Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
Nat Neurosci. 2010 Feb;13(2):253-60. doi: 10.1038/nn.2466. Epub 2009 Dec 27.
Descending projections from sensory areas of the cerebral cortex are among the largest pathways in the brain, suggesting that they are important for subcortical processing. Although corticofugal inputs have been shown to modulate neuronal responses in the thalamus and midbrain, the behavioral importance of these changes remains unknown. In the auditory system, one of the major descending pathways is from cortical layer V pyramidal cells to the inferior colliculus in the midbrain. We examined the role of these neurons in experience-dependent recalibration of sound localization in adult ferrets by selectively killing the neurons using chromophore-targeted laser photolysis. When provided with appropriate training, animals normally relearn to localize sound accurately after altering the spatial cues available by reversibly occluding one ear. However, this ability was lost after eliminating corticocollicular neurons, whereas normal sound-localization accuracy was unaffected. The integrity of this descending pathway is therefore critical for learning-induced localization plasticity.
大脑皮层感觉区的下行投射是大脑中最大的通路之一，这表明它们对皮质下处理很重要。虽然已经证明皮质传出输入可以调节丘脑和中脑的神经元反应，但这些变化的行为重要性尚不清楚。在听觉系统中，主要的下行通路之一是从大脑皮层 V 层锥体神经元到中脑的下丘。我们通过使用发色团靶向激光光解选择性地杀死神经元，研究了这些神经元在成年雪貂中声音定位的经验依赖性重新校准中的作用。当提供适当的训练时，动物通常会在通过可逆地阻塞一只耳朵改变可用的空间线索后重新准确地定位声音。然而，在消除皮质-丘系神经元后，这种能力丧失了，而正常的声音定位准确性不受影响。因此，这条下行通路的完整性对于学习诱导的定位可塑性至关重要。
