How messenger substances influence individual decision-making
A research team of psychologists and physicists from Heinrich Heine University Düsseldorf (HHU) and Otto von Guericke University Magdeburg investigated the neurobiological processes in different types of decision-making. In the journal Nature Communications, they report that variations in the ratio of two messenger substances affects short-term and long-term strategic decisions in a different manner.
Longitudinal section of the brain: GABA/glutamate concentrations were measured at the locations marked (top: dorsal anterior cingulate cortex; further forward/bottom: ventromedial prefrontal cortex). (Photo: HHU / Luca Franziska Kaiser)
As indicated by other studies, different parts of the brain play a key role in different types of decisions. A research team led by Luca Franziska Kaiser and Prof. Dr. Gerhard Jocham from the HHU research group ‘Biological Psychology of Decision Making’, and Dr. Theo Gruendler together with colleagues in Magdeburg analysed the balance of the neuronal messenger substances GABA and glutamate in two types of decision-making. The primary research question was to find out how different concentrations of these substances influence the way in which humans make these decisions.
First, the researchers looked at so called ‘reward-based decisions’, which involve maximising reward by selecting the better of two options currently available. Luca Kaiser gives a simple example: “Where do I buy coffee on my way to work, depending on the price, quality and whether or not the café is on my way?” Previous results suggest that such decision-making processes in the brain are mainly processed in the ventromedial prefrontal cortex (vmPFC).
Unlike these reward-based decisions, ‘patch-leaving decisions’ are about long-term strategic considerations that include a careful balancing of immediate cost against (long-term) gain. An example of such a decision would be whether to move from Düsseldorf to Munich for a job offer. Prof. Jocham explains: “The job in Munich may offer a higher salary and a more interesting role, but may also involve stress and the effort involved in finding a place to live and moving to Munich – as well as higher rents and the loss of social contacts in Düsseldorf.” Thus, there are many factors that influence this type of decision. According to the literature, such decisions are made in the brain’s dorsal anterior cingulate cortex (dACC).
The two messenger substances glutamate and GABA may play a key role. The ratio between them, the so-called E/I balance, indexes the balance between excitatory and inhibitory neural transmission. The researchers used magnetic resonance spectroscopy to measure the concentrations of GABA and glutamate in different cortical areas of human volunteers.
The team then used the data to correlate the ratio of the two messenger substances with participants’ individual decision-making behaviour. In the patch-leaving scenario, subjects with a higher ratio of GABA to glutamate in dACC were quicker to leave a depleting resource. By contrast, people with higher concentrations of glutamate required a greater expected advantage before deciding to abandon their current patch.
In the other scenario, subjects with higher concentrations of GABA relative to glutamate in vmPFC exhibited significantly higher decision accuracy. They more reliably selected the higher-value option. Luca Kaiser says: “Our results show a correlation between decision-making behaviour and the balance of two messenger substances in the brain. People with a higher ratio of excitation to inhibition in dACC need a bigger incentive to move away from their status quo. By contrast, people with more GABA in vmPFC exhibit greater accuracy for short-term decisions.”
“My mother passed away suddenly while I was studying in America. It was such a dark moment for me. She had been the most important person in my life, and I wasn’t even with her when she died. I needed to get home to Zimbabwe for the funeral, but it was right before Christmas so every flight was booked. The only ticket I could afford was a middle seat. It was so cramped. I couldn’t even move my legs. But I happened to notice an empty seat in the exit row behind me. The flight attendant allowed me to change places, and I sat down next to a white girl. I remember thinking: ‘She’s going to hate me for taking up her space.’ But instead she smiled and made a joke. She said: ‘Welcome to exit row paradise.’ There was an immediate connection. Right away we began talking about deep things. I told her about my mother. And she told me that her father had also died suddenly while she was working overseas. We started sharing stories of our parents. And before we landed, she ordered two whiskey drinks in celebration of my mom. I spent two weeks in Zimbabwe. I told all my friends that my mother had put an angel on my flight. My trip home wasn’t much easier. This time I had a long layover in London, so I sat down in the airport bar and ordered a beer. And in she walked. God had put us on the same flight once again. When we pulled out our tickets and looked at our seat numbers, we couldn’t believe it. She was seat 61. I was 60. I hadn’t even been looking to meet someone. I was determined to stay single and focus on my schoolwork. But it was like she had been brought to me. Everyone who meets Hannah tells me how lucky I am. She is so kind, and smart, and accomplished. We dated for almost two years before we got married. When I gave a speech at our reception, I didn’t need notes. Because I knew our story. I told everyone about that girl I met on a plane. And I was looking at her as I spoke, and she was now my wife, and it made me so emotional. It was so hard to know how to feel. I wanted my mom to meet her so bad. But if my mom was still here, I’d never have met her. Somehow I’d found the most important person in my life because I lost the most important person in my life.”
