API

Relationship: 748

Title

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Hippocampal Physiology, Altered leads to Cognitive Function, Decreased

Upstream event

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Hippocampal Physiology, Altered

Downstream event

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Cognitive Function, Decreased

Key Event Relationship Overview

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AOPs Referencing Relationship

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Taxonomic Applicability

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Term Scientific Term Evidence Link
rat Rattus norvegicus High NCBI
mouse Mus musculus High NCBI
humans Homo sapiens High NCBI

Sex Applicability

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Sex Evidence
Male High
Female High

Life Stage Applicability

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Term Evidence
During brain development High

Key Event Relationship Description

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It is a well-accepted assertion that hippocampal synaptic integrity and plasticity are essential for spatial information processing in animals and spatial and episodic memory in humans (Burgess, 2002; Martin et al., 2000; Sweatt, 2016). A large number of studies with a variety of techniques and approaches have linked hippocampal functional deficits to decreased spatial ability, context learning, and fear learning. Study of human disease states and conditions where hippocampal function is impaired (i.e., brain trauma, Alzheimer’s disease, temporal lobe epilepsy, Down’s Syndrome), and imaging studies of hippocampal activation during memory challenge, makes itirrefutable that the hippocampus is essential for specific types of cognition abilities. Decades of animal research has reinforced this assertion.

There are many forms of synaptic plasticity and numerous ways in which physiological function of neural circuits can be assessed. Similarly, there are many forms of learning and memory and multiple tasks and specifics associated with these tasks that vary from laboratory to laboratory. An emerging field of computational cognitive neuroscience lies at the intersection of   computational neuroscience, machine learning and neural network theory. These computational and theoretical frameworks support the participation of the hippocampal synaptic transmission and plasticity in learning and memory in animals and humans (for review see: Ashby and Helie, 2012).

Evidence Supporting this KER

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The weight of evidence for proper hippocampal function and episodic memory in humans and the animal analogue, spatial and fear-based context learning, is strong. Seminal studies over the past 60 years firmly established the cellular basis of behavior with synaptic plasticity (LTP and LTD). And recent work has provided details on the local hippocampal circuitry needed for memory formation and behavioral change (Sweatt, 2016). In humans, virtual reality experiments in large-scale spatial contexts demonstrate the convergence of spatial memory performance in normal patients with fMRI of the hippocampus clearly demonstrating the essentiality of hippocampal function to spatial learning (Burgess, 2002). This assertion is consistent with a wealth of animal data on hippocampal learning and memory. In rodent models, functional impairment of the hippocampus assessed using electrophysiological techniques is correlated with deficits in spatial memory typically assessed using mazes, and memory for context often assessed in fear-based learning paradigms (O’Keefe and Nadel, 1978; Clark et al., 2000; Squire, 2004; Eichenbaum, 2000; Panjo and Bramham, 2014).

 

Biological Plausibility

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The biological plausibility of the KER is rated as strong. It is well accepted that the normal hippocampal function is critical for the acquisition and memory of context and spatially mediated tasks in rodents and humans (Sweatt, 2016).

Empirical Evidence

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Empirical support for this KER is strong. The requisite of hippocampal integrity to optimal visuo-spatial context learning (i.e., episodic memory) in humans and spatial learning in rodents is well documented. In vivo recording in conscious behaving animals has demonstrated activity-dependent neural changes taking place in the hippocampus during spatial learning (Gruart and Delgado-Garcia, 2007). Impairments in hippocampal function induced by drugs, chemicals, lesions, mutant or knock out models that cause changes in synaptic transmission, plasticity, and hippocampal network activity, are coincident with deficits in spatial and context-based fear learning (O’Keefe and Nadel, 1978; Bannerman et al., 2014; Lynch, 2004; Verret et al., 2012). Similarly, treatments found to enhance or facilitate hippocampal synaptic transmission and plasticity are associated with improved learning and memory (Deng et al., 2010; Novkovic et al., 2015; Andrade et al., 2015; Trivino-Paredes et al., 2016).  For example, n-methyl-d-aspartate (NMDA)-mediated glutamatergic synaptic transmission is essential for the induction of hippocampal synaptic plasticity in the form of LTP. Blockade of this form of plasticity by selective NMDA-receptors blockers impairs LTP and hippocampal tests of learning and memory (reviewed in Sweatt, 2016). Perturbation of hippocampal plasticity and impaired spatial learning have been reported in adult offspring following prenatal ethanol exposure (An and Zhang, 2015).  The fyn mutant mouse (fyn is a tyrosine kinase pathway) displays impairments in hippocampal synaptic transmission and plasticity, as well asspatial learning deficits (Grant et al., 1992). Brain-derived neurotrophic factor (BDNF) knock out animals exhibit synaptic plasticity deficits and learning impairments (Aarse et al., 2016; Panja and Bramham, 2014). In the Jacob/Nfsm model which also exhibits pronounced alterations in BDNF-mediated signaling, hippocampal synaptic transmission and plasticity impairments were accompanied by deficits in contextual fear conditioning and novel location recognition tasks (Spilker et al., 2016).  Finally, in rodent models of developmental TH insufficiency, impairments in hippocampal synaptic transmission and plasticity are coincident with deficits in learning tasks that require the hippocampus (Opazo et al., 2008; Gilbert and Sui, 2006, Gilbert, 2011, Gilbert et al., 2016).

