False positives to confusable objects predict medial temporal lobe atrophy
Article first published online: 30 MAY 2013
Copyright © The Authors. Hippocampus Published by Wiley Periodicals, Inc.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Volume 23, Issue 9, pages 832–841, September 2013
How to Cite
Kivisaari, S. L., Monsch, A. U. and Taylor, K. I. (2013), False positives to confusable objects predict medial temporal lobe atrophy. Hippocampus, 23: 832–841. doi: 10.1002/hipo.22137
- Issue published online: 23 AUG 2013
- Article first published online: 30 MAY 2013
- Accepted manuscript online: 23 APR 2013 02:36AM EST
- Manuscript Accepted: 15 APR 2013
- Grant sponsor: Swiss Government Scholarship
- Finnish Cultural Foundation
- Finnish Concordia Fund
- Swiss National Science Foundation Ambizione Fellowship. Grant Number: PZ00P1_126493
- Swiss Foundation for Aging Research financed by the Loterie Romande
- Swiss Alzheimer's Association
- Novartis Foundation
- GlaxoSmithKline Research Grant
- perirhinal cortex;
- object memory;
- Alzheimer's disease;
- declarative memory
Animal models agree that the perirhinal cortex plays a critical role in object recognition memory, but qualitative aspects of this mnemonic function are still debated. A recent model claims that the perirhinal cortex is required to recognize the novelty of confusable distractor stimuli, and that damage here results in an increased propensity to judge confusable novel objects as familiar (i.e., false positives). We tested this model in healthy participants and patients with varying degrees of perirhinal cortex damage, i.e., amnestic mild cognitive impairment and very early Alzheimer's disease (AD), with a recognition memory task with confusable and less confusable realistic object pictures, and from whom we acquired high-resolution anatomic MRI scans. Logistic mixed-model behavioral analyses revealed that both patient groups committed more false positives with confusable than less confusable distractors, whereas healthy participants performed comparably in both conditions. A voxel-based morphometry analysis demonstrated that this effect was associated with atrophy of the anteromedial temporal lobe, including the perirhinal cortex. These findings suggest that also the human perirhinal cortex recognizes the novelty of confusable objects, consistent with its border position between the hierarchical visual object processing and medial temporal lobe memory systems, and explains why AD patients exhibit a heightened propensity to commit false positive responses with inherently confusable stimuli. © The Authors. Hippocampus Published by Wiley Periodicals, Inc.