Neural computation of innate defensive behavioral decisions

In general, our actions are not mere reflexes in response to external stimuli. Most of the time, external stimuli interact with internal factors—such as our emotions, or memories—to influence how we act. These actions, in turn, affect both what new stimuli we receive and also change our internal brain state. Together, these factors make for the complexities of behavior. This interplay between external stimuli and internal states is the focus of research in our laboratory. We will study this interplay in mice, using so-called “approach and avoidance” behaviors. An approach behavior might include interactions with other mice, such as mating or fighting. An avoidance behavior might include freezing or fleeing in the face of a predator. Both behaviors depend on external stimuli—attack behavior, for example, may be triggered by seeing another mouse—but also internal factors such as the animal’s state of arousal. We will focus on attack behaviors. To study those behaviors, we will monitor the activity of many neurons simultaneously in brain areas responsible for vision and in those responsible for the mouse’s emotional state. With modern tools, these measurements can be taken even while the mouse performs the attack behavior. From our observations, we will develop computational models of the mouse’s behavior. To test these models, we can use sophisticated genetic techniques to manipulate or eliminate the activity of neurons and observe the effect on the mouse’s behavior. Because similar behaviors in humans engage emotions—via a part of the brain called the limbic system—an understanding of the neural circuits under study here will be highly relevant to psychiatric disorders such as PTSD, phobias, autism, or schizophrenia.

Markus Meister, California Institute of Technology

David Anderson, California Institute of Technology

Pietro Perona, California Institute of Technology