Hippocampus最新文献

{"title":"Changes in Naturalistic Viewing in Healthy Aging and Amnestic Mild Cognitive Impairment","authors":"Anisha Khosla,&nbsp;Jordana S. Wynn,&nbsp;Arber Kacollja,&nbsp;Elaheh Shahmiri,&nbsp;Nicole D. Anderson,&nbsp;Kelly Shen,&nbsp;Jennifer D. Ryan","doi":"10.1002/hipo.70037","DOIUrl":"10.1002/hipo.70037","url":null,"abstract":"<div>\u0000 \u0000 <p>Visual exploration—where the eyes move and when—is guided by prior experiences. Memory-guided viewing behavior is altered in healthy aging and is further disrupted in amnestic mild cognitive impairment (aMCI), a condition in which there is accelerated structural and functional decline of the hippocampus and associated medial temporal lobe structures (HC/MTL). Computational modeling has demonstrated the potential for rapid information flow from the HC/MTL to regions responsible for the cognitive control of eye movements, such that visual exploration behavior could be impacted in the moment and on an ongoing fashion. It was predicted here, then, that older adults and individuals with aMCI would show changes in naturalistic viewing compared to younger adults, even in the absence of any memory task. Multivariate analyses revealed that viewing for younger adults was characterized by larger saccade amplitudes and a larger area of exploration; the opposite pattern was reliably expressed by individuals with aMCI. Viewing patterns of healthy older adults were associated with shorter gaze durations. The entropy of viewing in older adults was associated with overall cognitive status, as determined by the Montreal Cognitive Assessment, highlighting the top-down influence of cognitive function on active vision. Lower scores on the memory subtest were reliably associated with a pattern of viewing characterized by fewer fixations (with longer durations), saccades, regions explored, smaller area of exploration, and lower entropy, mimicking some of the viewing features of the aMCI group and suggesting that increasing HC/MTL decline results in less exploratory viewing patterns. These findings reveal the ongoing influence of the hippocampus and its extended system on moment-to-moment naturalistic viewing.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Issue Information - Editorial Board","authors":"","doi":"10.1002/hipo.23618","DOIUrl":"https://doi.org/10.1002/hipo.23618","url":null,"abstract":"","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23618","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145181664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tau PET Burden Is Associated With Hippocampal Microstructure and Episodic Memory in Amyloid Positive Older Adults","authors":"Daniel D. Callow,&nbsp;Nisha Rani,&nbsp;Kylie H. Alm,&nbsp;Corinne Pettigrew,&nbsp;Anja Soldan,&nbsp;Sara Sheikhbahaei,&nbsp;Michael Miller,&nbsp;Marilyn Albert,&nbsp;Arnold Bakker,&nbsp;the BIOCARD Research Team","doi":"10.1002/hipo.70038","DOIUrl":"https://doi.org/10.1002/hipo.70038","url":null,"abstract":"<div>\u0000 \u0000 <p>Growing evidence suggests that hippocampal gray matter microstructure, assessed through diffusion-weighted imaging (DWI), is a sensitive marker of neurodegeneration in Alzheimer's disease (AD). While hippocampal atrophy is a characteristic feature of AD, microstructural changes likely precede macrostructural changes such as volumetric loss, offering important insights into the early phases of the disease. This study assessed the relationships between hippocampal microstructure (assessed with mean diffusivity [MD] from DWI) and Braak-staged tau burden (measured by positron emission tomography [PET]) with performance on an episodic memory composite score, among individuals with and without amyloid burden, assessed by PET imaging. The study included 192 participants without dementia (14 with mild cognitive impairment [MCI]) from the BIOCARD cohort (mean age = 68), of which 52 (27%) were amyloid positive. In multiple linear regression analyses, increased hippocampal MD was associated with worse memory and greater tau PET burden in Braak stages II–IV, but only in individuals who were amyloid positive (e.g., significant amyloid × hippocampal MD interactions). Building on prior findings linking early Braak-staged tau to memory, we further assessed whether tau PET burden statistically mediated the relationship between elevated hippocampal MD and poorer memory performance. Tau PET burden in Braak stages II–IV was found to statistically mediate the relationship between elevated hippocampal MD and poorer memory performance, independent of hippocampal volume, but only in amyloid-positive participants. These associations were only significant when MCI participants were included in the analysis. These findings suggest hippocampal microstructure may be sensitive to AD-related pathological burden and associated neurodegeneration, particularly in the early symptomatic phase, and is associated with tau PET and cognitive decline, even after accounting for hippocampal volume.