Abstract
Time perception relies on the motor system. Involves core brain regions of this system, including those associated with feelings generated from sensorimotor states. Perceptual timing is also distorted when movement occurs during timing tasks, possibly by interfering with sensorimotor afferent feedback. However, it is unknown if the perception of time is an active process associated with specific patterns of muscle activity. We explored this idea based on the phenomenon of electromyographic gradients, which consists of the dynamic increase of muscle activity during cognitive tasks that require sustained attention, a critical function in perceptual timing. We aimed to determine whether facial muscle dynamic activity indexes the subjective representation of time. We asked participants to judge stimuli durations (varying in familiarity) while we monitored the time course of the activity of the zygomaticus-major and corrugator-supercilii muscles, both associated with cognitive and affective feelings. The dynamic electromyographic activity in corrugator-supercilii over time reflected objective time and this relationship predicted subjective judgments of duration. Furthermore, the zygomaticus-major muscle signaled the bias that familiarity introduces in duration judgments. This suggests that subjective duration could be an embodiment process based in motor information changing over time and their associated feelings.
Highlights
Time perception relies on the motor system
A distributed neural network has been identified in general explicit timing[3,6], only regions that are strongly implied in motor functions are consistently activated across fMRI studies[4], the basal ganglia (BG), the cerebellum, the supplementary motor area (SMA) and the inferior frontal gyrus (IFG) that extends contiguously to the insular cortex (INS), as shown by the Wiener’ meta-analysis[5]
There was no main effect of familiarity on duration estimates, F(1,26) = 0.73, p = 0.399, η2 = 0.03 (MFam = 0.879 s vs MUnfam = 0.874 s), there was an interaction between familiarity and block, F(1,26) = 5.12, p = 0.032, η2 = 0.16
Summary
Time perception relies on the motor system. Involves core brain regions of this system, including those associated with feelings generated from sensorimotor states. A distributed neural network has been identified in general explicit timing[3,6], only regions that are strongly implied in motor functions are consistently activated across fMRI studies[4], the basal ganglia (BG), the cerebellum, the supplementary motor area (SMA) and the inferior frontal gyrus (IFG) that extends contiguously to the insular cortex (INS), as shown by the Wiener’ meta-analysis[5] (but see other meta-analyzes[7,8]) All these structures are involved in temporal and voluntary control of movement[4,9,10,11] that is highly dependent on the sensorimotor feedback information (including somatic-kinesthetic afferent signals) in order to adjust and guide motor action[10,11,12,13]. This idea was explored focusing on two different facial muscles that are linked to both affective and effort conscious feelings – the zygomaticus-major and corrugator-supercilii muscles –, and stems from the following observations
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