Alterations on rodent ultrasonic vocalizations and consequent effects on mate selection

In this study, the effects of altering different components of a rodent’s mating calls and their consequent effects on mate selection were explored. Rodents have become an established animal model in laboratory studies due to their inexpensive cost and common mammalian attributes shared with humans. While amphibian studies examined female selection of male mates based on acoustic features, to this date no mammalian model has been used to investigate these questions. From previous research, we know that unilateral dopamine depletion in the nigro-striatal pathway within the brain results in a drop in intensity and bandwidth of its calls. This is seen commonly in patients that suffer from Parkinson’s Disease: soft voice with monotonic pitch. My project seeks to go one step farther and ask whether it is the intensity, bandwidth, or both which modulates a female’s preferential behavior towards a mating call. To answer this question, our lab constructed an experiment involving two new sets of stimuli (only intensity reduced: -4dB and only bandwidth reduced) to be tested on two sets of rats: sexually-experienced and sexually-naïve. Using a T-maze setup to track our female rats’ preferential behaviors, we observed that both sexually experienced and inexperienced female rodents show a high preference for the normal intensity calls over those of low intensity. However, when given a choice between normal calls and low-bandwidth altered calls, the sexually experienced rats preferred the normal calls whereas the sexually-naïve rats seemed to exhibit no such preference. These results help us to conclude that sexually-experienced female rats prefer normal, or relatively higher, intensities and bandwidths of calls. However, the results from testing these calls on sexually-naïve female rats broaches a new question of the role of sexual experience in determining preference in mating calls. Further research can be conducted investigating whether the preference would differ had the females undergone sexual experience with Parkinson’s diseased rats who produce low intensity and low bandwidth calls which could elucidate the role of sexual experience in discerning mating calls.