The Development Of Locomotor Behaviors In Common Marmoset

The common marmoset (Callithrix jacchus) is the smallest primate inthe world, and has attracted extensive attentions for use as a non-humanprimate animal model in biomedical research, especially for the study ofhuman neuropsychiatric disorders and human physiology and diseases. motordevelopment has been extensively studied in human infants and children,with several established scales to evaluate the motor ability. However, theunderlying neural mechanism is still controversial. An important limitation isthe lack of good animal models in understanding of the human motordevelopment，and marmosets show great potential as non-human primatemodels. But still little is known about the gross motor development ofmarmosets. In the present study, we found that marmosets had a criticalperiod for the motor development from postnatal2to5weeks, and obtained most motor skills at the age of8weeks. This study provided a method toassess the motor abilities of marmosets, and will be useful for the evaluationof motor performance in the future marmoset models of human diseases.Interestingly, we found that marmosets showed a “head to tail” sequence ofmotor development, similar to that of human, suggesting that commonmarmosets may be an ideal model to study the neural mechanism of humanmotor development.Furthermore, the light-dark box is widely used for the evaluation ofanxiety in rodents, but little is known about the light-dark preference inmarmosets. Here we modified the light-dark test to study anxiety, fear, andexploration behaviors in marmosets. We found that both adult and youngmarmosets like to explore the open area, but the young animals showed moreinterest than that of adults. But when the two closed compartments wereadjusted to one light and one dark, the adult marmosets showed significantpreference to the dark compartment, and the young animals had no suchpreference. These results showed that the exploratory behavior and thelight-dark preference in marmosets depend on the age of animal. Our studyprovides a new method to study the behaviors of marmosets.