Does the Medial Temporal Lobe Bind Phonological Memories?

The medial temporal lobes play a central role in the consolidation of new memories. Medial temporal lesions impair episodic learning in amnesia, and disrupt vocabulary acquisition. To investigate the role of consolidation processes in phonological memory and to understand where and how, in amnesia, these processes begin to fail, we reexamined phonological memory in the amnesic patient HM. While HM's word span performance was normal, his supraspan recall was shown to be markedly impaired, with his recall characterized by a distinctive pattern of phonological errors, where he recombined phonemes from the original list to form new response words. These were similar to errors observed earlier for patients with specifically semantic deficits. Amnesic Korsakoff's patients showed a similar, though much less marked, pattern. We interpret the data in terms of a model of lexical representation where temporal lobe damage disrupts the processes that normally bind semantic and phonological representations.

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Hippocampal Volume Influences The Correlations Between White Matter Disruption and Tau Protein in aMCI and mild AD

10.21203/rs.3.rs-108135/v1 ◽

2020 ◽

Author(s):

Thamires Naela Cardoso Magalhães ◽

Raphael Fernandes Casseb ◽

Christian Luiz Baptista Gerbelli ◽

Luciana Ramalho Pimentel-Silva ◽

Mateus Henrique Nogueira ◽

...

Keyword(s):

White Matter ◽

Medial Temporal Lobe ◽

Hippocampal Volume ◽

Tau Proteins ◽

Cortical Atrophy ◽

Medial Temporal Lobes ◽

Temporal Lobes ◽

Prodromal Ad ◽

Transentorhinal Cortex

Abstract Background: Alzheimer’s disease (AD) is classically considered a grey matter (GM) disease that starts in the transentorhinal cortex and spreads to limbic and neocortical regions. However, white matter (WM) damage could be more severe and widespread than expected cortical atrophy. The role of AD biomarkers and WM integrity throughout the brain is unclear, especially in amnestic Mild Cognitive Impairment (aMCI) patients, a possible prodromal AD dementia stage. If WM damage can be detected even before the development of cortical atrophy and overt dementia and in the AD process, Aβ42 Tau (and its phosphorylated form) could directly affect WM. Methods: We analyzed in this study 183 individuals - 48 aMCI in the AD continuum (altered CSF Aβ42), 30 patients with very mild or mild AD dementia and 105 normal controls. All subjects underwent neuropsychological evaluation and MRI exams. aMCI and mild AD individuals were also submitted to CSF puncture to evaluate AD biomarkers.Results: We observed several significant differences in WM integrity regarding the DTI measures between individuals and we found significant correlations between fornix and right cingulum hippocampal tracts and Tau and p-Tau proteins. Conclusions: We hypothesize that significant correlations with tracts anatomically far from more well-established GM atrophic regions, like medial temporal lobes, would support a more direct effect of pathological proteins on WM, whereas medial temporal lobe (MTL) correlations would favor WD and/or a direct spreading of pathology from the hippocampus.

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Visual Working Memory Is Impaired when the Medial Temporal Lobe Is Damaged

Journal of Cognitive Neuroscience ◽

10.1162/jocn.2006.18.7.1087 ◽

2006 ◽

Vol 18 (7) ◽

pp. 1087-1097 ◽

Cited By ~ 137

Author(s):

Ingrid R. Olson ◽

Katherine Sledge Moore ◽

Marianna Stark ◽

Anjan Chatterjee

Keyword(s):

Working Memory ◽

Medial Temporal Lobe ◽

Memory Load ◽

Short Term ◽

Medial Temporal Lobes ◽

Temporal Lobes ◽

Impaired Memory ◽

Rehearsal Strategies ◽

Verbal Component

The canonical description of the role of the medial temporal lobes (MTLs) in memory is that short-term forms of memory (e.g., working memory [WM]) are spared when the MTL is damaged, but longer term forms of memory are impaired. Tests used to assess this have typically had a heavy verbal component, potentially allowing explicit rehearsal strategies to maintain the WM trace over the memory delay period. Here we test the hypothesis that the MTL is necessary for visual WM when verbal rehearsal strategies are difficult to implement. In three patients with MTL damage we found impairments in spatial, face, and color WM, at delays as short as 4 sec. Impaired memory could not be attributed to memory load or perceptual problems. These findings suggest that the MTLs are critical for accurate visual WM.

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Hippocampal Volume Influences the Correlations Between White Matter Disruption and Tau Protein in aMCI and mild AD

10.21203/rs.3.rs-78713/v1 ◽

2020 ◽

Author(s):

Thamires Naela Cardoso Magalhães ◽

Raphael Fernandes Casseb ◽

Christian Luiz Baptista Gerbelli ◽

Mateus Henrique Nogueira ◽

Luciana Ramalho Pimentel-Silva ◽

...

