Ultrasonographic Investigation of Human Fetus Responses to Maternal Communicative and Non-communicative Stimuli.

Gabriella A Ferrari,Cecilia Tosato,Emanuela Iappini,Merhi Hussain,Elisabetta Palagi,Luisa Romei,Elisa Demuru,Maria Boerci,Guido Dalla Rosa Prati,Elena Scesa,Ylenia Nicolini,Pier F Ferrari

doi:10.3389/fpsyg.2016.00354

Abstract

During pregnancy fetuses are responsive to the external environment, specifically to maternal stimulation. During this period, brain circuits develop to prepare neonates to respond appropriately. The detailed behavioral analysis of fetus’ mouth movements in response to mothers’ speech may reveal important aspects of their sensorimotor and affective skills; however, to date, no studies have investigated this response. Given that newborns at birth are capable of responding with matched behaviors to the social signals emitted by the caregiver, we hypothesize that such precocious responses could emerge in the prenatal period by exploiting infants’ sensitivity to their mother’s voice. By means of a two-dimensional (2D) ultrasonography, we assessed whether fetuses at 25 weeks of gestation, showed a congruent mouthmotor response to maternal acoustic stimulation. Mothers were asked to provide different stimuli, each characterized by a different acoustic output (e.g., chewing, yawning, nursery rhymes, etc.) and we recorded the behavioral responses of 29 fetuses. We found that, when mothers sang the syllable LA in a nursery rhyme, fetuses significantly increased mouth openings. Other stimuli provided by the mother did not produce other significant changes in fetus’ behavior. This finding suggests that fetuses are sensitive only to specific maternal vocalizations (LA) and that fetal matched responses are rudimentary signs of early mirroring behaviors that become functional in the postnatal period. In conclusion, fetuses seem to be predisposed to respond selectively to specific maternal stimuli. We propose that such responses may play a role in the development of behavioral and emotional attunement with their mothers long before birth.

Highlights

Researchers have been interested in cognitive and social abilities of the fetus since the late 1800s
For example, prenatal exposure to the maternal voice or specific speech sequences influences the way vocal and speech sounds are processed by the newborn (DeCasper and Spence, 1986; Fifer and Moon, 1995)
DeCasper et al (1994), measuring fetal heart rate (FHR) changes, found that fetuses could discriminate between a tape-recorded familiar rhyme and a novel rhyme

Summary

Introduction

Researchers have been interested in cognitive and social abilities of the fetus since the late 1800s (review by Kisilevsky and Low, 1998). Kisilevsky et al (2003), measuring both FHR and body movements, highlighted that when fetuses were exposed to a tape recording of their mother reading a passage, they showed a 5-bpm increase in heart rate over the first 20 s following voice onset, an increase that was sustained until the end of the recording span. Voegtline et al (2013) confirmed that near-term fetuses displayed an orienting response to their mother reading aloud, shown by a reduction in motor activity and a deceleration in FHR response within 30 s after she began reading These results show that the fetus is able to learn prenatally and suggest that fetuses are sensitive to the communicative input of the mother. They indicate a possible role for prenatal experience of voices in subsequent language development and attachment

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