Researchers from University College London have identified key brain regions that are crucial for logical thinking and problem-solving. This research, published on the 15th in the journal Brain, helps to better understand how the human brain supports understanding, drawing conclusions, and processing new problems, namely reasoning ability. Studying brain injuries is both difficult and time-consuming, and requires a large number of patients with specific brain injuries. This type of injury may affect a person's way of thinking, feeling, or acting. However, few research institutions have access to enough patients to conduct experiments. Previous studies mainly relied on functional imaging techniques of healthy individuals. These results can sometimes be misleading as they provide evidence of correlation rather than causality. To determine which brain regions are necessary for specific functions, in this new study, researchers used the "damage defect mapping" method, which is the most effective way to locate brain function. They conducted a study on 247 patients with unilateral focal brain injury in the left or right frontal lobe of the brain. In addition, there were 81 healthy individuals as the control group. To evaluate the reasoning ability of these patients, researchers developed two new tests. One of them is a language analogy reasoning task, in which participants need to find relationships between words to solve problems, such as "If A is smarter than B and A is smarter than C, is B smarter than C?" The other is a nonverbal deductive reasoning task, in which participants need to use pictures, shapes, or numbers to find logical patterns and solve problems, such as "Which set of numbers is most similar to 1, 2, or 3- is it 5, 6, 7 or 6, 5, 7?" The results showed that patients with right anterior lobe damage performed worse in both tests compared to patients with damage to other areas of the brain. They make about 15% more mistakes than other patients and healthy individuals. Research has shown that there is a close connection between the right forebrain network involved in reasoning and the right forebrain network that is crucial for fluid intelligence (i.e., people's ability to solve problems without prior experience). This indicates that a common region in the brain plays a crucial role in both reasoning and fluid intelligence. (New Society)