# The basal ganglia mediate the inter-hemispheric transfer of complex tool-use skill

## TL;DR

Learning to use a complex tool with one hand improves performance with the other hand, and this transfer involves the brain's basal ganglia.

## Contribution

The study identifies the basal ganglia as a key mediator in the inter-hemispheric transfer of complex tool-use skills.

## Key findings

- Training with the left hand improved tool-use performance for both hands.
- Functional connectivity changes occurred between right PMd and IPS during training.
- Basal ganglia connectivity with PMd correlated with untrained right-hand performance.

## Abstract

Motor skills learned in one hand generalize to the other hand via plastic changes in motor systems. Such “intermanual transfer” may arise during complex tool-use learning, but its neural underpinnings remain unknown. Using resting-state fMRI, we explored neurobehavioral effects occurring while right-handed participants were trained to use a novel complex tool with their left hand. Behaviorally, training improved tool-use performance equally for both hands, demonstrating a robust effect of intermanual transfer. For both hands, this behavioral effect correlated with functional connectivity changes between right dorsal premotor cortex (PMd) and intraparietal sulcus (IPS). For the untrained right hand, additional change emerged in right basal ganglia (BG), which showed increased behavior-connectivity correlation with bilateral PMd. Thus, tool-use skill learned by left-hand training is represented in the right PMd-IPS network and transferred to left PMd responsible for right-hand performance, pointing to a pivotal role of BG in generalizing complex tool-use skill across hands.

•Complex tool-use skill learned in the left hand generalizes to the right hand•The right PMd-IPS network is established during left-hand training•The right BG-left PMd connectivity reflects untrained right-hand performance•The BG mediate the rapid intermanual transfer of complex tool-use skill

Complex tool-use skill learned in the left hand generalizes to the right hand

The right PMd-IPS network is established during left-hand training

The right BG-left PMd connectivity reflects untrained right-hand performance

The BG mediate the rapid intermanual transfer of complex tool-use skill

Behavioral neuroscience; Cellular neuroscience