Meeting Abstract

62.5  Jan. 7  Acoustically-evoked immediate-early gene expression in the pallium of the t�ngara frog MANGIAMELE, L.A.*; BURMEISTER, S.S.; University of North Carolina, Chapel Hill lisaman@email.unc.edu

The anuran auditory system is a good model for studying the neural mechanisms of sexual communication. Previous studies have focused on the role of the auditory midbrain and thalamus in the perception of biologically relevant sounds; however, few have investigated the role of the telencephalon in processing auditory stimuli. In frogs, the medial pallium (MP) and dorsal pallium (DP) are multimodal sensory integration areas that receive ascending auditory input from the thalamus. The MP is considered homologous to the mammalian hippocampus. Although controversial, some propose that DP is homologous to mammalian neocortex. To assess whether the pallium may play a part in processing sexual signals in frogs, we measured neural activity-dependent gene expression in the MP and DP of female t�ngara frogs listening to conspecific male calls. Females were housed in acoustically-isolated chambers for 6 hr followed by sacrifice (no sound group) or the presentation of a 30 min mating chorus followed by 30 minutes of silence before sacrifice. We quantified egr-1 gene expression by in situ hybridization and found that acoustic stimulus presentation caused a 3-fold increase in egr-1 expression in the dorsal MP (p=.01). We did not find an effect in the ventral part of the MP (p=.07). In the DP mating calls induced a 2-fold increase in egr-1 expression in the anterior half of both the dorsal (p=.03) and ventral (p=.001) subdivisions, but we found no differences in the posterior half. These results show that acoustically-evoked neural activity varies spatially in the pallium and may suggest a role of the MP in auditory memory. This is the first report of auditory responses in the DP and may support homology with sensory cortex.