Effect of early auditory experience on tone discrimination in mice after birth

Aim: To observe the influence of early sound exposure on frequency modulation (FM) in different directions in Kunming mice after birth, and discuss the neural mechanism of Chinese tone discrimination. Methods: Kunming mice were used in experiment and divided into two groups: exposed group and normal group. Mice were given upward sound exposure in exposed group early after birth, and normally fed in normal group as control. All animal after two- or three-month birth were randomly subdivided into two groups with upward and downward in each, which were trained with praxiology at the same time. Upward FM-electricity defensive conditioned reflex was trained in upward normal group and upward exposed group. The downward FM-electricity defensive conditioned reflex was given in downward normal group and downward exposed group. The corresponsive accuracy and time were recorded respectively in these four subgroups. Results: The corresponsive mean accuracy[2 a time lag: (51.25 ± 22.09)%; 4 s time lag: (95.00 ± 1.17) %] in upward exposed group was significantly higher than that in upward normal group [(36.73 ± 20.04) %, (93.75 ± 0.59) %] (t=6.248 1, P <0.001), but the corresponsive time was significantly lower in the former group(P <0.001). Moreover, the corresponsive mean accuracy in upward exposed groups was higher than that in downward exposed group (P <0.001), but the corresponsive time was significantly lower in the former group (P <0.001), but there was no significant difference between two normal groups (P=0.052 6, P=0.055 0). Conclusion: The early upward FM exposure influences the mice's upward FM direction discrimination, but not the downward. So the properties of reaction to FM direction need to develop further.