Question

    The brain has a powerful ability to remember and connect events separated in time. And now, in that new study in mice published in Neuron, scientists at Columbia’s Zuckerman Institute have cast light on how the brain can form lasting links.

The hippocampus—a small, seahorse-shaped region buried deep in the brain—is an important headquarters for learning and memory. Previous experiments in mice showed that disruption (中断) to the hippocampus leaves the animals with trouble learning to associate two events separated by tens of seconds.

“The traditional view has been that cells in the hippocampus keep up a level of continuous activity to associate such events,” said Dr. Ahmed, co-first author of the study. “Turning these cells off would thus disrupt learning.”

To test this view, the researchers imaged parts of the hippocampus of mice as the animals were exposed to two different stimuli (刺激物): a neutral (神经的) sound followed by a small but unpleasant puff of air. A fifteen-second delay separated the two events. The scientists repeated this experiment across several trials. Over time, the mice learned to associate the sound with the soon-to-follow puff of air. Using advanced microscopy, they recorded the activity of thousands of neurons (神经元) , a type of brain cell, in the animals’ hippocampus over the course of each trial for many days.

“We expected to see continuous neural activity that lasted during the fifteen-second gap, an indication of the hippocampus at work linking the auditory sound and the air puff,” said computational neuroscientist Stefano Fusi, PhD. “But when we began to analyze the data, we saw no such activity.” Instead, the neural activity recorded during the fifteen-second time gap was sparse (稀少的). Only a small number of neurons worked, and they did so seemingly at random.

To understand activity, they had to shift the way they analyzed data and use tools designed to make sense of random processes. Finally, the researchers discovered a complex pattern in the randomness: a style of mental computing that seems to be a remarkably efficient way that neurons store information.

“We were happy to see that the brain doesn’t maintain ongoing activity over all these seconds because that’s not the most efficient way to store information,” said Dr. Ahmed. “The brain seems to have a more efficient way to build this bridge.”

In addition to helping to map the circuitry involved in associative learning, these findings also provide a starting point to more deeply explore disorders, such as panic and post-traumatic stress disorder.

1.What can we learn about the hippocampus?

A.It weakens with the memory decline.

B.It is a brain region crucial for memory.

C.It serves as a tool of learning languages.

D.It is involved in the visual area of the brain.

2.The new study in mice indicates that ______.

A.continuous activity happens as expected

B.no neurons stay active at intervals of 15 seconds

C.a complex pattern helps the brain learn associations

D.neuronal information is stored in well-designed tools

3.From the last two paragraphs, we can infer that the findings ______.

A.inspire deeper explorations of disorders

B.provide evidence for language learning

C.build a bridge between different parts of the brain

D.help map some aspects of a person’s experiences

Answer

1.B

2.C

3.A

【解析】

本文是说明文。大脑有一种强大的能力，可以记忆并将不同时间的事件联系起来。科学家们通过对老鼠的研究，揭示了大脑是如何形成持久联系的。文章介绍了研究过程，研究结果和意义。

1.

细节理解题。根据第二段The hippocampus—a small, seahorse-shaped region buried deep in the brain—is an important headquarters for learning and memory.可知海马区是一个位于大脑深处的小的海马状区域，是学习和记忆的重要总部，它是大脑中对记忆至关重要的区域。故选B。

2.

推理判断题。根据第四段提到的研究过程A fifteen-second delay separated the two events. The scientists repeated this experiment across several trials. Over time, the mice learned to associate the sound with the soon-to-follow puff of air. Using advanced microscopy, they recorded the activity of thousands of neurons (神经元) , a type of brain cell, in the animals’ hippocampus over the course of each trial for many days.可知两个声音之间有15秒的延迟，科学家们重复这个实验。随着时间的推移，老鼠们学会了将这种声音与随后即将到来的呼吸气流联系起来。使用先进的显微镜，他们记录了成千上万的神经元的活动。在老鼠身上进行的研究表明重复的复杂的模式可以帮助大脑学会联想，故选C。

3.

推理判断题。最后两段说明了这一发现的重要作用，尤其是最后一段In addition to helping to map the circuitry involved in associative learning, these findings also provide a starting point to more deeply explore disorders, such as panic and post-traumatic stress disorder.可知这个发现除了能帮助绘制联想学习相关的神经图示，还为深入地探索疾病，如恐慌和创伤后应激障碍提供了一个起点。A项激发对疾病的更深层次的探索，是其作用之一。故选A。