【英语时差8,16】手为什么会发抖-上

（单词翻译）

Hold your hand out and try to keep it perfectly¹ still. After a moment, it will probably begin to shake. Hold that same hand out just before you give a major presentation to your new boss, and you’ll notice that those normal small tremors² increase substantially. Why? The answer has to do with how nervous feelings influence a response cycle between two parts of your brain. These parts are called the basal ganglia and the cortex. In order for your brain to control the steadiness of your hand, the cortex and the basal ganglia exchange signals with each other. First, the cortex sends a signal to the basal ganglia; the basal ganglia, in turn, responds returning a signal to the cortex. These signals are the basis of motor control.