以前的研究表明，脑部结构变化和感官体验之间有一个关联，但类似变化是否也伴随着学习却并不确定。对正在学习成鸟鸣叫模式的斑胸草雀幼鸟的声音控制核HVC（higher vocal centre）中的单个神经元所做的高分辨率双光子活体成像表明，学习的确涉及这样的变化。在学习它们第一首歌的24小时内，斑胸草雀幼鸟HVC中在正常情况下处于动态的树状脊会变得更大、更稳定，突触活动得到增强。（生物谷Bioon.com）
生物谷推荐原始出处：
Nature 463, 948-952 (18 February 2010) | doi:10.1038/nature08759
Rapid spine stabilization and synaptic enhancement at the onset of behavioural learning
Todd F. Roberts1, Katherine A. Tschida1, Marguerita E. Klein1 & Richard Mooney1
1 Department of Neurobiology, Duke University Medical Center, Durham, North Carolina 27710, USA
Behavioural learning depends on the brain’s capacity to respond to instructive experience and is often enhanced during a juvenile sensitive period. How instructive experience acts on the juvenile brain to trigger behavioural learning remains unknown. In vitro studies show that forms of synaptic strengthening thought to underlie learning are accompanied by an increase in the stability, number and size of dendritic spines, which are the major sites of excitatory synaptic transmission in the vertebrate brain1, 2, 3, 4, 5, 6, 7. In vivo imaging studies in sensory cortical regions reveal that these structural features can be affected by disrupting sensory experience and that spine turnover increases during sensitive periods for sensory map formation8, 9, 10, 11, 12. These observations support two hypotheses: first, the increased capacity for behavioural learning during a sensitive period is associated with enhanced spine dynamics on sensorimotor neurons important for the learned behaviour; second, instructive experience rapidly stabilizes and strengthens these dynamic spines. Here we report a test of these hypotheses using two-photon in vivo imaging to measure spine dynamics in zebra finches, which learn to sing by imitating a tutor song during a juvenile sensitive period13, 14. Spine dynamics were measured in the forebrain nucleus HVC, the proximal site where auditory information merges with an explicit song motor representation15, 16, 17, 18, 19, immediately before and after juvenile finches first experienced tutor song20. Higher levels of spine turnover before tutoring correlated with a greater capacity for subsequent song imitation. In juveniles with high levels of spine turnover, hearing a tutor song led to the rapid (~24-h) stabilization, accumulation and enlargement of dendritic spines in HVC. Moreover, in vivo intracellular recordings made immediately before and after the first day of tutoring revealed robust enhancement of synaptic activity in HVC. These findings suggest that behavioural learning results when instructive experience is able to rapidly stabilize and strengthen synapses on sensorimotor neurons important for the control of the learned behaviour.
