scholarly journals Neuronal activity–driven oligodendrogenesis in selected brain regions is required for episodic memories

2021 ◽  
Author(s):  
Luendreo Barboza ◽  
Benjamin Bessieres ◽  
Omina Nazarzoda ◽  
Cristina Alberini
Keyword(s):  
Neuronal Activity ◽  
Medial Temporal Lobe ◽  
Molecular Mechanisms ◽  
Dorsal Hippocampus ◽  
Brain Regions ◽  
Memory Formation ◽  
Anterior Cingulate ◽  
Long Term Memory ◽  
Episodic Memories

The formation of long-term episodic memories requires the activation of molecular mechanisms in several regions of the medial temporal lobe, including the hippocampus and anterior cingulate cortex (ACC). The extent to which these regions engage distinct mechanisms and cell types to support memory formation is not well understood. Recent studies reported that oligodendrogenesis is essential for learning and long-term memory; however, whether these mechanisms are required only in selected brain regions is still unclear. Also still unknown are the temporal kinetics of engagement of learning-induced oligodendrogenesis and whether this oligodendrogenesis occurs in response to neuronal activity. Here we show that in rats and mice, episodic learning rapidly increases the oligodendrogenesis and myelin biogenesis transcripts olig2, myrf, mbp, and plp1, as well as oligodendrogenesis, in the ACC but not in the dorsal hippocampus (dHC). Region-specific knockdown and knockout of Myrf, a master regulator of oligodendrocyte maturation, revealed that oligodendrogenesis is required for memory formation in the ACC but not the dHC. Chemogenetic neuronal silencing in the ACC showed that neuronal activity is critical for learning-induced oligodendrogenesis. Hence, an activity-dependent increase in oligodendrogenesis in selected brain regions, specifically in the ACC but not dHC, is critical for the formation of episodic memories.

scholarly journals The evidence for hippocampal long-term potentiation as a basis of memory for simple tasks

2008 ◽  
Vol 80 (1) ◽  
pp. 115-127 ◽  
Author(s):  
Iván Izquierdo ◽  
Martín Cammarota ◽  
Weber C. Da Silva ◽  
Lia R.M. Bevilaqua ◽  
Janine I. Rossato ◽  
...  
Keyword(s):  
Long Term Potentiation ◽  
Brain Regions ◽  
Memory Formation ◽  
Long Term Memory ◽  
Ca1 Region ◽  
Term Potentiation ◽  
The One ◽  
Similar Task ◽  
Stimulation Of

Long-term potentiation (LTP) is the enhancement of postsynaptic responses for hours, days or weeks following the brief repetitive afferent stimulation of presynaptic afferents. It has been proposed many times over the last 30 years to be the basis of long-term memory. Several recent findings finally supported this hypothesis: a) memory formation of one-trial avoidance learning depends on a series of molecular steps in the CA1 region of the hippocampus almost identical to those of LTP in the same region; b)hippocampal LTP in this region accompanies memory formation of that task and of another similar task. However, CA1 LTP and the accompanying memory processes can be dissociated, and in addition plastic events in several other brain regions(amygdala, entorhinal cortex, parietal cortex) are also necessary for memory formation of the one-trial task, and perhaps of many others.

scholarly journals CREB overexpression in dorsal CA1 ameliorates long-term memory deficits in aged rats

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Xiao-Wen Yu ◽  
Daniel M Curlik ◽  
M Matthew Oh ◽  
Jerry CP Yin ◽  
John F Disterhoft
Keyword(s):  
Molecular Mechanisms ◽  
Pyramidal Neurons ◽  
Dorsal Hippocampus ◽  
Memory Deficits ◽  
Camp Response Element Binding ◽  
Intrinsic Excitability ◽  
Long Term Memory ◽  
Term Memory ◽  
Age Related

The molecular mechanisms underlying age-related cognitive deficits are not yet fully elucidated. In aged animals, a decrease in the intrinsic excitability of CA1 pyramidal neurons is believed to contribute to age-related cognitive impairments. Increasing activity of the transcription factor cAMP response element-binding protein (CREB) in young adult rodents facilitates cognition, and increases intrinsic excitability. However, it has yet to be tested if increasing CREB expression also ameliorates age-related behavioral and biophysical deficits. To test this hypothesis, we virally overexpressed CREB in CA1 of dorsal hippocampus. Rats received CREB or control virus, before undergoing water maze training. CREB overexpression in aged animals ameliorated the long-term memory deficits observed in control animals. Concurrently, cells overexpressing CREB in aged animals had reduced post-burst afterhyperpolarizations, indicative of increased intrinsic excitability. These results identify CREB modulation as a potential therapy to treat age-related cognitive decline.

scholarly journals Autobiographical Memory Retrieval and Hippocampal Activation as a Function of Repetition and the Passage of Time

2007 ◽  
Vol 2007 ◽  
pp. 1-14 ◽  
Author(s):  
Lynn Nadel ◽  
Jenna Campbell ◽  
Lee Ryan
Keyword(s):  
Autobiographical Memory ◽  
Temporal Lobe ◽  
Memory Retrieval ◽  
Medial Temporal Lobe ◽  
Perirhinal Cortex ◽  
Brain Regions ◽  
Long Term Memory ◽  
Memory Traces ◽  
Multiple Trace Theory

