高等动物（包括人类）的大脑演化出一套功能各不相同的感觉通道，用于接收和处理来自外界的各种不同的信息。通常一个外界事件往往包含多种感觉模态信息，为能够真实地反映和编码外界事物，大脑需要对来自不同通道的信息进行整合。已有的研究表明，神经系统许多区域都存在着能够会聚和整合多种感觉信息的神经元，它们能增强源于对同一事件不同模态的刺激反应，抑制对无关刺激的反应，构成脑信息处理的一种最佳协同形式。然而，这种在发育中形成的多感觉整合模式和规则，在成年后还能够改变吗？
俞黎平等人的最新研究成果《多感觉整合可塑性：上丘多感觉神经元短时经验——依赖的改变》，给出了肯定的回答。他们在成年猫的研究中发现，上丘多感觉神经元仍然具有很大的信息整合可塑性，只要接受几分钟短暂的序列视觉和听觉的组合刺激训练，就可诱导神经元对相应刺激信息的整合。实验中发现，随着序列信号的重复刺激，神经元很快适应了这种带有事件性质的刺激组合，使前后两种刺激信号所引起的反应开始靠近，逐渐融合，具体表现为前一个反应的时程被延长了，后一个反应的潜伏期缩短了，表现出神经元能整合这种新异序列的多感觉信息了，整合效应在序列训练停止后仍然存在。
这项研究说明，经过训练，成年后的多感觉神经元仍然能够快速地适应外界环境变化，从而在一个更宽广的范围内实现对多模态信息的整合，这可能是多感觉信息加工的另一个重要规则。同时，该项研究还对人们理解脑的“预测”和“注意”等高级认知功能提供了新思维。（生物谷Bioon.com）
生物谷推荐原始出处：
The Journal of Neuroscience, December 16, 2009, 29(50):15910-15922; doi:10.1523/JNEUROSCI.4041-09.2009
Adult Plasticity in Multisensory Neurons: Short-Term Experience-Dependent Changes in the Superior Colliculus
Liping Yu,1 Barry E. Stein,2 and Benjamin A. Rowland2
1East China Normal University, School of Life Sciences, Institute of Cognitive Neuroscience, Shanghai, China, and 2Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157-1010
Multisensory neurons in the superior colliculus (SC) have the capability to integrate signals that belong to the same event, despite being conveyed by different senses. They develop this capability during early life as experience is gained with the statistics of cross-modal events. These adaptations prepare the SC to deal with the cross-modal events that are likely to be encountered throughout life. Here, we found that neurons in the adult SC can also adapt to experience with sequentially ordered cross-modal (visual-auditory or auditory-visual) cues, and that they do so over short periods of time (minutes), as if adapting to a particular stimulus configuration. This short-term plasticity was evident as a rapid increase in the magnitude and duration of responses to the first stimulus, and a shortening of the latency and increase in magnitude of the responses to the second stimulus when they are presented in sequence. The result was that the two responses appeared to merge. These changes were stable in the absence of experience with competing stimulus configurations, outlasted the exposure period, and could not be induced by equivalent experience with sequential within-modal (visual-visual or auditory-auditory) stimuli. A parsimonious interpretation is that the additional SC activity provided by the second stimulus became associated with, and increased the potency of, the afferents responding to the preceding stimulus. This interpretation is consistent with the principle of spike-timing-dependent plasticity, which may provide the basic mechanism for short term or long term plasticity and be operative in both the adult and neonatal SC.
