HippocampusPub Date : 2024-01-08DOI: 10.1002/hipo.23598
Lydia Jiang, Jessica Robin, Nathanael Shing, Negar Mazloum-Farzaghi, Natalia Ladyka-Wojcik, Niroja Balakumar, Nicole D. Anderson, Jennifer D. Ryan, Morgan D. Barense, Rosanna K. Olsen
{"title":"Impaired perceptual discrimination of complex objects in older adults at risk for dementia","authors":"Lydia Jiang, Jessica Robin, Nathanael Shing, Negar Mazloum-Farzaghi, Natalia Ladyka-Wojcik, Niroja Balakumar, Nicole D. Anderson, Jennifer D. Ryan, Morgan D. Barense, Rosanna K. Olsen","doi":"10.1002/hipo.23598","DOIUrl":"10.1002/hipo.23598","url":null,"abstract":"<p>Tau pathology accumulates in the perirhinal cortex (PRC) of the medial temporal lobe (MTL) during the earliest stages of the Alzheimer's disease (AD), appearing decades before clinical diagnosis. Here, we leveraged perceptual discrimination tasks that target PRC function to detect subtle cognitive impairment even in nominally healthy older adults. Older adults who did not have a clinical diagnosis or subjective memory complaints were categorized into “at-risk” (score <26; <i>n</i> = 15) and “healthy” (score ≥26; <i>n</i> = 23) groups based on their performance on the Montreal Cognitive Assessment. The task included two conditions known to recruit the PRC: faces and complex objects (greebles). A scene condition, known to recruit the hippocampus, and a size control condition that does not rely on the MTL were also included. Individuals in the at-risk group were less accurate than those in the healthy group for discriminating greebles. Performance on either the face or size control condition did not predict group status above and beyond that of the greeble condition. Visual discrimination tasks that are sensitive to PRC function may detect early cognitive decline associated with AD.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 4","pages":"197-203"},"PeriodicalIF":3.5,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23598","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139377492","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}
HippocampusPub Date : 2024-01-04DOI: 10.1002/hipo.23596
Benjamin J. Clark, Patrick A. LaChance, Shawn S. Winter, Max L. Mehlman, Will Butler, Ariyana LaCour, Jeffrey S. Taube
{"title":"Comparison of head direction cell firing characteristics across thalamo-parahippocampal circuitry","authors":"Benjamin J. Clark, Patrick A. LaChance, Shawn S. Winter, Max L. Mehlman, Will Butler, Ariyana LaCour, Jeffrey S. Taube","doi":"10.1002/hipo.23596","DOIUrl":"10.1002/hipo.23596","url":null,"abstract":"<p>Head direction (HD) cells, which fire persistently when an animal's head is pointed in a particular direction, are widely thought to underlie an animal's sense of spatial orientation and have been identified in several limbic brain regions. Robust HD cell firing is observed throughout the thalamo-parahippocampal system, although recent studies report that parahippocampal HD cells exhibit distinct firing properties, including conjunctive aspects with other spatial parameters, which suggest they play a specialized role in spatial processing. Few studies, however, have quantified these apparent differences. Here, we performed a comparative assessment of HD cell firing characteristics across the anterior dorsal thalamus (ADN), postsubiculum (PoS), parasubiculum (PaS), medial entorhinal (MEC), and postrhinal (POR) cortices. We report that HD cells with a high degree of directional specificity were observed in all five brain regions, but ADN HD cells display greater sharpness and stability in their preferred directions, and greater anticipation of future headings compared to parahippocampal regions. Additional analysis indicated that POR HD cells were more coarsely modulated by other spatial parameters compared to PoS, PaS, and MEC. Finally, our analyses indicated that the sharpness of HD tuning decreased as a function of laminar position and conjunctive coding within the PoS, PaS, and MEC, with cells in the superficial layers along with conjunctive firing properties showing less robust directional tuning. The results are discussed in relation to theories of functional organization of HD cell tuning in thalamo-parahippocampal circuitry.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 4","pages":"168-196"},"PeriodicalIF":3.5,"publicationDate":"2024-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139097687","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}
HippocampusPub Date : 2023-12-25DOI: 10.1002/hipo.23592
Kim Ngan Hoang, Yushan Huang, Esther Fujiwara, Nikolai Malykhin
