Abbott L F, Chance Frances S
Volen Center and Department of Biology, Brandeis University, Waltham, MA 02454-9110, USA.
Prog Brain Res. 2005;149:147-55. doi: 10.1016/S0079-6123(05)49011-1.
In 1998, Sherman and Guillery proposed that there are two types of inputs to cortical neurons; drivers and modulators. These two forms of input are required to explain how, for example, sensory driven responses are controlled and modified by attention and other internally generated gating signals. One might imagine that driver signals are carried by fast ionotropic receptors, whereas modulators correspond to slower metabotropic receptors. Instead, we have proposed a novel mechanism by which both driver and modulator inputs could be carried by transmission through the same types of ionotropic receptors. In this scheme, the distinction between driver and modulator inputs is functional and changeable rather than anatomical and fixed. Driver inputs are carried by excitation and inhibition acting in a push-pull manner. This means that increases in excitation are accompanied by decreases in inhibition and vice versa. Modulators correspond to excitation and inhibition that covary so that they increase or decrease together. Theoretical and experimental work has shown that such an arrangement modulates the gain of a neuron, rather than driving it to respond. Constructing drivers and modulators in this manner allows individual excitatory synaptic inputs to play either role, and indeed to switch between roles, depending on how they are linked with inhibition.
1998年，谢尔曼和吉列里提出，皮质神经元存在两种类型的输入：驱动输入和调制输入。这两种输入形式是解释诸如感觉驱动反应如何通过注意力及其他内部产生的门控信号得到控制和调节所必需的。有人可能会设想，驱动信号由快速离子otropic受体携带，而调制器则对应较慢的代谢型受体。相反，我们提出了一种新机制，通过该机制，驱动输入和调制输入都可以通过相同类型的离子otropic受体传递来实现。在这个方案中，驱动输入和调制输入之间的区别是功能性的且可变的，而非解剖学上固定不变的。驱动输入由以推挽方式起作用的兴奋和抑制携带。这意味着兴奋增加时抑制会减少，反之亦然。调制器对应协同变化的兴奋和抑制，即它们同时增加或减少。理论和实验工作表明，这样一种安排会调节神经元的增益而非驱动其做出反应。以这种方式构建驱动输入和调制输入允许单个兴奋性突触输入根据其与抑制如何连接来发挥任一作用，甚至在不同作用之间切换。
