scholarly journals Spatial memory formation requires netrin-1 expression by neurons in the adult mammalian brain.

2018 ◽  
Author(s):  
Edwin Wong ◽  
Stephen D Glasgow ◽  
Lianne J Trigiani ◽  
Daryan Chitsaz ◽  
Vladmir Rymar ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Learning And Memory ◽  
Critical Role ◽  
Long Term Potentiation ◽  
Memory Formation ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Conditional Deletion ◽  
The Impact ◽  
Adult Mammalian Brain

Netrin-1 was initially characterized as an axon guidance molecule that is essential for normal embryonic neural development; however, many types of neurons continue to express netrin-1 in the post-natal and adult mammalian brain. Netrin-1 and the netrin receptor DCC are both enriched at synapses. In the adult hippocampus, activity-dependent secretion of netrin-1 by neurons potentiates glutamatergic synapse function, and is critical for long-term potentiation, an experimental cellular model of learning and memory. Here, we assessed the impact of neuronal expression of netrin-1 in the adult brain on behavior using tests of learning and memory. We show that adult mice exhibit impaired spatial memory following conditional deletion of netrin-1 from glutamatergic neurons in the hippocampus and neocortex. Further, we provide evidence that mice with conditional deletion of netrin-1 do not display aberrant anxiety-like phenotypes and show a reduction in self-grooming behaviour. These findings reveal a critical role for netrin-1 expressed by neurons in the regulation of spatial memory formation.

scholarly journals Spatial memory formation requires netrin-1 expression by neurons in the adult mammalian brain

2019 ◽  
Vol 26 (3) ◽  
pp. 77-83 ◽  
Author(s):  
Edwin W. Wong ◽  
Stephen D. Glasgow ◽  
Lianne J. Trigiani ◽  
Daryan Chitsaz ◽  
Vladimir Rymar ◽  
...  
Keyword(s):  
Spatial Memory ◽  
Memory Formation ◽  
Mammalian Brain ◽  
Adult Mammalian Brain

BDNF and Control of Synaptic Plasticity in the Adult Brain

2009 ◽  
Vol 24 (S1) ◽  
pp. 1-1
Author(s):  
C. Bramham
Keyword(s):  
Synaptic Plasticity ◽  
Dentate Gyrus ◽  
Antidepressant Drugs ◽  
Long Term Potentiation ◽  
Memory Formation ◽  
Adult Brain ◽  
Early Gene ◽  
Perforant Path ◽  
Mammalian Brain

Experience-dependent changes in synaptic connectivity are thought to play a vital role not only in memory formation, but also in long-term adaptive responses involved in mood regulation, reward behavior, and pain control. The neurotrophin, brain-derived neurotrophic factor (BDNF), which has recently been implicated in memory formation and aspects of major depression, is also an important regulator of long-term synaptic plasticity in the adult mammalian brain. We have investigated BDNF function in the dentate gyrus, a brain region implicated in depression and the action of antidepressant drugs. Local infusion of BDNF into the dentate gyrus generated a long-term potentiation (LTP) of synaptic efficacy at medial perforant path-granule cell synapses. This LTP is associated with expression of the immediate early gene, Arc, in postsynaptic granule cells and transport of Arc mRNA to synaptic regions on dendrites. Using local infusion of antisense oligodeoxynucleotides to block Arc synthesis, we show that Arc is required for the induction and time-dependent consolidation of BDNF-induced LTP. The sustained synthesis of Arc during a critical time-window is required for local expansion of the actin cytoskeletal network in dendritic spines. These results identify Arc as a critical mediator of BDNF in long-term synaptic plasticity in the adult brain. Microarray expression profiling has further revealed a panel of genes that, like Arc, are strongly upregulated following acute BDNF infusion or chronic treatment with the antidepressant fluoxetine.

