ONTOGENY OF THE LOCOMOTOR-ACTIVITY RHYTHM IN THE COMMON MARMOSET (CALLITHRIX-JACCHUS)

The ontogeny of locomotor activity rhythm in the common marmoset was s tudied in three animals, observed during infant and juvenile stages, a nd in adult age. Animals were kept with their families in outdoor cage s under natural temperature, humidity and light cycles. Data were coll ected from sunrise to sunset, three consecutive days a week, at 5 min intervals randomly distributed in the clock hours, and were recorded a s the total of arbitrary cage sections traveled by the animal each int erval. Animal 3 was observed continuously one day a week in order to d etect less than 2 h period harmonic components. Animals' weekly data s eries were analyzed by Fourier analysis and Siegel's test to detect si gnificant harmonic components. Results showed a main 24 h period compo nent for all records and a secondary 8 h period component in at least 34% of animal's week data series. The power content of the 24 h compon ent showed an increase with age, reaching some stability near the 16th week of life suggesting that this component is mature at the end of t he animal's infant stage. However, for the 8 h component an oscillatin g pattern was observed following the environmental annual temperature cycle; this may indicate a seasonal modulation of daily locomotor acti vity profiles.