Adult Neurogenesis, Glia, and the Extracellular Matrix

In the paper

“Beginning less than 1 week after their generation, new granule cells extend axons, known as mossy fibers, through the hilus toward the CA3 and CA2 subregions of the hippocampus (Llorens-Martín et al., 2015; Zhao et al., 2006).”

What the sources say

• Not checked yetcites Llorens-Martín et al., 2015 source
• Not checked yetcites Zhao et al., 2006 source

In the paper

“Electrophysiological studies of new cells produced in the adult dentate gyrus have shown that this capability emerges relatively quickly (within a week) post-mitosis.”

In the paper

“Within 2 weeks of their generation, new neurons begin to take on the morphological characteristics of mature granule cells with a single dendritic tree extending toward the molecular layer and the formation of dendritic spines, primary sites of excitatory synapses (Zhao et al., 2006) (Figure 1A).”

What the sources say

• Not checked yetcites Zhao et al., 2006 source

In the paper

“Relatively high numbers of new neurons have also been reported in the adult human hippocampus (Boldrini et al., 2018; Eriksson et al., 1998; Knoth et al., 2010; Spalding et al., 2013).”

What the sources say

• Not checked yetcites Boldrini et al., 2018 source
• Not checked yetcites Eriksson et al., 1998 source
• Not checked yetcites Knoth et al., 2010 source

In the paper

“Mossy fibers from new granule cells begin to form synapses with excitatory pyramidal cells in the CA3 and CA2 subregions (Gu et al., 2012; Llorens-Martín et al., 2015; Toni et al., 2008) as well as with hilar mossy cells (Toni et al., 2008) by approximately 2–3 weeks post-mitosis (Figure 1B).”

What the sources say

• Not checked yetcites Gu et al., 2012
• Not checked yetcites Llorens-Martín et al., 2015 source
• Not checked yetcites Toni et al., 2008 source

In the paper

“Adult-generated granule neurons also display other unusual electrophysiological properties that disappear as they reach full maturity, including enhanced synaptic plasticity with a lower threshold for LTP induction (Ge et al., 2007; Schmidt-Hieber et al., 2004).”

What the sources say

• Not checked yetcites Ge et al., 2007
• Not checked yetcites Schmidt-Hieber et al., 2004 source

In the paper

“In the rodent brain, the number of new neurons is substantial, with as many as 9,000 new granule cells being added to the young adult rat dentate gyrus daily (Cameron and McKay, 2001).”

What the sources say

• Not checked yetcites Cameron and McKay, 2001

In the paper

“In the adult mammalian hippocampus, new neurons arise from stem and progenitor cell division, a process known as adult neurogenesis.”

What the sources say

• Not checked yetcites Seri et al., 2001 source

In the paper

“The heightened plasticity of adult-generated neurons make them uniquely positioned to play a role in hippocampal-related functions, of which there are many candidates.”

In the paper

“Furthermore, new neurons, presumably through their unique electrophysiological properties and sparse connections to CA3 neurons (Amaral et al., 2007), have been found to participate in pattern separation (Clelland et al., 2009; Danielson et al., 2016; Sahay et al., 2011), the process of making similar neural inputs distinct.”

What the sources say

• Not checked yetcites Clelland et al., 2009 source
• Not checked yetcites Danielson et al., 2016 source
• Not checked yetcites Sahay et al., 2011 source

In the paper

“In some of these cases, e.g., physical exercise, evidence suggests that the number of new neurons is increased by actions at multiple stages in the adult neurogenesis process, including by stimulating the proliferation of radial stem cells and amplifying progenitor cells, leading to an increase in the production of neuroblasts (Bednarczyk et al., 2010; Kronenberg et al., 2006; Lugert et al., 2010;”

What the sources say

• Not checked yetcites Bednarczyk et al., 2010
• Not checked yetcites Kronenberg et al., 2006 source
• Not checked yetcites Lugert et al., 2010 source

In the paper

“Adult neurogenesis in the hippocampus seems to provide resilience to stress-induced anxiety (Anacker et al., 2018; Hill et al., 2015; Snyder et al., 2011).”

What the sources say

• Not checked yetcites Anacker et al., 2018 source
• Not checked yetcites Hill et al., 2015 source
• Not checked yetcites Snyder et al., 2011 source

In the paper

“Reports have shown that reduction of new neurons impairs cognitive performance on hippocampal-dependent tests, including object memory, contextual fear conditioning, as well as spatial learning and memory in the Morris water maze, Barnes maze, and radial arm maze (reviewed in Cameron and Glover, 2015; Gonçalves et al., 2016a) (Figure 1C).”

What the sources say

• Not checked yetcites Cameron and Glover, 2015
• Not checked yetcites Gonçalves et al., 2016a

In the paper

“Many different types of stress (social and physical) diminish the number of new neurons in the hippocampus (Dagytė et al., 2009; De Miguel et al., 2018; Llorens-Martín et al., 2016; Mirescu et al., 2004; Opendak et al., 2016).”

