scholarly journals Neural Circuitry–Neurogenesis Coupling Model of Depression

2021 ◽  
Vol 22 (5) ◽  
pp. 2468
Author(s):  
Il Bin Kim ◽  
Seon-Cheol Park
Keyword(s):  
Entorhinal Cortex ◽  
Coupling Model ◽  
Neural Circuitry ◽  
Hippocampal Neurogenesis ◽  
Pattern Separation ◽  
Dependent Process ◽  
Hippocampal Activity ◽  
Mechanistic Understanding ◽  
Activity Dependent ◽  
Memory Pattern

Depression is characterized by the disruption of both neural circuitry and neurogenesis. Defects in hippocampal activity and volume, indicative of reduced neurogenesis, are associated with depression-related behaviors in both humans and animals. Neurogenesis in adulthood is considered an activity-dependent process; therefore, hippocampal neurogenesis defects in depression can be a result of defective neural circuitry activity. However, the mechanistic understanding of how defective neural circuitry can induce neurogenesis defects in depression remains unclear. This review highlights the current findings supporting the neural circuitry-regulated neurogenesis, especially focusing on hippocampal neurogenesis regulated by the entorhinal cortex, with regard to memory, pattern separation, and mood. Taken together, these findings may pave the way for future progress in neural circuitry–neurogenesis coupling studies of depression.

scholarly journals The Entorhinal Cortex and Adult Neurogenesis in Major Depression

2021 ◽  
Vol 22 (21) ◽  
pp. 11725
Author(s):  
Il Bin Kim ◽  
Seon-Cheol Park
Keyword(s):  
Entorhinal Cortex ◽  
Adult Neurogenesis ◽  
Potential Role ◽  
Neural Circuitry ◽  
Hippocampal Neurogenesis ◽  
Dependent Manner ◽  
Hippocampal Function ◽  
Comprehensive Understanding ◽  
Activity Dependent

Depression is characterized by impairments in adult neurogenesis. Reduced hippocampal function, which is suggestive of neurogenesis impairments, is associated with depression-related phenotypes. As adult neurogenesis operates in an activity-dependent manner, disruption of hippocampal neurogenesis in depression may be a consequence of neural circuitry impairments. In particular, the entorhinal cortex is known to have a regulatory effect on the neural circuitry related to hippocampal function and adult neurogenesis. However, a comprehensive understanding of how disruption of the neural circuitry can lead to neurogenesis impairments in depression remains unclear with respect to the regulatory role of the entorhinal cortex. This review highlights recent findings suggesting neural circuitry-regulated neurogenesis, with a focus on the potential role of the entorhinal cortex in hippocampal neurogenesis in depression-related cognitive and emotional phenotypes. Taken together, these findings may provide a better understanding of the entorhinal cortex-regulated hippocampal neurogenesis model of depression.

scholarly journals Isolating the key factors defining the magnitude of hippocampal neurogenesis’ effects on anxiety, memory and pattern separation

2019 ◽  
Author(s):  
Thiago F. A. França
Keyword(s):  
Hippocampal Neurogenesis ◽  
Pattern Separation ◽  
Simple Mathematical Model ◽  
Behavioral Task ◽  
Key Factors ◽  
Future Studies ◽  
Inhibitory Circuits ◽  
Baseline Levels ◽  
The Impact ◽  
Memory Pattern

AbstractIn this paper, I analyze the hypothesis that hippocampal neurogenesis (HN) exerts its effects on behavior via activation of inhibitory circuits in the hippocampus. Using a very simple mathematical model (half-borrowed from biochemistry) to aid the reasoning, I show that the key factors determining the magnitude of HN’s effects on behavior are: the baseline levels of HN in the animal, the efficiency of the animal’s inhibitory circuits, the strength/intensity of the stimulus presented to the animal and how much accuracy the behavioral task requires from the information contained in the hippocampal representations. Taken together, those factors can help explain patterns observed in the behavioral results for memory, pattern separation and anxiety. The conclusions of the analysis suggest that HN’s effects on inhibitory circuits can explain the impact of neurogenesis in both emotion and cognition and provide a framework to interpret future studies with rodents and possibly with other species as well.

scholarly journals Heterosynaptic NMDA Receptor Plasticity in Hippocampal Dentate Granule Cells

2022 ◽  
Author(s):  
Alma Rodenas-Ruano ◽  
Kaoutsar Nasrallah ◽  
Stefano Lutzu ◽  
Maryann Castillo ◽  
Pablo E. Castillo
Keyword(s):  
Dentate Gyrus ◽  
Entorhinal Cortex ◽  
Information Transfer ◽  
Granule Cells ◽  
Hippocampal Slices ◽  
Dentate Granule Cells ◽  
Hippocampus Proper ◽  
Receptor Plasticity ◽  
Activity Dependent

