Hippocampus最新文献

{"title":"The Suprapyramidal and Infrapyramidal Blades of the Dentate Gyrus Exhibit Different GluN Subunit Content and Dissimilar Frequency-Dependent Synaptic Plasticity In Vivo","authors":"Christina Strauch,&nbsp;Juliane Böge,&nbsp;Olena Shchyglo,&nbsp;Valentyna Dubovyk,&nbsp;Denise Manahan-Vaughan","doi":"10.1002/hipo.70002","DOIUrl":"https://doi.org/10.1002/hipo.70002","url":null,"abstract":"<p>The entorhinal cortex sends afferent information to the hippocampus by means of the perforant path (PP). The PP input to the dentate gyrus (DG) terminates in the suprapyramidal (sDG) and infrapyramidal (iDG) blades. Different electrophysiological stimulation patterns of the PP can generate hippocampal synaptic plasticity. Whether frequency-dependent synaptic plasticity differs in the sDG and iDG is unclear. Here, we compared medial PP–DG responses in freely behaving adult rats and found that synaptic plasticity in the sDG is broadly frequency dependent, whereby long-term depression (LTD, &gt; 24 h) is induced with stimulation at 1 Hz, short-term depression (&lt; 2 h) is triggered by 5 or 10 Hz, and long-term potentiation (LTP) of increasing magnitudes is induced by 200 and 400 Hz stimulation, respectively. By contrast, although the iDG expresses STD following 5 or 10 Hz stimulation, LTD induced by 1 Hz is weaker, LTP is not induced by 200 Hz and LTP induced by 400 Hz stimulation is significantly smaller in magnitude than LTP induced in sDG. Furthermore, the stimulus–response relationship of iDG is suppressed compared to sDG. These differences may arise from differences in granule cell properties, or the complement of NMDA receptors. Patch clamp recordings, in vitro, revealed reduced firing frequencies in response to high currents, and different action potential thresholds in iDG compared to sDG. Assessment of the expression of GluN subunits revealed significantly lower expression levels of GluN1, GluN2A, and GluN2B in the middle molecular layer of iDG compared to sDG. Taken together, these data indicate that synaptic plasticity in the iDG is weaker, less persistent and less responsive to afferent frequencies than synaptic plasticity in sDG. Effects may be mediated by weaker NMDA receptor expression and differences in neuronal responses in iDG versus sDG. These characteristics may explain reported differences in experience-dependent information processing in the suprapyramidal and infrapyramidal blades of the DG.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70002","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143481330","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":"Are Wayfinding Abilities Correlated With Specific Brain Anatomy? An Investigation on Regular Car Drivers Using a Navigational Map in an Unknown Environment","authors":"Jordan Navarro,&nbsp;Jean Ribot,&nbsp;Damien Schnebelen,&nbsp;Perrine Seguin,&nbsp;Marie Claude Ouimet,&nbsp;Emanuelle Reynaud","doi":"10.1002/hipo.70000","DOIUrl":"https://doi.org/10.1002/hipo.70000","url":null,"abstract":"<div>\u0000 \u0000 <p>The ability to navigate spatially in the physical world is a fundamental cognitive skill. This study examines the anatomical correlates of map-assisted wayfinding in an unfamiliar virtual environment using structural magnetic resonance magining (MRI). Thirty-three participants were required to reach up to seven different locations represented on a navigational map in a simulated environment, while their gazing behavior was recorded, and, in close temporal proximity, the anatomical MRI of their brain was acquired. Significant predictors of wayfinding performance were the volumes of the right hippocampus, left retrosplenial cortex, and posterior cingulate cortex—left inferior frontal gyrus, right superior frontal gyrus, and right cerebellar lobule VIIB. Detailed analyses revealed a dissociation between two clusters of gray matter density in the right hippocampus. Compared with the poorest wayfinders, the best wayfinders exhibited more gray matter density in a cluster located in the right posterior hippocampus but less gray matter density in a cluster located in the anterior section of the hippocampus. In addition, top performers spent more time gazing at the map, highlighting the benefit of using external aids during navigation tasks. Altogether, these results underscore how structural adaptations are associated with spatial navigation performance.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455734","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":"The Modulation by the Locus Coeruleus of Recent and Remote Memory Retrieval is Activity-Dependent","authors":"Natalia Babushkina,&nbsp;Denise Manahan-Vaughan","doi":"10.1002/hipo.70004","DOIUrl":"https://doi.org/10.1002/hipo.70004","url":null,"abstract":"<p>The hippocampus plays a crucial role in acquiring, storing, and retrieving associative experience. Whereas neuromodulatory control of the hippocampus by the locus coeruleus (LC) enhances memory acquisition and consolidation, less is known about its influence on memory retrieval. The LC fires at tonic (0.5–8 Hz) and phasic frequencies (10–25 Hz), relative to arousal and affective states. Here, we explored to what extent LC stimulation at different frequencies (2–100 Hz) and respective stimulation patterns, before retrieval of recently acquired or remote spatial memory, alter working memory (WM) or reference memory (RM) in male rats. Here, animals learned a spatial memory task in an eight-arm radial maze over