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Meng S, Lu Y, Hu J, Luo B, Sun X, Wang X, Jiang Q. Tooth Loss Leads to Cognitive Impairment and Mitochondrial Disturbance in Wistar Rats. Int Dent J 2025; 75:100818. [PMID: 40311189 PMCID: PMC12084507 DOI: 10.1016/j.identj.2025.03.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2025] [Revised: 03/25/2025] [Accepted: 03/31/2025] [Indexed: 05/03/2025] Open
Abstract
BACKGROUND The link between tooth loss and cognitive impairment has become increasingly significant. Recent findings suggest that mitochondrial alteration in hippocampal neurons may mediate this relationship. OBJECTIVE This study aimed to explore the mediating role of mitochondria in the relationship between tooth loss and cognitive function in Wistar rats. METHOD Male Wistar rats (n = 20, 12 weeks old) were randomly divided into tooth extraction (TE) and sham groups. The model was established through upper molar extraction and sham operation respectively. Cognitive evaluations were performed using Morris water maze (MWM) test 8 weeks after the model establishment. Hippocampal neuron morphology was observed. Mitochondrial function was evaluated by ATP level and mitochondrial membrane potential (MMP). Mitophagy assessment involved conducting immunohistochemical and immunofluorescent staining of PTEN-induced kinase 1 (PINK1), Parkin (E3 ubiquitin ligase), translocase of outer mitochondrial membrane 20 (TOMM20), and microtubule-associated protein 1A/1B-light chain 3 (LC3). Additionally, mitophagy protein alterations were analyzed using western blotting. RESULTS Memory impairment in the TE group was obvious 8 weeks after model establishment. Substantial hippocampal mitochondrial dysfunction was observed in the TE group, evidenced by notably decreased ATP production, decreased MMP level, and abnormal mitochondrial morphology in the hippocampus. Diminished mitophagy was detected by immunofluorescent staining, and further confirmed by immunostaining and western blotting, indicating diminished mitophagy marker levels in PINK1 and Parkin, along with decreased LC3II/I ratios and elevated Sequestosome-1 (SQSTM1/P62) levels, highlighting hippocampal mitophagy deficiency following tooth loss. CONCLUSIONS Tooth loss leads to mitochondrial disturbance and inhibits PINK1/Parkin-mediated mitophagy in hippocampal neurons, inducing cognitive impairment. CLINICAL RELEVANCE This study reveals mitochondria may mediate the effect of tooth loss on cognitive function, offering a theoretical basis for the prevention of oral health-associated cognitive decline.
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Affiliation(s)
- Shixiang Meng
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Yunping Lu
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Jiangqi Hu
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Bin Luo
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Xu Sun
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Xiaoyu Wang
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China
| | - Qingsong Jiang
- Department of Prosthodontics, Beijing Stomatology Hospital & School of Stomatology, Capital Medical University, Beijing, China.
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Hernández-Vivanco A, de la Vega-Ruiz R, Montes-Mellado A, Azcoitia Í, Méndez P. Activational and organizational effects of sex hormones on hippocampal inhibitory neurons. J Neurosci 2025; 45:e1764242025. [PMID: 40097180 PMCID: PMC12044036 DOI: 10.1523/jneurosci.1764-24.2025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2024] [Revised: 02/12/2025] [Accepted: 02/16/2025] [Indexed: 03/19/2025] Open
Abstract
Peripheral and brain-produced sex hormones exert sex-specific regulation of hippocampal cognitive function. Estrogens produced by neuronal aromatase regulate inhibitory neurons (INs) and hippocampal-dependent memory in adult female mice, but not in males. How and when this sex effect is established and how peripheral and brain sources of estrogens interact in the control of hippocampal INs is currently unknown. Using ex-vivo electrophysiology, fiber photometry, molecular analysis, estrous cycle monitoring and neonatal hormonal manipulations, we unveil estrous cycle dependent and independent features of CA1 Parvalbumin (PV) INs and hippocampal inhibition in adult female mice. Before puberty, aromatase is expressed in PV INs and regulates synaptic inhibition in female but not in male mice. Neonatal testosterone administration altered prepubertal female mouse hippocampus-dependent memory, PV IN function and estrogenic regulation of adult female synaptic inhibition and PV IN perineuronal nets. Our results suggest that sex differences in brain-derived estrogen regulation of CA1 inhibition are established by organizational effects of neonatal gonadal hormones and highlight the role of INs as mediators of the sexual differentiation of the hippocampus.Significance statement The actions of sex hormones on the hippocampus, a brain region involved in memory, differ between males and females but how and when these differences are established is not known. Our work identifies a population of hippocampal inhibitory neurons (INs) that are sensitive to hormonal fluctuations associated with the female estrous cycle. INs may produce estrogen, the main female sex hormone, before the onset of adult gonadal production (puberty). Brain-produced estrogen regulates female, but not male, juvenile INs, an effect that is abolished by a neonatal surge of testosterone that typically occurs in males around birth. Thus, early in life, sex hormones impact IN function suggesting a role for this neuronal population in the sexual differentiation of the hippocampus.