In humans, hippocampal physiology assessed using neuroimaging reveals activation of hippocampus upon engagement in spatial learning and episodic memory providing a direct linkage of these two specific KEs (Burgess, 2002). In fMRI studies of congenitally hypothyroid children, or children born to women with altered thyroid function during pregnancy, changes in hippocampal activity patterns during memory encoding and retention were observed and associated with memory impairments (Wheeler et al., 2012; 2015; Willoughby et al., 2013; 2014).

Temporal Evidence:  The temporal nature of this KER is developmental (Seed et al., 2005). This has been demonstrated in multiple studies.  It is well-recognized that there are critical developmental windows for disruption of the functional development of the hippocampus and the integrity of this structure is essential for later development of spatial ability, context learning, and fear learning. A wealth of studies have shown correlation between hippocampal LTP and spatial learning performance, as well as the role of glutamatergic synaptic transmission and BDNF-mediated signaling pathways in these processes (Bramham, 2007; Andero et al., 2014; Morris et al., 1986; Sweatt, 2016; Migaud et al., 1998). Although studies on reversibility are rare, deficits in hippocampal synaptic transmission and plasticity in slices from BDNF knockout animals can be rescued with recombinant BDNF (Patterson et al., 1996).

Dose-Response Evidence: Limited dose-response information is available.  Studies have investigated dose-dependency of both electrophysiological and behavioral impairments in animals suffering from developmental TH insufficiency (e.g., Gilbert and Sui, 2006; Gilbert, 2011; Gilbert et al., 2016).

Uncertainties and Inconsistencies

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There are no inconsistencies in this KER, but there are some uncertainties. It is a widely-held assertion that synaptic transmission and plasticity in the hippocampus underlie spatial learning (Martin et al., 2000; Gruart and Delgado-Garcia, 2007; Bramham, 2007). However, the causative relationship of which specific alterations in synaptic function are associated with specific cognitive deficits is difficult to ascertain given the many forms of learning and memory, and the complexity of synaptic interactions in even the simplest brain circuit.

Quantitative Understanding of the Linkage

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Response-response Relationship

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Information does not exist to develop quantitative relationships between the KEs in this KER.

Time-scale

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Known modulating factors

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Known Feedforward/Feedback loops influencing this KER

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Domain of Applicability

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The majority of data in support of this KER is from rodent models. The evolutionary conservation of the role of the hippocampus in spatial cognitive functions suggests, with some uncertainty, that this KER is also applicable to other mammalian species.

References

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Andero R, Choi DC, Ressler KJ. BDNF-TrkB receptor regulation of distributed adult neural plasticity, memory formation, and psychiatric disorders. Prog Mol Biol Transl Sci. 2014. 122:169-92.

Andrade-Talavera Y, Benito I, Casañas JJ, Rodríguez-Moreno A, Montesinos ML.  Rapamycin restores BDNF-LTP and the persistence of long-term memory in a model of Down's syndrome. Neurobiol Dis. 2015. 82:516-25

Ashby FG, Helie S. The Neurodynamics of Cognition: A Tutorial on Computational Cognitive Neuroscience. J Math Psychol. 2011 Aug 1;55(4):273-289.

Bannerman DM, Sprengel R, Sanderson DJ, McHugh SB, Rawlins JNP, Monyer H, Seeburg PH (2014) Hippocampal synaptic plasticity, spatial memory and anxiety. Nat Rev Neurosci 15:181-192.

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Deng W, Aimone JB, Gage FH (2010) New neurons and new memories: how does adult hippocampal neurogenesis affect learning and memory Nat Rev Neurosci 11:339-350.

Gilbert ME (2011) Impact of low-level thyroid hormone disruption induced by propylthiouracil on brain development and function. Toxicol Sci 124:432-445.

