Medial prefrontal cortex supports source memory accuracy for self-referenced items

Abstract

Previous behavioral work suggests that processing information in relation to the self enhances subsequent item recognition. Neuroimaging evidence further suggests that regions along the cortical midline, particularly those of the medial prefrontal cortex (PFC), underlie this benefit. There has been little work to date, however, on the effects of self-referential encoding on source memory accuracy or whether the medial PFC might contribute to source memory for self-referenced materials. In the current study, we used fMRI to measure neural activity while participants studied and subsequently retrieved pictures of common objects superimposed on one of two background scenes (sources) under either self-reference or self-external encoding instructions. Both item recognition and source recognition were better for objects encoded self-referentially than self-externally. Neural activity predictive of source accuracy was observed in the medial PFC (Brodmann area 10) at the time of study for self-referentially but not self-externally encoded objects. The results of this experiment suggest that processing information in relation to the self leads to a mnemonic benefit for source level features, and that activity in the medial PFC contributes to this source memory benefit. This evidence expands the purported role that the medial PFC plays in self-referencing.

Keywords:

• Medial prefrontal cortex
• Self-reference
• Source memory

Acknowledgments

The authors would like to thank Michael Dulas and Yashu Jiang for their invaluable assistance during the development of this project. This research was supported by a grant from the American Federation for Aging Research to A. Duarte and by NIH Grant T32 AG00175 to E. D. Leshikar.

Notes

¹ Note that a liberal threshold for an exclusive mask is more conservative in excluding regions from the masked SPM. The procedure of exclusively masking main effects by their interaction is formally equivalent to the original definition of a “cognitive conjunction” (Price & Friston, 1997).