Abstract: Objective This research aimed to define a criterion for the motion initiation of voluntary movements and analyze the motion initiation dysfunction in mouse models of Parkinson's disease (PD). Methods The Parkinsonian mouse models were established by 6-hydroxydopamine (6-OHDA) administration. The behavioral states were divided into the resting and the moving states, and the motion initiation events were identified according to the movement velocity of mice. The motion initiation latency was defined as the interim from the resting state to the moving state and was used to compare the difference between parkinsonian and control mice. Results Although there was no significant difference in the average motion initiation latency between parkinsonian mice and control mice, the data showed a skewed discrete distribution. Based on the distribution characteristics, we further analyzed the latency in different time domains. In the range of latency ≤0.5 s, the number of motion initiation events was higher and the latency was shorter in parkinsonian mice, comparing with control mice (P<0.05). When latency >0.5 s, the latency of parkinsonian mice was significantly longer than that of control mice (P<0.05). Conclusion The motion initiation latency could be an effective criterion for evaluating the motion initiation of voluntary movements in mice. It provided a credible behavior paradigm for investigating the motion initiation dysfunction in PD.

Key words: Parkinson's disease, motion initiation, latency, initiation dysfunction, voluntary movements