Postnatal Development of the Hippocampus in Male Albino Rats: A Histomorphometric Study

QJM ◽  
2020 ◽  
Vol 113 (Supplement_1) ◽  
Author(s):  
A A A Baraka ◽  
K A Hafez ◽  
A I A Othman ◽  
A M M Sadek
Keyword(s):  
Dentate Gyrus ◽  
Postnatal Development ◽  
Learning And Memory ◽  
Hippocampal Formation ◽  
Critical Role ◽  
Mammalian Brain ◽  
Albino Rats ◽  
Ammon's Horn ◽  
Hippocampus Proper ◽  
Ammon’S Horn

Abstract Introduction In recent year deterioration in cognitive, learning, and memory become one of the significant problems in human life. Hippocampus is a pivotal part of the brain’s limbic system which serves a critical role in memory, learning process and regulating the emotions. In most regions of the brain, neurons are generated only at specific periods of early development, and not born in the adulthood. In contrast, hippocampal neurons are generated throughout development and adult life. The hippocampal dentate gyrus was reported to be one of the few regions of the mammalian brain where neurogenesis continue to occur throughout adulthood. The neurogenesis in the dentate gyrus was thought to play an important role in hippocampus-dependent learning and memory. The hippocampal formation is composed of the hippocampus proper, the dentate gyrus and the subiculum. The hippocampus proper is the largest part and is subdivided into fields designated as Cornu Ammonis or Ammon’s horn (CA) from CA1 to CA4. Ammon's horn is continuous with the subiculum, which acts as the main output source of the hippocampal formation. Aim of the Study To study the postnatal development of the hippocampal formation. Materials and Methods Five male albino rats from the following postnatal ages day 1, week 1, week 2, week3 and week 4 were studied by histological, immunohistochemical, and morphometric methods. Results The general architecture of the hippocampus proper with its polymorphic, pyramidal, and molecular layers was present at day1, whereas the details of the adult structure appeared at week 2. In the dentate gyrus, distinct lamination appeared at week 1 and its maturation continued with the production of neurons at the interhilar zone that peaked at week 2. The number and density of pyramidal axons and dendrites increase by age. Astrocytes increased in size and staining affinity for glial filaments, and acquired a stellate shape with age. Furthermore, the number of granule cell layers increased concomitantly with the increase in thickness of the molecular and polymorphic layers of both the hippocampus proper and the dentate gyrus. Conclusion The important sequences of events in the growth and maturation of the hippocampal formation in male albino rat occurred in the first 2 postnatal weeks.

Applying Basic Neuroscience to Aphasia Therapy

1995 ◽  
Vol 4 (4) ◽  
pp. 88-93 ◽  
Author(s):  
Kristen A. Keefe
Keyword(s):  
Learning And Memory ◽  
Neural Plasticity ◽  
Behavioral Interventions ◽  
Cortical Reorganization ◽  
Mammalian Brain ◽  
Cortical Injury ◽  
Aphasia Therapy ◽  
Neural Processes ◽  
Adult Mammalian Brain ◽  
Environmental Demands

Advances in basic neuroscience have increased our knowledge about the neural processes underlying learning and memory and the cortical reorganization that occurs in response to environmental demands and cortical injury. This article provides a selective review of published studies conducted in animals that examine functional and structural substrates of neural plasticity in the adult mammalian brain, and discusses the implications of this knowledge for aphasia therapy. The processes and constraints identified in the studies reviewed can be used to refine and justify current aphasia therapies, as well as to design additional behavioral interventions.

scholarly journals Neurotrophin signalling in amygdala-dependent cued fear learning

2020 ◽  
Vol 382 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Susanne Meis ◽  
Thomas Endres ◽  
Volkmar Lessmann
Keyword(s):  
Synaptic Plasticity ◽  
Learning And Memory ◽  
Neurotrophic Factor ◽  
Memory Formation ◽  
Fear Learning ◽  
Mammalian Brain ◽  
Pavlovian Fear Conditioning ◽  
Cortical Afferents ◽  
Trkb Receptors ◽  
Tropomyosin Related Kinase B

