Abnormal semantic knowledge in a case of developmental amnesia

Blumenthal, Anna; Duke, Devin; Bowles, Ben; Gilboa, Asaf; Rosenbaum, R. Shayna; Köhler, Stefan; Masamune, Ken

doi:10.1016/j.neuropsychologia.2017.06.018

Cited by 21 publications

(18 citation statements)

References 86 publications

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“…However, just because some patients with DA perform the Vocabulary or Information subtest of the WAIS correctly does not mean that they have normal semantic memory. Recent findings suggest that their semantic knowledge structure differs from that of healthy individuals (Blumenthal et al, ; D'Angelo et al, ; Patient HC). There is also the question of whether these patients acquire new semantic knowledge in a similar way to healthy individuals, with available evidence suggesting that they do so at a slower pace (e.g., Gardiner et al, ; Martins et al, ).…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…Furthermore, hippocampal amnesic patients perform significantly worse than comparison participants on measures of semantic richness and vocabulary depth for previously acquired, highly familiar words (Klooster and Duff, 2015). In a case of developmental amnesia, abnormal extrinsic feature knowledge for object concepts and typicality judgments for nonliving concepts have been reported (Blumenthal et al, 2017). Despite these demonstrations of hippocampal involvement in language processing, it is unknown if these disruptions following hippocampal damage and declarative memory impairment extend to the individual words used to describe representations in memory.…”

Section: Introductionmentioning

confidence: 99%

The influence of the hippocampus and declarative memory on word use: Patients with amnesia use less imageable words

2017

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Hippocampal functioning contributes to our ability to generate multifaceted, imagistic event representations. Patients with hippocampal damage produce event narratives that contain fewer details and fewer imagistic features. We hypothesized that impoverished memory representations would influence language at the word level, yielding words lower in imageability and concreteness. We tested this by examining language produced by patients with bilateral hippocampal damage and severe declarative memory impairment, and brain-damaged and healthy comparison groups. Participants described events from the real past, imagined past, imagined present, and imagined future. We analyzed the imageability and concreteness of words used. Patients with amnesia used words that were less imageable than those of comparison groups across time periods, even when accounting for the amount of episodic detail in narratives. Moreover, all participants used words that were relatively more imageable when discussing real past events than other time periods. Taken together, these findings suggest that the memory that we have for an event affects how we talk about that event, and this extends all the way to the individual words that we use.

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“…During retrieval, the participants used information in the prior knowledge system to aid memory by retrieving information and associations made during encoding. By contrast, as the functional features are more connected with contextual information, encoding them requires hippocampus involvement ( Blumenthal et al, 2017 ). The involvement of the hippocampus inhibits processing information related to prior knowledge ( van Kesteren et al, 2012 ).…”

Section: Discussionmentioning

confidence: 99%

“…Perceptual information represents how an object looks, smells and sounds ( Warrington and Shallice, 1984 ; Martin, 2007 ), and these features are intrinsic to the entity or object itself. In contrast, functional features are extrinsic because how an object is used and what it is used for are based on relationships between the object and something else, such as actions performed on the object by some agents ( Barr and Caplan, 1987 ; Blumenthal et al, 2017 ). As the perceptual features are intrinsic to the object, they are more associated with the preexisting conceptual knowledge system.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, it is suggested that the hippocampus is important for learning functional but not perceptual features of conceptual knowledge. Blumenthal et al (2017) showed that a developmental amnesic patient generated fewer functional features than controls due to hippocampus damage but produced as many perceptual features as controls. On the other hand, studies have suggested that information congruent to prior knowledge can be easily assimilated into the knowledge system without depending heavily on the hippocampus ( Tse et al, 2007 ; van Kesteren et al, 2010 ).…”

Section: Introductionmentioning

confidence: 99%

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Acquiring New Factual Information: Effect of Prior Knowledge

et al. 2018

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One influential theory on object knowledge is feature-based model, which proposes that the object knowledge is organized by different feature types, such as sensory/perceptual and motor/functional ones. Previous studies have shown that prior knowledge enhances the processes of acquiring and remembering relevant information. However, whether the effect of prior knowledge is applied to different types of conceptual information over time remains unclear. In this study, we addressed this question by testing memory of different types of object features at various retention intervals. The level of prior knowledge was manipulated as object features from familiar and unfamiliar categories. In Experiments 1 and 2, sentences that described the perceptual and functional features of new words were presented. Sentences with episodic features were additionally presented in Experiment 2. The participants were then tested with recognition (Experiment 1) and recall (Experiment 2) tasks at different retention intervals. The results showed that prior knowledge enhanced memory for perceptual features but not for functional and episodic features. Such enhancement depended on the recollection process. In addition, the effect of prior knowledge on perceptual features remained stable over time. This study clarified how different types of new factual information were acquired and maintained and highlighted the importance of prior knowledge in acquiring new conceptual knowledge with the passage of time.

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Abnormal semantic knowledge in a case of developmental amnesia

Cited by 21 publications

References 86 publications

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

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

The influence of the hippocampus and declarative memory on word use: Patients with amnesia use less imageable words

Acquiring New Factual Information: Effect of Prior Knowledge

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