Enhancement of Divergent Creative Thinking After Transcranial Near-Infrared Photobiomodulation Over the Default Mode Network

Transcranial photobiomodulation (tPBM) has been used for cognitive enhancement in healthy people. However, its effect on creativity has not been investigated. The default mode network (DMN) is associated with divergent thinking (DT; but not convergent thinking, CT), and also with anxiety, which in turn has been negatively related to creativity. We aimed to use tPBM over the DMN to assess the effect on DT compared to sham. Additionally, we assessed the possible mediating effect of anxiety between tPBM and DT. In this single-blind, between-subjects study, 58 healthy participants were randomly assigned to tPBM or sham group. tPBM was applied using near-infrared light (810 nm, 40 Hz; 50% duty cycle), through light-emitting diode devices combining transcranial plus intranasal PBM over the cortical nodes of the DMN for 20 min (240 J/cm² in total). DT and CT were assessed before (baseline) and after tPBM with the Unusual Uses (UU), Picture Completion (PC) and Remote Associates test (RAT). ANCOVA (post-stimulation controlling for baseline) results showed that tPBM group had significantly higher scores compared to sham in total UU, PC, and total DT. tPBM may be effective for DT enhancement. The lack of effect on CT reveals a specific link between DMN and DT.