The dentate gyrus is a key relay station that controls information transfer from the entorhinal cortex to the hippocampus proper. This process heavily relies on dendritic integration by dentate granule cells (GCs) of excitatory synaptic inputs from medial and lateral entorhinal cortex via medial and lateral perforant paths (MPP and LPP, respectively). N-methyl-D-aspartate receptors (NMDARs) can contribute significantly to the integrative properties of neurons. While early studies reported that excitatory inputs from entorhinal cortex onto GCs can undergo activity-dependent long-term plasticity of NMDAR-mediated transmission, the input-specificity of this plasticity along the dendritic axis remains unknown. Here, we examined the NMDAR plasticity rules at MPP-GC and LPP-GC synapses using physiologically relevant patterns of stimulation in acute rat hippocampal slices. We found that MPP-GC, but not LPP-GC synapses, expressed homosynaptic NMDAR-LTP. In addition, induction of NMDAR-LTP at MPP-GC synapses heterosynaptically potentiated distal LPP-GC NMDAR plasticity. The same stimulation protocol induced homosynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-LTP at MPP-GC but heterosynaptic AMPAR-LTD at distal LPP synapses, demonstrating that NMDAR and AMPAR are governed by different plasticity rules. Remarkably, heterosynaptic but not homosynaptic NMDAR-LTP required Ca2+ release from intracellular, ryanodine-dependent Ca2+ stores. Lastly, the induction and maintenance of both homo- and heterosynaptic NMDAR-LTP were blocked by GluN2D antagonism, suggesting the recruitment of GluN2D-containing receptors to the synapse. Our findings uncover a mechanism by which distinct inputs to the dentate gyrus may interact functionally and contribute to hippocampal-dependent memory formation.

scholarly journals Functional Imbalance of Anterolateral Entorhinal Cortex and Hippocampal Dentate/CA3 Underlies Age-Related Object Pattern Separation Deficits

Neuron ◽  
2018 ◽  
Vol 97 (5) ◽  
pp. 1187-1198.e4 ◽  
Author(s):  
Zachariah M. Reagh ◽  
Jessica A. Noche ◽  
Nicholas J. Tustison ◽  
Derek Delisle ◽  
Elizabeth A. Murray ◽  
...  
Keyword(s):  
Entorhinal Cortex ◽  
Pattern Separation ◽  
Age Related ◽  
Related Object

scholarly journals Time-resolved neural reinstatement and pattern separation during memory decisions in human hippocampus

2018 ◽  
Vol 115 (31) ◽  
pp. E7418-E7427 ◽  
Author(s):  
Lynn J. Lohnas ◽  
Katherine Duncan ◽  
Werner K. Doyle ◽  
Thomas Thesen ◽  
Orrin Devinsky ◽  
...  
Keyword(s):  
Critical Role ◽  
Pattern Separation ◽  
Time Resolved ◽  
Memory Processing ◽  
Fine Grained ◽  
Human Hippocampus ◽  
Hippocampal Activity ◽  
High Frequency Activity ◽  
Occipitotemporal Cortex

Mnemonic decision-making has long been hypothesized to rely on hippocampal dynamics that bias memory processing toward the formation of new memories or the retrieval of old ones. Successful memory encoding may be best optimized by pattern separation, whereby two highly similar experiences can be represented by underlying neural populations in an orthogonal manner. By contrast, successful memory retrieval is thought to be supported by a recovery of the same neural pattern laid down during encoding. Here we examined how hippocampal pattern completion and separation emerge over time during memory decisions. We measured electrocorticography activity in the human hippocampus and posterior occipitotemporal cortex (OTC) while participants performed continuous recognition of items that were new, repeated (old), or highly similar to a prior item (similar). During retrieval decisions of old items, both regions exhibited significant reinstatement of multivariate high-frequency activity (HFA) associated with encoding. Further, the extent of reinstatement of encoding patterns during retrieval was correlated with the strength (HFA power) of hippocampal encoding. Evidence for encoding pattern reinstatement was also seen in OTC on trials requiring fine-grained discrimination of similar items. By contrast, hippocampal activity showed evidence for pattern separation during these trials. Together, these results underscore the critical role of the hippocampus in supporting both reinstatement of overlapping information and separation of similar events.

Temporal Lobe Epilepsy

2017 ◽  
Author(s):  
Edward H. Bertram
Keyword(s):  
Animal Models ◽  
Temporal Lobe Epilepsy ◽  
Entorhinal Cortex ◽  
Temporal Lobe ◽  
Medial Temporal Lobe ◽  
Focal Epilepsy ◽  
Neural Circuitry ◽  
Human Condition ◽  
Physiological Changes ◽  
Limbic Structures

Temporal lobe epilepsy, as discussed in this chapter, is a focal epilepsy that involves primarily the limbic structures of the medial temporal lobe (amygdala, hippocampus, and entorhinal cortex). In recent years animal models have been developed that mirror the pathology and pathophysiology of this disease. This chapter reviews the human condition, the structural and physiological changes that support the development of seizures. The neural circuitry of seizure initiation will be reviewed with a goal of creating a framework for developing more effective treatments for this disease.

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