Post-traumatic stress disorder is a malady of memory. Sufferers are often haunted by recurrent nightmares, distressing thoughts and flashbacks so intense in color, smell and sound that they feel as if they are reliving the trauma. But what if these unbearable memories could be selectively erased? Sheena Josselyn, a professor of physiology and psychology, who studies how the brain encodes, stores and uses information, is intrigued by the idea and has been investigating how to “silence” memories --make them temporarily inaccessible-- in mice. She thinks it’s possible that a variation of this technique could one day help treat post-traumatic stress disorder in humans. 

　　Studies with mice have found that although their brains contain billions of neurons, only a few are necessary to form a fearful memory. Researchers working with mice began by teaching them to fear a tone: when it sounds, they feel a mild shock to their feet (not to hurt them, just to scare them). The next time the mice hear the tone, they crouch and freeze, signaling fear. The researchers discovered that they could trigger the memory of that fear even without presenting the tone. They did this by stimulating the small group of nerve cells holding that memory through a technology called optogenetics. Using the same technology, they found they could also suppress the fearful memory. With optogenetics, scientists insert proteins into neurons to make them sensitive to light. Depending on the type of protein and color of light used, these cells can then be activated or deactivated by shining pulses of the light directly into the brain. If the light activates the cells, the mice freeze as if they’ve just heard the tone. If the light deactivates the cells, the memory is suppressed. While optogenetics is an invasive procedure and technologically not feasible with humans, Josselyn hopes that the general principles learned from these studies could eventually help scientists create new drugs for treating memory disorders such as post-traumatic stress disorder and Alzheimer’s. 

　　But should you erase a bad memory? Absolutely not, says Josselyn. She emphasizes that this future technology should not be applied to everyday bad things, and that these discoveries need to go hand in hand with a real thinking about the ethics involved in potentially manipulating memories in people. Their use would only be considered in extreme cases after all other treatment options have been explored. The goal is not to sanitize life or make people super happy, but rather to make everyone a functional person, capable of moments of joy.

Scientists reported that the human brain is _____13_____ prepared to assist others, including strangers, and that this _____14_____ behavior can be observed in as young as 18-month-old children. Moreover, the latest discovery of mirror neurons in humans _____15_____ the scientists believe that the human brain can affect a person’s helpful behavior. Mirror neurons located throughout the brain can help us feel what others feel and thus make us feel _____16_____. Without them, we would not know or care about other people’s feelings.

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         Standing proud in the savannah with their red blankets and painted shields, the Maasai people are one of the widely known symbols of East Africa. Their unique style, as remarked by Karen Blixen, author of Out of Africa, “has grown from the inside, and is an expression of the race and its history.” 

        The Maasai are a semi-nomadic group in Kenya and northern Tanzania, wandering in bands and living almost entirely on the meat, blood, and milk of their herds. Over the years, the fearless tribesmen have stood strong against slavery, and resisted the urging of the Kenyan and Tanzanian governments to adopt a more modern lifestyle. In fact, they are one of the few tribes that have retained most of their traditions. Up until recently, the only way for a Maasai boy to achieve warrior status was to single-handedly kill a lion with his spear.
        Maasai clothing varies with age, gender, and place. The most recognizable piece of clothing is the shúkà, a sheet of fabric worn wrapped around the body. Red is a popular color, and women generally opt for checked, striped, or patterned pieces of cloth. Young men wear black for several months after their circumcision, a ritual signifying their coming of age. A Maasai warrior is rarely seen without his spear and shield. In Blixen’s words, “their weapons and finery are as much a part of their being as are a stag’s antlers” (a male deer’s horns).
        Beadwork is an important part of Maasai culture. Beaded jewelry is made by women, and is famous for its complexity. Natural materials such as clay, shells, and ivory were used before trading with the Europeans in the 19th century. They were then replaced by colorful glass beads, allowing for more detailed beadwork and color patterns. Multicolored beadwork is popular among both men and women. Each color holds a special meaning: White stands for peace, green for land and production, while red—the most favored color among the Maasai—is the symbol of unity and bravery.

     Hikikomori is a psychological condition which makes people shut themselves off from society, often staying in their houses for months on end. There are at least half a million of them in Japan. It was once thought of as a young person’s condition, but sufferers are getting older and staying locked away for longer. It is an economic as well as a social threat to the country, and is seriously worrying Japanese government.
    As of 2015, there were 541,000 hikikomori aged 15-39 in Japan, according to government statistics. There is no data on other age groups, suggesting that the figure is likely to be far larger. Some families are also loath to report hikikomori in their households, Kingston said. Doctors began to observe hikikomori as a social phenomenon around the mid-1980s, when young men exhibited signs of lethargy, refused to communicate, and spent most of their time in their rooms. There’s no unifying reason why people become hikikomori. Some withdraw from society because they feel they don’t know what
to do with their lives and can no longer cope with the pressure from people around them. Others are triggered by events in their lives, like bad grades or heartbreak. Hikikomori feel a deep sense of shame that they cannot work at a job like ordinary people. They think of themselves as worthless and unqualified for happiness. Almost all feel remorse at having betrayed their parents’ expectations.
    As hikikomori refuse to participate in society, let alone go to work, Japan’s economy also suffers. They diminish the size of the workforce, so they contribute to a tighter labor market. Also, they are not self-sufficient, so when family support dries up due to death or financial problems, they will need to rely on state assistance.
    Japanese government plans to set up counseling centers and have support staff visit hikikomori at home in a bid to boost the country’s flagging workforce. But some criticize this may put pressure on hikikomori. Professor Jeff Kingston,an Asian studies professor in Tokyo, said, “One can only hope that more access to various therapies and public health campaigns to destigmatize the phenomenon will encourage more to seek help, find it, and learn to manage their symptoms so that they can lead more productive and fulfilling lives.”