Blais B S, Shouval H Z, Cooper L N
Departments of Physics and Neuroscience and Institute for Brain and Neural Systems, Brown University, Providence RI 02912, USA.
Proc Natl Acad Sci U S A. 1999 Feb 2;96(3):1083-7. doi: 10.1073/pnas.96.3.1083.
Although investigations in computational neuroscience have been extensive, the opportunity (that has made such a marked difference in physical sciences) to test detailed and subtle quantitative consequences of a theory against experimental results is rare. In this paper, we outline a testable consequence of two contrasting theories of synaptic plasticity applied to the disconnection in visual cortex of the closed eye in monocular deprivation. This disconnection is sometimes thought to be the consequence of a process that stems from a competition of inputs for a limited resource such as neurotrophin. Such a process leads to what we call spatial competition, or heterosynaptic synaptic modification. A contrasting view-exemplified by the Bienenstock, Cooper, and Munro (BCM) theory-is that patterns of input activity compete in the temporal domain. This temporal competition is homosynaptic and does not require a conserved resource. The two mechanisms, homosynaptic and heterosynaptic, are the distinguishing characteristics of two general classes of learning rules we explore by using a realistic environment composed of natural scenes. These alternative views lead to opposite dependence on the level of presynaptic activity of the rate of disconnection of the closed eye in monocular deprivation. This strong and testable consequence sets the stage for a critical distinguishing experiment. This experiment has been done and supports the second view. These results have important implications for the processes of learning and memory storage in neocortex.
尽管计算神经科学领域的研究已经十分广泛，但像在物理科学中那样将理论的详细且微妙的定量结果与实验结果进行对比检验的机会却很少。在本文中，我们概述了两种相互对立的突触可塑性理论应用于单眼剥夺中闭眼视觉皮层去连接现象时的一个可检验结果。这种去连接有时被认为是源于诸如神经营养因子等有限资源的输入竞争过程的结果。这样一个过程会导致我们所说的空间竞争，即异突触性突触修饰。一种与之形成对比的观点——以比嫩斯托克、库珀和蒙罗（BCM）理论为代表——认为输入活动模式在时间域中竞争。这种时间竞争是同突触性的，并且不需要一种守恒资源。同突触性和异突触性这两种机制是我们通过使用由自然场景构成的现实环境来探索的两类学习规则的显著特征。这些不同观点导致在单眼剥夺中闭眼去连接速率对突触前活动水平的依赖性相反。这个强有力且可检验的结果为一个关键的区分性实验奠定了基础。这个实验已经完成，并且支持了第二种观点。这些结果对新皮层中学习和记忆存储过程具有重要意义。
