Transcranial random noise stimulation (tRNS) over prefrontal cortex does not influence the evaluation of facial emotions

ABSTRACT

Cerebral asymmetries for emotion processing are controversial, the right hemisphere being considered either superior in the recognition of all emotions, or superior in the recognition of negative emotions (together with the left-hemispheric superiority for positive emotions). In a number of previous studies, tDCS was applied on the left/right prefrontal cortex (PFC) in order to disentangle this issue, but the results remain controversial. We applied hf-tRNS/sham stimulation over the left/right PFC, during the presentation of neutral, angry and happy faces presented as broadband images (supraliminal condition), and as “hybrid” stimuli in which an emotional face in low spatial frequency is superimposed to the neutral expression of the same individual in high spatial frequency (subliminal condition), during a friendliness evaluation task. The results showed that angry and happy unfiltered stimuli were judged as the most unfriendly and friendly, respectively. Importantly, we found that hf-tRNS applied over the left/right PFC did not influence friendliness evaluations for emotional faces.

KEYWORDS:

• Transcranial random noise stimulation (tRNS)
• hybrid faces
• Right hemisphere hypothesis
• Valence hypothesis
• subliminal emotions
• hemispheric asymmetry

Supplementary material

Supplemental data for this article can be accessed here.

Acknowledgments

We thank Mariarosita Campagna and Rosa Russiello, who helped us in recruiting and testing participants.

Disclosure statement

No potential conflict of interest was reported by the authors.