Severity of memory impairment in monkeys as a function of locus and extent of damage within the medial temporal lobe memory system

Hippocampus ◽  
1994 ◽  
Vol 4 (4) ◽  
pp. 483-495 ◽  
Author(s):  
Stuart Zola-Morgan ◽  
Larry R. Squire ◽  
Seth J. Ramus
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Impairment ◽  
Memory System ◽  
Extent Of Damage

scholarly journals Early stages of tau pathology and its associations with functional connectivity, atrophy and memory

Brain ◽  
2021 ◽  
Author(s):  
David Berron ◽  
Jacob W Vogel ◽  
Philip S Insel ◽  
Joana B Pereira ◽  
Long Xie ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Entorhinal Cortex ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Impairment ◽  
Memory Performance ◽  
Hippocampal Atrophy ◽  
Tau Pathology ◽  
Β Amyloid ◽  
With Memory

Abstract In Alzheimer’s disease, postmortem studies have shown that the first cortical site where neurofibrillary tangles appear is the transentorhinal region, a subregion within the medial temporal lobe that largely overlaps with area 35, and the entorhinal cortex. Here we used tau-PET imaging to investigate the sequence of tau pathology progression within the human medial temporal lobe and across regions in the posterior-medial system. Our objective was to study how medial temporal tau is related to functional connectivity, regional atrophy, and memory performance. We included 215 β-amyloid negative cognitively unimpaired, 81 β-amyloid positive cognitively unimpaired and 87 β-amyloid positive individuals with mild cognitive impairment, who each underwent [18]F-RO948 tau and [18]F-flutemetamol amyloid PET imaging, structural T1-MRI and memory assessments as part of the Swedish BioFINDER-2 study. First, event-based modelling revealed that the entorhinal cortex and area 35 show the earliest signs of tau accumulation followed by the anterior and posterior hippocampus, area 36 and the parahippocampal cortex. In later stages, tau accumulation became abnormal in neocortical temporal and finally parietal brain regions. Second, in cognitively unimpaired individuals, increased tau load was related to local atrophy in the entorhinal cortex, area 35 and the anterior hippocampus and tau load in several anterior medial temporal lobe subregions was associated with distant atrophy of the posterior hippocampus. Tau load, but not atrophy, in these regions was associated with lower memory performance. Further, tau-related reductions in functional connectivity in critical networks between the medial temporal lobe and regions in the posterior-medial system were associated with this early memory impairment. Finally, in patients with mild cognitive impairment, the association of tau load in the hippocampus with memory performance was partially mediated by posterior hippocampal atrophy. In summary, our findings highlight the progression of tau pathology across medial temporal lobe subregions and its disease-stage specific association with memory performance. While tau pathology might affect memory performance in cognitively unimpaired individuals via reduced functional connectivity in critical medial temporal lobe-cortical networks, memory impairment in mild cognitively impaired patients is associated with posterior hippocampal atrophy.

scholarly journals Distinct Cortical Anatomy Linked to Subregions of the Medial Temporal Lobe Revealed by Intrinsic Functional Connectivity

2008 ◽  
Vol 100 (1) ◽  
pp. 129-139 ◽  
Author(s):  
Itamar Kahn ◽  
Jessica R. Andrews-Hanna ◽  
Justin L. Vincent ◽  
Abraham Z. Snyder ◽  
Randy L. Buckner
Keyword(s):  
Functional Connectivity ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Temporal Cortex ◽  
Memory System ◽  
Retrosplenial Cortex ◽  
The Body ◽  
Parallel Pathways ◽  
Ventral Medial Prefrontal Cortex ◽  
Adjacent Structures

