scholarly journals Adult neurogenesis produces a large pool of new granule cells in the dentate gyrus

2001 ◽  
Vol 435 (4) ◽  
pp. 406-417 ◽  
Author(s):  
Heather A. Cameron ◽  
Ronald D.G. Mckay
Keyword(s):  
Dentate Gyrus ◽  
Adult Neurogenesis ◽  
Granule Cells ◽  
Large Pool

scholarly journals Heterogeneities in afferent connectivity dominate local heterogeneities in the emergence of response decorrelation in the dentate gyrus

2017 ◽  
Author(s):  
Poonam Mishra ◽  
Rishikesh Narayanan
Keyword(s):  
Olfactory Bulb ◽  
Dentate Gyrus ◽  
Adult Neurogenesis ◽  
Information Transfer ◽  
Granule Cells ◽  
Dominant Role ◽  
Critical Role ◽  
Local Network ◽  
Afferent Inputs ◽  
The Impact

ABSTRACTThe ability of a neuronal population to effectuate response decorrelation has been identified as an essential prelude to efficient neural encoding. To what extent are diverse forms of local and afferent heterogeneities essential in accomplishing such response decorrelation in the dentate gyrus (DG)? Here, we incrementally incorporated four distinct forms of biological heterogeneities into conductance-based network models of the DG and systematically delineate their relative contributions to response decorrelation. We incorporated intrinsic heterogeneities by stochastically generating several electrophysiologically-validated basket and granule cell models that exhibited significant parametric variability, and introduced synaptic heterogeneities through randomized local synaptic strengths. In including adult neurogenesis, we subjected the valid model populations to randomized structural plasticity and matched neuronal excitability to electrophysiological data. We assessed networks comprising different combinations of these three local heterogeneities with identical or heterogeneous afferent inputs from the entorhinal cortex. We found that the three forms of local heterogeneities were independently and synergistically capable of mediating significant response decorrelation when the network was driven by identical afferent inputs. Strikingly, however, when we incorporated afferent heterogeneities into the network to account for the unique divergence in DG afferent connectivity, the impact of all three forms of local heterogeneities were significantly suppressed by the dominant role of afferent heterogeneities in mediating response decorrelation. Our results unveil a unique convergence of cellular- and network-scale degeneracy in the emergence of response decorrelation in the DG, and constitute a significant departure from the literature that assigns a critical role for local network heterogeneities in input discriminability.SIGNIFICANCE STATEMENTThe olfactory bulb and the dentate gyrus (DG) networks assimilate new neurons in adult rodents, with adult neurogenesis postulated to subserve efficacious information transfer by reducing correlations in neuronal responses to afferent inputs. Heterogeneities emerging from the lateral dendro-dendritic synapses, mediated by locally-projecting neurogenic inhibitory granule cells, are known to play critical roles in channel decorrelation in the olfactory bulb. However, the contributions of different heterogeneities in mediating response decorrelation in DG, comprising neurogenic excitatory granule cells projecting beyond DG and endowed with uniquely divergent afferent inputs, have not been delineated. Here, we quantitatively demonstrate the dominance of afferent heterogeneities, over multiple local heterogeneities, in the emergence of response decorrelation in DG, together unveiling cross-region degeneracy in accomplishing response decorrelation.

scholarly journals Dominant role of adult neurogenesis-induced structural heterogeneities in driving plasticity heterogeneity in dentate gyrus granule cells

2021 ◽  
Author(s):  
Sameera Shridhar ◽  
Poonam Mishra ◽  
Rishikesh Narayanan
Keyword(s):  
Dentate Gyrus ◽  
Adult Neurogenesis ◽  
Granule Cells ◽  
Dominant Role ◽  
Activity Patterns ◽  
Brain Regions ◽  
Intrinsic Excitability ◽  
Context Specific ◽  
Structural Heterogeneities ◽  
Strong Relationships

ABSTRACTNeurons and synapses manifest pronounced variability in the amount of plasticity induced by identical activity patterns. The mechanisms underlying such plasticity heterogeneity, implicated in context-specific resource allocation during encoding, have remained unexplored. Here, we employed a systematic, unbiased, and physiologically constrained search to identify the mechanisms behind plasticity heterogeneity in dentate gyrus granule cells. We found that each of intrinsic, synaptic, and structural heterogeneities independently yielded heterogeneous plasticity profiles obtained with two different induction protocols. However, prior predictions about strong relationships between neuronal intrinsic excitability and plasticity emerged only when adult-neurogenesis-induced structural heterogeneities were accounted for. Strikingly, despite the concomitant expression of heterogeneities in structural, synaptic, and intrinsic neuronal properties, similar plasticity profiles were attainable through synergistic interactions among these heterogeneities. Importantly, consequent to strong relationships with intrinsic excitability measurements, we found that synaptic plasticity in the physiological range was achieved in immature cells despite their electrophysiologically-observed weak synaptic strengths. Together, our analyses unveil the dominance of neurogenesis-induced structural heterogeneities in driving plasticity heterogeneity in granule cells. Broadly, these analyses emphasize that the mechanistic origins of and the implications for plasticity heterogeneities need quantitative characterization across brain regions, particularly focusing on context-specific encoding of learned behavior.

scholarly journals Hippocampal Transplants of Fetal GABAergic Progenitors Regulate Adult Neurogenesis in Mice with Temporal Lobe Epilepsy

