Original Research Article
Recollection- and familiarity-based decisions reflect memory strength
Martin Wiesmann 1 and Alumit Ishai 2*
1 Institute of Neuroinformatics, University and ETH Zurich, Switzerland
2 Institute of Neuroradiology, University of Zurich, Switzerland
2 Institute of Neuroradiology, University of Zurich, Switzerland
We used event-related fMRI to investigate whether recollection- and familiarity-based memory judgments are modulated by the degree of visual similarity between old and new art paintings. Subjects performed a flower detection task, followed by a Remember/Know/New surprise memory test. The old paintings were randomly presented with new paintings, which were either visually similar or visually different. Consistent with our prediction, subjects were significantly faster and more accurate to reject new, visually different paintings than new, visually similar ones. The proportion of false alarms, namely remember and know responses to new paintings, was significantly reduced with decreased visual similarity. The retrieval task evoked activation in multiple visual, parietal and prefrontal regions, within which remember judgments elicited stronger activation than know judgments. New, visually different paintings evoked weaker activation than new, visually similar items in the intraparietal sulcus. Contrasting recollection with familiarity revealed activation predominantly within the precuneus, where the BOLD response elicited by recollection peaked significantly earlier than the BOLD response evoked by familiarity judgments. These findings suggest that successful memory retrieval of pictures is mediated by activation in a distributed cortical network, where memory strength is manifested by differential hemodynamic profiles. Recollection- and familiarity-based memory decisions may therefore reflect strong memories and weak memories, respectively.
Keywords: encoding, episodic memory, fMRI, retrieval
Copyright: © 2008 Wiesmann and Ishai. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: Alumit Ishai, Institute of Neuroradiology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. e-mail: ishai@hifo.uzh.ch
Citation: Wiesmann M and Ishai A (2008) Recollection- and familiarity-based decisions reflect memory strength. Front. Syst. Neurosci. (2008) 2:1. doi:10.3389/neuro.06.001.2008
Received: 24 January 2008; paper pending published: 18 March 2008; accepted: 08 May 2008; published online: 26 May 2008.
Edited by:
Wolfram Schultz, University of Cambridge, UK
Reviewed by:
Zoe Kourtzi, Birmingham University, UK
Larry Squire, University of California, San Diego, USA
Larry Squire, University of California, San Diego, USA
*Correspondence: Alumit Ishai, Institute of Neuroradiology, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland. e-mail: ishai@hifo.uzh.ch