What the sources say

• Not checked yetcites Dagytė et al., 2009 source
• Not checked yetcites De Miguel et al., 2018
• Not checked yetcites Llorens-Martín et al., 2016 source

In the paper

“Several experiences that are rewarding for rodents, such as voluntary physical exercise, environmental enrichment, and sexual experience, robustly enhance the number of new neurons (reviewed in Opendak and Gould, 2015).”

What the sources say

• Not checked yetcites Opendak and Gould, 2015

In the paper

“Mice with fewer new neurons were unable to discriminate between novel and previously encountered mice (Garrett et al., 2015).”

What the sources say

• Not checked yetcites Garrett et al., 2015 source

In the paper

“Taken together with the findings from seizure and stroke studies, these data suggest the effect that new neurons have on behavior is not simply a direct linear relationship where more necessarily leads to improved function.”

In the paper

“Also along the lines of research on the effects of physical exercise, enriched environment living is also associated with improved hippocampal function (reviewed in Simpson and Kelly, 2011).”

What the sources say

• Not checked yetcites Simpson and Kelly, 2011

In the paper

“The ECM aids in the communication between neurons and glial cells by incorporating their secreted signaling molecules into the extracellular space where they interact with other ECM molecules and/or cell surface receptors (Dityatev and Rusakov, 2011).”

What the sources say

• Not checked yetcites Dityatev and Rusakov, 2011 source

In the paper

“Through their direct contact and/or secretion of factors, glia and the ECM participate in adult neurogenesis and the integration of new neurons into the hippocampal circuitry.”

In the paper

“Studies have shown that microglia have both beneficial and detrimental effects on adult neurogenesis in the hippocampus, depending on the circumstances.”

In the paper

“In addition to their stimulatory effects on synapses, microglia play an important role in synapse elimination by phagocytosis (Paolicelli et al., 2011l; Schafer et al., 2012) after the recognition of immune complement proteins on weak synapses (Schafer et al., 2012) (Figure 2B).”

What the sources say

• Not checked yetcites Paolicelli et al., 2011l
• Not checked yetcites Schafer et al., 2012 source

In the paper

“Examination of afferent and efferent synapses of adult-born neurons has shown that astrocytic processes ensheath synapses from adult-born neurons (Krzisch et al., 2015)”

What the sources say

• Not checked yetcites Krzisch et al., 2015 source

In the paper

“In response to damage and disease, microglia transition to a proinflammatory state where they release cytokines, such as IL-1β, 1L-6, and TNF-α, which can impair new neuron production and cell survival (reviewed in Borsini et al., 2015) (Figure 2A).”

What the sources say

• Not checked yetcites Borsini et al., 2015 source

In the paper

“Microglia respond to increases in neural activity in the hippocampus by increasing their process numbers and prolonging their contact with synapses (Pfeiffer et al., 2016)”

What the sources say

• Not checked yetcites Pfeiffer et al., 2016 source

In the paper

“Addition of microglia to hippocampal cultures increases the number of both excitatory and inhibitory synapses through their release of IL-10 (Lim et al., 2013).”

What the sources say

• Not checked yetcites Lim et al., 2013 source

In the paper

“Blockade of vesicular release from astrocytes has been shown to impair new neuron survival and dendritic maturation by reducing dendritic branching and numbers of dendritic spines on new neurons (Sultan et al., 2015), suggesting that astrocytes are important regulators of adult neurogenesis at many stages in the process.”

What the sources say

• Not checked yetcites Sultan et al., 2015 source

In the paper

“Time-lapse imaging of microglia has shown that microglial contacts with dendrites induce spine formation in hippocampal cultures (Weinhard et al., 2018), suggesting that microglia may aid in reorganization of postsynaptic sites to produce more efficient synapses.”

What the sources say

• Not checked yetcites Weinhard et al., 2018 source

In the paper

“Astrocytes also participate in circuit refinement by synaptic engulfment of both inhibitory and excitatory synapses through MEGF10 and MERTK pathways during development and in adulthood (Chung et al., 2013) (Figure 2B).”

What the sources say

• Not checked yetcites Chung et al., 2013 source

In the paper

“Available evidence indicates that astrocytes and microglia play a role in adult neurogenesis, but the extent to which these cells influence functional connectivity of new neurons remains incompletely explored.”

In the paper

“In vivo imaging studies of astrocytes have shown that astrocytes are sensitive to changes in neural activity and respond with increases in intracellular calcium levels (Wang et al., 2006; Winship et al., 2007).”

