The effect of non-invasive vagus nerve stimulation on memory recall in reading: A pilot study

Expert reading acquisition is marked by fluent, effortless decoding, and adequate comprehension skills and is required for modern daily life. In spite of its importance, many individuals struggle with reading comprehension even when decoding skills are adequate. Unfortunately, effective reading comprehension interventions are limited, especially for adults. A growing body of research suggests that non-invasive transcutaneous stimulation of the auricular vagus nerve (taVNS) may drive neural plasticity for low-level reading skills such as speech sound perception and letter-sound learning, but it is unknown whether taVNS can improve higher level skills as well. Thus, the current pilot study was designed to evaluate the effect of taVNS paired with passage reading on reading comprehension performance. Twenty-four typically developing young adults were recruited and screened for baseline reading and working memory skills. Participants received either sham or active taVNS while reading short passages out loud. Immediately following each passage, participants answered a series of test questions that required either direct recall of passage details or more complete comprehension of the passage content. While taVNS did not improve the mechanics of reading (e.g., reading rate or accuracy), there was a significant effect of active taVNS on test performance. This effect was driven by significant improvement on accuracy for memory questions while there was no effect of taVNS on comprehension question accuracy. These findings suggest that taVNS may be beneficial for enhancing memory, but its efficacy may be limited in higher cognitive domains.