Females exhibit behavioral preferences for mating with males of their own species, and they often prefer conspecific males displaying elaborate sexual signals to males with simpler signals. Although female mate preferences have been the subject of many theoretical and experimental studies, little attention has been given to understanding the neural processes influencing mate choice. To address this gap, my dissertation research focused on understanding sensory processing of acoustic male signals in female túngara frogs (Physalaemus pustulosus). I used the expression of the activity-regulated genes, egr-1 and Arc, to characterize neural responses to male signals that vary in their relevance and attractiveness to females. I first asked which brain areas process conspecific signals and where conspecific recognition may occur. I then asked whether differences in the level of neural activity elicited when females hear preferred versus less-preferred conspecific signals can explain female mate preferences for certain male callers.

I found that neural responses to conspecific signals are widespread in the female túngara frog auditory system, as well as in pallial regions that were previously unknown to process auditory information. By comparing neural responses to acoustic stimuli that females recognize as conspecific signals to stimuli that are not recognized, I determined that the laminar nucleus of the torus semicircularis, a subdivision of the auditory midbrain, shows selective responses to stimuli that elicit species recognition. These findings indicate that activity in the laminar nucleus closely corresponds with behavioral decisions made by female frogs, and they raise the possibility that conspecific recognition may emerge from selectivity in a single auditory nucleus. Finally, I tested whether female-preferred, elaborate male signals elicit greater neural activity than simpler signals. I failed to find neural activity biases towards preferred signals in the ascending auditory system and forebrain, including the pallium, demonstrating that variation in the acoustic complexity and attractiveness of male signals is not simply encoded by the magnitude of the neural response evoked by those signals. Although further studies are needed to understand how the brain encodes attractiveness, my research represents an important contribution towards understanding the neural mechanisms underlying female mate choice decisions.