Effects of transcutaneous auricular vagus nerve stimulation on associative memory and event-related potential P300: a single-blind experiment on healthy adults

Transcutaneous auricular vagus nerve stimulation (taVNS) is attracting attention as a new neuromodulation to improve cognitive function. The effects of this neuromodulation on associative memory and its mechanisms have not been fully investigated. This crossover, single-blind, active-versus-sham design experiment examined the effects of taVNS on associative memory performance and event-related potential P300, a biomarker of norepinephrine. The experiment consisted of an associative memory task with encoding and retrieval as a set, performed three times with a 10 min rest period, on 14 healthy adults. Participants received taVNS or sham during the 10 min rest between the time 1 and time 2. Event-related potentials were measured at each time of the associative memory task. The washout for this experiment was set at one week. We analyzed the effects of taVNS by means of a general linear mixed model with performance on three associative memory tasks and peak amplitude of event-related potential P300 as dependent variables. The results presented a main effect of taVNS on response time in an associative memory task. We also found a main effect of taVNS on the peak amplitude of event-related potential P300 at Fz, Cz, and Pz. This study indicated that when NE secretion is promoted by taVNS, associative memory performance is enhanced. This noninvasive neuromodulation has potential applications in rehabilitation for cognitive function and should be further investigated for application. Registration : University Hospital Medical Information Network Center (No. UMIN000055911), date: January 24, 2024 “retrospectively registered”.