Wurtz Robert H, Sommer Marc A, Cavanaugh James
Laboratory of Sensorimotor Research, National Eye Institute, National Institutes of Health, Bethesda, MD 20892-4435, USA.
Prog Brain Res. 2005;149:207-25. doi: 10.1016/S0079-6123(05)49015-9.
A traditional view of the thalamus is that it is a relay station which receives sensory input and conveys this information to cortex. This sensory input determines most of the properties of first order thalamic neurons, and so is said to drive, rather than modulate, these neurons. This holds as a rule for first order thalamic nuclei, but in contrast, higher order thalamic nuclei receive much of their driver input back from cerebral cortex. In addition, higher order thalamic neurons receive inputs from subcortical movement-related centers. In the terminology popularized from studies of the sensory system, can we consider these ascending motor inputs to thalamus from subcortical structures to be modulators, subtly influencing the activity of their target neurons, or drivers, dictating the activity of their target neurons? This chapter summarizes relevant evidence from neuronal recording, inactivation, and stimulation of pathways projecting from the superior colliculus through thalamus to cerebral cortex. The study concludes that many inputs to the higher order nuclei of the thalamus from subcortical oculomotor areas - from the superior colliculus and probably other midbrain and pontine regions - should be regarded as motor drivers analogous to the sensory drivers at the first order thalamic nuclei. These motor drivers at the thalamus are viewed as being at the top of a series of feedback loops that provide information on impending actions, just as sensory drivers provide information about the external environment.
传统观点认为，丘脑是一个中继站，接收感觉输入并将这些信息传递至皮层。这种感觉输入决定了一级丘脑神经元的大部分特性，因此可以说它驱动而非调节这些神经元。这通常适用于一级丘脑核团，但与之相反的是，高级丘脑核团的大部分驱动输入是从大脑皮层反馈回来的。此外，高级丘脑神经元还接收来自皮层下与运动相关中心的输入。在从感觉系统研究中普及的术语里，我们能否将这些从皮层下结构到丘脑的上行运动输入视为调制器，即微妙地影响其靶神经元的活动，或者视为驱动者，即决定其靶神经元的活动呢？本章总结了从神经元记录、失活以及对从上丘经丘脑投射至大脑皮层的通路进行刺激所获得的相关证据。该研究得出结论，来自皮层下动眼区域（从上丘以及可能的其他中脑和脑桥区域）至丘脑高级核团的许多输入，应被视为类似于一级丘脑核团中的感觉驱动者的运动驱动者。丘脑处的这些运动驱动者被视为处于一系列反馈回路的顶端，这些反馈回路提供有关即将发生动作的信息，就如同感觉驱动者提供有关外部环境的信息一样。