The hippocampus and adjacent cortical structures in the medial temporal lobe (MTL) contribute to memory through interactions with distributed brain areas. Studies of monkey and rodent anatomy suggest that parallel pathways converge on distinct subregions of the MTL. To explore the cortical areas linked to subregions of the MTL in humans, we examined cortico-cortical and hippocampal-cortical correlations using high-resolution, functional connectivity analysis in 100 individuals. MTL seed regions extended along the anterior to posterior axis and included hippocampus and adjacent structures. Results revealed two separate brain pathways that correlated with distinct subregions within the MTL. The body of the hippocampus and posterior parahippocampal cortex correlated with lateral parietal cortex, regions along the posterior midline including posterior cingulate and retrosplenial cortex, and ventral medial prefrontal cortex. By contrast, anterior hippocampus and the perirhinal/entorhinal cortices correlated with distinct regions in the lateral temporal cortex extending into the temporal pole. The present results are largely consistent with known connectivity in the monkey and provide a novel task-independent dissociation of the parallel pathways supporting the MTL memory system in humans. The cortical pathways include regions that have undergone considerable areal expansion in humans, providing insight into how the MTL memory system has evolved to support a diverse array of cognitive domains.

The case of the amnesic intelligence officer

1994 ◽  
Vol 24 (4) ◽  
pp. 1037-1045 ◽  
Author(s):  
M. D. Kopelman ◽  
R. E. A. Green ◽  
E. M. Green ◽  
P. D. R. Lewis ◽  
N. Stanhope
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Impairment ◽  
Neuropsychological Testing ◽  
Memory Loss ◽  
Anterograde Amnesia ◽  
Clinical History ◽  
Moderate Degree ◽  
Retrograde Memory ◽  
Past Life

SynopsisThis paper describes a patient whose amnesia for an offence (fraud) and two fugue episodes occurred against the background of an underlying organic amnesia. The fugue states conformed in their duration and precipitating factors to previous accounts in the literature. The organic, anterograde memory impairment was attributed to multiple small infarcts and a larger infarction in the left medial temporal lobe, which were evident on MRI and PET scans after the patient had developed transient neurological signs. At follow-up, the anterograde amnesia had persisted, and the patient also showed some difficulty in retrieving autobiographical memories of past incidents or events, although other aspects of his retrograde memory were intact (including his knowledge of facts about his past life and his general knowledge of public events). The difficulty in retrieving autobiographical incidents may have resulted from the presence of a moderate degree of frontal lobe dysfunction or, just possibly, from ischaemia in the left anterior temporal lobe. The persistence of the organic memory impairment and the importance of both the clinical history and neuropsychological testing in assessment are discussed, as well as the need to examine for possible organic factors in patients who may initially appear to manifest purely ‘psychogenic’ memory loss.

scholarly journals What can narratives tell us about the neural bases of human memory?

2020 ◽  
Author(s):  
Hongmi Lee ◽  
Buddhika Bellana ◽  
janice chen
Keyword(s):  
Temporal Lobe ◽  
Neural Activity ◽  
Default Mode Network ◽  
Medial Temporal Lobe ◽  
Activity Patterns ◽  
Human Memory ◽  
Memory System ◽  
Situation Models ◽  
Neural Synchrony ◽  
Default Mode

Narratives are increasingly used to study naturalistic human memory and its brain mechanisms. Narratives—audiovisual movies, spoken stories, and written stories—consist of multiple inter-related and temporally unfolding events which are rich in semantic and emotional content. These characteristics drive intersubject neural synchrony in the default mode network, where abstract situation models are represented and reinstated. Medial temporal lobe structures interact with the cortical sub-regions of the default mode network to support the encoding and recall of narrative events. Narrative memories are frequently communicated across individuals, resulting in the transmission of experiences and neural activity patterns between people. Recent advances in neuroimaging and naturalistic stimulus analysis provide valuable insights into narrative memory and the human memory system in general.

scholarly journals The parahippocampal gyrus links the default-mode cortical network with the medial temporal lobe memory system

2013 ◽  
Vol 35 (3) ◽  
pp. 1061-1073 ◽  
Author(s):  
Andrew M. Ward ◽  
Aaron P. Schultz ◽  
Willem Huijbers ◽  
Koene R.A. Van Dijk ◽  
Trey Hedden ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory System ◽  
Cortical Network ◽  
Parahippocampal Gyrus ◽  
Default Mode
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