scholarly journals Medial temporal lobe high-frequency activity at feedback signals error and predicts subsequent memory during spatial learning

2021 ◽  
Author(s):  
Rebecca Stevenson ◽  
John Janecek ◽  
Myra Larson ◽  
Lilit Mnatsakanyan ◽  
Sumeet Vadera ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
High Frequency ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Memory Task ◽  
Object Location ◽  
Opposite Pattern ◽  
Feedback Processing ◽  
Depth Electrodes ◽  
High Frequency Activity

Abstract The ability to incorporate information about feedback is critical for associative learning. The medial temporal lobe (MTL) and prefrontal cortex (PFC) are thought to be involved in processing feedback as new associations are learned. However, the relative contributions of these regions to feedback processing and subsequent memory performance in humans are poorly understood. To address this question, we tested pre-surgical epilepsy patients with depth electrodes implanted in the MTL and PFC using a spatial memory task in which subjects learned object-location associations over time. We found increased high-frequency activity (HFA; 40-100 Hz), thought to reflect local excitatory activity, in the MTL and dorsolateral PFC (dlPFC) at feedback for high error trials. In the MTL, this HFA error signal predicted greater trial-by-trial decreases in error from one training block to the next indicating that these signals are involved in updating memory representations or modifying incorrect associations during learning. The opposite pattern of activity was observed during retrieval, with greater MTL and dlPFC HFA predicting lower error, replicating previous results from our group. Overall, these data suggest putative mechanisms for the learning of object-location associations.

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 Egocentric Navigation Abilities Predict Episodic Memory Performance

2020 ◽  
Vol 14 ◽  
Author(s):  
Giorgia Committeri ◽  
Agustina Fragueiro ◽  
Maria Maddalena Campanile ◽  
Marco Lagatta ◽  
Ford Burles ◽  
...  
Keyword(s):  
Episodic Memory ◽  
Semantic Memory ◽  
Path Integration ◽  
Medial Temporal Lobe ◽  
Declarative Memory ◽  
Memory Performance ◽  
Memory Task ◽  
Recognition Task ◽  
Future Research ◽  
Egocentric Navigation

The medial temporal lobe supports both navigation and declarative memory. On this basis, a theory of phylogenetic continuity has been proposed according to which episodic and semantic memories have evolved from egocentric (e.g., path integration) and allocentric (e.g., map-based) navigation in the physical world, respectively. Here, we explored the behavioral significance of this neurophysiological model by investigating the relationship between the performance of healthy individuals on a path integration and an episodic memory task. We investigated the path integration performance through a proprioceptive Triangle Completion Task and assessed episodic memory through a picture recognition task. We evaluated the specificity of the association between performance in these two tasks by including in the study design a verbal semantic memory task. We also controlled for the effect of attention and working memory and tested the robustness of the results by including alternative versions of the path integration and semantic memory tasks. We found a significant positive correlation between the performance on the path integration the episodic, but not semantic, memory tasks. This pattern of correlation was not explained by general cognitive abilities and persisted also when considering a visual path integration task and a non-verbal semantic memory task. Importantly, a cross-validation analysis showed that participants' egocentric navigation abilities reliably predicted episodic memory performance. Altogether, our findings support the hypothesis of a phylogenetic continuity between egocentric navigation and episodic memory and pave the way for future research on the potential causal role of egocentric navigation on multiple forms of episodic memory.

Cognitive refractory state caused by spontaneous epileptic high-frequency oscillations in the human brain

2019 ◽  
Vol 11 (514) ◽  
pp. eaax7830 ◽  
Author(s):  
Su Liu ◽  
Josef Parvizi
Keyword(s):  
Cognitive Deficits ◽  
High Frequency ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Physiological Responses ◽  
Epileptic Activity ◽  
Epileptic Focus ◽  
Surgical Removal ◽  
High Frequency Oscillations ◽  
Refractory State

Epileptic brain tissue is often considered physiologically dysfunctional, and the optimal treatment of many patients with uncontrollable seizures involves surgical removal of the epileptic tissue. However, it is unclear to what extent the epileptic tissue is capable of generating physiological responses to cognitive stimuli and how cognitive deficits ensuing surgical resections can be determined using state-of-the-art computational methods. To address these unknowns, we recruited six patients with nonlesional epilepsies and identified the epileptic focus in each patient with intracranial electrophysiological monitoring. We measured spontaneous epileptic activity in the form of high-frequency oscillations (HFOs), recorded stimulus-locked physiological responses in the form of physiological high-frequency broadband activity, and explored the interaction of the two as well as their behavioral correlates. Across all patients, we found abundant normal physiological responses to relevant cognitive stimuli in the epileptic sites. However, these physiological responses were more likely to be “seized” (delayed or missed) when spontaneous HFOs occurred about 850 to 1050 ms before, until about 150 to 250 ms after, the onset of relevant cognitive stimuli. Furthermore, spontaneous HFOs in medial temporal lobe affected the subjects’ memory performance. Our findings suggest that nonlesional epileptic sites are capable of generating normal physiological responses and highlight a compelling mechanism for cognitive deficits in these patients. The results also offer clinicians a quantitative tool to differentiate pathological and physiological high-frequency activities in epileptic sites and to indirectly assess their possible cognitive reserve function and approximate the risk of resective surgery.

