Conditioned Fear Can Be Transmitted Transgenerationally in Rodents
Scientists often use fear conditioning to study rodents’ learning and behavior. If a particular stimulus (such as a light, a sound, or an odor) is presented paired with the delivery of a mild shock, the animal begins to associate the stimulus with the shock and will freeze when it is presented and avoid the stimulus.
New research shows that if a pregnant rat (known as a dam) goes through fear conditioning that pairs an odor with a shock, the rat’s offspring will also avoid that odor into adolescence. Even if the pups are raised by a different mother who never went through the fear conditioning, they still avoid the odor into adolescence, showing that they do not learn the behavior through watching their mother.
The conditioning is specific to the particular odor, such that a different odor not used in the fear conditioning does not evoke a heightened reaction from the pups. It appears that the pup learns the fear through chemical signals, such as alarm pheromones that can pass through the placenta.