Gilbert ME, Sanchez-Huerta K, Wood C (2016) Mild Thyroid Hormone Insufficiency During Development Compromises Activity-Dependent Neuroplasticity in the Hippocampus of Adult Male Rats. Endocrinology 157:774-787.

Gilbert ME, Sui L (2006) Dose-dependent reductions in spatial learning and synaptic function in the dentate gyrus of adult rats following developmental thyroid hormone insufficiency. Brain Res 1069:10-22.

Grant SG, O'Dell TJ, Karl KA, Stein PL, Soriano P, Kandel ER. Impaired long-term potentiation, spatial learning, and hippocampal development in fyn mutant mice. Science. 1992 Dec 18;258(5090):1903-10.

Gruart A, Delgado-García JM. Activity-dependent changes of the hippocampal CA3-CA1 synapse during the acquisition of associative learning in conscious mice. Genes Brain Behav. 2007 Jun;6 Suppl 1:24-31.

Lynch, M.A. (2004). Long-Term Potentiation and Memory. Physiological Reviews. 84:87-136.

Martin SJ, Grimwood PD, Morris RG. Synaptic plasticity and memory: an evaluation of the hypothesis. Annu Rev Neurosci. 2000. 23:649-711.

Migaud M, Charlesworth P, Dempster M, Webster LC, Watabe AM, Makhinson M, He Y, Ramsay MF, Morris RG, Morrison JH, O'Dell TJ, Grant SG. Enhanced long-term potentiation and impaired learning in mice with mutant postsynaptic density-95 protein. Nature. 1998 Dec 3;396(6710):433-9.

Morris RG, Frey U. Hippocampal synaptic plasticity: role in spatial learning or the automaticrecording of attended experience? Philos Trans R Soc Lond B Biol Sci. 1997 Oct 29;352(1360):1489-503. Review

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O’Keefe, J. and Nadel, L. (1978). The Hippocampus as a Cognitive Map. Oxford: Oxford University Press.

Opazo MC, Gianini A, Pancetti F, Azkcona G, Alarcón L, Lizana R, Noches V, Gonzalez PA, Marassi MP, Mora S, Rosenthal D, Eugenin E, Naranjo D, Bueno SM, Kalergis AM, Riedel CA (2008), Maternal hypothyroxinemia impairs spatial learning and synaptic nature and function in the offspring. Endocrinology 149:5097-5106

Panja, D. and C. R. Bramham (2014). "BDNF mechanisms in late LTP formation: A synthesis and breakdown." Neuropharmacology 76 Pt C: 664-676.

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Patterson SL, Abel T, Deuel TA, Martin KC, Rose JC, Kandel ER. Recombinant BDNF rescues deficits in basal synaptic transmission and hippocampal LTP in BDNF knockout mice. Neuron. 1996 Jun;16(6):1137-45.

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Spilker C, Nullmeier S, Grochowska KM, Schumacher A, Butnaru I, Macharadze T, Gomes GM, Yuanxiang P, Bayraktar G, Rodenstein C, Geiseler C, Kolodziej A, Lopez-Rojas J, Montag D, Angenstein F, Bär J, D'Hanis W, Roskoden T, Mikhaylova M, Budinger E, Ohl FW, Stork O, Zenclussen AC, Karpova A, Schwegler H, Kreutz MR. A Jacob/Nsmf Gene Knockout Results in Hippocampal Dysplasia and Impaired BDNF Signaling in Dendritogenesis. PLoS Genet. 2016 Mar 15;12(3):e1005907Squire LR 2004. Memory systems of the brain: A brief history and current perspective. Neurobiology of Learning and Memory, 82: 171-177

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Wheeler SM, McAndrews MP, Sheard ED, Rovet J (2012) Visuospatial associative memory and hippocampal functioning in congenital hypothyroidism. J Int Neuropsychol Soc 18:49-56.

Wheeler SM, McLelland VC, Sheard E, McAndrews MP, Rovet JF (2015) Hippocampal Functioning and Verbal Associative Memory in Adolescents with Congenital Hypothyroidism. Front Endocrinol (Lausanne) 6:163.

Willoughby KA, McAndrews MP, Rovet JF (2014) Effects of maternal hypothyroidism on offspring hippocampus and memory. Thyroid 24:576-584.

Willoughby KA, McAndrews MP, Rovet J (2013) Effects of early thyroid hormone deficiency on children's autobiographical memory performance. J Int Neuropsychol Soc 19:419-429.