How the brain creates behavior

By Eva Emerson

Some behaviors—finding food to eat and water to drink—are crucial to survival. From the point of view of USC College neuroscientist Larry W. Swanson, who studies such basic drives as hunger and thirst, these behaviors provide critical insights into the brain.

Since the late 1960s, Swanson, the Milo Don and Lucille Appleman Professor of Biological Sciences, has investigated the biological basis of behaviors through studies of what are called motivated behaviors. His studies led to the discovery and mapping of distinct neural circuits responsible for producing and controlling ingestive (eating and drinking), sleep-wake, defensive and reproductive behaviors.

“These drives are separate but overlapping in the brain,” says Swanson, director of the USC Neuroscience Graduate Program. The behaviors may affect each other—for example, Swanson has shown that during sleep, food- and water-seeking behaviors are effectively shut down.

The circuitry underlying these drives extends into many areas of the brain, allowing the complex behaviors to emerge. Like a simple reflex, motivated behaviors may be triggered by a stimulus (a pang of hunger), but the resulting response is much more complex.

The mapping of the neural pathways involved in the behaviors set the stage for studies of how the brain controls these behaviors. Swanson has focused on how stress and sexual hormones affect the neural networks underlying the drives.

Swanson is also well known for producing the first maps of the fine structures of the brain and for developing advanced computer graphic tools that have proved invaluable research resources for neuroscientists.