Meeting Abstract
The preoptic area is a highly conserved member of the social behavior network of vertebrates, although relatively little is known about its role in the behavior of anurans. The anuran preoptic area is better known as part of an audioendocrine circuit that mediates effects of social cues on gonadal function (ovulation in females, androgen secretion in males). At the same time, extensive evidence points to the importance of the auditory midbrain (i.e., torus semicircularis/inferior colliculus) in mediating behavioral responses to mating calls. Yet, accumulating evidence suggests that the preoptic area may play an important role in the expression mating preferences of anurans. Neuroanatomically, the preoptic area is poised to mediate forebrain influences on auditory response of the midbrain, and it has descending projections to the medulla and spinal cord that could directly influence motor responses. Indeed, lesions of the preoptic area abolish phonotaxis. We have found that, in túngara frogs, estradiol enhances responses of the preoptic area to mating calls in a manner that mirrors the effects of estradiol on phonotaxis. In contrast, while estradiol increases auditory responses in the midbrain, it appears to simply lower its threshold to all calls. Likewise, in spadefoot toads, we find that catecholamine levels in the auditory midbrain respond to the acoustic properties of mating calls independently of mate preferences. In the preoptic area, catecholamines demonstrate significant plasticity in response to mating calls, in a pattern that predicts preferences. Thus, a combination of neuroanatomy, direct tests of function, and associations between neural response patterns and mate choice behavior point to the preoptic area as a gatekeeper of mating preferences in frogs.
