scholarly journals The Role of Adult-Born Neurons in the Constantly Changing Olfactory Bulb Network

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Sarah Malvaut ◽  
Armen Saghatelyan
Keyword(s):  
Olfactory Bulb ◽  
Synapse Formation ◽  
Daily Basis ◽  
Mammalian Brain ◽  
Neuronal Progenitors ◽  
Neuronal Precursors ◽  
Continuous Progress ◽  
Adult Born Neurons ◽  
Migratory Stream

The adult mammalian brain is remarkably plastic and constantly undergoes structurofunctional modifications in response to environmental stimuli. In many regions plasticity is manifested by modifications in the efficacy of existing synaptic connections or synapse formation and elimination. In a few regions, however, plasticity is brought by the addition of new neurons that integrate into established neuronal networks. This type of neuronal plasticity is particularly prominent in the olfactory bulb (OB) where thousands of neuronal progenitors are produced on a daily basis in the subventricular zone (SVZ) and migrate along the rostral migratory stream (RMS) towards the OB. In the OB, these neuronal precursors differentiate into local interneurons, mature, and functionally integrate into the bulbar network by establishing output synapses with principal neurons. Despite continuous progress, it is still not well understood how normal functioning of the OB is preserved in the constantly remodelling bulbar network and what role adult-born neurons play in odor behaviour. In this review we will discuss different levels of morphofunctional plasticity effected by adult-born neurons and their functional role in the adult OB and also highlight the possibility that different subpopulations of adult-born cells may fulfill distinct functions in the OB neuronal network and odor behaviour.

scholarly journals Wnt-Frizzled Signaling Regulates Activity-Mediated Synapse Formation

2021 ◽  
Vol 14 ◽  
Author(s):  
Samuel Teo ◽  
Patricia C. Salinas
Keyword(s):  
Wnt Signaling ◽  
Neuronal Activity ◽  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Model Systems ◽  
Mammalian Brain ◽  
Excitatory Synapses ◽  
Wnt Ligands

The formation of synapses is a tightly regulated process that requires the coordinated assembly of the presynaptic and postsynaptic sides. Defects in synaptogenesis during development or in the adult can lead to neurodevelopmental disorders, neurological disorders, and neurodegenerative diseases. In order to develop therapeutic approaches for these neurological conditions, we must first understand the molecular mechanisms that regulate synapse formation. The Wnt family of secreted glycoproteins are key regulators of synapse formation in different model systems from invertebrates to mammals. In this review, we will discuss the role of Wnt signaling in the formation of excitatory synapses in the mammalian brain by focusing on Wnt7a and Wnt5a, two Wnt ligands that play an in vivo role in this process. We will also discuss how changes in neuronal activity modulate the expression and/or release of Wnts, resulting in changes in the localization of surface levels of Frizzled, key Wnt receptors, at the synapse. Thus, changes in neuronal activity influence the magnitude of Wnt signaling, which in turn contributes to activity-mediated synapse formation.

scholarly journals The Microtubule Severing Protein Katanin Regulates Proliferation of Neuronal Progenitors in Embryonic and Adult Neurogenesis

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Franco L. Lombino ◽  
Mary Muhia ◽  
Jeffrey Lopez-Rojas ◽  
Monika S. Brill ◽  
Edda Thies ◽  
...  
Keyword(s):  
Adult Neurogenesis ◽  
Critical Role ◽  
Mammalian Brain ◽  
Cellular Functions ◽  
Microtubule Severing ◽  
Neuronal Progenitor ◽  
Neuronal Progenitors ◽  
Adult Hippocampus

Abstract Microtubule severing regulates cytoskeletal rearrangement underlying various cellular functions. Katanin, a heterodimer, consisting of catalytic (p60) and regulatory (p80) subunits severs dynamic microtubules to modulate several stages of cell division. The role of p60 katanin in the mammalian brain with respect to embryonic and adult neurogenesis is poorly understood. Here, we generated a Katna1 knockout mouse and found that consistent with a critical role of katanin in mitosis, constitutive homozygous Katna1 depletion is lethal. Katanin p60 haploinsufficiency induced an accumulation of neuronal progenitors in the subventricular zone during corticogenesis, and impaired their proliferation in the adult hippocampus dentate gyrus (DG) subgranular zone. This did not compromise DG plasticity or spatial and contextual learning and memory tasks employed in our study, consistent with the interpretation that adult neurogenesis may be associated with selective forms of hippocampal-dependent cognitive processes. Our data identify a critical role for the microtubule-severing protein katanin p60 in regulating neuronal progenitor proliferation in vivo during embryonic development and adult neurogenesis.

scholarly journals Doublecortin Expression in the Olfactory Bulb and Rostral Stream in Infantile Rats after Exposure to Neurotoxin

2019 ◽  
Vol 7 (4) ◽  
pp. 50-55
Author(s):  
D. A. Pozhilov ◽  
T. A. Rumyantseva ◽  
V. E. Varentsov ◽  
A. V. Moskalenko
Keyword(s):  
Olfactory Bulb ◽  
Rostral Migratory Stream ◽  
Numerical Density ◽  
Neuronal Progenitors ◽  
Neurotoxic Effects ◽  
Immature Neurons ◽  
Mature Neurons ◽  
Old Rats ◽  
The Brain ◽  
Migratory Stream