Keyword(s):

Medial Temporal Lobe ◽

Hippocampal Volume ◽

Cortical Atrophy ◽

Medial Temporal Lobes ◽

Temporal Lobes ◽

Prodromal Ad ◽

Transentorhinal Cortex ◽

The Brain ◽

Normal Controls

Abstract BackgroundAlzheimer’s disease (AD) is classically considered a grey matter (GM) disease that starts in transentorhinal cortex and spread to limbic and neocortical regions. However, withe matter (WM) damage could be more severe and widespread than expected cortical atrophy. It is not clear the role of AD biomarkers and WM integrity throughout the brain, especially including amnestic Mild Cognitive Impairment (aMCI) patients, a possible prodromal AD dementia stage, if WM damage can be detected even before the development of cortical atrophy and overt dementia and in AD process, Aβ42 Tau (and its phosphorylated form) could directly affect WM.MethodsWe analyzed in this study 183 individuals - 48 aMCI in the AD continuum (altered CSF Aβ42), 30 patients with very mild or mild AD dementia and 105 normal controls. All subjects underwent neuropsychological evaluation and MRI exam. aMCI and mild AD individuals were also submitted to CSF puncture to evaluate AD biomarkers.ResultsWe observed several significant differences in WM integrity regarding the DTI measures between individuals and we found significant correlations between fornix and right cingulum hippocampal tracts and Tau and p-Tau proteins.ConclusionsWe hypothesize that significant correlations with tracts anatomically far from more well-established GM atrophic regions, like medial temporal lobes, would support a more direct effect of pathological proteins on WM, whereas medial temporal lobe (MTL) correlations would favor WD and/or a direct spreading of pathology from hippocampus.

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Theories of episodic memory

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2001.0941 ◽

2001 ◽

Vol 356 (1413) ◽

pp. 1395-1408 ◽

Cited By ~ 48

Author(s):

Andrew R. Mayes ◽

Neil Roberts

Keyword(s):

Episodic Memory ◽

Medial Temporal Lobe ◽

Functional Neuroimaging ◽

Memory Storage ◽

Visual Object ◽

Medial Temporal Lobes ◽

Temporal Lobes ◽

Episodic Information ◽

Encoding And Retrieval

Theories of episodic memory need to specify the encoding (representing), storage, and retrieval processes that underlie this form of memory and indicate the brain regions that mediate these processes and how they do so. Representation and re–representation (retrieval) of the spatiotemporally linked series of scenes, which constitute an episode, are probably mediated primarily by those parts of the posterior neocortex that process perceptual and semantic information. However, some role of the frontal neocortex and medial temporal lobes in representing aspects of context and high–level visual object information at encoding and retrieval cannot currently be excluded. Nevertheless, it is widely believed that the frontal neocortex is mainly involved in coordinating episodic encoding and retrieval and that the medial temporal lobes store aspects of episodic information. Establishing where storage is located is very difficult and disagreement remains about the role of the posterior neocortex in episodic memory storage. One view is that this region stores all aspects of episodic memory ab initio for as long as memory lasts. This is compatible with evidence that the amygdala, basal forebrain, and midbrain modulate neocortical storage. Another view is that the posterior neocortex only gradually develops the ability to store some aspects of episodic information as a function of rehearsal over time and that this information is initially stored by the medial temporal lobes. A third view is that the posterior neocortex never stores these aspects of episodic information because the medial temporal lobes store them for as long as memory lasts in an increasingly redundant fashion. The last two views both postulate that the medial temporal lobes initially store contextual markers that serve to cohere featural information stored in the neocortex. Lesion and functional neuroimaging evidence still does not clearly distinguish between these views. Whether the feeling that an episodic memory is familiar depends on retrieving an association between a retrieved episode and this feeling, or by an attribution triggered by a priming process, is unclear. Evidence about whether the hippocampus and medial temporal lobe cortices play different roles in episodic memory is conflicting. Identifying similarities and differences between episodic memory and both semantic memory and priming will require careful componential analysis of episodic memory.

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Autobiographical memory unknown: Pervasive autobiographical memory loss encompassing personality trait knowledge in an individual with medial temporal lobe amnesia

10.31234/osf.io/dva23 ◽

2021 ◽

Author(s):

Aubrey Anne Ladd Wank ◽

Anna Robertson ◽

Sean C. Thayer ◽

Mieke Verfaellie ◽

Steven Z. Rapcsak ◽

...

Keyword(s):

Prefrontal Cortex ◽

Personality Traits ◽

Autobiographical Memory ◽

Medial Prefrontal Cortex ◽

Temporal Lobe ◽

Medial Temporal Lobe ◽

Critical Role ◽

Memory Loss ◽

Medial Temporal Lobes ◽

Temporal Lobes

Autobiographical memory consists of distinct memory types varying from highly abstract to episodic. Self trait knowledge, which is considered one of the more abstract types of autobiographical memory, is thought to rely on regions of the autobiographical memory neural network implicated in schema representation, including the medial prefrontal cortex, and critically, not the medial temporal lobes. The current case study introduces an individual who, as a consequence of bilateral posterior cerebral artery strokes, experienced extensive medial temporal lobe damage with sparing of the medial prefrontal cortex. Interestingly, in addition to severe retrograde and anterograde episodic and autobiographical fact amnesia, this individual’s self trait knowledge was impaired for his current and pre-morbid personality traits. Yet, further assessment revealed that this individual had preserved conceptual knowledge for personality traits, could reliably and accurately rate another person’s traits, and could access his own self-concept in a variety of ways. In addition to autobiographical memory loss, he demonstrated impairment on non-personal semantic memory tests, most notably on tests requiring retrieval of unique knowledge. This rare case of amnesia suggests a previously unreported role for the medial temporal lobes in personal trait knowledge, which we propose reflects the critical role of this neural region in the storage and retrieval of personal semantics that are experience-near, meaning autobiographical facts grounded in spatiotemporal contexts.

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