Roy, A. C. | bioRxiv Science

bioRxiv2025

Reaching for a domain-general syntax: processing linguistic structures and grasping an object with a tool share similar neural codes in the basal ganglia.

Are actions organized like sentences? Recent evidence showed reciprocal transfer between tool use and syntactic comprehension, reflecting shared basal ganglia resources for action and language. The proposed mechanism is that embedding a tool into the motor plan increases the hierarchical structure of actions, paralleling the organization of sentences. If so, overlap with linguistic computations should emerge specifically during the initiation and/or reach-to-grasp phase, when tool embedding dynamically updates the relation with the target, rather than when the object is stably held in the tool grip. Forty French native speakers completed a sentence comprehension task involving object- and subject-relative clauses, and a motor task consisting of grasping and manipulating an object either with a tool or with the bare hand. Using both univariate and multivariate analyses, we found that the comprehension of syntactically complex sentences and the reach-to-grasp phase of tool use elicited overlapping and similar neural codes within the basal ganglia. This phase-specific convergence identifies the basal ganglia as a hub for domain-general hierarchical computations, unifying syntactic embedding for language and tool use.

neuroscience↗

bioRxiv2021

Body representation plasticity is altered in Developmental Coordination Disorder

Developmental Coordination Disorder (DCD) is a pathological condition characterized by impaired motor skills. Current theories advance that a deficit of the internal models is mainly responsible for DCD childrens altered behavior. Yet, accurate movement execution requires not only correct movement planning, but also integration of sensory feedback into body representation for action (Body Schema) to update the state of the body. Here we advance and test the hypothesis that the plasticity of this body representation is altered in DCD. To probe Body Schema (BS) plasticity, we submitted a well-established tool-use paradigm to seventeen DCD children, required to reach for an object with their hand before and after tool use, and compared their movement kinematics to that of a control group of Typically Developing (TD) peers. We also asked both groups to provide explicit estimates of their arm length to probe plasticity of their Body Image (BI). Results revealed that DCD children explicitly judged their arm shorter after tool use, showing changes in their BI comparable to their TD peers. Unlike them, though, DCD did not update their implicit BS estimate: kinematics showed that tool use affected their peak amplitudes, but not their latencies. Remarkably, the kinematics of tool use showed that the motor control of the tool was comparable between groups, both improving with practice, confirming that motor learning abilities are preserved in DCD. This study thus brings evidence in favor of an alternative theoretical account of the DCD etiology. Our findings point to a deficit in the plasticity of the body representation used to plan and execute movements. Though not mutually exclusive, this widens the theoretical perspective under which DCD should be considered: DCD may not be limited to a problem affecting the internal models and their motor functions, but may concern the state of the effector they have to use.

neuroscience↗