Entorhinal Cortex Lesions Disrupt the Relational Organization of Memory in Monkeys
Open Access
- 3 November 2004
- journal article
- Published by Society for Neuroscience in Journal of Neuroscience
- Vol. 24 (44) , 9811-9825
- https://doi.org/10.1523/jneurosci.1532-04.2004
Abstract
Recent accounts suggest that the hippocampal system critically supports two central characteristics of episodic memory: the ability to establish and maintain representations for the salient relationships between experienced events (relational representation) and the capacity to flexibly manipulate memory (flexible memory expression). To test this proposal in monkeys, intact controls and subjects with bilateral aspiration lesions of the entorhinal cortex were trained postoperatively on two standard memory tasks, delayed nonmatchingto-sample (DNMS) and two-choice object discrimination (OD) learning, and three procedures intended to emphasize relational representation and flexible memory expression: a paired associate (PA) task, a transitive inference (TI) test of learning and memory for hierarchical stimulus relationships, and a spatial delayed recognition span (SDRS) procedure. The latter assessments each included critical “probe” tests that asked monkeys to evaluate the relationships among previously learned stimuli presented in novel combinations. Subjects with entorhinal cortex lesions scored as accurately as controls on all phases of DNMS and OD, procedures that can be solved on the basis of memory for individual stimuli. In contrast, experimental monkeys displayed deficits relative to controls on all phases of the PA, TI, and SDRS tasks that emphasized the flexible manipulation of memory for the relationships between familiar items. Together, the findings support the conclusion that the primate hippocampal system critically enables the relational organization of declarative memory.Keywords
This publication has 68 references indexed in Scilit:
- Hippocampal activation during transitive inference in humansHippocampus, 2004
- Cellular networks underlying human spatial navigationNature, 2003
- Perirhinal and parahippocampal cortices of the macaque monkey: Cytoarchitectonic and chemoarchitectonic organizationJournal of Comparative Neurology, 2003
- Transitivity, flexibility, conjunctive representations, and the hippocampus. II. A computational analysisHippocampus, 2003
- Transitivity, flexibility, conjunctive representations, and the hippocampus. I. An empirical analysisHippocampus, 2003
- The Hippocampus, Memory, and Place CellsNeuron, 1999
- Differential Effects of Early Hippocampal Pathology on Episodic and Semantic MemoryScience, 1997
- Memory and the hippocampus: A synthesis from findings with rats, monkeys, and humans.Psychological Review, 1992
- The entorhinal cortex of the monkey: I. Cytoarchitectonic organizationJournal of Comparative Neurology, 1987
- Some connections of the entorhinal (area 28) and perirhinal (area 35) cortices of the rhesus monkey. I. Temporal lobe afferentsBrain Research, 1975