Acute inhibition of estradiol production in songbirds suppresses burst firing of auditory neurons and disrupts their ability to process and respond to song stimuli ( Remage-Healey et al., 2010). For example, exposing female midshipman fish to estradiol during the non-breeding season makes their auditory nerves more sensitive to the frequency of the male mating call ( Sisneros et al., 2004).
Therefore, changes in these gonadal steroids may influence vocal motor behavior through the receptor-coupled effector mechanisms.īoth estradiol and progesterone can also influence auditory function. Evidence suggests that the vocal folds contain specific estrogen and progesterone receptors in the vocalis muscle and lamina propria ( Ferguson et al., 1987 Newman et al., 2000). As compared to premenopausal women, postmenopausal women suffer from vocal deficits including lower voice fundamental frequency (F 0), lower vocal intensity, and more voice instability, and their voice quality was improved with hormone replacement therapy ( D'Haeseleer et al., 2009). In humans, fluctuations of gonadal steroids drive changes in voice quality such as roughness, breathiness, and asthenia ( Meurer et al., 2009 Raj et al., 2010 Çelik et al., 2013) and may influence the timing of voice onset and offset ( Wadnerkar et al., 2006). Evidence from birdsong research shows that estrogen helps maintain the plasticity of the song system to acquire new sensory models of song, and the lack of estrogen during the normal critical period of song learning impairs the development of adult song ( Schlinger, 1997). In addition to their known involvement in those brain functions, gonadal steroids are believed to influence the control of vocal communication. Gonadal steroids, such as estradiol and progesterone, have demonstrable effects on behavior and neuronal activity involved in cognitive functions, emotional control, and sensory processing ( Fernandez et al., 2003 Eisner et al., 2004 Jacobs and D'Esposito, 2011). These findings show neurobehavioral evidence for the modulation of auditory-motor integration for vocal pitch regulation across the menstrual cycle, and provide important insights into the neural mechanisms and functional outcomes of gonadal steroids' influence on speech motor control in adult women. At the cortical level, ERP P2 responses were smaller during the luteal phase (when progesterone levels were high) than the menstrual and follicular phases (when progesterone levels were low). Furthermore, there was a significant negative correlation between the magnitudes of vocal responses and estradiol levels. The behavioral results showed that the menstrual phase (when estradiol levels are low) as associated with larger magnitudes of vocal responses than the follicular and luteal phases (when estradiol levels are high). Measurement of vocal and cortical responses to pitch feedback perturbations and assessment of estradiol and progesterone levels were performed in all three phases. Participants produced sustained vowels while hearing their voice unexpectedly pitch-shifted during the menstrual, follicular, and luteal phases of the menstrual cycle. The present event-related potential (ERP) study sought to examine the interaction between gonadal steroids and auditory feedback-based vocal pitch regulation across the menstrual cycle. Less is known, however, about the influence of gonadal steroids on auditory-motor integration for voice control in humans. In adult females, previous work has demonstrated that changes in auditory function and vocal motor behaviors may accompany changes in gonadal steroids. 4Guangdong Provincial Key Laboratory of Brain Function and Disease, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China.3Department of Rehabilitation Medicine, The First Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.2 Province People's Hospital, Hefei, China 2Department of Rehabilitation Medicine, Anhui No.1Department of Rehabilitation Medicine, The Sixth Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.Xiaoxia Zhu 1, Yang Niu 2, Weifeng Li 3, Zhou Zhang 3, Peng Liu 3, Xi Chen 3 and Hanjun Liu 3,4 *