The aim of the study was to investigate changes of neuroblasts’ numeral destiny in rats’ olfactory bulb and rostral migratory stream after neurotoxic action in infant age.Material and methods. The distribution of DCX, a marker of immature neurons, was studied to reveal the dynamics of its expression in the evolutionary period of ontogenesis in olfactory bulbs and rostral migratory stream in 30, 60, 90, and 180-day-old rats. Modeling of neurotoxic effects was carried out by three times injections of capsaicin on the 30–32 day of life in a total dose of 120 mg/kg. The material for the study was sampled on the 15-, 30- and 60th days of the experiment. The marker was detected on parasagittal paraffin sections, taking into account the layers of the olfactory bulb. The numerical density of DCX+ neurons (pcs/mm2) and their part in the total number of cells were determined.Results. The standard age indicators of the numerical density of immature neurons and their share in the cell population, as well as similar indicators for two months after toxic effects, were established. The administration of toxic doses of capsaicin causes a massive death of mature neurons. Compensatory reaction manifested by activation of neurogenesis in the brain stem niches and an increase in the numerical density neuroblasts in the rostral stream.Conclusions. Activation of neurogenesis during neurodegeneration causes an increase in the number of DCX + neuronal progenitors in the olfactory bulb after 30 days after exposure and maintaining high levels until the end of observation.

scholarly journals Embryonic and postnatal neurogenesis produce functionally distinct subclasses of dopaminergic neuron

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Elisa Galliano ◽  
Eleonora Franzoni ◽  
Marine Breton ◽  
Annisa N Chand ◽  
Darren J Byrne ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Sensory Processing ◽  
Dopaminergic Neuron ◽  
Initial Segment ◽  
Mammalian Brain ◽  
Postnatal Life ◽  
Postnatal Neurogenesis ◽  
Functional Roles ◽  
Long Latency ◽  
Adult Born Neurons

Most neurogenesis in the mammalian brain is completed embryonically, but in certain areas the production of neurons continues throughout postnatal life. The functional properties of mature postnatally generated neurons often match those of their embryonically produced counterparts. However, we show here that in the olfactory bulb (OB), embryonic and postnatal neurogenesis produce functionally distinct subpopulations of dopaminergic (DA) neurons. We define two subclasses of OB DA neuron by the presence or absence of a key subcellular specialisation: the axon initial segment (AIS). Large AIS-positive axon-bearing DA neurons are exclusively produced during early embryonic stages, leaving small anaxonic AIS-negative cells as the only DA subtype generated via adult neurogenesis. These populations are functionally distinct: large DA cells are more excitable, yet display weaker and – for certain long-latency or inhibitory events – more broadly tuned responses to odorant stimuli. Embryonic and postnatal neurogenesis can therefore generate distinct neuronal subclasses, placing important constraints on the functional roles of adult-born neurons in sensory processing.

scholarly journals Synaptic Functions of Invertebrate Varicosities: What Molecular Mechanisms Lie Beneath

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Carlo Natale Giuseppe Giachello ◽  
Pier Giorgio Montarolo ◽  
Mirella Ghirardi
Keyword(s):  
Nervous System ◽  
Molecular Mechanisms ◽  
Synapse Formation ◽  
Mammalian Brain ◽  
Functional Changes ◽  
Synapse Plasticity ◽  
Molecular Events ◽  
Number Of Factors ◽  
Synaptic Functions

In mammalian brain, the cellular and molecular events occurring in both synapse formation and plasticity are difficult to study due to the large number of factors involved in these processes and because the contribution of each component is not well defined. Invertebrates, such asDrosophila, Aplysia, Helix, Lymnaea,andHelisoma, have proven to be useful models for studying synaptic assembly and elementary forms of learning. Simple nervous system, cellular accessibility, and genetic simplicity are some examples of the invertebrate advantages that allowed to improve our knowledge about evolutionary neuronal conserved mechanisms. In this paper, we present an overview of progresses that elucidates cellular and molecular mechanisms underlying synaptogenesis and synapse plasticity in invertebrate varicosities and their validation in vertebrates. In particular, the role of invertebrate synapsin in the formation of presynaptic terminals and the cell-to-cell interactions that induce specific structural and functional changes in their respective targets will be analyzed.

scholarly journals Embryonic and postnatal neurogenesis produce functionally distinct subclasses of dopaminergic neuron

2017 ◽  
Author(s):  
Elisa Galliano ◽  
Eleonora Franzoni ◽  
Marine Breton ◽  
Annisa N. Chand ◽  
Darren J. Byrne ◽  
...  
Keyword(s):  
Olfactory Bulb ◽  
Sensory Processing ◽  
Dopaminergic Neuron ◽  
Initial Segment ◽  
Mammalian Brain ◽  
Postnatal Life ◽  
Postnatal Neurogenesis ◽  
Functional Roles ◽  
Long Latency ◽  
Adult Born Neurons

AbstractMost neurogenesis in the mammalian brain is completed embryonically, but in certain areas the production of neurons continues throughout postnatal life. The functional properties of mature postnatally-generated neurons often match those of their embryonically-produced counterparts. However, we show here that in the olfactory bulb (OB), embryonic and postnatal neurogenesis produce functionally distinct subpopulations of dopaminergic (DA) neurons. We define two subclasses of OB DA neuron by the presence or absence of a key subcellular specialisation: the axon initial segment (AIS). Large AIS-positive axon-bearing DA neurons are exclusively produced during early embryonic stages, leaving small anaxonic AIS-negative cells as the only DA subtype generated via adult neurogenesis. These populations are functionally distinct: large DA cells are more excitable, yet display weaker and – for certain long-latency or inhibitory events – more broadly-tuned responses to odorant stimuli. Embryonic and postnatal neurogenesis can therefore generate distinct neuronal subclasses, placing important constraints on the functional roles of adult-born neurons in sensory processing.

Sign in / Sign up

Export Citation Format

Share Document