When we're unsure how to respond, how does our brain decide whether a situation is pleasant or not?

We are all familiar with the expression "we don't know whether to laugh or cry," referring to a situation that includes both positive and negative elements. But how does the brain actually desire "whether to laugh or cry"? Dr. Okon-Singer explains 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 Dr. Okon-Singer of the Department of Psychology at the University of Haifa sought to locate the neural mechanism that "chooses" whether a given situation is positive or negative and classifies different situations that are emotionally unclear. In order 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 movie 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. Dr. Okon-Singer explains that these two areas effectively function as "remote controls" that spring into action when the brain recognizes that there is an emotional conflict. The two areas seem to "speak" to each other and interpret the situation in order 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 added.

Dr. Okon-Singer anticipates 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 by 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 the interpretations among these populations more positive," the researchers concluded.