Multiple trace theory (MTT) predicts that hippocampal memory traces expand and strengthen as a function of repeated memory retrievals. We tested this hypothesis utilizing fMRI, comparing the effect of memory retrieval versus the mere passage of time on hippocampal activation. While undergoing fMRI scanning, participants retrieved remote autobiographical memories that had been previously retrieved either one month earlier, two days earlier, or multiple times during the preceding month. Behavioral analyses revealed that the number and consistency of memory details retrieved increased with multiple retrievals but not with the passage of time. While all three retrieval conditions activated a similar set of brain regions normally associated with autobiographical memory retrieval including medial temporal lobe structures, hippocampal activation did not change as a function of either multiple retrievals or the passage of time. However, activation in other brain regions, including the precuneus, lateral prefrontal cortex, parietal cortex, lateral temporal lobe, and perirhinal cortex increased after multiple retrievals, but was not influenced by the passage of time. These results have important implications for existing theories of long-term memory consolidation.

scholarly journals Metabolomic profiling reveals a differential role for hippocampal glutathione reductase in infantile memory formation

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Benjamin Bessières ◽  
Emmanuel Cruz ◽  
Cristina M Alberini
Keyword(s):  
Glutathione Reductase ◽  
Reduced Glutathione ◽  
Memory Formation ◽  
Long Term Memory ◽  
Adult Rats ◽  
Metabolomic Profiling ◽  
Behavioral Assessments ◽  
Cellular Defenses ◽  
Episodic Memories

The metabolic mechanisms underlying the formation of early-life episodic memories remain poorly characterized. Here, we assessed the metabolomic profile of the rat hippocampus at different developmental ages both at baseline and following episodic learning. We report that the hippocampal metabolome significantly changes over developmental ages and that learning regulates differential arrays of metabolites according to age. The infant hippocampus had the largest number of significant changes following learning, with downregulation of 54 metabolites. Of those, a large proportion was associated with the glutathione-mediated cellular defenses against oxidative stress. Further biochemical, molecular, and behavioral assessments revealed that infantile learning evokes a rapid and persistent increase in the activity of neuronal glutathione reductase, the enzyme that regenerates reduced glutathione from its oxidized form. Inhibition of glutathione reductase selectively impaired long-term memory formation in infant but not in juvenile and adult rats, confirming its age-specific role. Thus, metabolomic profiling revealed that the hippocampal glutathione-mediated antioxidant pathway is differentially required for the formation of infantile memory.

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.

scholarly journals Canadian Association of Neurosciences Review: Learning at a Snail's Pace

2006 ◽  
Vol 33 (4) ◽  
pp. 347-356 ◽  
Author(s):  
Kashif Parvez ◽  
David Rosenegger ◽  
Michael Orr ◽  
Kara Martens ◽  
Ken Lukowiak
Keyword(s):  
Molecular Mechanisms ◽  
Neural Circuit ◽  
Lymnaea Stagnalis ◽  
Declarative Memory ◽  
Memory Formation ◽  
Model System ◽  
Long Term Memory ◽  
Canadian Association ◽  
Invertebrate Model

ABSTRACT:While learning and memory are related, they are distinct processes each with different forms of expression and underlying molecular mechanisms. An invertebrate model system, Lymnaea stagnalis, is used to study memory formation of a non-declarative memory. We have done so because: 1) We have discovered the neural circuit that mediates an interesting and tractable behaviour; 2) This behaviour can be operantly conditioned and intermediate-term and long-term memory can be demonstrated; and 3) It is possible to demonstrate that a single neuron in the model system is a necessary site of memory formation. This article reviews how Lymnaea has been used in the study of behavioural and molecular mechanisms underlying consolidation, reconsolidation, extinction and forgetting.

scholarly journals The Possible Contribution of the Amygdala to Memory

1993 ◽  
Vol 6 (3) ◽  
pp. 167-170 ◽  
Author(s):  
R. Babinsky ◽  
P. Calabrese ◽  
H. F. Durwen ◽  
H. J. Markowitsch ◽  
D. Brechtelsbauer ◽  
...  
Keyword(s):  
Temporal Lobe ◽  
Basal Forebrain ◽  
Medial Temporal Lobe ◽  
Long Term Memory ◽  
Memory Functions ◽  
Memory Disorder ◽  
Neuropsychological Investigation ◽  
Episodic Memories

The processing of episodic memories is believed to depend on the proper functioning of so-called bottleneck structures through which information apparently must pass in order to be stored long term. These regions are seen in the basal forebrain, the medial diencephalon, and the medial temporal lobe. We here report a case with circumscribed bilateral temporal lobe damage, principally involving the amygdaloid area. Neuropsychological investigation demonstrated preserved intelligence, intact general memory and several other undisturbed cognitive functions, but a specific, affect-related, memory disorder. We conclude from these findings that the role of the amygdala is to process mnemonic events in a way that a specific emotional significance can be found and reactivated. Therefore it is suggested that the amygdala is likely to be a bottleneck structure for affect-related long-term memory functions.

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