Dissecting Mechanisms of Motivation within the Nucleus Accumbens Using Optogenetics

Studies mapping psychological functions to discrete brain regions often require manipulations that yield changes in a particular area and observing a subsequent shift in behavior. As investigators tap into neural underpinnings of behavior, it is useful to utilize technologies that permit temporally and spatially discrete shifts in neural signaling and neurobiological processes. This chapter contains protocols for creating "Fos plumes," a means of mapping alterations in neural activity induced by neural manipulations. By localizing increases or decreases in c-Fos in targeted brain regions, the relative spread of each manipulation can be mapped, and the functional roles of individual mechanisms within particular brain areas can be defined. The chapter also provides examples of behavioral testing protocols using optogenetics to localize psychological functions in the nucleus accumbens (NAc), a brain region involved in the production of motivated behaviors. Together, these methods provide avenues for researchers to localize and causally demonstrate the impact of neural manipulations in the brain.