{"title":"Effects of healthy aging and mnemonic strategies on verbal memory performance across the adult lifespan: Mediating role of posterior hippocampus","authors":"Kim Ngan Hoang, Yushan Huang, Esther Fujiwara, Nikolai Malykhin","doi":"10.1002/hipo.23592","DOIUrl":"10.1002/hipo.23592","url":null,"abstract":"<p>In this study, we aimed to understand the contributions of hippocampal anteroposterior subregions (head, body, tail) and subfields (cornu ammonis 1-3 [CA1-3], dentate gyrus [DG], and subiculum [Sub]) and encoding strategies to the age-related verbal memory decline. Healthy participants were administered the California Verbal Learning Test-II to evaluate verbal memory performance and encoding strategies and underwent 4.7 T magnetic resonance imaging brain scan with subsequent hippocampal subregions and subfields manual segmentation. While total hippocampal volume was not associated with verbal memory performance, we found the volumes of the posterior hippocampus (body) and Sub showed significant effects on verbal memory performance. Additionally, the age-related volume decline in hippocampal body volume contributed to lower use of semantic clustering, resulting in lower verbal memory performance. The effect of Sub on verbal memory was statistically independent of encoding strategies. While total CA1-3 and DG volumes did not show direct or indirect effects on verbal memory, exploratory analyses with DG and CA1-3 volumes within the hippocampal body subregion suggested an indirect effect of age-related volumetric reduction on verbal memory performance through semantic clustering. As semantic clustering is sensitive to age-related hippocampal volumetric decline but not to the direct effect of age, further investigation of mechanisms supporting semantic clustering can have implications for early detection of cognitive impairments and decline.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 2","pages":"100-122"},"PeriodicalIF":3.5,"publicationDate":"2023-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23592","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139032309","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}
HippocampusPub Date : 2023-12-22DOI: 10.1002/hipo.23593
Jasmin A. Strickland, Joseph M. Austen, Rolf Sprengel, David J. Sanderson
{"title":"Knockout of NMDARs in CA1 and dentate gyrus fails to impair temporal control of conditioned behavior in mice","authors":"Jasmin A. Strickland, Joseph M. Austen, Rolf Sprengel, David J. Sanderson","doi":"10.1002/hipo.23593","DOIUrl":"10.1002/hipo.23593","url":null,"abstract":"<p>The hippocampus has been implicated in temporal learning. Plasticity within the hippocampus requires NMDA receptor-dependent glutamatergic neurotransmission. We tested the prediction that hippocampal NMDA receptors are required for learning about time by testing mice that lack postembryonal NMDARs in the CA1 and dentate gyrus (DG) hippocampal subfields on three different appetitive temporal learning procedures. The conditional knockout mice (<i>Grin1</i><sup><i>ΔDCA1</i></sup>) showed normal sensitivity to cue duration, responding at a higher level to a short duration cue than compared to a long duration cue. Knockout mice also showed normal precision and accuracy of response timing in the peak procedure in which reinforcement occurred after 10 s delay within a 30 s cue presentation. Mice were tested on the matching of response rates to reinforcement rates on instrumental conditioning with two levers reinforced on a concurrent variable interval schedule. Pressing on one lever was reinforced at a higher rate than the other lever. <i>Grin1</i><sup><i>ΔDGCA1</i></sup> mice showed normal sensitivity to the relative reinforcement rates of the levers. In contrast to the lack of effect of hippocampal NMDAR deletion on measures of temporal sensitivity, <i>Grin1</i><sup><i>ΔDGCA1</i></sup> mice showed increased baseline measures of magazine activity and lever pressing. Furthermore, reversal learning was enhanced when the reward contingencies were switched in the lever pressing task, but this was true only for mice trained with a large difference between relative reinforcement rates between the levers. The results failed to demonstrate a role for NMDARs in excitatory CA1 and DG neurons in learning about temporal information.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 3","pages":"126-140"},"PeriodicalIF":3.5,"publicationDate":"2023-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23593","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138884884","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}
HippocampusPub Date : 2023-12-15DOI: 10.1002/hipo.23595
Zhixin Fan, Xiayu Gong, Hanfang Xu, Yue Qu, Bozhi Li, Lanxin Li, Yuqi Yan, Lili Wu, Can Yan
{"title":"Hippocampal parvalbumin and perineuronal nets: Possible involvement in anxiety-like behavior in rats","authors":"Zhixin Fan, Xiayu Gong, Hanfang Xu, Yue Qu, Bozhi Li, Lanxin Li, Yuqi Yan, Lili Wu, Can Yan","doi":"10.1002/hipo.23595","DOIUrl":"10.1002/hipo.23595","url":null,"abstract":"<p>The excitatory-inhibitory imbalance has been considered an important mechanism underlying stress-related psychiatric disorders. In the present study, rats were exposed to 6 days of inescapable foot shock (IFS) to induce stress. The open field test and elevated plus maze test showed that IFS-exposed rats exhibited increased anxiety-like behavior. Immunofluorescence showed that IFS rats had a decreased density of GAD67-immunoreactive interneurons in the dorsal hippocampal CA1 region, while no significant change in the density of CaMKIIα-immunoreactive