Neural response patterns to social acoustic signals and the role of the sexually dimorphic swim bladder in the plainfin midshipman fish, Porichthys notatus

Abstract

The reception and processing of socially relevant auditory signals is crucial for the reproduction and survival of many species including the plainfin midshipman fish, Porichthys notatus. Numerous behavioral, physiological and neuroanatomical studies have made P. notatus a robust model system for studying vocal acoustic communication. The ways in which fish are able to perceive acoustic information varies across species and I will detail the underlying morphological structures, including the swim bladder, that fish have adapted to enhance underwater hearing. I characterize the morphology of the midshipman swim bladder chapter two, in each of the three sexual phenotypes; females, type I and type II males. Using micro-computerized tomography I measure and quantify the swim bladder’s shape and relative distance to the inner ear organs in each midshipman sexual phenotype. In chapter three, using the immediate early gene cFos as a marker for neuronal activation, I quantify the response properties of gravid female midshipman to both conspecific advertisement calls and heterospecific white seabass calls. Specifically, I demonstrate the brain areas differentially activated during the perception of these socially relevant acoustic signals. To assess the role of the swim bladder in the neural processing of acoustic signals, in chapter four I conducted playback of conspecific advertisement calls to reproductive females with their swim bladders experimentally removed. Finally, in chapter five, I summarize the conclusions of my work as well as the broader implications and suggestions for future studies.