Time or place? Dissociation between object-in-place and relative recency in young APPswe/PS1dE9 mice.

Charlotte Bonardi,Paul Armstrong,Marie-Christine Pardon

doi:10.1037/bne0000431

Abstract

This study tests the predictions of a novel analysis of recognition memory based on a theory of associative learning, according to which recognition comprises two independent underlying processes, one relying on the to-be-recognized item having been experienced recently (self-generated priming), and the other on it being predicted by some other stimulus (retrieval-generated priming). A single experiment examined recognition performance in the amyloid precursor protein (APP)swe/PS1dE9 (APP/PS1) mouse, a double-transgenic model of Alzheimer's disease (AD), and wild type (WT) littermates. Performance on two variants of the spontaneous object recognition (SOR) was compared in 5-month-old APPswe/PS1dE9 (APP/PS1) mice, a double-transgenic model of AD, and their WT littermates, using junk objects. In the relative recency task animals were exposed to object A, and then object B, followed by a test with both A and B. In the object-in-place task the mice were exposed to both A and B, and then tested with two copies of A, occupying the same positions as the preeexposed objects. The WT mice showed a preference for exploring the first-presented object A in the relative recency task, and the copy of A in the "wrong" position (i.e., the one placed where B had been during the preexposure phase) in the object-in-place task. The APP/PS1 mice performed like the WT mice in the relative recency task, but showed a selective impairment in the object-in-place task. We interpret these findings in terms of-Wagner's (Information processing in animals: Memory Mechanisms, 1981, Erlbaum) theory of associative learning, sometimes opponent process (SOP), as a selective deficit in retrieval-generated priming. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Highlights

Recognition memory plays an integral role in human cognitive activity and is a fundamental part of episodic memory
A substantial amount of research is conducted on the topic, in both humans and animal subjects; for example, in 2015 Grayson and colleagues noted that in the previous ten years no fewer than 34 reviews had been published on object recognition in rodents alone (Grayson et al, 2015)
Use of this task highlights the difficulty of mapping recognition memory as conceptualised in the human literature onto rodents: in humans the distinction between recollection and familiarity is frequently captured by the distinction between 'remember' and 'know' judgements, that cannot be reproduced in animals in this, or any type of task

Summary

Introduction

Recognition memory plays an integral role in human cognitive activity and is a fundamental part of episodic memory. The model explains associative learning by asserting that, for example, when two novel stimuli are paired this will result in both having elements in A1, which allows an excitatory association to form between them; this means that when one of the stimuli is presented it can activate elements of the other directly into A2; this process is called retrieval-generated priming. This analysis suggests at least two potential mechanisms for accurate performance on the SOR task. Both these mechanisms reduce responding to the pre-exposed object relative to the novel item, whose elements can enter A1 freely at test

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