glutamatergic neurons was seen. We investigated the expression of different interneuron subtype markers, including parvalbumin (PV), somatostatin (SST), and calretinin (CR), and noted a marked decline in the density of PV-immunoreactive interneurons in the dorsal CA1 region of IFS rats. The perineuronal net (PNN) is a specialized extracellular matrix structure primarily around PV interneurons. We used Wisteria floribunda agglutinin lectin to label the PNNs and observed that IFS rats had an increased proportion of PNN-coated PV-positive interneurons in CA1. The number of PSD95-positive excitatory synaptic puncta on the soma of PNN-free PV-positive interneurons was significantly higher than that of PNN-coated PV-positive interneurons. Our findings suggest that the effect of IFS on the hippocampal GABAergic interneurons could be cell-type-specific. Loss of PV phenotype in the dorsal hippocampal CA1 region may contribute to anxiety in rats. The dysregulated PV-PNN relationship in CA1 after traumatic stress exposure might represent one of the neurobiological correlates of the observed anxiety-like behavior.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 3","pages":"156-165"},"PeriodicalIF":3.5,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138685963","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}
HippocampusPub Date : 2023-12-14DOI: 10.1002/hipo.23594
Kevan Kidder, Ryan Gillis, Jesse Miles, Sheri J. Y. Mizumori
{"title":"The medial prefrontal cortex during flexible decisions: Evidence for its role in distinct working memory processes","authors":"Kevan Kidder, Ryan Gillis, Jesse Miles, Sheri J. Y. Mizumori","doi":"10.1002/hipo.23594","DOIUrl":"10.1002/hipo.23594","url":null,"abstract":"<p>During decisions that involve working memory, task-related information must be encoded, maintained across delays, and retrieved. Few studies have attempted to causally disambiguate how different brain structures contribute to each of these components of working memory. In the present study, we used transient optogenetic disruptions of rat medial prefrontal cortex (mPFC) during a serial spatial reversal learning (SSRL) task to test its role in these specific working memory processes. By analyzing numerous performance metrics, we found: (1) mPFC disruption impaired performance during only the choice epoch of initial discrimination learning of the SSRL task; (2) mPFC disruption impaired performance in dissociable ways across all task epochs (delay, choice, return) during flexible decision-making; (3) mPFC disruption resulted in a reduction of the typical vicarious-trial-and-error rate modulation that was related to changes in task demands. Taken together, these findings suggest that the mPFC plays an outsized role in working memory retrieval, becomes involved in encoding and maintenance when recent memories conflict with task demands, and enables animals to flexibly utilize working memory to update behavior as environments change.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 3","pages":"141-155"},"PeriodicalIF":3.5,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138628136","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}
HippocampusPub Date : 2023-12-11DOI: 10.1002/hipo.23591
Yuxi Chen, Audrey Branch, Cecelia Shuai, Michela Gallagher, James J. Knierim
{"title":"Object-place-context learning impairment correlates with spatial learning impairment in aged Long–Evans rats","authors":"Yuxi Chen, Audrey Branch, Cecelia Shuai, Michela Gallagher, James J. Knierim","doi":"10.1002/hipo.23591","DOIUrl":"10.1002/hipo.23591","url":null,"abstract":"<p>The hippocampal formation is vulnerable to the process of normal aging. In humans, the extent of this age-related deterioration varies among individuals. Long–Evans rats replicate these individual differences as they age, and therefore they serve as a valuable model system to study aging in the absence of neurodegenerative diseases. In the Morris water maze, aged memory-unimpaired (AU) rats navigate to remembered goal locations as effectively as young rats and demonstrate minimal alterations in physiological markers of synaptic plasticity, whereas aged memory-impaired (AI) rats show impairments in both spatial navigation skills and cellular and molecular markers of plasticity. The present study investigates whether another cognitive domain is affected similarly to navigation in aged Long–Evans rats. We tested the ability of young, AU, and AI animals to recognize novel object-place-context (OPC) configurations and found that performance on the novel OPC recognition paradigm was significantly correlated with performance on the Morris water maze. In the first OPC test, young and AU rats, but not AI rats, successfully recognized and preferentially explored objects in novel OPC configurations. In a second test with new OPC configurations, all age groups showed similar OPC associative recognition memory. The results demonstrated similarities in the behavioral expression of associative, episodic-like memory between young and AU rats and revealed age-related, individual differences in functional decline in both navigation and episodic-like memory abilities.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 2","pages":"88-99"},"PeriodicalIF":3.5,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138566534","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}