What the sources say

• Not checked yetcites Wang et al., 2006 source
• Not checked yetcites Winship et al., 2007 source

In the paper

“Microglia participate in stem cell proliferation and survival through their release of important trophic factors and anti-inflammatory cytokines (Battista et al., 2006; Borsini et al., 2015).”

What the sources say

• Not checked yetcites Battista et al., 2006 source
• Not checked yetcites Borsini et al., 2015 source

In the paper

“Similar to astrocytes, microglia express many neurotransmitter receptors such as glutamate and purinergic receptors that sense changes in neural activity (York et al., 2018).”

What the sources say

• Not checked yetcites York et al., 2018 source

In the paper

“Astrocytic secretion of TGF-β regulates complement expression to initiate microglia to begin synaptic elimination (Bialas and Stevens, 2013).”

What the sources say

• Not checked yetcites Bialas and Stevens, 2013 source

In the paper

“A link between declining adult neurogenesis and reduced hippocampal function has also been observed with aging where reduced cell proliferation and diminished adult neurogenesis in general are associated with age-related cognitive decline (Klempin and Kempermann, 2007) (Table 1).”

What the sources say

• Not checked yetcites Klempin and Kempermann, 2007

In the paper

“In addition to its suppressive effects on adult neurogenesis, stress causes dendritic retraction on CA3 pyramidal neurons (Schoenfeld et al., 2017; reviewed in McEwen, 2018), one of the main targets of new granule neurons.”

What the sources say

• Not checked yetcites Schoenfeld et al., 2017 source
• Not checked yetcites McEwen, 2018 source

In the paper

“In both mothers and fathers, parenting has suppressive effects on adult neurogenesis (Darnaudéry et al., 2007; Glasper et al., 2011; Hyer et al., 2016; Leuner et al., 2007; Pawluski and Galea, 2007; Mahmoud et al., 2016).”

What the sources say

• Not checked yetcites Darnaudéry et al., 2007 source
• Not checked yetcites Glasper et al., 2011 source
• Not checked yetcites Hyer et al., 2016 source

In the paper

“Through their release of signaling molecules such as glutamate, ATP, d-serine, or GABA, as well as trophic factors, astrocytes influence synaptic activity at certain synapses, a process known as gliotransmission (reviewed in Harada et al., 2015; Parpura and Zorec, 2010) (Figure 2B).”

What the sources say

• Not checked yetcites Harada et al., 2015
• Not checked yetcites Parpura and Zorec, 2010

In the paper

“suggesting that astrocytes likely regulate synaptic signaling between new hippocampal neurons and their connections.”

In the paper

“With regard to the function of new neurons, these data suggest that the complex effects of experience on brain function cannot be explained by just knowing the numbers of new neurons, but instead must incorporate the effects of experience on the synaptic connectivity of new neurons.”

In the paper

“Astrocytes secrete several regulatory factors that affect presynaptic and postsynaptic maturation (Christopherson et al., 2005; Kucukdereli et al., 2011) (Figure 2B).”

What the sources say

• Not checked yetcites Christopherson et al., 2005 source
• Not checked yetcites Kucukdereli et al., 2011 source

In the paper

“In the CA2 subregion, however, PNNs also enwrap excitatory pyramidal cells (Carstens et al., 2016).”

What the sources say

• Not checked yetcites Carstens et al., 2016 source

In the paper

“Glial cells play important roles in the production and elimination of synaptic connections, while PNNs may attract or repel axons of new neurons.”

In the paper

“Reelin, an ECM glycoprotein secreted by GABAergic interneurons in the adult brain (Pesold et al., 1998)”

What the sources say

• Not checked yetcites Pesold et al., 1998 source

In the paper

“changes in PNNs surrounding these cells may have an important influence on adult neurogenesis.”

In the paper

“The functional activity of tenascin stems from its interaction with other ECM proteins and receptors (Jones and Jones, 2000).”

What the sources say

• Not checked yetcites Jones and Jones, 2000

In the paper

“MMPs can modulate structural plasticity by loosening the ECM structure allowing for a more permissive environment.”

In the paper

“Disruption of reelin signaling in hippocampal stem cells causes aberrant migration such that new granule neurons are scattered throughout the dentate gyrus area, where they form aberrant dendrites (Teixeira et al., 2012).”

What the sources say

• Not checked yetcites Teixeira et al., 2012 source

In the paper

“Accumulating evidence suggests that PNN formation is driven by neuronal activity (Dityatev et al., 2007)”

What the sources say

• Not checked yetcites Dityatev et al., 2007 source

In the paper

“and inhibitory control of new neurons may be indirectly altered through the expression of PNNs on PV+ interneurons.”

In the paper

“Enhanced neural activity in the hippocampus increases the active form of MMP9 into the perisynaptic space (Bozdagi et al., 2007; Nagy et al., 2006; Wiera et al., 2013).”

