Figure 4.

Simplified outline of the main pathways and brainstem nerve centers possibly involved in the facial and mouth–tongue responses induced by fetal intravaginal music stimulation. The music would activate the ascending auditory pathway and the motor response could be mediated by circuits related with vocalization. The PAG would work as a center to integrate the auditory signals, acting as an effector center of the social behavior network. AHT: anterior hypothalamus; Amb: nucleus ambiguus; BNST-meAMY: bed nucleus of the stria terminalis-medial amygdala; Co: cochlea; CoN: cochlear nuclei; IC: inferior colliculus; IX: glossopharyngeal nerve; LL: lateral lemniscus; LS: lateral septum; mVN: motor trigeminal nucleus; PAG: periaqueductal gray; POA: preoptic area; rAmb: nucleus retroambiguus; SC: superior colliculus; SoC: superior olivary complex; V: trigeminal nerve; VC: vocalization center of the pontine reticular formation; VII: facial nerve; VIIN: facial nucleus; VIII: vestibulocochlear nerve; VMHT: ventromedial hypothalamus; X: vagus nerve; XI: accessory nerve; XII: hypoglossal nerve; XIIN: hypoglossal nucleus