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 6","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145181626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lateralization of Hippocampal Dentate Spikes and Sharp-Wave Ripples in Urethane Anesthetized Rats Depends on Cholinergic Tone","authors":"Miriam S. Nokia,&nbsp;Sanna Lensu,&nbsp;Suvi-Maaria Lehtonen,&nbsp;Tero Harjupatana,&nbsp;Markku Penttonen","doi":"10.1002/hipo.70035","DOIUrl":"10.1002/hipo.70035","url":null,"abstract":"<p>Neural activity and bodily functions are inherently rhythmic and related to each other. The occurrence of hippocampal sharp-wave ripples (SPW-Rs) and dentate spikes (DSs) supporting memory consolidation is regulated by the overall state of the brain, and they also seem to aggregate to a certain phase of the breathing cycle in naturally sleeping mice. Further, SPW-Rs and DSs synchronize to a variable degree between hemispheres, but how this is affected by the neural and bodily state is unclear. Here, we recorded dorsal hippocampal local-field potentials, electrocardiogram, and respiration for several hours under urethane anesthesia in adult male Sprague–Dawley rats. For a subset of rats, we injected atropine (50 mg/kg, i.p.) halfway into the recording to decrease cholinergic and parasympathetic tone. We found variable relation of hippocampal oscillations to breathing phase and none to the cardiac cycle phase. A decrease in breathing rate implying increased parasympathetic tone preceded the start of SPW-R bouts. Roughly 90% of DSs and half of SPW-Rs were unilateral. In most rats, SPW-Rs were more often bilateral during slow breathing compared to faster breathing. Atropine reduced the proportion of bilateral SPW-Rs. Both nonrapid eye movement sleep-like state and atropine increased the proportion of bilateral DSs under urethane anesthesia. Finally, in naturally sleeping rats, both DSs and SPW-Rs were bilateral ~60% of the time. In sum, urethane seems to desynchronize DSs but not SPW-Rs, and a low cholinergic and/or parasympathetic tone seems to dissociate SPW-Rs and to synchronize DSs in the two hippocampi. Whether these findings have relevance in terms of memory consolidation and behavior should be investigated in the future.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12455560/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145124217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unpacking the Medial Temporal Lobe: Separating Recollection and Familiarity","authors":"Andrew P. Yonelinas","doi":"10.1002/hipo.70033","DOIUrl":"https://doi.org/10.1002/hipo.70033","url":null,"abstract":"<p>Our understanding of how the medial temporal lobe (MTL) contributes to human cognition has advanced enormously over the past half a century. My work in the 1990s characterizing the role of recollection and familiarity processes in episodic memory led me to study the MTL's role in these two memory processes. In the current paper, I provide a personal commentary in which I describe the motivating ideas, as well as the invaluable impact of mentors, colleagues, and students that led to a series of studies showing that conscious recollection is critically dependent on the hippocampus, whereas familiarity-based judgments are dependent on regions such as the perirhinal cortex.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70033","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145007993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Dendritic Spine Loss on Excitability of Hippocampal CA1 Pyramidal Neurons: A Computational Study of Early Alzheimer Disease","authors":"Chengju Tian,&nbsp;Isabel Reyes,&nbsp;Alexandra Johnson,&nbsp;Arjun V. Masurkar","doi":"10.1002/hipo.70025","DOIUrl":"https://doi.org/10.1002/hipo.70025","url":null,"abstract":"<p>Synaptic spine loss is an early pathophysiologic hallmark of Alzheimer disease (AD) that precedes overt loss of dendritic architecture and frank neurodegeneration. While spine loss signifies a decreased engagement of postsynaptic neurons by presynaptic targets, the degree to which loss of spines and their passive components impacts the excitability of postsynaptic neurons and responses to surviving synaptic inputs is unclear. Using passive multicompartmental models of CA1 pyramidal neurons (PNs), implicated in early AD, we find that spine loss alone drives a boosting of remaining inputs to their proximal and distal dendrites, targeted by CA3 and entorhinal cortex (EC), respectively. This boosting effect is higher in distal versus proximal dendrites and can be mediated by spine loss restricted to the distal compartment, enough to impact synaptic input integration, somatodendritic backpropagation, and plateau potential generation. This has particular relevance to very early stages of AD in which pathophysiology extends from EC to CA1.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70025","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144832782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-Term Memory Engrams From Development to Adulthood","authors":"Abigail L. Yu,&nbsp;Laura A. DeNardo","doi":"10.1002/hipo.70032","DOIUrl":"https://doi.org/10.1002/hipo.70032","url":null,"abstract":"<p>Memories formed in adulthood can last a lifetime, whereas those formed early in life are rapidly forgotten through a process known as infantile amnesia. In recent years, tremendous progress has been made in understanding the memory engram—the physical trace of a memory in the brain—and how it transforms as memories evolve from recent to remote. This review focuses on engram cells and examines their roles in memory encoding, consolidation, retrieval, and forgetting from development to adulthood. We concentrate on four key brain regions: the hippocampus, the retrosplenial cortex, the medial prefrontal cortex, and the anterior thalamic nuclei. We first focus on the adult brain, highlighting recent studies that reveal the distinct contributions of engram cells in each brain region, with particular emphasis on synaptic plasticity and memory consolidation. We then explore how coordinated activity across these regions supports long-term memory. In the second section, we review emerging knowledge of engram cells in the developing brain, examining how developmental differences in their functions contribute to infant memory generalization and infantile amnesia. Compared to adults, much less is known about how, or to what extent, early-life memories undergo consolidation. In the final section, we synthesize current knowledge of memory consolidation and retrieval in the adult brain with what is known about the development of the four brain regions we discuss. We then propose key directions for future research. In sum, this review brings together recent findings that deepen our understanding of the dynamic changes in memory engrams that underlie consolidation and long-term storage and explores how developmental differences may shape the maturation of memory processes.