Questions36-40 Exploration of all sorts is rooted in the notion of taking risks. Risk underlies any journey into the unknown, whether it is a ship captain’s voyage into the uncharted seas, a scientist’s research on dangerous diseases, or an entrepreneur’s investment in a new venture. But what exactly pushed Christopher Columbus to embark on a voyage across the Atlantic, or Edward Jenner to test his theory for an early smallpox vaccine on a child, or Henry Ford to bet that automobiles could replace horses? Many people willingly expose themselves to varying degrees of risk in their pursuit of certain goals, like financial reward, political gain, or saving lives. But as the danger increases, the number of people willing to go forward shrinks, until the only ones who remain are the extreme risk takers. Scientists have begun to open up the neurological black box containing the mechanisms for risk-taking and tease out the biological factors that may prompt someone to become an explorer. Their research has centered on neurotransmitters, the chemicals that control communication in the brain. One neurotransmitter that is crucial to the risk-taking equation is dopamine, which helps control motor skills but also helps drive us to seek out and learn new things as well as process emotions such as anxiety and fear. People whose brains don’t produce enough dopamine, such as those who are afflicted with Parkinson’s disease, often struggle with apathy and a lack of motivation. On the opposite end of the spectrum, robust dopamine production holds one of the keys to understanding risk-taking, says Larry Zweifel, a neurobiologist at the University of Washington. “When you’re talking about someone who takes risks to accomplish something—climb a mountain, start a company, run for office, become a Navy SEAL—that’s driven by motivation, and motivation is driven by the dopamine system. That is what compels humans to move forward.” Dopamine helps elicit a sense of satisfaction when we accomplish tasks: the riskier the task, the larger the hit of dopamine. Part of the reason we don’t all climb mountains or run for office is that we don’t have the same amount of dopamine. Molecules on the surface of nerve cells called autoreceptors control how much dopamine we make and use, essentially controlling our appetite for risk.
      【題組】37. What do the words tease out in paragraph 3 mean?
      (A) entangle
      (B) unravel
      (C) weave
      (D) satirize
      (E) separate