HippocampusPub Date : 2023-12-04DOI: 10.1002/hipo.23587
Shicheng Jiang, Bei Liu, Kaiwen Lin, Lianjun Li, Rongrong Li, Shuo Tan, Xinyu Zhang, Lei Jiang, Hong Ni, Yuanyuan Wang, Haihu Ding, Jing Hu, Hao Qian, Rongjing Ge
{"title":"Impacted spike frequency adaptation associated with reduction of KCNQ2/3 exacerbates seizure activity in temporal lobe epilepsy","authors":"Shicheng Jiang, Bei Liu, Kaiwen Lin, Lianjun Li, Rongrong Li, Shuo Tan, Xinyu Zhang, Lei Jiang, Hong Ni, Yuanyuan Wang, Haihu Ding, Jing Hu, Hao Qian, Rongjing Ge","doi":"10.1002/hipo.23587","DOIUrl":"10.1002/hipo.23587","url":null,"abstract":"<p>Numerous epilepsy-related genes have been identified in recent decades by unbiased genome-wide screens. However, the available druggable targets for temporal lobe epilepsy (TLE) remain limited. Furthermore, a substantial pool of candidate genes potentially applicable to TLE therapy awaits further validation. In this study, we reveal the significant role of KCNQ2 and KCNQ3, two M-type potassium channel genes, in the onset of seizures in TLE. Our investigation began with a quantitative analysis of two publicly available TLE patient databases to establish a correlation between seizure onset and the downregulated expression of KCNQ2/3. We then replicated these pathological changes in a pilocarpine seizure mouse model and observed a decrease in spike frequency adaptation due to the affected M-currents in dentate gyrus granule neurons. In addition, we performed a small-scale simulation of the dentate gyrus network and confirmed that the impaired spike frequency adaptation of granule cells facilitated epileptiform activity throughout the network. This, in turn, resulted in prolonged seizure duration and reduced interictal intervals. Our findings shed light on an underlying mechanism contributing to ictogenesis in the TLE hippocampus and suggest a promising target for the development of antiepileptic drugs.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 2","pages":"58-72"},"PeriodicalIF":3.5,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138482351","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}
HippocampusPub Date : 2023-12-02DOI: 10.1002/hipo.23589
Han Yin Cheng, Dorothy W. Overington, Kate J. Jeffery
{"title":"A configural context signal simultaneously but separably drives positioning and orientation of hippocampal place fields","authors":"Han Yin Cheng, Dorothy W. Overington, Kate J. Jeffery","doi":"10.1002/hipo.23589","DOIUrl":"10.1002/hipo.23589","url":null,"abstract":"<p>Effective self-localization requires that the brain can resolve ambiguities in incoming sensory information arising from self-similarities (symmetries) in the environment structure. We investigated how place cells use environmental cues to resolve the ambiguity of a rotationally symmetric environment, by recording from hippocampal CA1 in rats exploring a “2-box.” This apparatus comprises two adjacent rectangular compartments, identical but with directionally opposed layouts (cue card at one end and central connecting doorway) and distinguished by their odor contexts (lemon vs. vanilla). Despite the structural and visual rotational symmetry of the boxes, no place cells rotated their place fields. The majority changed their firing fields (remapped) between boxes but some repeated them, maintaining a translational symmetry and thus adopting a relationship to the layout that was conditional on the odor. In general, the place field ensemble maintained a stable relationship to environment orientation as defined by the odors, but sometimes the whole ensemble rotated its firing <i>en bloc</i>, decoupling from the odor context cues. While the individual elements of these observations—odor remapping, place field repetition, ensemble rotation, and decoupling from context—have been reported in isolation, the combination in the one experiment is incompletely explained within current models. We redress this by proposing a model in which odor cues enter into a three-way association with layout cues and head direction, creating a configural context signal that facilitates two separate processes: place field orientation and place field positioning. This configuration can subsequently still function in the absence of one of its components, explaining the ensemble decoupling from odor. We speculate that these interactions occur in retrosplenial cortex, because it has previously been implicated in context processing, and all the relevant signals converge here.</p>","PeriodicalId":13171,"journal":{"name":"Hippocampus","volume":"34 2","pages":"73-87"},"PeriodicalIF":3.5,"publicationDate":"2023-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/hipo.23589","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138470235","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}