Action Preparation: an integrated Perspective of Choice and Motor Control
(2019) 13th Congress of the Belgian Society for Neuroscience — Location: Brussels (24.May.2019)
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- Abstract
- Adaptive sensorimotor interaction requires fine movement preparation (Gallivan, Chapman, Wolpert, & Flanagan, 2018). By applying transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) to elicit motor evoked potentials (MEPs) in muscles of the contralateral hand (Bestmann & Duque, 2016), many studies have shown that action preparation is associated with a transient decrease in the excitability of the corticospinal pathway; this phenomenon has been referred to as preparatory inhibition (Duque, Greenhouse, Labruna, & Ivry, 2017). Intriguingly, while a growing number of studies support the extreme robustness of this effect, the role of such preparatory inhibition remains fundamentally unclear. Our long-term goal is to test the hypothesis that preparatory inhibition reflects the operation of processes that assist action preparation at the level of both choice and motor control. In the context of choice, preparatory inhibition would serve to regulate a speed-accuracy tradeoff (SAT), with more inhibition favoring accuracy over speed. Furthermore, in the context of motor control, preparatory inhibition would facilitate the fine-tuning of muscle activity, with stronger inhibition increasing the gain of motor commands. To test these hypotheses, we recently developed a new experimental task that combines the Tokens Task (Thura & Cisek, 2014, 2017) and some features of the Pac-Man video-game (https://fr.wikipedia.org/wiki/Pac-Man). In brief, at each trial of this task, called the “Tok-Man” Task, tokens jump one-by-one from a central circle to one of two lateral circles. Subjects must then foresee which of both circles will receive more tokens by the end of the trial, and report it by pressing a button on a keyboard with their left or right index finger. Subjects may respond whenever they feel confident to make a choice, but necessarily before the last token jump. Once their choice is made, the motor control part of the trial initiates, by showing a Pac-Man on the screen. Subjects have to perform tapping movements with the chosen index finger to move the Pac-Man towards the chosen circle, while grabbing additional tokens on its way. In summary, the SAT in this task is manipulated by requiring subjects to make either fast or slow (accurate) choices, while motor tuning requirements are manipulated by requiring subjects to prepare faster or slower tapping movements. Importantly, these requirements are manipulated independently of each other, thus crossing choice and motor control instructions in four different block types. The goal here is to report preliminary behavioral data acquired on healthy subjects with this new Tok-Man Task (n=10). Our data indicates that participants adjusted their SAT according to the choice instruction: when the emphasis was on decision speed over accuracy, subjects made faster and less accurate choices. Moreover, subjects were able to change the speed of their tapping movements according to the motor control instruction, and were able to do so regardless of the SAT requirement. Hence, participants were globally able to follow choice and motor control instructions separately.
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Citations
Fievez, F., Cos, I., Derosiere, G., Quoilin, C., LAMBERT, J., & Duque, J. (2019). Action Preparation: an integrated Perspective of Choice and Motor Control. Front. Neurosci. Conference Proceedings: 13th National Congress of the Belgian Society for Neuroscience, 1(1), 1. https://doi.org/10.3389/conf.fnins.2019.96.00081 (Original work published 2019)