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Affiliation(s)
| | | | | | - Íñigo Azcoitia
- Department of Cell Biology, Universidad Complutense de Madrid, Madrid 28040, Spain
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3
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Froula JM, Rose JJ, Krook-Magnuson C, Krook-Magnuson E. Distinct Functional Classes of CA1 Hippocampal Interneurons Are Modulated by Cerebellar Stimulation in a Coordinated Manner. J Neurosci 2024; 44:e0887242024. [PMID: 39448264 PMCID: PMC11622179 DOI: 10.1523/jneurosci.0887-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2024] [Revised: 10/02/2024] [Accepted: 10/11/2024] [Indexed: 10/26/2024] Open
Abstract
There is mounting evidence that the cerebellum impacts hippocampal functioning, but the impact of the cerebellum on hippocampal interneurons remains obscure. Using miniscopes in freely behaving male and female mice, we found optogenetic stimulation of Purkinje cells alters the calcium activity of a large percentage of CA1 interneurons. This includes both increases and decreases in activity. Remarkably, this bidirectional impact occurs in a coordinated fashion, in line with interneurons' functional properties. Specifically, CA1 interneurons activated by cerebellar stimulation are commonly locomotion-active, while those inhibited by cerebellar stimulation are commonly rest-active interneurons. We additionally found that subsets of CA1 interneurons show altered activity during object investigations. Importantly, these interneurons also show coordinated modulation by cerebellar stimulation: CA1 interneurons that are activated by cerebellar stimulation are more likely to be activated, rather than inhibited, during object investigations, while interneurons that show decreased activity during cerebellar stimulation show the opposite profile. We examined two different stimulation locations (IV/V vermis or simplex) and two different stimulation approaches (7 Hz or a single 1 s light pulse)-in all cases, the cerebellum induces similar coordinated CA1 interneuron changes congruent with an explorative state. Overall, our data show that CA1 interneurons are impacted by cerebellar manipulation in a bidirectional and coordinated fashion and are therefore likely to play an important role in cerebello-hippocampal communication.
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Affiliation(s)
- Jessica M Froula
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Jarrett J Rose
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
| | - Chris Krook-Magnuson
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455
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Kong E, Zabeh E, Liao Z, Mihaila TS, Wilson C, Santhirasegaran C, Peterka DS, Losonczy A, Geiller T. Recurrent Connectivity Shapes Spatial Coding in Hippocampal CA3 Subregions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.11.07.622379. [PMID: 39574766 PMCID: PMC11581023 DOI: 10.1101/2024.11.07.622379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2024]
Abstract
Stable and flexible neural representations of space in the hippocampus are crucial for navigating complex environments. However, how these distinct representations emerge from the underlying local circuit architecture remains unknown. Using two-photon imaging of CA3 subareas during active behavior, we reveal opposing coding strategies within specific CA3 subregions, with proximal neurons demonstrating stable and generalized representations and distal neurons showing dynamic and context-specific activity. We show in artificial neural network models that varying the recurrence level causes these differences in coding properties to emerge. We confirmed the contribution of recurrent connectivity to functional heterogeneity by characterizing the representational geometry of neural recordings and comparing it with theoretical predictions of neural manifold dimensionality. Our results indicate that local circuit organization, particularly recurrent connectivity among excitatory neurons, plays a key role in shaping complementary spatial representations within the hippocampus.