2022 ◽  
Author(s):  
Muhammad Nauman Arshad ◽  
Simon Oppenheimer ◽  
Jaye Jeong ◽  
Bilge Buyukdemirtas ◽  
Janice R Naegele
Keyword(s):  
Temporal Lobe Epilepsy ◽  
Dentate Gyrus ◽  
Temporal Lobe ◽  
Adult Neurogenesis ◽  
Granule Cell ◽  
Granule Cells ◽  
Granule Cell Layer ◽  
Spontaneous Seizures ◽  
Type 3

GABAergic interneurons within the dentate gyrus of the hippocampus regulate adult neurogenesis, including proliferation, migration, and maturation of new granule cells born in the subgranular zone (SGZ) of the dentate gyrus (DG). In temporal lobe epilepsy (TLE), some adult-born granule cells migrate ectopically into the hilus, and these cells contribute to increased hyperexcitability and seizures. Yet, transplanting embryonic day 13.5 fetal mouse medial ganglionic eminence (MGE) GABAergic progenitors into the hippocampus of mice with TLE ameliorates spontaneous seizures, due in part, to increased postsynaptic inhibition of adult-born granule cells. Here, we asked whether MGE progenitor transplantation affects earlier stages of adult neurogenesis, by comparing patterns of neurogenesis in naive mice and epileptic (TLE) mice, with or without MGE transplants. In naive and TLE mice, transplanted MGE cells showed comparable migration and process outgrowth. However, in TLE mice with MGE transplants, fewer adult-born Type 3 progenitors migrated ectopically. Furthermore, more Type 3 progenitors survived and migrated into the granule cell layer (GCL), as determined by immunostaining for doublecortin or the thymidine analogue, bromodeoxyuridine (BrdU). To determine whether MGE transplants affected earlier stages of adult neurogenesis, we compared proliferation in the SGZ two-hours after pulse labeling with BrdU in naive vs. TLE mice and found no significant differences. Furthermore, MGE progenitor transplantation had no effect on cell proliferation in the SGZ. Moreover, when compared to naive mice, TLE mice showed increases in inverted Type 1 progenitors and Type 2 progenitors, concomitant with a decrease in the normally oriented radial Type 1 progenitors. Strikingly, these alterations were abrogated by MGE transplantation. Thus, MGE transplants appear to reverse seizure-induced abnormalities in adult neurogenesis by increasing differentiation and radial migration of adult-born granule cell progenitors, outcomes that may ameliorate seizures.

scholarly journals Intact memory for local and distal cues in male and female rats that lack adult neurogenesis

2018 ◽  
Author(s):  
Desiree R Seib ◽  
Erin Chahley ◽  
Oren Princz-Lebel ◽  
Jason S Snyder
Keyword(s):  
Dentate Gyrus ◽  
Adult Neurogenesis ◽  
Granule Cells ◽  
Sensory Information ◽  
Female Rats ◽  
Male Rats ◽  
Separation Function ◽  
Male And Female ◽  
Male And Female Rats ◽  
Adult Born Neurons

ABSTRACTThe dentate gyrus is essential for remembering the fine details of experiences that comprise episodic memory. Dentate gyrus granule cells receive highly-processed sensory information and are hypothesized to perform a pattern separation function, whereby similar sensory inputs are transformed into orthogonal neural representations. Behaviorally, this is believed to enable distinct memory for highly interfering stimuli. Since the dentate gyrus is comprised of a large number of adult-born neurons, which have unique synaptic wiring and neurophysiological firing patterns, it has been proposed that neurogenesis may contribute to this process in unique ways. Some behavioral evidence exists to support this role, whereby neurogenesis-deficient rodents are impaired at discriminating the fine visuospatial details of experiences. However, the extent to which newborn neurons contribute to dentate gyrus-dependent learning tasks is unclear. Furthermore, since most studies of dentate gyrus function are conducted in male rats, little is known about how females perform in similar situations, and whether there might be sex differences in the function of adult neurogenesis. To address these issues, we examined spatial discrimination memory in transgenic male and female rats that lacked adult neurogenesis. The first task probed memory for the position of local objects in an open field, assessed by behavioral responses to novel object locations. The second task examined memory for distal environmental cues. All rats were able to successfully discriminate local and distal cue changes. Males and females also performed comparably, although females displayed higher levels of rearing and locomotion. Collectively, our results indicate that rats are capable of learning about local and distal cues in the absence of adult neurogenesis.

Degree and pattern of calbindin immunoreactivity in granule cells of the dentate gyrus differ in mesial temporal sclerosis, cortical malformation- and tumor-related epilepsies

2011 ◽  
Vol 1399 ◽  
pp. 66-78 ◽  
Author(s):  
Hajnalka Ábrahám ◽  
Zsófia Richter ◽  
Csilla Gyimesi ◽  
Zsolt Horváth ◽  
József Janszky ◽  
...  
Keyword(s):  
Dentate Gyrus ◽  
Granule Cells ◽  
Mesial Temporal Sclerosis ◽  
Cortical Malformation

scholarly journals Fluorescent Labeling of Newborn Dentate Granule Cells in GAD67-GFP Transgenic Mice: A Genetic Tool for the Study of Adult Neurogenesis

PLoS ONE ◽  
2010 ◽  
Vol 5 (9) ◽  
pp. e12506 ◽  
Author(s):  
Shengli Zhao ◽  
Yang Zhou ◽  
Jimmy Gross ◽  
Pei Miao ◽  
Li Qiu ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Adult Neurogenesis ◽  
Granule Cells ◽  
Fluorescent Labeling ◽  
Dentate Granule Cells ◽  
Genetic Tool
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