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70032","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144782770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differentiated Presynaptic Input to OLMɑ2 Cells Along the Hippocampal Dorsoventral Axis: Implications for Hippocampal Microcircuit Function","authors":"Angelica Thulin,&nbsp;Katharina Henriksson,&nbsp;Ingrid Nogueira,&nbsp;Klas Kullander","doi":"10.1002/hipo.70026","DOIUrl":"https://doi.org/10.1002/hipo.70026","url":null,"abstract":"<p>The dorsal and ventral hippocampus have distinct processing properties, but it remains unclear if interneuron subtypes differ in connectivity along the dorsoventral axis. Oriens lacunosum-moleculare (OLM) interneurons, identified by the <i>Chrna2</i> gene, are known to regulate memory processes differently along this axis. OLMɑ2 cells bidirectionally modulate risk-taking behavior, while ventral hippocampal medial prefrontal cortex (mPFC)-projecting neurons regulate approach and avoidance behaviors. Using rabies virus-mediated monosynaptic retrograde tracing, we show that OLMɑ2 cells receive differential innervation across the dorsal, intermediate, and ventral hippocampus. We find that CA1 and CA3 inputs differ between hippocampal poles, suggesting that OLMɑ2 cells may have distinct feedback and feed-forward inhibitory roles in the hippocampal microcircuit. Intermediate OLMɑ2 cells uniquely receive substantial input from the subiculum and dorsal/medial raphe nuclei, as well as widespread CA2 inputs potentially linked to social memory. The medial septum and diagonal band of Broca provide cholinergic, GABAergic, and glutamatergic inputs across the axis, likely influencing disinhibition and oscillatory activity during various behavioral states. Excitatory input to intermediate-ventral OLMɑ2 cells partly arises from CA1 projection neurons targeting the mPFC. This suggests a gate-switching function that favors CA3 input to projection neurons by two different mechanisms related to feedback and feed-forward inhibition. In conclusion, OLMɑ2 cells exhibit distinct presynaptic input profiles along the dorsoventral axis, with major differences in the proportions of intrahippocampal inputs, highlighting their diverse roles in hippocampal microcircuits.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70026","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144767735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evidence of Disrupted Hippocampal Gray- and White-Matter Development in Adolescent Anxiety Disorders, Independent From Early-Life Stress","authors":"Karina Pedroza-Sotelo,&nbsp;Hillary Schwarb,&nbsp;Randy P. Auerbach,&nbsp;Satrajit S. Ghosh,&nbsp;Aude Henin,&nbsp;Stefan G. Hofmann,&nbsp;Diego A. Pizzagalli,&nbsp;Anastasia Yendiki,&nbsp;Susan Whitfield-Gabrieli,&nbsp;John D. E. Gabrieli,&nbsp;Nicholas A. Hubbard","doi":"10.1002/hipo.70028","DOIUrl":"https://doi.org/10.1002/hipo.70028","url":null,"abstract":"<p>Early-life stress and depression among youths are linked to hippocampal gray- and white-matter alterations. Less is known about hippocampal alterations in adolescent anxiety disorders (Anx) or the role that stress or comorbid depressive disorders (Anx + Dep) might play. Here, structural- and diffusion-MRI along with early-life stress-exposure reports were acquired from 197 adolescents (13.58–17.00 years) with Anx, Anx + Dep, and those without (Controls). A normative model externally validated on a large, healthy sample revealed that Anx were more likely than Controls and Anx + Dep to exhibit undersized hippocampal gray-matter volumes for their ages. Volume reductions among Anx were further localized to subfield CA1. No significant gray-matter differences were observed between Anx + Dep and Controls. Standardized probabilistic tractography in hippocampal white-matter pathways demonstrated that, relative to Controls, Anx and Anx + Dep exhibited lower fractional anisotropy specifically in the cingulum-temporal branch. All effects were specific to hippocampal structures. Group differences were not accounted for by early-life stress exposures, despite Anx and Anx + Dep reporting more than Controls. Findings indicated that gray-matter expansion, principally within CA1, may be disrupted among adolescents with anxiety disorders, but not those with comorbid depression. The progressive strengthening of hippocampal-cortical circuits occurring during adolescence may also be disrupted in adolescents with anxiety disorders, regardless of depression.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70028","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144758558","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Issue Information - Editorial Board","authors":"","doi":"10.1002/hipo.23617","DOIUrl":"https://doi.org/10.1002/hipo.23617","url":null,"abstract":"","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 5","pages":""},"PeriodicalIF":2.7,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23617","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144725439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}