The Neural Correlates of Motor Skill Automaticity

TLDR

Acquiring a new skill reduces the need for effortful control, leading to automaticity when performance of a primary task is minimally affected by concurrent tasks. The study examined the neural basis of automaticity by having subjects perform a serial reaction time task under single‑ and dual‑task conditions across two fMRI sessions separated by 3 h of behavioral training over multiple days, using the diminishing dual‑task cost as an index of automaticity. Behavioral data confirmed that subjects automated the serial reaction time task, and fMRI showed that training reduced dual‑task activation in bilateral ventral premotor, right middle frontal, and right caudate regions, while lateral and dorsolateral prefrontal–striatal circuits supported executive processes and supplementary motor area–putamen/globus pallidus activity decreased for learned sequences but not random ones.

Abstract

Acquisition of a new skill is generally associated with a decrease in the need for effortful control over performance, leading to the development of automaticity. Automaticity by definition has been achieved when performance of a primary task is minimally affected by other ongoing tasks. The neural basis of automaticity was examined by testing subjects in a serial reaction time (SRT) task under both single-task and dual-task conditions. The diminishing cost of dual-task performance was used as an index for automaticity. Subjects performed the SRT task during two functional magnetic imaging sessions separated by 3 h of behavioral training over multiple days. Behavioral data showed that, by the end of testing, subjects had automated performance of the SRT task. Before behavioral training, performance of the SRT task concurrently with the secondary task elicited activation in a wide network of frontal and striatal regions, as well as parietal lobe. After extensive behavioral training, dual-task performance showed comparatively less activity in bilateral ventral premotor regions, right middle frontal gyrus, and right caudate body; activity in other prefrontal and striatal regions decreased equally for single-task and dual-task conditions. These data suggest that lateral and dorsolateral prefrontal regions, and their corresponding striatal targets, subserve the executive processes involved in novice dual-task performance. The results also showed that supplementary motor area and putamen/globus pallidus regions showed training-related decreases for sequence conditions but not for random conditions, confirming the role of these regions in the representation of learned motor sequences.