Transcutaneous Auricular Vagus Nerve Stimulation Strengthens Semantic Representations of Foreign Language Tone Words during Initial Stages of Learning

Abstract

Difficulty perceiving phonological contrasts in a second language (L2) can impede initial L2 lexical learning. Such is the case for English speakers learning tonal languages, like Mandarin Chinese. Given the hypothesized role of reduced neuroplasticity in adulthood limiting L2 phonological perception, the current study examined whether transcutaneous auricular vagus nerve stimulation (taVNS), a relatively new neuromodulatory technique, can facilitate L2 lexical learning for English speakers learning Mandarin Chinese over 2 days. Using a double-blind design, one group of participants received 10 min of continuous priming taVNS before lexical training and testing each day, a second group received 500 msec of peristimulus (peristim) taVNS preceding each to-be-learned item in the same tasks, and a third group received passive sham stimulation. Results of the lexical recognition test administered at the end of each day revealed evidence of learning for all groups, but a higher likelihood of accuracy across days for the peristim group and a greater improvement in response time between days for the priming group. Analyses of N400 ERP components elicited during the same tasks indicate behavioral advantages for both taVNS groups coincided with stronger lexico-semantic encoding for target words. Comparison of these findings to pupillometry results for the same study reported in Pandža, Phillips, Karuzis, O'Rourke, and Kuchinsky (2020) suggest that positive effects of priming taVNS (but not peristim taVNS) on lexico-semantic encoding are related to sustained attentional effort.

Transcutaneous cervical vagus nerve stimulation improves sensory performance in humans

“…In the current study, we randomized stimuli across trials (i.e., different letters and tone frequencies in the visual and auditory tasks, respectively) to minimize learning, and still observed tVNS-evoked improvements. These findings contrast with phasic VNS protocols common in motor and sensory learning protocols that repeatedly pair specific (i.e., non-randomized) stimuli with short VNS bursts over several days or weeks and induce relatively delayed and lasting sensory improvements specific to the paired stimulus [47][48][49][50][51][52][53][54][55][56][57] . Thus, our findings position continuous tcVNS as a new research avenue that can lead to tools for promoting general and on-demand improvements in sensory processing.…”

Electroencephalographic Patterns in taVNS: A Systematic Review

“…Most of the studies analyzed ERP metrics on this review. Among the common oscillation assessments during events we detected early events, such as P100 [ 34 ], P180 [ 33 ], P200 [ 27 , 34 ], P300 [ 28 , 29 , 33 , 36 , 40 , 42 , 43 ], and N200 [ 27 , 28 , 34 , 36 ], and late events, such as P600 [ 33 ], N400 [ 35 ], and N450 [ 33 ].…”

Rapid Effects of Vagus Nerve Stimulation on Sensory Processing Through Activation of Neuromodulatory Systems

“…This mechanism of action can be strengthened over multiple sessions of pairing to produce long-term permanent reorganization of sensory pathways that alters perception. Taken together, these works suggest phasic VNS has great potential as a next generation neuromodulation technology for rehabilitative motor and sensory therapies ( Neuhaus et al, 2007 ; Kreuzer et al, 2014 ; Engineer et al, 2015 ; Tyler et al, 2017 ; Vanneste et al, 2017 ; Kilgard et al, 2018 ; Adcock et al, 2020 ; Llanos et al, 2020 ; Thakkar et al, 2020 ; Altidor et al, 2021 ; Phillips et al, 2021 ).…”