Exploring the neurophysiological effects of combined electrical and auditory stimulation in healthy subjects

Background: Today, effective treatments for patients suffering from disorders of consciousness are lacking. Transcranial direct current stimulation (tDCS) and music have both shown promise in enhancing signs of consciousness. Given the potential for tDCS effects to be enhanced by complementary stimuli, this study aims to investigate its combination with music in a cohort of healthy participants at the cognitive and neurophysiological levels.
Methods: This randomized controlled double-blind crossover study involved four stimulation conditions: tDCS combined with music (tDCS/music) or white noise (tDCS/noise), and sham-tDCS with music (sham-tDCS/music) or white noise (sham-tDCS/noise), which were applied to 24 healthy human adults (<35 years old). Participants’ performance (i.e., accuracy and time response) on Stroop and 3-back cognitive tests was measured before and after each condition. A 20-channel electroencephalogram explored the neurophysiological effects of the interventions.
Results: Cognitive performance (behavioral measures) and power spectral analyses revealed no significant differences between the interventions. A significant increase in global connectivity in the alpha band was found in post- compared to pre-intervention in music (p=0.0026) and tDCS/music (p=0.0028) conditions. The other conditions did not show any significant changes.
Conclusion: Overall, these findings suggest that a single tDCS session combined with music does not enhance cognitive functions in healthy subjects. However, music alone or combined with tDCS exhibited promise in increasing brain activity associated with cognitive performance. Further research, particularly involving multiple sessions of tDCS with or without music, is necessary to better understand the potential of these interventions, especially in patients with disorders of consciousness.