a period of 15 days. LC stimulation before recent memory testing did not affect WM. However, LC stimulation at 20 or 100 Hz, but not 5–10 Hz, impaired retrieval of recently consolidated RM. These frequency-dependent impairments were abolished by intracerebral β-adrenergic receptor (β-AR), but not D1/D5 receptor, antagonism. When memory retrieval was assessed 4 weeks after initial consolidation (Day 34), RM was significantly impaired compared to the final day of recent memory testing (on Day 6). RM was not altered by LC stimulation before remote memory retrieval. However, LC stimulation at 2–100 Hz improved WM. Taken together, these data suggest that frequency-dependent NA release from the LC disrupts retrieval of recently acquired RM via activation of β-AR. Strikingly, increasing LC activity <i>in general</i> improves WM of a remotely acquired spatial learning task, assessed 4 weeks after the recent memory testing, suggesting that the increased effort of sustaining WM of a task learned in the past requires higher LC engagement.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70004","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143455736","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":"Donepezil Reverses Alcohol-Induced Changes in Hippocampal Neurogenic and Glial Responses Following Adolescent Intermittent Ethanol Exposure Into Adulthood in Female Rats","authors":"Kala N. Nwachukwu,&nbsp;James C. Nelson,&nbsp;Kennedy M. Hill,&nbsp;Kennedy A. Clark,&nbsp;Kati Healey,&nbsp;H. Scott Swartzwelder,&nbsp;S. Alex Marshall","doi":"10.1002/hipo.70001","DOIUrl":"https://doi.org/10.1002/hipo.70001","url":null,"abstract":"<p>Adolescent intermittent ethanol (AIE) exposure leads to persisting increases in glial markers and significantly decreases the neurogenic niche in the dentate gyrus of the hippocampus. Our previous study indicated that donepezil (DZ), a cholinesterase inhibitor, can reverse the AIE effect of decreased doublecortin (DCX), a neurogenic marker, and increased cleaved caspase 3, a marker of apoptosis, in the dentate gyrus of male rats. However, to date, no studies have assessed the effects of DZ on AIE effects in females. The purpose of this study was to determine whether DZ can reverse neuroimmune, neurogenic, and neuronal death effects in adulthood after AIE in female rats. Adolescent female rats were given 14 doses of ethanol (5 g/kg) over 24 days by intragastric gavage. Seventeen days later, DZ (2.5 mg/kg, 1.88 mL/kg, i.g., in water) was then administered daily for 4 days prior to sacrifice. Immunohistochemical techniques were utilized to determine the effects of DZ on AIE-induced changes in neurogenesis, cell death, glial, and neuroimmune markers. As expected, AIE decreased the neurogenic markers DCX, SOX2, and Ki-67 in the dentate gyrus and also caused an increase in the glial markers GFAP and Iba-1 in the hippocampus. The effects of AIE on neurogenic and glial markers were reversed by DZ treatment, but the reversal of AIE effects on glial markers was regionally specific within the hippocampus. Overall, these findings indicate that systemic DZ in adult female rats ameliorates the effects of AIE on neurogenesis, neuronal cell death, neuroimmune markers, and glial activation markers. Future studies will determine if DZ alters hippocampally driven behaviors, as well as the mechanisms underlying donepezil's effects.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.70001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143439182","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":"Perinatal Protein Restriction Induces Anhedonic-Like Behavior: Disturbed Hippocampal Neurotrophic Signaling and Neuronal Structural Plasticity in Adult Offspring","authors":"María C. Gutiérrez,&nbsp;Ramiro G. Comas Mutis,&nbsp;María C. Perondi,&nbsp;Gastón D. Calfa,&nbsp;Analía Valdomero","doi":"10.1002/hipo.70003","DOIUrl":"https://doi.org/10.1002/hipo.70003","url":null,"abstract":"<div>\u0000 \u0000 <p>Early protein malnutrition has been shown to affect the brain reward circuitry, leading to enduring molecular, neurochemical, and behavioral alterations. This study explored how maternal protein restriction contributes to anhedonia, a key depression symptom, focusing on the hippocampal BDNF–TrkB signaling and structural plasticity changes in the CA1 subregion of the dorsal hippocampus (DH). To achieve our goal, adult rats submitted to a protein restriction schedule from the 14th day of gestation up to 30 days of age (PR-rats) were subjected to the sucrose preference test (SPT) and compared with animals fed a normoprotein diet. Immediately after SPT, we assessed the levels of BDNF and its receptor TrkB and structural plasticity changes. Interestingly, PR-rats showed a significant decrease in sucrose preference. Furthermore, perinatal protein-restriction-induced anhedonia correlated with decreased BDNF and p-TrkB levels in the DH, alongside reduced dendritic spine density in CA1 pyramidal neurons, particularly mature spines (i.e., stubby and mushroom spines). These findings suggest that decreased hippocampal BDNF–TrkB signaling accompanied by structural remodeling in the CA1 pyramidal neurons may contribute to the reduced ability of undernourished animals to respond to rewarding stimuli, increasing their vulnerability to anhedonia later in life.