How the motor system both encodes and influences our sense of time

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Highlights

  • The core timing mechanism resides within the motor system.

  • Interval tuning in SMA is a dynamic signal encoding time in different contexts.

  • The prediction of sensorimotor events is transmitted from motor to sensory areas.

  • Actions lead to highly selective distortions of perceived time.

  • Actions distort the subjective timeline before, during and after a movement.

Several lines of evidence suggest that motoric brain structures may form the core amodal component of a neural network supporting a wide range of timed behaviours. Here, we review recent findings which elucidate the neural computations that occur within motor regions, and in particular the supplementary motor area, in order to support precisely timed actions. Although motor activity may help us represent time, it is also clear that action both enriches and complicates the interpretation of sensory inputs. Hence, in the second half of this review, we consider the latest findings regarding the perceptual distortions that our actions can impose upon our subjective perception of time.

Introduction

Precise timing is an implicit component of all skilled actions, and often also an explicit requirement, as in musical production and dancing. It is possible to view motor timing as a specific process generated by a dedicated timer. However, it is now clear that brain regions traditionally viewed as motoric form part of a core timing network which interacts dynamically with sensory regions to support a range of timing needs. Perception, meanwhile, is not merely a passive process; it is also an active one operating in tandem with the motor system. This implies that, just as for other aspects of perception, we should take our actions into account when interpreting the temporal meaning of sensory inputs. In this paper we provide a selective review of recent work in these two areas. First, we consider the neural mechanisms that support timed behaviours, with a particular focus on the role of the supplementary motor area (SMA), a key node in the cortico-thalamic-basal ganglia timing circuit (CTBGc). Second, we consider the ways in which temporal perception is affected by our ongoing actions.

Section snippets

Neural mechanisms for timed behaviours

Speech comprehension and articulation, as well as music appreciation and execution, depend on intricate loops linking the perception and execution of timed intervals. Hence, the timing mechanism engaged in these complex activities is multimodal and needs to extract temporal information from incoming stimuli and develop predictive signals about upcoming sensory and motor events. This scheme distinguishes time sensation (bottom-up) and time prediction (top-down). There is a vast

Time perception in the context of action

Actions induce distortions of the subjective timeline. Numerous distortions have been reported, affecting the events (and thus the intervals they define) occurring before, during, and after action (summarized in Figure 2). Here, we provide a brief update on classic findings.

In the chronostasis illusion, a new percept that is revealed by an action is experienced as longer than a control percept. For example, the target of a saccadic eye movement has a subjectively expanded duration, which may

Conclusions

In this brief review, we have highlighted how time is represented within core motor areas and translated into meaningful predictions and actions. Balancing the roles of core and dedicated timing systems in order to provide a more complete mechanistic explanation of their interactions and interdependencies will provide a key challenge for the future. We have also provided a concise update regarding the many ways in which time can be distorted by our actions. Researchers should focus on nailing

Conflict of interest statement

Nothing declared.

Acknowledgements

We thank Raul Paulín and Luis Prado for their technical assistance. Hugo Merchant was supported by the grants CONACYT: 236836 and PAPIIT: IN201214-25.

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