Episodic Memory formation: A review of complex Hippocampus input pathways

Progress in Neuro-Psychopharmacology and Biological Psychiatry, Journal Year: 2023, Volume and Issue: 126, P. 110757 - 110757

Published: April 21, 2023

Language: Английский

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Structural connections between the noradrenergic and cholinergic system shape the dynamics of functional brain networks

NeuroImage, Journal Year: 2022, Volume and Issue: 260, P. 119455 - 119455

Published: July 7, 2022

Complex cognitive abilities are thought to arise from the ability of brain adaptively reconfigure its internal network structure as a function task demands. Recent work has suggested that this inherent flexibility may in part be conferred by widespread projections ascending arousal systems. While different components system often studied isolation, there anatomical connections between neuromodulatory hubs we hypothesise crucial for mediating key features adaptive dynamics, such balance integration and segregation. To test hypothesis, estimated strength structural connectivity noradrenergic cholinergic systems (the locus coeruleus [LC] nucleus basalis Meynert [nbM], respectively). We then asked whether LC nbM inter-connectivity was related individual differences emergent, dynamical signatures functional measured resting state fMRI data, attractor topography. observed significant positive relationship white-matter extent network-level following BOLD signal peaks relative activity. In addition, individuals with denser streamlines interconnecting also demonstrated heightened shift novel states. These results suggest stronger have greater capacity mediate flexible dynamics required support complex, behaviour. Furthermore, our highlight underlying static can impose some constraints on dynamic brain.

Language: Английский

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Tau follows principal axes of functional and structural brain organization in Alzheimer’s disease

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: June 12, 2024

Abstract Alzheimer’s disease (AD) is a brain network disorder where pathological proteins accumulate through networks and drive cognitive decline. Yet, the role of connectivity in facilitating this accumulation remains unclear. Using in-vivo multimodal imaging, we show that distribution tau reactive microglia humans follows spatial patterns variation, so-called gradients organization. Notably, less distinct (“gradient contraction”) are associated with decline regions greater tau, suggesting an interaction between reduced differentiation on cognition. Furthermore, by modeling subject-specific gradient space, demonstrate frontoparietal temporo-occipital cortices baseline within their functionally structurally connected hubs, respectively. Our work unveils for both functional structural organization pathology AD, supports space as promising tool to map progression.

Language: Английский

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Hippocampal subfields and their neocortical interactions during autobiographical memory

Imaging Neuroscience, Journal Year: 2024, Volume and Issue: 2, P. 1 - 13

Published: Feb. 22, 2024

Abstract Advances in ultra-high field 7 Tesla functional magnetic resonance imaging (7 T fMRI) have provided unprecedented opportunities to gain insights into the neural underpinnings supporting human memory. The hippocampus, a heterogeneous brain structure comprising several subfields, plays central role during vivid re-experiencing of autobiographical memories (AM). However, due technical limitations, how hippocampal subfields differentially support AM, whether this contribution is specific one portion along long-axis, and are functionally connected with other regions typically associated AM retrieval remains elusive. Here, we leveraged advances parallel employed submillimeter Echo Planar Imaging sequence over whole while participants re-experienced vivid, detail-rich AM. We found that all long-axis were engaged retrieval. Nonetheless, only pre/parasubiculum within anterior body hippocampus contributed above Moreover, whole-brain connectivity analyses same data revealed part was strongly such as ventromedial prefrontal cortex (vmPFC) medial/lateral parietal regions. In context broader literature, our results recent proposals may play an important scene-based cognition, its engagement personal past events.

Language: Английский

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Automated protocols for delineating human hippocampal subfields from 3 Tesla and 7 Tesla magnetic resonance imaging data

Hippocampus, Journal Year: 2024, Volume and Issue: 34(6), P. 302 - 308

Published: April 9, 2024

Abstract Researchers who study the human hippocampus are naturally interested in how its subfields function. However, many researchers precluded from examining because their manual delineation magnetic resonance imaging (MRI) scans (still gold standard approach) is time consuming and requires significant expertise. To help ameliorate this issue, we present here two protocols, one for 3T MRI other 7T MRI, that permit automated segmentation into six subregions, namely dentate gyrus/cornu ammonis (CA)4, CA2/3, CA1, subiculum, pre/parasubiculum, uncus along entire length of hippocampus. These protocols particularly notable relative to existing resources they were trained tested using large numbers healthy young adults (n = 140 at 3T, n 40 7T) whose hippocampi manually segmented by experts scans. Using inter‐rater reliability analyses, showed quality segmentations produced these was high comparable expert segmenters. We provide full open access anticipate will save a amount time. They could also catalyze subfield research, which essential gaining understanding functions.

