rectangular pulse, with a pulse width of 500 μs and a frequency of 25 Hz (Neuser et al, 2020 ; Sun et al, 2021a ; Shen et al, 2022 ). The current intensity was set according to the sensory threshold of each subject.…”

“…Recently, some brain imaging studies, such as functional magnetic resonance imaging (fMRI) studies, found that taVNS could influence a range of cortex and subcortex regions, including the contralateral postcentral gyrus, bilateral insula, frontal cortex, right operculum, left cerebellum, insula, hippocampus, amygdala, and thalamus (Yakunina et al, 2017;Badran et al, 2018). Moreover, behavioral studies have confirmed that taVNS could improve a series of cognitive functions, such as WM (Sun et al, 2021a), inhibitory control processes (Beste et al, 2016), and divergent thinking (Colzato et al, 2018). Considering similar modulatory effects and the complementary modulatory mechanism of tDCS and taVNS (top-down and bottom-up mechanisms) on cognition, the effects of their simultaneous joint stimulation with dual-path mechanisms are worthy of exploring.…”

“The Wandering Nerve Linking Heart and Mind” – The Complementary Role of Transcutaneous Vagus Nerve Stimulation in Modulating Neuro-Cardiovascular and Cognitive Performance

“…The most recent studies in this area have involved a spatial stimulation and response inhibition multitask, with notable improved results in accuracy with 25 min pre-assessment t-VNS stimulation ( Sun et al, 2021 ) and improved objective attention, arousal and multitasking ability in sleep deprived military personnel ( McIntire et al, 2021 ).…”