Time perception is a fundamental component of biological behavior and underlies higher functions such as prediction, decision-making, learning and motor control. Traditional theories posit that the brain may contain a dedicated internal “neural clock” or rhythmic structure to generate temporal representations on the scale of seconds to minutes. However, in many timing tasks, animals often exhibit highly repetitive and stereotyped behaviors—such as continuous lever pressing or rhythmic stepping. For decades, these behaviors were regarded as “incidental” or “stereotypic,” and their functional significance remained unclear.
The latest research from Professor Xin Jin’s team demonstrates that the stereotype movements animals produce while waiting for an event are not merely ways of “passing time”, but instead constitute the core mechanism by which the brain measures time. This discovery challenges the traditional view that the brain relies on an independent “neural clock,” and offers a new perspective on the interplay between time perception, motor control, and related neurological disorders. The findings were published in Science Advances.
In the study, mice were trained to obtain a reward after waiting approximately 30 seconds. During the waiting period, they spontaneously generated rhythmic, continuous lever-pressing behaviors. By using optogenetics to precisely manipulate these behavioral patterns during the waiting interval, the researchers found that briefly suppressing these repetitive actions caused the mice’s time judgements to shift later - the animals “believed” that 30 seconds had not yet passed. Conversely, enhancing these actions through stimulation of movement-related thalamic regions led the mice to stop earlier, indicating an advanced judgment that “time is up.” Quantitative analyses revealed a highly linear relationship between shifts in time judgment and the number of actions reduced or increased.
Fig. 1. Optogenetic suppression of the stereotyped movements during the waiting period delays action timing.
Traditionally, the dopamine system has been viewed as the brain’s “time regulator.” However, this study shows that dopamine activity primarily reflects actions rather than time itself. Only when dopamine manipulations significantly altered the animals’ behavior did corresponding changes in timing judgments emerge. These results suggest that dopamine does not directly “accelerate or decelerate” an internal clock; instead, it modulates action generation—and actions themselves serve as the fundamental units of timing. Based on these findings, the research team developed a new movement-centered brain timing model in which each action functions as a timing “pulse”. Once a sufficient number of pulses accumulate to reach a threshold, the animal stops its behavior. This model successfully recapitulates all experimental observations and provides a behaviorally grounded framework for understanding temporal computation.
Fig. 2. The proposed new “motor integration model” for action timing, where the animal’s own motor behavior serves as the pacemaker for the internal clock.
The “motor integration model” proposed in this study redefines the theoretical foundation of time-perception research. It suggests that time estimation arises from the integration of the animal’s own behavioral events rather than from independent neural oscillatory structures, offering a new framework for understanding how the brain “keeps time” without a stopwatch. Beyond revising classical theories of time perception, this discovery may help explain the pronounced timing deficits observed in motor disorders such as Parkinson’s disease, and could further inform applications in artificial intelligence and robotic timing control. The study invites a reexamination of what it truly means for the brain to “measure time”.
Journal Reference:
Strassmann, P., Cai, X., Zhang, B., Howard, C.D., Cook, J., & Jin, X*. (2025). A behavioral integration mechanism underlies action timing. Science Advances, 12(1): eaea5558.
>> To read the article in Chinese at the School of Life Sciences, East China Normal University, click here.