How does the human brain react to fear? It depends on whether a threat is close or far away. In a version of the computer game Pacman, 14 participants were monitored with functional magnetic resonance imaging (Science 2007;317:1079-83 doi: 10.1126/science.1144298). They received a shock to the hand if they were caught by a virtual predator in the maze. The prefrontal cortex, which is involved in planning complex tasks, is active when the threat is far away. When the threat is near, activity shifts to the periaqueductal grey, which governs the fight or flight response.
Could obesity be caught like a cold? The condition is traditionally attributed to diet, lifestyle, and genetic predisposition. A virus that causes infections of the respiratory system and eye has been shown to turn adult stem cells taken from fatty tissue into fat cells. However, this does not show the virus to be the only cause,