1. Familiarity and recollection vs representational models of medial temporal lobe structures: A single-case study.
- Author
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Lacot E, Vautier S, Kőhler S, Pariente J, Martin CB, Puel M, Lotterie JA, and Barbeau EJ
- Subjects
- Hippocampus physiopathology, Humans, Image Processing, Computer-Assisted, Intelligence Tests, Magnetic Resonance Imaging, Male, Memory Disorders diagnostic imaging, Meningoencephalitis diagnostic imaging, Middle Aged, Neuropsychological Tests, Parahippocampal Gyrus physiopathology, Photic Stimulation, Temporal Lobe diagnostic imaging, Memory Disorders etiology, Meningoencephalitis complications, Meningoencephalitis pathology, Mental Recall physiology, Recognition, Psychology physiology, Temporal Lobe pathology
- Abstract
Although it is known that medial temporal lobe (MTL) structures support declarative memory, the fact these structures have different architectonics and circuitry suggests they may also play different functional roles. Selective lesions of MTL structures offer an opportunity to understand these roles. We report, in this study, on JMG, a patient who presents highly unusual lesions that completely affected all MTL structures except for the right hippocampus and parts of neighbouring medial parahippocampal cortex. We first demonstrate that JMG shows preserved recall for visual material on 5 experimental tasks. This finding suggests that his right hippocampus is functional, even though it appears largely disconnected from most of its MTL afferents. In contrast, JMG performed very poorly, as compared to control subjects, on 7 tasks of visual recognition memory for single items. Although he sometimes performed above chance, neither familiarity nor recollection appeared fully preserved. These results indicate that extrahippocampal structures, damaged bilaterally in JMG, perform critical operations for item recognition; and that the hippocampus cannot take over that role, including recollection, when these structures are largely damaged. Finally, in a set of 3 recognition memory tasks with scenes as stimuli, JMG performed at the level of control participants and obtained normal indices of familiarity and recollection. Overall, our findings suggest that the right hippocampus and remnants of parahippocampal cortex can support recognition memory for scenes in the absence of preserved item-recognition memory. The patterns of dissociations, which we report in the present study, provide support for a representational account of the functional organization of MTL structures., (Copyright © 2017 Elsevier Ltd. All rights reserved.)
- Published
- 2017
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