New Worlds: How the brain decides what is good or bad
“When someone offends you while smiling, should your brain interpret it as a smile or an offense?” asks Dr. Hadas Okon-Singer of Haifa.
By JUDY SIEGEL-ITZKOVICHStress Relief Techniques(photo credit: PR)
Israeli and German researchers have identified different neural networks that operate when we perceive a situation as positive or negative.“We don’t know whether to laugh or cry” is a familiar expression, referring to a situation that includes both positive and negative elements. But how does the brain actually decide whether to laugh or cry? University of Haifa and Max Planck Institute researchers used emotionally confusing video clips to study the issue.“When someone offends you while smiling, should your brain interpret it as a smile or an offense?” said Dr. Hadas Okon-Singer of Haifa.“The mechanism we found includes two areas in the brain that act almost as ‘remote controls’ that together determine what value to attribute to a situation and accordingly which other brain areas should be on and which should be off,” said Okon-Singer, one of the leaders of the study.She explained that previous studies have identified the mechanisms by which the brain determines whether something is positive or negative. However, most of these studies focused on dichotomous situations – the participants were submitted either to a completely positive stimulus (a smiling baby or a pair of lovers) or a completely negative one (a dead body). The present study sought to examine complex cases involving both positive and negative stimuli.In a new study published recently in the journal Human Brain Mapping, a group of researchers led by Dr. Christiane Rohr of the Max Planck Institute in Germany and Okon-Singer of the psychology department of at the University of Haifa sought to locate the neural mechanism that “chooses” whether a given situation is positive or negative and classifies situations that are emotionally unclear. To simulate the lack of emotional clarity, the researchers presented the participants with scenes from emotionally conflicting movies, such as Quentin Tarantino’s Reservoir Dogs.This movie includes many complex situations, such as a scene where one person is torturing another while smiling, dancing, and talking to his victim in a friendly manner.The participants in the study watched the scenes while they were inside an MRI machine, and later reported whether they felt that each scene they viewed included a conflict. For each moment in the movie, the participants also rated the extent to which they felt that the positive elements were dominant, so that the scene was pleasant to watch, or the extent that negative elements prevailed, so that the scene was unpleasant to view.As in previous studies, the researchers identified two active networks – one that operates when we perceive the situation as positive, and another that operates when we perceive it as negative. For the first time, however, they identified how the brain switches between these two networks.The study found that the transition between activity in the positive or negative network is facilitated by two areas in the brain – the superior temporal sulcus (STS) and the inferior parietal lobule (IPL). These areas form part of the negative and positive networks, but also acted when the participants felt that the movie scene embodied an emotional conflict. The STS was found to be associated with the interpretation of positive situations, while the IPL is associated with the interpretation of negative situations.These two areas effectively function as “remote controls” that spring into action when the brain recognizes that there is an emotional conflict, said Okon-Singer. The two areas seem to “speak” to each other and interpret the situation to decide which one will be on and which one off, thereby determining which network will be active.“The study suggests that these areas can influence the value – positive or negative – that will be dominant in an emotional conflict through control of other areas of the brain,” she said, anticipating that the discovery of the areas of the brain that enable us to identify emotional situations and conflicts will now facilitate further research to examine why this mechanism does not work properly in some people.“We hope that understanding the neural basis of the interpretation of situations as positive or negative will in the future help us to understand the neural systems of populations that have emotional difficulties. This will enable us to develop therapeutic techniques to make interpretations among these populations more positive,” the researchers concluded.SCANS REVEAL BIRDS’ BUILT-IN AIR CONDITIONERSBirds’ beaks come in an incredible range of shapes and sizes, adapted for survival in environments around the world. But as a new study from The Auk: Ornithological Advances reveals, there is even more to bird beaks than meets the eye. The insides of birds’ bills are filled with complex structures that help them meet the demands of hot climates.Nasal conchae are complex structures inside bird bills that moderate the temperature of air being inhaled and reclaim water from air being exhaled. Dr. Raymond Danner of the University of North Carolina and his colleagues from Cornell University and the National Museum of Natural History used CT scans to examine the conchae of two subspecies of song sparrows. One lives in warm, dry sand dunes, while the other lives in moister habitats farther inland. In this first comparison of conchae structure of birds living along a moisture gradient, the conchae of the dune-dwelling sparrows had a larger surface area and were situated farther out in the bill than those of their inland relatives, hypothetically increasing their beaks’ ability to cool air and recapture water.Danner and his colleagues used song sparrow specimens that were collected in Delaware and the District of Columbia and preserved in ethanol and iodine to help soft tissues show up in scans. The contrast-enhanced CT scans they used to visualize the insides of the sparrows’ bills is a relatively new technique that is letting researchers see the details of these soft, cartilaginous structures for the first time.“We had been studying the function of the bird bill as a heat radiator, with a focus on heat loss from the external surface and adaptation to local climates, when we began to wonder about the thermoregulatory processes that occur within the bill,” said Danner, who noted that now scientists realize how complicated bird beaks can be.