What the sources say

• Not checked yetcites Bozdagi et al., 2007 source
• Not checked yetcites Nagy et al., 2006 source
• Not checked yetcites Wiera et al., 2013 source

In the paper

“Active extracellular proteases, such as matrix metalloproteinases (MMPs), play key roles in driving plasticity in response to changes in neural activity by degrading components of the ECM (Ferrer-Ferrer and Dityatev, 2018).”

What the sources say

• Not checked yetcites Ferrer-Ferrer and Dityatev, 2018

In the paper

“One of the most widely studied MMPs in the adult hippocampus, MMP9, is involved in hippocampal synaptic plasticity.”

What the sources say

• Not checked yetcites Bozdagi et al., 2007 source
• Not checked yetcites Nagy et al., 2006 source
• Not checked yetcites Wiera et al., 2013 source

In the paper

“In addition to glutamatergic input, new granule neurons also receive local inhibitory input (Espósito et al., 2005; Ge et al., 2006)”

What the sources say

• Not checked yetcites Espósito et al., 2005 source
• Not checked yetcites Ge et al., 2006

In the paper

“which may facilitate the local potency of growth factors on adult-born neurons.”

In the paper

“Chondroitin sulfate proteoglycans bind neurotrophic factors such as FGF-2 and BDNF (Karumbaiah et al., 2015)”

What the sources say

• Not checked yetcites Karumbaiah et al., 2015 source

In the paper

“In the hippocampus, PNNs primarily surround inhibitory interneurons, many of which are fast-spiking PV+ interneurons (Lensjø et al., 2017b; Yamada et al., 2015).”

What the sources say

• Not checked yetcites Lensjø et al., 2017b
• Not checked yetcites Yamada et al., 2015 source

In the paper

“In addition to adult-generated neurons themselves, associated glial cells and ECM are differentially sensitive to experience and pathological conditions (reviewed in Ruddy and Morshead, 2018).”

What the sources say

• Not checked yetcites Ruddy and Morshead, 2018

In the paper

“In neural stem cultures, tenascin-R has been shown to modulate proliferation and differentiation of neural stem cells through interactions with the cell-surface receptor β1 integrin (Liao et al., 2008).”

What the sources say

• Not checked yetcites Liao et al., 2008 source

In the paper

“Using hippocampal slice culture and live imaging from wild-type and reelin-deficient mice, reelin has been shown to act as an attractant to control the migration direction of new granule neurons toward the molecular layer (Wang et al., 2018).”

What the sources say

• Not checked yetcites Wang et al., 2018 source

In the paper

“The maturation of PNNs in the developing cortex coincides with the closure of the critical periods of synaptogenesis and circuit refinement (Beurdeley et al., 2012; Ye and Miao, 2013).”

What the sources say

• Not checked yetcites Beurdeley et al., 2012 source
• Not checked yetcites Ye and Miao, 2013 source

In the paper

“In the developing and adult brain, evidence suggests that reelin is an important mediator of circuit formation by regulating dendritic tree maturation, spine formation and stability, glutamatergic neurotransmission, and synaptic plasticity (Pujadas et al., 2010) (Figure 3B).”

What the sources say

• Not checked yetcites Pujadas et al., 2010 source

In the paper

“Early life stress in mice has been shown to increase PNNs surrounding PV+ inhibitory interneurons in the hippocampus (Murthy et al., 2019).”

What the sources say

• Not checked yetcites Murthy et al., 2019 source

In the paper

“The combination of increased adult neurogenesis along with glial reactivity and reduced PNNs may set the stage for improper new neuron connections with their targets and ultimately, impaired hippocampal function (Figure 4C).”

In the paper

“Rats given access to running wheels also have decreased PNN expression in the hippocampus (Smith et al., 2015b).”

What the sources say

• Not checked yetcites Smith et al., 2015b

In the paper

“under optimal function conditions as observed with physical exercise, healthy glial cells and reduced PNNs may enhance new neuron connections with their targets cells (Figure 4A)”

In the paper

“Experience-dependent or pathological disruptions in glial cells or PNNs are likely to produce abnormal connectivity of new neurons and therefore impaired hippocampal function.”

In the paper

“Since physical exercise and stress have for the most part opposite effects on adult neurogenesis, synaptic connectivity, and behavior, it is perhaps not surprising that these experiences also have different effects on glia and PNN structures.”

In the paper

“Seizure-induced reactive astrocytes (Shapiro et al., 2008; Yang et al., 2010), reactive microglia (Shapiro et al., 2008; Yang et al., 2010), and reduced the expression of PNNs (McRae and Porter, 2012; Rankin-Gee et al., 2015) around postsynaptic neurons of adult-generated cells likely contribute to the functional impairments.”

What the sources say

• Not checked yetcites Shapiro et al., 2008 source
• Not checked yetcites Yang et al., 2010 source
• Not checked yetcites McRae and Porter, 2012 source