单选题
Brains are different from computers, but the analogy can be helpful. Like the PC on your desk, your mind is equipped with two basic types of memory: "working memory" for juggling information in the present moment, and "long-term memory" for storing it over extended periods. Contrary to popular wisdom, our brains don't record everything that happens to us and then bury it until a hypnotist or a therapist helps us dredge it up. Most of what we perceive hovers briefly in working memory, a mental play space akin to a computer's RAM, then simply evaporates. Working memory enables you to perform simple calculations in your head or retain phone numbers long enough to dial them. And like RAM, it lets you analyze and invent things without creating a lasting record.
Long-term memory acts more like a hard drive, physically recording past experiences in the brain region known as cerebral cortex. The cortex, or outer layer of the brain, houses a thicket of 10 billion vine—like nerve cells, which communicate by relaying chemical and electrical impulses. We can will things into long-term memory simply by rehearsing them. But the decision to store or discard a piece of information rarely involves any conscious thought. It's usually handled automatically by the hippocampus, a small, two-winged structure nestled deep in the center of the brain. Like the key-board on your computer, the hippocampus serves as a kind of switching station. As neurons out in the cortex receive sensory information. They relay it to the hippocampus. If the hippocampus responds, the sensory neurons start forming a durable network. But without that act of consent, the experience vanishes forever.
By storing only the information we're most likely to use, our brains make the world manageable. Perfect retention may sound like a godsend, but when the hippocampus gets overly permissive, the results can be devastating. At the other end of the spectrum stands impairments of the memory, which can be caused by brain surgery as well as normal aging. Other memory busters include depression, anxiety and a simple lack of stimulation—all of which keep us from paying full attention to our surroundings. What, then, are the best ways to protect your memory? Obviously, anyone concerned about staying sharp should make a point of sleeping enough and managing stress. And because the brain is at the mercy of the circulatory system, a heart-healthy lifestyle may have cognitive benefits as well.

单选题 According to the passage, the working memory and the long-term memory are respectively for ______.
A. processing information and recording information.
B. calculation and confirming the calculations.
C. storing information and performing calculations.
D. storing information and processing the storage.

单选题 According to the first paragraph, which of the following is NOT true?
A. what we are in contacts with may not be all stored in the the brain.
B. what we are in contacts with are just short-lived in the brain.
C. all of our immediate knowledge may be all ready for use.
D. only some information in the working memory can be retrieved later.

单选题 The hippocampus is compared to a keyboard because ______.
A. only when information is related to the hippocampus can the sensory neurons start functioning.
B. all the input of information can be functioned by the hippocampus.
C. the hippocampus can transform all the information received into the cortex.
D. only when the hippocampus is functioning can the information be used.

单选题 What a human brain can remember and use largely depends on ______.
A. the cooperation between the cerebal cortex and the hippocampus.
B. the cooperation between the cerebal cortex and the neurons.
C. how the neurons and the hippicampus are working.
D. how much effort a human being is made in storing received information.

单选题 Which of the following is NOT true?
A. All the information in the working memory can be stored in the long-term memory.
B. Only some of the information can be stored in the long-term memory.
C. If the received information is not juggled, it may soon depart from the memory.
D. All the information in the long-term memory is from the working memory.