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404305","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.23614","DOIUrl":"https://doi.org/10.1002/hipo.23614","url":null,"abstract":"","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 2","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23614","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404304","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":"Scientific Histories of Hippocampal Research: Introduction to the Special Issue","authors":"Michael E. Hasselmo,&nbsp;Lynn Nadel","doi":"10.1002/hipo.23680","DOIUrl":"10.1002/hipo.23680","url":null,"abstract":"<div>\u0000 \u0000 <p>Numerous scientific advances and discoveries have arisen from research on the hippocampal formation. This special issue provides first-person historical descriptions of these advances and discoveries in hippocampal research, written by those directly involved in the research. This is the first section of a special issue that will also include future articles on this topic. Here, we discuss some of the factors that motivated this special issue, and the major themes of hippocampal research that are addressed.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142931040","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":"Visual Exploration and the Primate Hippocampal Formation","authors":"Elizabeth A. Buffalo","doi":"10.1002/hipo.23673","DOIUrl":"10.1002/hipo.23673","url":null,"abstract":"<p>During the 1990s and early 2000s, research in humans and in the nonhuman primate model of human amnesia revealed that tasks involving free viewing of images provided an exceptionally sensitive measure of recognition memory. Performance on these tasks was sensitive to damage restricted to the hippocampus as well as to damage that included medial temporal lobe cortices. Early work in my laboratory used free-viewing tasks to assess the neurophysiological correlates of recognition memory, and the use of naturalistic visual exploration opened rich avenues to assess other aspects of the impact of eye movements on neural activity in the hippocampus and entorhinal cortex. Here, I summarize two main lines of this work and some of the stories of the trainees who made essential contributions to these discoveries.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11685163/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142909507","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":"How Ideas About Context and Remapping Developed in Brooklyn","authors":"John L. Kubie","doi":"10.1002/hipo.23671","DOIUrl":"10.1002/hipo.23671","url":null,"abstract":"<div>\u0000 \u0000 <p>In 1979, I joined Jim Ranck's group in Brooklyn and began recording hippocampal neurons. The first project was to record single neurons across three behaviors in different chambers: pellet retrieval on a radial-arm maze, bar-pressing for food reward in an operant chamber, and maternal pup-retrieval in a large home box. We found spatial firing in all three chambers, with a single-neuron's firing pattern unpredictable from one chamber to the next. We interpreted the spatial firing patterns as representing “context.” Later, in the 1980s, I began collaborating with Bob Muller (and Jim Ranck). In the first of a pair of 1987 papers, we used computerized data acquisition, recorded in simple, reduced environments to demonstrate robust, stable place cell firing and the characteristic features of firing fields. In the second paper we showed that when a rat is transferred from one environment to another, the set of place cells “remaps.” “Remapping” was defined later, in a pair of 1990 papers. “Context” was introduced in the early three-behavior experiment but was not discussed in the 1987 papers. What is the true relationship between the biological observation of “remapping” and the psychological concept of “context”? This difficult question is addressed here and in more detail in our recent paper.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142894158","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":"Development of the SPEAR Model: Separate Phases of Encoding and Retrieval Are Necessary for Storing Multiple Overlapping Associative Memories","authors":"Michael E. Hasselmo","doi":"10.1002/hipo.23676","DOIUrl":"10.1002/hipo.23676","url":null,"abstract":"<div>\u0000 \u0000 <p>In keeping with the historical focus of this special issue of Hippocampus, this paper reviews the history of my development of the SPEAR model. The SPEAR model proposes that separate phases of encoding and retrieval (SPEAR) allow effective storage of multiple overlapping associative memories in the hippocampal formation and other cortical structures. The separate phases for encoding and retrieval are proposed to occur within different phases of theta rhythm with a cycle time on the order of 125 ms. The same framework applies to the slower transition between encoding and consolidation dynamics regulated by acetylcholine. The review includes description of the experimental data on acetylcholine and theta rhythm that motivated this model, the realization that existing associative memory models require these different dynamics, and the subsequent experimental data supporting these dynamics. The review also includes discussion of my work on the encoding of episodic memories as spatiotemporal trajectories, and some personal description of the episodic memories from my own spatiotemporal trajectory as I worked on this model.</p>\u0000 </div>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"35 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142894156","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}