Okinawa islanders conflicted over tourism amid virus pandemic
As more people in Tokyo and elsewhere were beginning to hole up at home during the coronavirus pandemic, others were venturing out to visit
By Okinawa Times
As more people in Tokyo and elsewhere were beginning to hole up at home during the coronavirus pandemic, others were venturing out to visit islands in Okinawa Prefecture.
People on the resort island of Miyako as well as others in the Yaeyama archipelago, which had seen the same tourist flows as usual until recently, are conflicted as they welcome tourists while at the same time fear infection. Most of the visitors have been young people.
In an unusual move, Ishigaki Mayor Yoshitaka Nakayama held a news conference on March 31 to warn tourists against a groundless assertion spreading on social media that “southern islands are safe from the virus.”
According to the Ishigaki City Tourism Exchange Association (ICTEA), although a number of school excursions and tours were canceled due to the pandemic, individual and group tourists had visited the city in March as usual.
That month is known as graduation trip season. Many of the visitors arrived via low-cost carriers from Narita and Kansai airports, the association said.
A 19-year-old college student from Kyoto who visited Ishigaki Island on April 1 explained she felt it would be safe to go because “Okinawa reports very few coronavirus patients.”
“I have taken my mask off because of the heat. Many on the island don’t wear them anyway,” she said.
However, local residents have mixed feelings.
A 44-year-old civil servant insisted that entry restrictions should be imposed on tourists. She feared that Ishigaki’s medical infrastructure is “not sufficiently equipped,” with only three beds that can cater to patients with infectious diseases at Yaeyama Hospital. Because the island is small, one case could lead to an exponential rise in cases, the woman warned.
Other residents expressed fear of infection, while acknowledging that they “welcome tourists.”
While the ICTEA showed understanding of the residents’ concerns, it also underscored the plight the tourism industry is facing.
The association argued that the number of tourists on graduation trips was not larger than the previous year’s level, and transportation and hotel occupancy rates have fallen by 30 to 40 percent.
“Financially unstable companies increasingly find themselves cornered,” association Secretary-General Masami Nishinakano said. “Obviously, life is more important than money. Still, I can’t help but worry about the uncertain future.”
On nearby Miyako Island, the downtown beach of Yonaha Maehama was crowded with visitors, as were souvenir shops on Ikema Island, which is linked by a highway.
But a restaurant owner in her 60s in the city said the number of customers has drastically dropped since mid-March.
“Sometimes, only two tourists were on a large bus. We are barely holding on thanks to local customers, but it’s very hard when (there are few tourists).”
Social media posts openly rejecting tourists coming to Miyako Island, apparently by local residents, have increased.
Shunjin Nema, secretary-general of the tourism association for Miyako Island, said, “I intend to ease residents’ concerns by asking our members to thoroughly follow the infection preventive measures recommended by the government.”
On April 8, Okinawa Gov. Denny Tamaki asked residents from outside the prefecture, including Tokyo and six other prefectures initially put under a state of emergency that has since been expanded nationwide, to refrain from visiting Okinawa. He said that the request would be in place until the state of emergency ends on May 6.
Lately, Haruki Murakami doesn’t give many interviews. But in 2017, he made an exception for the novelist Mieko Kawakami, whose work he admires, and who has written of the influence Murakami has had on her fiction, which is just beginning to appear in English. They apparently hit it off. The pair spent 16 hours together across four occasions in Tokyo, resulting in the book, The Owl Spreads Its Wings with the Falling of the Dusk, published in Japanese by Kodansha in 2017. In this segment of the conversation, Kawakami asks Murakami why his female characters play the roles they do, and behave like they do, and Murakami responds.
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