Prenatal music exposure influences weight, ghrelin expression, and morphology of rat hypothalamic neuron cultures

Developmental programming by prenatal sounds: insights into possible mechanisms

In recent years, the impact of prenatal sound on development, notably for programming individual phenotypes for postnatal conditions, has increasingly been revealed. However, the mechanisms through which sound affects physiology and development remain mostly unexplored. Here, I gather evidence from neurobiology, developmental biology, cellular biology and bioacoustics to identify the most plausible modes of action of sound on developing embryos. First, revealing often-unsuspected plasticity, I discuss how prenatal sound may shape auditory system development and determine individuals' later capacity to receive acoustic information. I also consider the impact of hormones, including thyroid hormones, glucocorticoids and androgen, on auditory plasticity. Second, I review what is known about sound transduction to other - non-auditory - brain regions, and its potential to input on classical developmental programming pathways. Namely, the auditory pathway has direct anatomical and functional connectivity to the hippocampus, amygdala and/or hypothalamus, in mammals, birds and anurans. Sound can thus trigger both immediate and delayed responses in these limbic regions, which are specific to the acoustic stimulus and its biological relevance. Third, beyond the brain, I briefly consider the possibility for sound to directly affect cellular functioning, based on evidence in earless organisms (e.g. plants) and cell cultures. Together, the multi-disciplinary evidence gathered here shows that the brain is wired to allow multiple physiological and developmental effects of sound. Overall, there are many unexplored, but possible, pathways for sound to impact even primitive or immature organisms. Throughout, I identify the most promising research avenues for unravelling the processes of acoustic developmental programming.

Maternal music exposure during pregnancy influences reflexive motor behaviors in mice offspring

Evidence supports that music can modulate many physiological roles, exerting clear effects on the central nervous system. For this effect to be positive, music should be tuned at a frequency of 432 Hz. This study aims to determine the effects of prenatal exposure to music on reflexive motor behaviors in mice offspring. Six pregnant female NMRI mice (8-10 weeks old) were randomly and equally allocated into two groups. Group 1 as control was placed in a normal housing area (average room noise 35 dB), and Group 2 was exposed to music pitched at 432 Hz for 2 h a day played at constant volume (75/80 dB) during pregnancy. Following delivery, four pups from each pregnant mouse were selected, and reflexive motor behaviors including ambulation, hind-limb foot angle, surface righting, grip strength, front- and hind-limb suspension, and negative geotaxis were determined. Based on the findings, prenatal exposure to music significantly increased ambulation score, grip strength, and front- and hind-limb suspension compared to the control group (P < 0.05). Also, prenatal exposure to music significantly decreased hind-limb foot angle, negative geotaxis, and surface righting compared to the control group (P < 0.05). These results suggested that music exposure during pregnancy had a significant positive effect on all tested reflexive motor behaviors in mice offspring.

Animal Signals, Music and Emotional Well-Being

Playing music or natural sounds to animals in human care is thought to have beneficial effects. An analysis of published papers on the use of human-based music with animals demonstrates a variety of different results even within the same species. These mixed results suggest the value of tailoring music to the sensory systems of the species involved and in selecting musical structures that are likely to produce the desired effects. I provide a conceptual framework based on the combined knowledge of the natural communication system of a species coupled with musical structures known to differentially influence emotional states, e.g., calming an agitated animal versus stimulating a lethargic animal. This new concept of animal-based music, which is based on understanding animal communication, will lead to more consistent and specific effects of music. Knowledge and appropriate use of animal-based music are important in future research and applications if we are to improve the well-being of animals that are dependent upon human care for their survival.