2023届高考英语一轮复习外刊语法填空Neuroscience 讲义

外刊语法填空——含全文翻译和重难点句型讲解 Neuroscience Silent synapses How adult brains learn the new without forgetting the old Learning new things is hard. 1.___________(Remember) what has already been learned is harder. Any successful learning system, be it a brain or a piece of artificial-intelligence software, 2._______ strike the right balance between stability and flexibility. It must be stable enough to remember important old things yet flexible enough to learn new ones 3.________ destroying old memory traces—preferably for as long as it exists. Learning is a result of changes in the pattern of neural connectivity in the brain. Each connection between nerve cells, called a synapse, is a tiny gap between the ends of branches ramifying from such cells. Messages jump 4. ________ these gaps in the form of molecules called neurotransmitters. Current estimates suggest there are 600 trillion synapses in a human brain. How, then, to deal with the stability-plasticity dilemma—particularly as brains age and, as it were, fill up? Research by Dimitra Vardalaki, Kwanghun Chung and Mark Harnett at the Massachusetts Institute of Technology, just published in Nature, suggests one way is to preserve into adulthood a type of memory-forming synapse found in children. These are called silent synapses. Silent synapses are, however, useless 5.________ they can be switched on at the appropriate moment. And the researchers confirmed this is possible. They were able to induce the silent versions on filopodia to turn into mature, active synapses by pairing the simulated release of glutamate with a subsequent surge of electricity inside the neuron. This pairing of events caused silent synapses to start, within minutes, displaying receptor molecules characteristic of active synapses. The same pairing, applied 6.________ mature synapses, did nothing. The researchers thereby show it is hard to get a mature synapse ________(change) the strength of its connection (thus satisfying the stability side of