主题：《自然 神经科学》2006年6月刊:有更多的神经元也许并不能使你更聪明 -- 衲子
More neurons may not make you smarter
by Kalyani Narasimhan
News and Views
Nature Neuroscience 9, 722 (2006)
The hippocampus continues to add new neurons even in adulthood. When animals are housed in 'enriched' or stimulating environments with opportunities for exercise and/or games, they show greater neurogenesis in the hippocampus. Animals exposed to these more complex cages also show improvements in several tasks of memory and anxiety.
A study by René Hen and colleagues on page 729 reports, however, that there is no link between the increased neurogenesis that comes with enriched environments and improvements in the memory tasks. The authors used a focused dose of radiation to prevent neurogenesis selectively in the hippocampus of mice before placing them in enriched cages. When tested six weeks later on an anxiety and spatial memory task, these animals still did better than animals housed in standard cages, suggesting that the lack of neurogenesis did not matter to their learning ability.
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翻译:
即使在成年期, 大脑的海马体(注:掌管记忆)依然不停地增加新的神经元. 当动物被养在有着体育运动和游戏的环境(又称作"富集"环境)里, 它们的海马体就会更大幅度地长出新的神经元. 这种环境下的动物对于完成有关'记忆'和'焦虑'的任务也会做得更好.
然而, René Hen和他的合作者研究发现, "富集"环境所导致的动物的增强的神经生长能力与它们完成记忆任务的进步, 这二者并无因果关系. 他们通过使用一种放射剂,来有选择地在老鼠的海马体内阻止新神经元的形成. 六周后的'焦虑'以及'空间记忆'的测试表明, 这些"富集"环境下的下了药的老鼠仍然比常规环境下的老鼠做得更好. 这个结果显示: 神经形成能力的缺失,并不影响学习能力.
Dar Meshi, et. al. "Hippocampal neurogenesis is not required for behavioral effects of environmental enrichment," NATURE NEUROSCIENCE, VOL. 9 No. 6, JUNE 2006
摘要:
Environmental enrichment increases adult hippocampal neurogenesis and alters hippocampal-dependent behavior in rodents. To investigate a causal link between these two observations, we analyzed the effect of enrichment on spatial learning and anxiety-like behavior while blocking adult hippocampal neurogenesis. We report that environmental enrichment alters behavior in mice regardless of their hippocampal neurogenic capability, providing evidence that the newborn cells do not mediate these effects of enrichment.
最后一段的总结:
In summary, the housing of adult mice in an enriched environment caused an increase in adult hippocampal neurogenesis, decreased anxiety-like behavior, faster habituation to an unfamiliar environment and improved spatial learning. Arrest of adult hippocampal neurogenesis did not markedly affect performance in these behavioral protocols, nor did it attenuate the effects of environmental enrichment. Therefore, the effects of enrichment on spatial learning, habituation to an unfamiliar environment, and conflict-based anxiety do not require adult hippocampal neurogenesis in our experimental conditions. This result is in contrast with recent data demonstrating that neurogenesis is required for the anxiolytic-like effects of antidepressants in mice. We propose that anxiolytic effects can be achieved through multiple pathways, including neurogenesis-dependent and -independent mechanisms. The effects of environmental enrichment on anxiety-like behavior and spatial learning seem to be mediated by a neurogenesis-independent mechanism. Candidate mechanisms may include the upregulation of growth factors such as brain-derived neurotrophic factor, as well as morphological changes such as increased dendritic branching and synaptogenesis.
既然'神经形成'被排除了, 学习能力的提升的机制多半是由神经树突的更多分叉和突触的形成所调控的.
全文:
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