Effect of early auditory stimulation on the choice of acoustical environment by adult Swiss albino mice (Mus musculus).

Nine-week-old untreated albino mice, when placed in a novel environment composed of a central cage surrounded by four dark boxes in which different sounds were emitted, explored the boxes for 1 or 2 hr. In most cases the mice settled into one of the four boxes and built their nest. Most of the control animals (65%) chose the silent compartment, whatever the sound delivered in the other boxes. An acoustic choice test was then carried out. A criterion of preference was adopted: If the mouse remained within one of the four boxes for at least 20 min during the third hour, that box was assumed to be its preference. Four groups of mice were exposed to a particular sound for 10 days: Group 1: Gestation Day 10 to birth; Group 2: birth to Day 10; Group 3: Day 10 to Day 20; Group 4: Day 20 to Day 30. Mice were then tested for box preference on Day 63 in the four-box choice, one of which contained the sound of the earlier exposure. Animals stimulated before the 10th day after birth behaved in the same way as controls, whereas animals stimulated between the 10th and the 20th days after birth exhibited a strong preference for the box delivering the sound of the previous treatment. This choice was significant, whatever the harmonic or impulsive nature of the sound. Animals stimulated between the 20th and 30th days showed (53%) a preference for the silent box, but among the others, 75% chose the sound received during infancy. The behavior of animals stimulated when adult was the same as that of the controls.