Distinct motor preparatory signals correlate with coarse vs fine control of self-paced action timing
Year: 2026
Type: article
Abstract: Making each action at the right time is crucial for motor control. In this study, we investigated how two prominent motor preparatory processes identified in human EEG-beta-band desynchronisation and the readiness potential (RP)-might each differently relate to the time of a simple voluntary action. In our paradigm, participants learned when to act in each block of trials, based on probabilistic trial-by-trial feedback. A reward schedule reinforced a specific optimal time to act in some blocks, but allowed greater variability around the same mean action time in other blocks. We found that contralateral motor beta-band power at the beginning of each trial was higher in trials with slow actions than in those with fast actions. In contrast, contralateral beta-band power reached stereotyped low values at the time of action, regardless of waiting times. Put together, this pattern is consistent with a neural implementation of distance-to-bound for a noisy accumulation process, in which baseline motor activity starts off closer to an action-triggering bound when fast actions are required. In turn, the RP was independent of the mean waiting time before action, but its slope increased when participants developed a precise motor plan. We suggest that beta desynchronisation and the RP track distinct, complementary processes involved in the temporal control of action. While beta-power activity at trial onset is consistent with a strategic adjustment of motor preparation to match the required pace of action, the modulation of the RP by motor plan precision is consistent with a temporally structured input to a ramping preparatory process. Simulations suggest that acting at the right time may involve increasing the strength of the input to this accumulator, which can drive the decision variable to drift towards the decision bound.
Source: Imaging Neuroscience
DOI: 10.1162/imag.a.1434
Language: English
Topic: Free Will and Agency
Subfield: Philosophy
Field: Arts and Humanities
Domain: Social Sciences
Open Access status: diamond
OpenAlex ID: W7221664723