Abstract The amygdala is a central hub for fear learning assessed by Pavlovian fear conditioning. Indeed, the prevailing hypothesis that learning and memory are mediated by changes in synaptic strength was shown most convincingly at thalamic and cortical afferents to the lateral amygdala. The neurotrophin brain-derived neurotrophic factor (BDNF) is known to regulate synaptic plasticity and memory formation in many areas of the mammalian brain including the amygdala, where BDNF signalling via tropomyosin-related kinase B (TrkB) receptors is prominently involved in fear learning. This review updates the current understanding of BDNF/TrkB signalling in the amygdala related to fear learning and extinction. In addition, actions of proBDNF/p75NTR and NGF/TrkA as well as NT-3/TrkC signalling in the amygdala are introduced.

scholarly journals Forepaw Sensorimotor Deprivation in Early Life Leads to the Impairments on Spatial Memory and Synaptic Plasticity in Rats

2009 ◽  
Vol 2009 ◽  
pp. 1-9 ◽  
Author(s):  
Yuanyuan Zhang ◽  
Fei Li ◽  
Xiaohua Cao ◽  
Xingming Jin ◽  
Chonghuai Yan ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Spatial Memory ◽  
Learning And Memory ◽  
Early Life ◽  
Hippocampal Slices ◽  
Long Term Potentiation ◽  
Perforant Path ◽  
Sprague Dawley ◽  
Cellular Mechanisms ◽  
Spatial Reference

To investigate the influence of forepaw sensorimotor deprivation on memory and synaptic plasticity, Sprague-Dawley rats were divided into two groups: a sham-operated group and a group deprived of forepaw sensorimotor function by microsurgical operation at postnatal day 13 (PN13). Behavioral and electrophysiological studies were performed at PN25, PN35, PN45, and PN60. Open field test was used to assess the spontaneous locomotor activity. Morris water maze was used to evaluate spatial reference learning and memory. The long-term potentiation (LTP) in the medial perforant path—dentate gyrus (MPP-DG) pathway was examined with hippocampal slices. We found that forepaw sensorimotor deprivation did not affect spontaneous activity of the rats. However, spatial reference learning and memory were significantly impaired in their early life (PN25, PN35, and PN45). In accordance with the behavior results, LTP in MPP-DG pathway was significantly suppressed in their early life. These data demonstrated that forepaw sensorimotor deprivation led to the impairments on spatial memory via inducing pronounced deficits in the MPP-DG pathway to exhibit LTP, one of the major cellular mechanisms underlying learning and memory.

scholarly journals An immune-CNS axis activates remote hippocampal stem cells following Spinal Transection Injury

2018 ◽  
Author(s):  
Sascha Dehler ◽  
Pak-Kin Lou ◽  
Maxim Skabkin ◽  
Sabrina Laudenklos ◽  
Andreas Neumann ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cell Activity ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Spinal Transection ◽  
Thoracic Spinal ◽  
Close Proximity ◽  
Stem Cell Activity ◽  
External Stimuli ◽  
Adult Mammalian Brain

AbstractExternal stimuli such as injury, learning, or stress influence the production of neurons by neural stem cells (NSCs) in the adult mammalian brain. These external stimuli directly impact stem cell activity by influencing areas directly connected or in close proximity to the neurogenic niches of the adult brain. However, very little is known on how distant injuries affect NSC activation state. In this study we demonstrate that a thoracic spinal transection injury activates the distally located hippocampal-NSCs. This activation leads to a transient increase production of neurons that functionally integrate to improve animal’s performance in hippocampal-related memory tasks. We further show that interferon-CD95 signaling is required to promote injury-mediated activation of remote NSCs. Thus, we identify an immune-CNS axis responsible for injury-mediated activation of remotely located NSCs.

Learning and Memory

The Neuron ◽  
2015 ◽  
pp. 489-528
Author(s):  
Irwin B. Levitan ◽  
Leonard K. Kaczmarek
Keyword(s):  
Learning And Memory ◽  
Molecular Mechanisms ◽  
Long Term Potentiation ◽  
Memory Formation ◽  
Spike Timing ◽  
Cellular Mechanisms ◽  
Long Term Depression ◽  
Nervous Systems ◽  
Term Potentiation