Language: Английский

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Evidence for convergence of distributed cortical processing in band-like functional zones in human entorhinal cortex

Current Biology, Journal Year: 2024, Volume and Issue: 34(23), P. 5457 - 5469.e2

Published: Nov. 1, 2024

Language: Английский

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Shaping the Space: A Role for the Hippocampus in Mental Imagery Formation

Vision, Journal Year: 2025, Volume and Issue: 9(1), P. 2 - 2

Published: Jan. 8, 2025

Mental imagery is claimed to underlie a host of abilities, such as episodic memory, working and decision-making. A popular view holds that mental relies on the perceptual system it can be said 'vision in reverse'. Whereas vision exploits bottom-up neural pathways visual system, top-down pathways. But contribution some other areas remains overlooked. In this article, I explore important contributions hippocampus, area traditionally associated with formation. highlight evidence which supports hippocampus contributes spatial model used for argue we distinguish different hippocampal circuits contribute kinds imagery, object scene temporal aspect. This has significant upshots research, opens new avenue further research into role variety tasks.

Language: Английский

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Two long-axis dimensions of hippocampal-cortical integration support memory function across the adult lifespan

eLife, Journal Year: 2025, Volume and Issue: 13

Published: March 20, 2025

The hippocampus is a complex structure critically involved in numerous behavior-regulating systems. In young adults, multiple overlapping spatial modes along its longitudinal and transverse axes describe the organization of functional integration with neocortex, extending traditional framework emphasizing differences between sharply segregated hippocampal subregions. Yet, it remains unknown whether these (i.e. gradients) persist across adult human lifespan, relate to memory molecular markers associated brain function cognition. two independent samples, we demonstrate that principal anteroposterior second-order, mid-to-anterior/posterior neocortical connectivity, representing distinct dimensions macroscale cortical organization, manifest lifespan. Specifically, individual topography second-order gradient predicted episodic mirrored dopamine D1 receptor distribution, capturing shared organization. Older age was less transitions gradients increased homogeneity). Importantly, youth-like profile preserved – age-related dedifferentiation as marker cognitive decline. Our results underscore critical role mapping multidimensional understanding neural circuits support

Language: Английский

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Linking Memory Impairment to Structural Connectivity in Extrahippocampal Temporal Lobe Epilepsy Surgery

Neurology International, Journal Year: 2025, Volume and Issue: 17(4), P. 52 - 52

Published: March 31, 2025

Objective: Temporal lobe epilepsy (TLE) constitutes the most common drug-refractory syndrome. Tailored approaches are required, as TLE originates from extrahippocampal lesions in about one-quarter of surgical candidates. Despite high success rates seizure control, concern persists regarding postoperative memory decline after lesionectomy. We investigated associations between structural connectivity and performance surgery. Methods: In total, 55 patients (25 females, 30 males; mean age 29.8 ± 14.5 years; duration 7.9 10.5 years, 31 left, 24 right TLE) with undergoing hippocampal-sparing surgery were evaluated standardized pre- neuropsychological testing. Lesion volumes intersected Human Connectome Project-derived tractography data employed to assess integrity via voxel-based connectome-informed lesion–symptom mapping identify cortical white matter structures associated cognitive outcomes. Results: Post-surgery, widespread disconnection several major pathways was found, correlating verbal delayed recall. Additionally, ipsilateral temporal further hippocampal atrophy. Conclusions: Our study highlights role alterations These findings expand traditional understanding function towards importance broader networks. Individualized, might protect neurocognitive function.

Language: Английский

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Closed-loop control of theta oscillations enhances human hippocampal network connectivity

Nature Communications, Journal Year: 2025, Volume and Issue: 16(1)

Published: April 30, 2025

Theta oscillations are implicated in regulating information flow within cortico-hippocampal networks to support memory and cognition. However, causal evidence tying theta network communication humans is lacking. Here we report experimental findings using a closed-loop, phase-locking algorithm apply direct electrical stimulation neocortical nodes of the hippocampal precisely timed ongoing rhythms human neurosurgical patients. We show that repetitive lateral temporal cortex synchronized increases while it delivered, suggesting entrainment neural activity. After stimulation, connectivity persistently increased relative baseline, as indicated by theta-phase synchrony hippocampus neocortex amplitudes evoked response isolated stimulation. These indicators not affected control delivered with approximately same rhythm but without phase locking theta. role routing signals across suggest phase-synchronized promising method modulate theta- hippocampal-dependent behaviors.

Language: Английский

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