Neurogenesis in an Adult Avian Song Nucleus Is Reduced by Decreasing Caspase-Mediated Apoptosis

Thompson, Christopher K.; Brenowitz, Eliot A.

doi:10.1523/jneurosci.5423-08.2009

Cited by 25 publications

(31 citation statements)

References 28 publications

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“…Reduction of this neuronal loss in HVC by infusion of a cocktail of caspase inhibitors reduces the number of new neurons added to HVC (Thompson and Brenowitz 2009). Within 2 d following the peak of cell death in HVC following the drop in T level, proliferation of neural progenitor cells in the VZ increases (Larson et al 2014).…”

Section: Ea Brenowitz and Ta Larsonmentioning

confidence: 99%

“…At the end of the breeding season, circulating T levels decrease, which prompts an increase in the death of mature HVC neurons (Thompson et al 2007;Thompson 2011). This death of mature HVC neurons during the transition from breeding to nonbreeding seasons creates "vacancies" for the addition of new neurons (Scharff et al 2000;Nottebohm 2004;Thompson and Brenowitz 2009).…”

Section: Neurogenesis In Adult Birdsmentioning

confidence: 99%

“…Even though the level of neuronal addition to HVC declines in zebra finches when song learning is completed, it does continue into adulthood after the birds have completed song learning. Like zebra finches, male song sparrows and white-crowned sparrows complete song learning in the first year of life, but continue to add new neurons to HVC and area X as adults (Tramontin and Brenowitz 1999;Thompson and Brenowitz 2009). As in canaries, wild song sparrows show higher levels of neuronal addition to HVC in the fall than in the spring, even though they retain the same songs throughout adulthood (Tramontin and Brenowitz 1999).…”

Section: Neuronal Turnover Enables Adult Birds To Learn To Produce Nementioning

confidence: 99%

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Neurogenesis in the Adult Avian Song-Control System

Brenowitz

Larson

2015

Cold Spring Harb Perspect Biol

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New neurons are added throughout the forebrain of adult birds. The song-control system is a model to investigate the addition of new long-projection neurons to a cortical circuit that regulates song, a learned sensorimotor behavior. Neuroblasts destined for the song nucleus HVC arise in the walls of the lateral ventricle, and wander through the pallium to reach HVC. The survival of new HVC neurons is supported by gonadally secreted testosterone and its downstream effectors including neurotrophins, vascularization, and electrical activity of postsynaptic neurons in nucleus RA (robust nucleus of the arcopallium). In seasonal species, the HVC!RA circuit degenerates in nonbreeding birds, and is reconstructed by the incorporation of new projection neurons in breeding birds. There is a functional linkage between the death of mature HVC neurons and the birth of new neurons. Various hypotheses for the function of adult neurogenesis in the song system can be proposed, but this remains an open question.

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Section: Ea Brenowitz and Ta Larsonmentioning

confidence: 99%

Section: Neurogenesis In Adult Birdsmentioning

confidence: 99%

Section: Neuronal Turnover Enables Adult Birds To Learn To Produce Nementioning

confidence: 99%

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Neurogenesis in the Adult Avian Song-Control System

Brenowitz

Larson

2015

Cold Spring Harb Perspect Biol

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“…There is a subsequent increase in the addition of new neurons to HVC in nonbreeding birds [23; 24]. The death of mature HVC neurons increases the addition of new neurons to HVC [25; 26], and does so by increasing neural stem cell proliferation in the adjacent ventricular zone [27]. …”

Section: Seasonal Plasticity In the Brainmentioning

confidence: 99%

Transsynaptic trophic effects of steroid hormones in an avian model of adult brain plasticity

Brenowitz

2015

Frontiers in Neuroendocrinology

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The avian song control system provides an excellent model for studying transsynaptic trophic effects of steroid sex hormones. Seasonal changes in systemic testosterone (T) and its metabolites regulate plasticity of this system. Steroids interact with the neurotrophin brain-derived neurotrophic factor (BDNF) to influence cellular processes of plasticity in nucleus HVC of adult birds, including the addition of newborn neurons. This interaction may also occur transsynpatically; T increases the synthesis of BDNF in HVC, and BDNF protein is then released by HVC neurons on to postsynaptic cells in nucleus RA where it has trophic effects on activity and morphology. Androgen action on RA neurons increases their activity and this has a retrograde trophic effect on the addition of new neurons to HVC. The functional linkage of sex steroids to BDNF may be of adaptive value in regulating the trophic effects of the neurotrophin and coordinating circuit function in reproductively relevant contexts.

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“…Caspase inhibitors have been used as effective therapeutic agents to reduce neurodegeneration in various neurodegenerative models. Among them, zVAD has been successfully used to prevent caspase activation in many studies Scholz et al, 2005;Dupret et al, 2007;Thompson and Brenowitz, 2009), and neuronal death is mediated by the activation of caspases in many brain regions, including the OB (Yuan et al, 2003;Yamaguchi and Mori, 2005). Moreover, zVAD is well tol-erated when administered for prolonged periods Li et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Turnover of Newborn Olfactory Bulb Neurons Optimizes Olfaction

Mouret¹,

Lepousez²,

Gras³

et al. 2009

J. Neurosci.

125

111

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Postdevelopmental neurogenesis occurs in the olfactory bulb (OB), to which new interneurons are continuously recruited. However, only a subset of the adult-generated interneurons survives, as many undergo programmed cell death. As part of homeostatic processes, the removal of new neurons is required alongside the addition of new ones, to ensure a stable neuron number. In addition to a critical role in tissue maintenance, it is still unclear whether this neuronal elimination affects the functioning of adult circuits. Using focal drug delivery restricted to the OB, we investigated the significance of programmed cell death in the adult OB circuits. Cell death was effectively blocked by the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone (zVAD). The zVAD effect differed with newborn interneuron location, either in the superficial (periglomerular cells) or in the deep (granule cells) OB layers. Furthermore, whereas sensory experience potentiated the effect of zVAD on the survival of new granule cells, it had no additional effect on the survival of new periglomerular cells. Thus, distinct mechanisms control the survival/elimination decision of newborn interneuron subtypes. However, zVAD had no effect on the olfactory sensory neurons projecting to the bulb. Remarkably, psychophysical analyzes revealed that a normal rate of new neuron elimination was essential for optimal odorant exploration and discrimination. This study highlights the importance of cell elimination for adjusting olfactory performance. We conclude that adult-generated OB interneurons are continually turned over, rather than simply added, and the precise balance between new and mature interneurons, set through active selection/ elimination processes, is essential for optimizing olfaction.

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Neurogenesis in an Adult Avian Song Nucleus Is Reduced by Decreasing Caspase-Mediated Apoptosis

Cited by 25 publications

References 28 publications

Neurogenesis in the Adult Avian Song-Control System

Neurogenesis in the Adult Avian Song-Control System

Transsynaptic trophic effects of steroid hormones in an avian model of adult brain plasticity

Turnover of Newborn Olfactory Bulb Neurons Optimizes Olfaction

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