Kuppermann B D, Kasamatsu T
Brain Res. 1984 Jun 4;302(1):91-9. doi: 10.1016/0006-8993(84)91288-5.
It was previously proposed that norepinephrine (NE)-containing nerve terminals in visual cortex are important for the maintenance of cortical plasticity. Observations at that time indicated that local microperfusion of exogenous NE for 1 week directly into kitten visual cortex, with no alteration of the visual environment, resulted in an unexpected bias in ocular dominance toward the contralateral eye. The proportion of binocular cells, however, remained close to normal. In the present study, we examined this contralateral bias in visual cortical neurons addressing the following two issues: the time needed for change in ocular dominance to occur, and its dependence on visually evoked activity. We found no bias in ocular dominance toward the contralateral eye when the continuous local perfusion of 48 microM NE lasted for 3 days. Such change became obvious after 1 week. However, if the animal was placed in the dark during the period of NE perfusion, no change whatsoever in ocular dominance was observed. These results suggest that NE itself does not affect ocular dominance circuitry directly, since both high levels of NE and an extended period of visually evoked activity are necessary for the observed change in ocular dominance to occur. We conclude that the present results are consistent with the previously proposed role for NE in the modulation of visual cortical plasticity.
先前有人提出，视皮层中含去甲肾上腺素（NE）的神经末梢对维持皮层可塑性很重要。当时的观察表明，在不改变视觉环境的情况下，将外源性NE直接局部微灌注到小猫视皮层1周，会导致眼优势向对侧眼出现意外的偏向。然而，双眼细胞的比例仍接近正常。在本研究中，我们针对以下两个问题研究了视皮层神经元中的这种对侧偏向：眼优势发生变化所需的时间，以及其对视诱发活动的依赖性。我们发现，当48微摩尔NE持续局部灌注3天时，未出现眼优势向对侧眼的偏向。1周后这种变化变得明显。然而，如果在NE灌注期间将动物置于黑暗中，则未观察到眼优势有任何变化。这些结果表明，NE本身并不直接影响眼优势回路，因为高水平的NE和长时间的视诱发活动都是观察到的眼优势变化发生所必需的。我们得出结论，目前的结果与先前提出的NE在调节视皮层可塑性中的作用一致。
