Searching for the inner self: evidence against a direct dependence of the self-prioritization effect on the ventro-medial prefrontal cortex.

The processing of self-referential material is supposed to be located in the medial prefrontal cortex (MPFC) and in particular in the ventro-medial prefrontal cortex (VMPFC). A reliable method to assess effects of self-relevance is the so-called matching paradigm in which the prioritization of newly learned self-associations in comparison to non-self-relevant associations can be measured. To assess the connection of activation in the VMPFC and self-referential processing, we measured the self-prioritization effect (SPE) before and after experimentally manipulating activation in the VMPFC. We applied either excitatory or inhibitory stimulation to the VMPFC via transcranial direct current stimulation (tDCS). In a sample of N = 65 healthy adults, we found a significant SPE before and after both types of stimulation and, remarkably, no systematic change of the SPE due to the stimulation. These results are evidential against a direct dependence of the SPE from activation in the VMPFC, indicating either that the SPE differs from other, more elaborate self-effects, and thereby is processed in different brain areas, or that the connection of SPE and VMPFC is correlational rather than causal.