Poster F93, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Hippocampus supports unconscious what-where-when memory formation: an fMRI study
Else Schneider1,2, Roland Wiest3, Katharina Henke1,2; 1University of Bern, Bern, Switzerland, 2Centre for Cognition, Learning and Memory, University of Bern, Bern, Switzerland, 3Institute of Diagnostic and Interventional Neuroradiology, University Hospital Bern, Bern, Switzerland
Episodic memory is widely believed to depend on conscious perception and conscious mentation. But there is growing evidence against this consciousness-centred view. Findings suggest that humans can learn and retrieve new semantic associations rapidly even if the information is presented subliminally, i.e. invisible to the conscious mind. Based on these findings, we investigated whether humans were able to unconsciously encode and later retrieve complex what-where-when associations (a proxy for episodic memory) by way of their hippocampus. Using fMRI we presented 36 distinct subliminal film clips displaying animals traversing a scene and hiding in a shelter for arbitrary time period to 24 participants. Another group of 24 participants performed the same fMRI experiment with conscious, supraliminal encoding of the film clips. After every third film clip, participants took a forced-choice memory task that targeted temporal and spatial aspects of the events displayed in the previous three film clips. Participants needed to give guess responses in the subliminal version and recollective responses in the supraliminal version of the experiment. Participants evidenced unconscious what-where-when memory by responding faster in correctly versus incorrectly answered test trials and by exhibiting activity increases in areas of the episodic memory system similar to participants in the supraliminal version of the experiment. These results suggest an unconscious form of episodic memory.
Topic Area: LONG-TERM MEMORY: Episodic