ReviewEstradiol-dependent modulation of auditory processing and selectivity in songbirds

The steroid hormone estradiol plays an important role in reproductive development and behavior and modulates a wide array of physiological and cognitive processes. Recently, reports from several research groups have converged to show that estradiol also powerfully modulates sensory processing, specifically, the physiology of central auditory circuits in songbirds. These investigators have discovered that (1) behaviorally-relevant auditory experience rapidly increases estradiol levels in the auditory forebrain; (2) estradiol instantaneously enhances the responsiveness and coding efficiency of auditory neurons; (3) these changes are mediated by a non-genomic effect of brain-generated estradiol on the strength of inhibitory neurotransmission; and (4) estradiol regulates biochemical cascades that induce the expression of genes involved in synaptic plasticity. Together, these findings have established estradiol as a central regulator of auditory function and intensified the need to consider brain-based mechanisms, in addition to peripheral organ dysfunction, in hearing pathologies associated with estrogen deficiency.

Research highlights► Estradiol levels are regulated by auditory experience and modulate auditory-based behaviors in songbirds. ► Brain-generated estradiol enhances the gain and auditory coding efficiency of central auditory neurons in real-time. ► Estradiol suppresses local GABAergic transmission in central auditory neurons via a pre-synaptic, non-genomic mechanism. ► Estradiol is necessary and sufficient for the induction of plasticity-associated genes in central auditory neurons. ► Catecholaminergic transmission may regulate estradiol's modulation of auditory processing and behavior.