Psychologists have described different kinds of learning and memory, and there is an ongoing search for the physical basis of these distinctions and for the cellular and molecular mechanisms responsible. Because of the complexity of most nervous systems, the search has focused to a large extent on animals with relatively simple nervous systems and on reduced preparations. Common themes have emerged, such as the requirement for signaling pathways linked to calcium and cyclic AMP, and the fact that pathways used in normal development continue to be used for plasticity in adults. At the same time, it is clear that there is an enormous diversity of cellular mechanisms that contribute to short-term and long-term phases of memory formation. These include long-term potentiation (LTP), long-term depression (LTD), spike-timing dependent plasticity, synaptic tagging, and synaptic scaling. Each type of synaptic connection has its own personality such that, in response to a particular pattern of stimulation, one synapse may increase its postsynaptic receptors while another may expand its presynaptic terminals.

scholarly journals PSA Depletion Induces the Differentiation of Immature Neurons in the Piriform Cortex of Adult Mice

2021 ◽  
Vol 22 (11) ◽  
pp. 5733
Author(s):  
Simona Coviello ◽  
Bruno Benedetti ◽  
Dominika Jakubecova ◽  
Maria Belles ◽  
Patrycja Klimczak ◽  
...  
Keyword(s):  
Piriform Cortex ◽  
Adult Brain ◽  
Mammalian Brain ◽  
Extrinsic Factors ◽  
Factors Affecting ◽  
Neuronal Markers ◽  
Adult Mice ◽  
Immature Neurons ◽  
Cortical Regions ◽  
The Impact

Immature neurons are maintained in cortical regions of the adult mammalian brain. In rodents, many of these immature neurons can be identified in the piriform cortex based on their high expression of early neuronal markers, such as doublecortin (DCX) and the polysialylated form of the neural cell adhesion molecule (PSA-NCAM). This molecule plays critical roles in different neurodevelopmental events. Taking advantage of a DCX-CreERT2/Flox-EGFP reporter mice, we investigated the impact of targeted PSA enzymatic depletion in the piriform cortex on the fate of immature neurons. We report here that the removal of PSA accelerated the final development of immature neurons. This was revealed by a higher frequency of NeuN expression, an increase in the number of cells carrying an axon initial segment (AIS), and an increase in the number of dendrites and dendritic spines on the immature neurons. Taken together, our results demonstrated the crucial role of the PSA moiety in the protracted development of immature neurons residing outside of the neurogenic niches. More studies will be required to understand the intrinsic and extrinsic factors affecting PSA-NCAM expression to understand how the brain regulates the incorporation of these immature neurons to the established neuronal circuits of the adult brain.

Remote spatial memory processing in the juvenile brain and contribution of the hippocampus

2020 ◽  
Author(s):  
Tanisse Teale
Keyword(s):  
Spatial Memory ◽  
Brain Regions ◽  
Memory Formation ◽  
Adult Brain ◽  
Memory Storage ◽  
Long Term Memory ◽  
Memory Recall ◽  
Term Memory ◽  
Mechanisms Of Memory

A majority of research into memory formation and consolidation is commonly focused on adult brains and organisms. Our work focuses on the mechanisms of memory within the developing, juvenile brain in an attempt to provide a more full understanding of the underlying neural mechanisms of memory formation, consolidation and storage. During juvenile development, the brain undergoes important remodeling and synaptic pruning towards shaping the adult brain. Thus, during this time, memories may be lost through the remodeling of hippocampal-neocortical connections. The significance of comparing juvenile and adult memory processes is critical in understanding the structural changes that occur within memory-specific circuits associated with long-term memory formation. To provide a comparison of the neurobehavioral aspects of long-term memory formation in juveniles and adults, we trained Long Evan’s rats on a spatial task on postnatal days 16, 18, 20, 25, 30 or 50 (adults). Each age group was then tested for memory recall 24 hours or 3 weeks later. We noted that memory recall showed a dramatic change at postnatal day 20 such that memory recall at postnatal day 25 was similar to adult levels. We then used immunohistochemistry to quantify and analyze neural activity patterns in brain regions thought to underlie the short- and long-term storage of spatial memories. Identification of these regional activity changes during juvenile periods and comparison with adults allows us to explore the function and organization of interacting brain regions in long-term spatial memory storage during development.

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