Forward Processing of Object–Location Association from the Ventral Stream to Medial Temporal Lobe in Nonhuman Primates

2019 ◽  
Vol 30 (3) ◽  
pp. 1260-1271 ◽  
Author(s):  
He Chen ◽  
Yuji Naya
Keyword(s):  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Spatial Information ◽  
Object Location ◽  
Object Identity ◽  
Downstream Target ◽  
Parahippocampal Cortex ◽  
Ventral Pathway ◽  
Additive Form ◽  
Location Association

Abstract While the hippocampus (HPC) is a prime candidate combining object identity and location due to its strong connections to the ventral and dorsal pathways via surrounding medial temporal lobe (MTL) areas, recent physiological studies have reported spatial information in the ventral pathway and its downstream target in MTL. However, it remains unknown whether the object–location association proceeds along the ventral MTL pathway before HPC. To address this question, we recorded neuronal activity from MTL and area anterior inferotemporal cortex (TE) of two macaques gazing at an object to retain its identity and location in each trial. The results showed significant effects of object–location association at a single-unit level in TE, perirhinal cortex (PRC), and HPC, but not in the parahippocampal cortex. Notably, a clear area difference emerged in the association form: 1) representations of object identity were added to those of subjects’ viewing location in TE; 2) PRC signaled both the additive form and the conjunction of the two inputs; and 3) HPC signaled only the conjunction signal. These results suggest that the object and location signals are combined stepwise at TE and PRC each time primates view an object, and PRC may provide HPC with the conjunctional signal, which might be used for encoding episodic memory.

Phase/amplitude reset and theta-gamma interaction in the human medial temporal lobe during a continuous word recognition memory task

Hippocampus ◽  
2005 ◽  
Vol 15 (7) ◽  
pp. 890-900 ◽  
Author(s):  
Florian Mormann ◽  
Juergen Fell ◽  
Nikolai Axmacher ◽  
Bernd Weber ◽  
Klaus Lehnertz ◽  
...  
Keyword(s):  
Word Recognition ◽  
Recognition Memory ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Memory Task ◽  
Recognition Memory Task ◽  
Phase Amplitude

Recollection memory deficits in patients with major depressive disorder predicted by past depressions but not current mood state or treatment status

2002 ◽  
Vol 32 (2) ◽  
pp. 251-258 ◽  
Author(s):  
G. M. MacQUEEN ◽  
T. M. GALWAY ◽  
J. HAY ◽  
L. T. YOUNG ◽  
R. T. JOFFE
Keyword(s):  
Medial Temporal Lobe ◽  
Mood State ◽  
Memory Performance ◽  
Memory Function ◽  
Memory Task ◽  
Antidepressant Medication ◽  
Memory Deficits ◽  
Memory Systems ◽  
Course Of Illness ◽  
Current Mood

Background. Neuropsychological studies have suggested that memory systems reliant on medial temporal lobe structures are impaired in patients with depression. There is less data regarding whether this impairment is specific to recollection memory systems, and whether clinical features predict impairment. This study sought to address these issues.Method. A computerized process-dissociation memory task was utilized to dissociate recollection and habit memory in 40 patients with past or current major depression and 40 age, sex and IQ matched non-psychiatric control subjects. The Cognitive Failures Questionnaire was used to assess patients’ perceptions of day-to-day memory failures.Results. Patients had impaired recollection memory (t = 4·7, P<0·001), but no impairment in habit memory when compared to controls. Recollection memory performance was not predicted by indices of current mood state, but was predicted by self-assessments of impairment (β = −0·33; P = 0·008) and past number of depressions (β = −0·41; P = 0·001). There was no evidence that standard therapy with antidepressant medication either improved or worsened memory performance.Conclusions. The results confirm that patients with multiple past depressions have reduced function on recollection memory tasks, but not on habit memory performance. The memory deficits were independent of current mood state but related to past course of illness and significant enough that patients detected impairment in day-to-day memory function.

scholarly journals Allocentric Spatial Memory Performance in a Virtual Reality-Based Task is Conditioned by Visuospatial Working Memory Capacity

2020 ◽  
Vol 10 (8) ◽  
pp. 552
Author(s):  
Joaquín Castillo Escamilla ◽  
José Javier Fernández Castro ◽  
Shishir Baliyan ◽  
Juan José Ortells-Pareja ◽  
Juan José Ortells Rodríguez ◽  
...  
Keyword(s):  
Working Memory ◽  
Virtual Reality ◽  
Spatial Memory ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Working Memory Capacity ◽  
Memory Task ◽  
Memory Capacity ◽  
Spatial Task ◽  
Analysis Of Covariance

Traditionally, the medial temporal lobe has been considered a key brain region for spatial memory. Nevertheless, executive functions, such as working memory, also play an important role in complex behaviors, such as spatial navigation. Thus, the main goal of this study is to clarify the relationship between working memory capacity and spatial memory performance. Spatial memory was assessed using a virtual reality-based procedure, the Boxes Room task, and the visual working memory with the computer-based Change Localization Task. One hundred and twenty-three (n = 123) participants took part in this study. Analysis of Covariance (ANCOVA) revealed a statistically significant relationship between working memory capacity and spatial abilities. Thereafter, two subgroups n = 60, were formed according to their performance in the working memory task (1st and 4th quartiles, n = 30 each). Results demonstrate that participants with high working memory capacity committed fewer mistakes in the spatial task compared to the low working memory capacity group. Both groups improved their performance through repeated trials of the spatial task, thus showing that they could learn spatial layouts independent of their working memory capacity. In conclusion, these findings support that spatial memory performance is directly related to working memory skills. This could be relevant for spatial memory assessment in brain lesioned patients.

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