Brainard M S, Knudsen E I
Keck Center for Integrative Neuroscience, Departments of Physiology and Psychiatry, University of California, San Francisco, San Francisco, California 94143-0444, USA.
J Neurosci. 1998 May 15;18(10):3929-42. doi: 10.1523/JNEUROSCI.18-10-03929.1998.
Previous studies have identified sensitive periods for the developing barn owl during which visual experience has a powerful influence on the calibration of sound localization behavior. Here we investigated neural correlates of these sensitive periods by assessing developmental changes in the capacity of visual experience to alter the map of auditory space in the optic tectum of the barn owl. We used two manipulations. (1) We equipped owls with prismatic spectacles that optically displaced the visual field by 23 degrees to the left or right, and (2) we restored normal vision to prism-reared owls that had been raised wearing prisms. In agreement with previous behavioral experiments, we found that the capacity of abnormal visual experience to shift the tectal auditory space map was restricted to an early sensitive period. However, this period extended until later in life (approximately 200 d) than described previously in behavioral studies (approximately 70 d). Furthermore, unlike the previous behavioral studies that found that the capacity to recover normal sound localization after restoration of normal vision was lost at approximately 200 d of age, we found that the capacity to recover a normal auditory space map was never lost. Finally, we were able to reconcile the behaviorally and neurophysiologically defined sensitive periods by taking into account differences in the richness of the environment in the two sets of experiments. We repeated the behavioral experiments and found that when owls were housed in a rich environment, the capacity to adjust sound localization away from normal extended to later in life, whereas the capacity to recover to normal was never lost. Conversely, when owls were housed in an impoverished environment, the capacity to recover a normal auditory space map was restricted to a period ending at approximately 200 d of age. The results demonstrate that the timing and even the existence of sensitive periods for plasticity of a neural circuit and associated behavior can depend on multiple factors, including (1) the nature of the adjustment demanded of the system and (2) the richness of the sensory and social environment in which the plasticity is studied.
先前的研究已经确定了仓鸮发育过程中的敏感期，在此期间视觉经验对声音定位行为的校准具有强大影响。在这里，我们通过评估视觉经验改变仓鸮视顶盖中听觉空间图谱的能力的发育变化，来研究这些敏感期的神经关联。我们采用了两种操作方法。（1）给仓鸮佩戴棱镜眼镜，使视野在光学上向左或向右偏移23度，（2）我们让自幼佩戴棱镜饲养的仓鸮恢复正常视力。与先前的行为实验一致，我们发现异常视觉经验改变顶盖听觉空间图谱的能力仅限于早期敏感期。然而，这个时期比先前行为研究中描述的（约70天）延长至生命后期（约200天）。此外，与先前的行为研究不同，先前的行为研究发现恢复正常视力后恢复正常声音定位的能力在约200日龄时丧失，而我们发现恢复正常听觉空间图谱的能力从未丧失。最后，通过考虑两组实验中环境丰富程度的差异，我们能够协调行为学和神经生理学定义的敏感期。我们重复了行为实验，发现当仓鸮饲养在丰富环境中时，偏离正常调整声音定位的能力会延长至生命后期，而恢复正常的能力从未丧失。相反，当仓鸮饲养在贫瘠环境中时，恢复正常听觉空间图谱的能力仅限于约200日龄结束的时期。结果表明，神经回路可塑性和相关行为敏感期的时间甚至存在都可能取决于多种因素，包括（1）系统所需调整的性质，以及（2）研究可塑性时感觉和社会环境的丰富程度。
