The Roles of Perirhinal Cortex, Postrhinal Cortex, and the Fornix in Memory for Objects, Contexts, and Events in the Rat

2005 ◽  
Vol 58 (3-4b) ◽  
pp. 202-217 ◽  
Author(s):  
M. J. Eacott ◽  
E. A. Gaffan
Keyword(s):  
Learning And Memory ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Memory System ◽  
Strong Connectivity ◽  
Postrhinal Cortex ◽  
Cortical Regions ◽  
Combining Information

Investigation of the anatomical substructure of the medial temporal lobe has revealed a number of highly interconnected areas, which has led some to propose that the region operates as a unitary memory system. However, here we outline the results of a number of studies from our laboratories, which investigate the contributions of the rat's perirhinal cortex and postrhinal cortex to memory, concentrating particularly on their respective roles in memory for objects. By contrasting patterns of impairment and spared abilities on a number of related tasks, we suggest that perirhinal cortex and postrhinal cortex make distinctive contributions to learning and memory: for example, that postrhinal cortex is important in learning about within-scene position and context. We also provide evidence that despite the strong connectivity between these cortical regions and the hippocampus, the hippocampus, as evidenced by lesions of the fornix, has a distinct function of its own—combining information about objects, positions, and contexts.

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.

scholarly journals Representations of local spatial information in the human medial temporal lobe during memory-guided navigation

2020 ◽  
Author(s):  
Shao-Fang Wang ◽  
Valerie A. Carr ◽  
Serra E. Favila ◽  
Jeremy N. Bailenson ◽  
Thackery I. Brown ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Spatial Information ◽  
Activity Patterns ◽  
Critical Role ◽  
Neural Representations ◽  
Parahippocampal Cortex ◽  
Pattern Similarity ◽  
Cortical Regions ◽  
Goal Directed Behavior

AbstractThe hippocampus (HC) and surrounding medial temporal lobe (MTL) cortical regions play a critical role in spatial navigation and episodic memory. However, it remains unclear how the interaction between the HC’s conjunctive coding and mnemonic differentiation contributes to neural representations of spatial environments. Multivariate functional magnetic resonance imaging (fMRI) analyses enable examination of how human HC and MTL cortical regions encode multidimensional spatial information to support memory-guided navigation. We combined high-resolution fMRI with a virtual navigation paradigm in which participants relied on memory of the environment to navigate to goal locations in two different virtual rooms. Within each room, participants were cued to navigate to four learned locations, each associated with one of two reward values. Pattern similarity analysis revealed that when participants successfully arrived at goal locations, activity patterns in HC and parahippocampal cortex (PHC) represented room-goal location conjunctions and activity patterns in HC subfields represented room-reward-location conjunctions. These results add to an emerging literature revealing hippocampal conjunctive representations during goal-directed behavior.

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

scholarly journals Tau pathology in the medial temporal lobe of athletes with chronic traumatic encephalopathy: a chronic effects of neurotrauma consortium study

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Christy M. Kelley ◽  
Sylvia E. Perez ◽  
Elliott J. Mufson
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Chronic Traumatic Encephalopathy ◽  
Stage Iv ◽  
Perirhinal Cortex ◽  
Stage Ii ◽  
Stage Iii ◽  
Dystrophic Neurites ◽  
Tau Pathology ◽  
African American Athletes

AbstractChronic traumatic encephalopathy (CTE) is a progressive neurodegenerative condition associated with repetitive traumatic brain injury (rTBI) seen in contact-sport athletes and military personnel. The medial temporal lobe (MTL; i.e., hippocampus, subiculum, and entorhinal and perirhinal cortices) memory circuit displays tau lesions during the pathological progression of CTE. We examined MTL tissue obtained from 40 male Caucasian and African American athletes who received a postmortem CTE neuropathological diagnosis defined as stage II, III, or IV. Sections were immunolabeled using an early (AT8) or a late (TauC3) marker for pathological tau and for amyloid beta (Aβ) species (6E10, Aβ1–42 and thioflavin S). Stereological analysis revealed that stage III had significantly less AT8-positive neurons and dystrophic neurites than stage IV in all MTL regions except hippocampal subfield CA3, whereas significantly more AT8-positive neurons, dystrophic neurites, and neurite clusters were found in the perirhinal cortex, entorhinal cortex, hippocampal CA1, and subiculum of CTE stage III compared with stage II. TauC3-positive pathology was significantly higher in the perirhinal and subicular cortex of stage IV compared to stage III and the perirhinal cortex of stage III compared to stage II. AT8-positive neurite clusters were observed in stages III and IV, but virtually absent in stage II. When observed, Aβ pathology appeared as amyloid precursor protein (APP)/Aβ (6E10)-positive diffuse plaques independent of region. Thioflavine S labeling, did not reveal evidence for fibril or neuritic pathology associated with plaques, confirming a diffuse, non-cored plaque phenotype in CTE. Total number of AT8-positive profiles correlated with age at death, age at symptom onset, and time from retirement to death. There was no association between AT8-positive tau pathology and age sport began, years played, or retirement age, and no difference between CTE stage and the highest level of sport played. In summary, our findings demonstrate different tau profiles in the MTL across CTE stages, proffering CA3 tau pathology and MTL dystrophic neurite clusters as possible markers for the transition between early (II) and late (III/IV) stages, while highlighting CTE as a progressive noncommunicative tauopathy.

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