Unitization supports lasting performance and generalization on a relational memory task: Evidence from a previously undocumented developmental amnesic case

D'Angelo, Maria C.; Kacollja, Arber; Rabin, Jennifer S.; Rosenbaum, R. Shayna; Ryan, Jennifer D.

doi:10.1016/j.neuropsychologia.2015.07.025

Cited by 25 publications

(48 citation statements)

References 34 publications

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“…The results of an updated neuropsychological evaluation performed when NC was 20‐yr old are shown in Table . As described in D'Angelo et al (), these results confirmed that in the context of average intelligence, N.C. was severely impaired on tests of delayed recall. N.C. also performed below expected levels on tests of working memory and more complex aspects of visuospatial processing (e.g., recognizing faces, integrating details into a complex figure).…”

Section: Methodssupporting

confidence: 86%

“…N.C. has previously been described in D'Angelo et al (). Briefly, N.C. is a young, right‐handed man with 14 yr of education, including high school and 1 yr of technical college.…”

Section: Methodsmentioning

confidence: 99%

“…T1 weighted and T2 weighted MRI scans (left and right, respectively) showing that N.C.'s lesion shows slightly hypointense on the T1‐weighted image and hyperintense on the coronal T2‐weighted image. Figure from D'Angelo et al ().…”

Section: Methodsmentioning

confidence: 99%

“…(Ryan et al, ), the present study examined whether D.A. 's impaired inference in the context of known pairwise relations would be replicated in a case of developmental amnesia, N.C. (D'Angelo et al, ). N.C. has damage to the EHS and diencephalic regions that does not include the hippocampus and vmPFC but that connects these regions.…”

Section: Introductionmentioning

confidence: 97%

“…This study was further motivated by the fact that N.C. is a developmental amnesic case, and thus there may be a greater chance of reorganization due to the early onset of the amnesia. Like other developmental amnesic cases, N.C. shows a dissociation of impaired episodic memory in the context of relatively spared semantic memory (Vargha‐Khadem et al, ; D'Angelo et al, ), which stands in contrast to adult‐acquired cases who typically show impaired semantic memory for learning that occurs after the onset of their amnesia (O'Kane et al, ; Bayley et al, ). One caveat is that the semantic learning observed in developmental amnesia occurs gradually over time and is typically not equivalent to the rapid learning observed in healthy adults (Gardiner et al, ) who can benefit from episodic encoding.…”

Section: Introductionmentioning

confidence: 99%

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Impaired inference in a case of developmental amnesia

2016

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Amnesia is associated with impairments in relational memory, which is critically supported by the hippocampus. By adapting the transitivity paradigm, we previously showed that age‐related impairments in inference were mitigated when judgments could be predicated on known pairwise relations, however, such advantages were not observed in the adult‐onset amnesic case D.A. Here, we replicate and extend this finding in a developmental amnesic case (N.C.), who also shows impaired relational learning and transitive expression. Unlike D.A., N.C.'s damage affected the extended hippocampal system and diencephalic structures, and does not extend to neocortical areas that are affected in D.A. Critically, despite their differences in etiology and affected structures, N.C. and D.A. perform similarly on the task. N.C. showed intact pairwise knowledge, suggesting that he is able to use existing semantic information, but this semantic knowledge was insufficient to support transitive expression. The present results suggest a critical role for regions connected to the hippocampus and/or medial prefrontal cortex in inference beyond learning of pairwise relations. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.

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Section: Methodssupporting

confidence: 86%

“…N.C. has previously been described in D'Angelo et al (). Briefly, N.C. is a young, right‐handed man with 14 yr of education, including high school and 1 yr of technical college.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Impaired inference in a case of developmental amnesia

2016

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Superior explicit memory despite severe developmental amnesia: In‐depth case study and neural correlates

et al. 2018

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The acquisition of new semantic memories is sometimes preserved in patients with hippocampal amnesia. Robust evidence for this comes from case reports of developmental amnesia suggesting that low-to-normal levels of semantic knowledge can be achieved despite compromised episodic learning. However, it is unclear whether this relative preservation of semantic memory results from normal acquisition and retrieval or from residual episodic memory, combined with effortful repetition. Furthermore, lesion studies have mainly focused on the hippocampus itself, and have seldom reported the state of structures in the extended hippocampal system. Preserved components of this system may therefore mediate residual episodic abilities, contributing to the apparent semantic preservation. We report an in-depth study of Patient KA, a 27-year-old man who had severe hypoxia at birth, in which we carefully explored his residual episodic learning abilities. We used novel speeded recognition paradigms to assess whether KA could explicitly acquire and retrieve new context-free memories. Despite a pattern of very severe amnesia, with a 44-point discrepancy between his intelligence and memory quotients, KA exhibited normal-to-superior levels of knowledge, even under strict time constraints. He also exhibited normal-to-superior recognition memory for new material, again under strict time constraints. Multimodal neuroimaging revealed an unusual pattern of selective atrophy within each component of the extended hippocampal system, contrasting with the preservation of anterior subhippocampal cortices. A cortical thickness analysis yielded a pattern of thinner but also thicker regional cortices, pointing toward specific temporal lobe reorganization following early injury. We thus report the first case of superior explicit learning and memory in a severe case of amnesia, raising important questions about how such knowledge can be acquired.

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Visual integration of objects and scenes increases recollection‐based responding despite differential MTL recruitment in young and older adults

Memel¹,

Ryan

2018

Hippocampus

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Unitization, the process of encoding previously independent units as one coherent representation, improves associative memory in both young and older adults, or in some cases, differentially benefits older adults. Unitization of verbal associative pairs may reduce reliance on the hippocampus (HC) for successful encoding and recognition by shifting to familiarity-based processing mediated by perirhinal cortex (PRC). However, this shift was not observed in a recent study of visual associative memory, with equivalent activation in HC and PRC during encoding of visually integrated (unitized) and nonintegrated object and scene pairs. Furthermore, behavioral findings from this study suggested an increase in recollection rather than familiarity during recognition of visually integrated pairs. The present study extends our previous work by focusing on the influence of visual integration on fMRI activation during associative recognition, rather than encoding and these patterns between young and older adults. In contrast to our findings from encoding, visual integration reduced HC and PRC activation during retrieval of object and scene associative pairs across both age groups. However, visual integration increased the correlation between bilateral HC and left parahippocampal (PHC) activation and behavioral performance among older adults, consistent with an increased reliance on recollection. In contrast, visual integration reduced the correlation between HC activation and behavioral performance in young adults, more consistent with findings from the verbal unitization literature. Taken together, these results suggest that associative memory for visually integrated pairs may involve differential recruitment of medial temporal regions in young and older adults.

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Unitization supports lasting performance and generalization on a relational memory task: Evidence from a previously undocumented developmental amnesic case

Cited by 25 publications

References 34 publications

Impaired inference in a case of developmental amnesia

Impaired inference in a case of developmental amnesia

Superior explicit memory despite severe developmental amnesia: In‐depth case study and neural correlates

Visual integration of objects and scenes increases recollection‐based responding despite differential MTL recruitment in young and older adults

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