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Affiliation(s)
- Eunji Kong
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Erfan Zabeh
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
| | - Zhenrui Liao
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Tiberiu S Mihaila
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Caroline Wilson
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Charan Santhirasegaran
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Darcy S Peterka
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY, United States
- Mortimer B. Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, United States
| | - Tristan Geiller
- Department of Neuroscience, Yale University, New Haven, CT, USA
- Wu Tsai Institute, Yale University, New Haven, CT, USA
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Degro CE, Vida I, Booker SA. Postsynaptic GABA B-receptor mediated currents in diverse dentate gyrus interneuron types. Hippocampus 2024; 34:551-562. [PMID: 39138952 DOI: 10.1002/hipo.23628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 06/24/2024] [Accepted: 07/19/2024] [Indexed: 08/15/2024]
Abstract
The processing of rich synaptic information in the dentate gyrus (DG) relies on a diverse population of inhibitory GABAergic interneurons to regulate cellular and circuit activity, in a layer-specific manner. Metabotropic GABAB-receptors (GABABRs) provide powerful inhibition to the DG circuit, on timescales consistent with behavior and learning, but their role in controlling the activity of interneurons is poorly understood with respect to identified cell types. We hypothesize that GABABRs display cell type-specific heterogeneity in signaling strength, which will have direct ramifications for signal processing in DG networks. To test this, we perform in vitro whole-cell patch-clamp recordings from identified DG principal cells and interneurons, followed by GABABR pharmacology, photolysis of caged GABA, and extracellular stimulation of endogenous GABA release to classify the cell type-specific inhibitory potential. Based on our previous classification of DG interneurons, we show that postsynaptic GABABR-mediated currents are present on all interneuron types albeit at different amplitudes, dependent largely on soma location and synaptic targets. GABABRs were coupled to inwardly-rectifying K+ channels that strongly reduced the excitability of those interneurons where large currents were observed. These data provide a systematic characterization of GABABR signaling in the rat DG to provide greater insight into circuit dynamics.
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Affiliation(s)
- Claudius E Degro
- Institute for Integrative Neuroanatomy, Charité-Universitätmedizin Berlin, Berlin, Germany
| | - Imre Vida
- Institute for Integrative Neuroanatomy, Charité-Universitätmedizin Berlin, Berlin, Germany
| | - Sam A Booker
- Institute for Integrative Neuroanatomy, Charité-Universitätmedizin Berlin, Berlin, Germany
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, UK
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh, UK
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Méndez P, de la Vega-Ruiz R, Montes-Mellado A. Estrogenic regulation of hippocampal inhibitory system across lifespan. J Neuroendocrinol 2024:e13441. [PMID: 39143852 DOI: 10.1111/jne.13441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Revised: 07/08/2024] [Accepted: 08/01/2024] [Indexed: 08/16/2024]
Abstract
Estrogens produced in peripheral tissues and locally in the brain are potent neuromodulators. The function of the hippocampus, a brain region essential for episodic memory and spatial navigation, relies on the activity of ensembles of excitatory neurons whose activity is temporally and spatially coordinated by a wide diversity of inhibitory neurons (INs) types. Over the last years, we have accumulated evidence that indicates that estrogens regulate the function of hippocampal INs through different mechanisms, including transcriptional regulation and rapid nongenomic signaling. Here, we argue that the well-documented influence of estrogens on episodic memory may be related to the actions of local and peripheral estrogens on the heterogenous populations of hippocampal INs. We discuss how physiological changes in peripheral sex hormone levels throughout lifespan may interact with local brain sources to regulate IN function at different stages of life, from early hippocampal development to the aging brain. We conclude that considering INs as mediators of sex hormone actions in the hippocampus across the healthy life span will benefit our understanding of sex-biased neurodevelopmental disorders and physiological aging.
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Watson TC, Booker SA. Somatostatin Interneurons Recruit Pre- and Postsynaptic GABA B Receptors in the Adult Mouse Dentate Gyrus. eNeuro 2024; 11:ENEURO.0115-24.2024. [PMID: 39084907 PMCID: PMC11334949 DOI: 10.1523/eneuro.0115-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 06/07/2024] [Accepted: 06/30/2024] [Indexed: 08/02/2024] Open
Abstract
The integration of spatial information in the mammalian dentate gyrus (DG) is critical to navigation. Indeed, DG granule cells (DGCs) rely upon finely balanced inhibitory neurotransmission in order to respond appropriately to specific spatial inputs. This inhibition arises from a heterogeneous population of local GABAergic interneurons (INs) that activate both fast, ionotropic GABAA receptors (GABAAR) and slow, metabotropic GABAB receptors (GABABR), respectively. GABABRs in turn inhibit pre- and postsynaptic neuronal compartments via temporally long-lasting G-protein-dependent mechanisms. The relative contribution of each IN subtype to network level GABABR signal setting remains unknown. However, within the DG, the somatostatin (SSt) expressing IN subtype is considered crucial in coordinating appropriate feedback inhibition on to DGCs. Therefore, we virally delivered channelrhodopsin 2 to the DG in order to obtain control of this specific SSt IN subpopulation in male and female adult mice. Using a combination of optogenetic activation and pharmacology, we show that SSt INs strongly recruit postsynaptic GABABRs to drive greater inhibition in DGCs than GABAARs at physiological membrane potentials. Furthermore, we show that in the adult mouse DG, postsynaptic GABABR signaling is predominantly regulated by neuronal GABA uptake and less so by astrocytic mechanisms. Finally, we confirm that activation of SSt INs can also recruit presynaptic GABABRs, as has been shown in neocortical circuits. Together, these data reveal that GABABR signaling allows SSt INs to control DG activity and may constitute a key mechanism for gating spatial information flow within hippocampal circuits.
