Impact of Transcutaneous Vagus Nerve Stimulation (taVNS) on cognitive flexibility as a function of task complexity

Patricio Mena-Chamorro¹Tomás Andrés Espinoza-Palavicino¹Mauricio Barramuño-Medina²Tatiana Romero-Arias³Germán Gálvez-García^1,4*

• ¹University of La Frontera, Temuco, Chile
• ²Autonomous University of Chile, Santiago, Santiago Metropolitan Region (RM), Chile
• ³European University of the Canary Islands, La Orotava, Spain
• ⁴University of Salamanca, Salamanca, Spain

This study aimed to evaluate the effect of transcutaneous vagus nerve stimulation (taVNS) on cognitive flexibility under different levels of task complexity. The hypothesis was that taVNS would enhance cognitive flexibility more effectively under demanding task conditions.Method: A within-subject design was used, involving 24 healthy adults who completed a Dimensional Change Card Sorting task combined with an auditory task of varying difficulty levels (low, medium, high). Participants underwent both active and sham taVNS conditions while performing the tasks. The complexity of the auditory task served to reduce cognitive resources available for the cognitive flexibility task, allowing an assessment of how taVNS modulates cognitive flexibility under different task difficulty conditions.The results show that switch costs in the Dimensional Change Card Sorting task increase with task difficulty. In addition, active taVNS reduced switch costs significantly in the high complexity condition, while no differences were observed in the low and medium complexity conditions. This indicates that taVNS is particularly effective in conditions of higher cognitive demand.The findings suggest that taVNS enhances cognitive flexibility, especially in more complex tasks, providing a better understanding of the effects of taVNS on cognitive control.