Animals would waste a lot of time and energy by trying to begin the breeding season without the resources they need to be successful (i.e., to raise their offspring successfully). It makes sense then to hypothesize that access to limited resources in the environment would play a role in controlling when animals decide to breed. In male starlings, we found that even when daylength and testosterone concentrations should cause our birds to sing, the birds only sang once they had access to a nest cavity — a limited resource that’s necessary for starlings to breed successfully. And yet it was testosterone that altered neural circuits that underlie the motivation to sing. Why? This led us to suggest that testosterone prepares to brain for courtship behavior, but in the absence of necessary resources, the brain is prevented from stimulating the behavior. See the published study in Hormones and Behavior.
I’m currently studying how interactions between neuromodulators that stimulate and neuromodulators that inhibit courtship singing could be important for seasonal changes in behavior. I’ve started by characterizing cells that receive input from both opioid and dopamine neurochemical systems (double-immunofluorescent labeling shown on left).