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Affiliation(s)
- Thomas C Watson
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
| | - Sam A Booker
- Simons Initiative for the Developing Brain, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh EH8 9XD, United Kingdom
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Froula JM, Rose JJ, Krook-Magnuson C, Krook-Magnuson E. Distinct functional classes of CA1 hippocampal interneurons are modulated by cerebellar stimulation in a coordinated manner. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.14.594213. [PMID: 38798335 PMCID: PMC11118308 DOI: 10.1101/2024.05.14.594213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
There is mounting evidence that the cerebellum impacts hippocampal functioning, but the impact of the cerebellum on hippocampal interneurons remains obscure. Using miniscopes in freely behaving animals, we find optogenetic stimulation of Purkinje cells alters the calcium activity of a large percentage of CA1 interneurons. This includes both increases and decreases in activity. Remarkably, this bidirectional impact occurs in a coordinated fashion, in line with interneurons' functional properties. Specifically, CA1 interneurons activated by cerebellar stimulation are commonly locomotion-active, while those inhibited by cerebellar stimulation are commonly rest-active interneurons. We additionally find that subsets of CA1 interneurons show altered activity during object investigations, suggesting a role in the processing of objects in space. Importantly, these neurons also show coordinated modulation by cerebellar stimulation: CA1 interneurons that are activated by cerebellar stimulation are more likely to be activated, rather than inhibited, during object investigations, while interneurons that show decreased activity during cerebellar stimulation show the opposite profile. Therefore, CA1 interneurons play a role in object processing and in cerebellar impacts on the hippocampus, providing insight into previously noted altered CA1 processing of objects in space with cerebellar stimulation. We examined two different stimulation locations (IV/V Vermis; Simplex) and two different stimulation approaches (7Hz or a single 1s light pulse) - in all cases, the cerebellum induces similar coordinated CA1 interneuron changes congruent with an explorative state. Overall, our data show that the cerebellum impacts CA1 interneurons in a bidirectional and coordinated fashion, positioning them to play an important role in cerebello-hippocampal communication. Significance Statement Acute manipulation of the cerebellum can affect the activity of cells in CA1, and perturbing normal cerebellar functioning can affect hippocampal-dependent spatial processing, including the processing of objects in space. Despite the importance of interneurons on the local hippocampal circuit, it was unknown how cerebellar activation impacts CA1 inhibitory neurons. We find that stimulating the cerebellum robustly affects multiple populations of CA1 interneurons in a bidirectional, coordinated manner, according to their functional profiles during behavior, including locomotion and object investigations. Our work also provides support for a role of CA1 interneurons in spatial processing of objects, with populations of interneurons showing altered activity during object investigations.
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Tamboli S, Singh S, Topolnik D, El Amine Barkat M, Radhakrishnan R, Guet-McCreight A, Topolnik L. Mouse hippocampal CA1 VIP interneurons detect novelty in the environment and support recognition memory. Cell Rep 2024; 43:114115. [PMID: 38607918 DOI: 10.1016/j.celrep.2024.114115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 02/17/2024] [Accepted: 03/29/2024] [Indexed: 04/14/2024] Open
Abstract
In the CA1 hippocampus, vasoactive intestinal polypeptide-expressing interneurons (VIP-INs) play a prominent role in disinhibitory circuit motifs. However, the specific behavioral conditions that lead to circuit disinhibition remain uncertain. To investigate the behavioral relevance of VIP-IN activity, we employed wireless technologies allowing us to monitor and manipulate their function in freely behaving mice. Our findings reveal that, during spatial exploration in new environments, VIP-INs in the CA1 hippocampal region become highly active, facilitating the rapid encoding of novel spatial information. Remarkably, both VIP-INs and pyramidal neurons (PNs) exhibit increased activity when encountering novel changes in the environment, including context- and object-related alterations. Concurrently, somatostatin- and parvalbumin-expressing inhibitory populations show an inverse relationship with VIP-IN and PN activity, revealing circuit disinhibition that occurs on a timescale of seconds. Thus, VIP-IN-mediated disinhibition may constitute a crucial element in the rapid encoding of novelty and the acquisition of recognition memory.
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Affiliation(s)
- Suhel Tamboli
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Sanjay Singh
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Dimitry Topolnik
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Mohamed El Amine Barkat
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | - Risna Radhakrishnan
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada
| | | | - Lisa Topolnik
- Neuroscience Axis, CRCHUQ-CHUL, Quebec City, PQ, Canada; Department of Biochemistry, Microbiology, and Bioinformatics, Université Laval, Quebec City, PQ, Canada.
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