neurogenesis function timecourses : 無料・フリー素材/写真
neurogenesis function timecourses / Functional Neurogenesis
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | From here:The previous timecourses are all well and good but sheer numbers of cells say nothing about whether the new neurons actually work. And markers like DCX or NeuN may give a general hint at the maturity of a neuron but not much more. Functional timecourses address these gaps. A direct measure of function would be whether a new neuron has electrophysiological properties that enable it to process information (e.g. input and output synapses, action potentials). Less direct signs of function can be inferred from the morphology of a new neuron and whether a new neuron is capable of expressing activity-dependent immediate early genes.What do these functional timecourses tell us?electrophysiology (Esposito 2005; Ge 2006), anatomy/morphology (Hastings 1999; Zhao 2006; Toni 2007; Toni 2008), and activity-dependent gene expression (Jessberger 2003; Snyder 2009) all point to new neurons forming their first synapses at 2-4 weeks of agearound 4 weeks of age, new neurons go through a phase where they have enhanced synaptic plasticity (Ge et al 2007) and enhanced activation during behavior (Snyder 2009)thus, at a young age, new neurons are more modifiable by experience than mature neurons. This may enable them to make a greater impact on behavior, either at this age or by shaping their further integration into the circuitry so they can alter brain function when fully mature and functionalyoung neurons have distinct neurotransmitter profiles: initially they receive GABAergic inputs and later receive excitatory glutamatergic inputs (Esposito 2005). Notably, GABA depolarizes immature neurons (Ge 2006), unlike its typically-inhibitory effects on mature neurons. Also, immature neurons have a unique form of the NMDA receptor (NR2B), which endows them with their enhanced plasticity (Ge 2007).blocking CREB signalling (Jagasia 2009) or the depolarizing effects of GABA (Ge 2006) inhibits the functional maturation of new neuronsby 8 weeks of age, new neurons are pretty much fully developed, though Zhao 2006, Toni 2007 and Toni 2008 show that 8-10 week-old neurons are still slightly underdeveloped, presynaptically and postsynapticallydoes this mean that 8-10 week-old neurons, despite no longer having enhanced synaptic plasticity or enhanced activation during behavior, might still function differently than fully mature neurons? |
| 撮影日 | 2010-03-07 22:05:47 |
| 撮影者 | Functional Neurogenesis , Washington, DC, United States |
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