Cerebral activations related to writing and drawing with each hand.

Adriaan R E Potgieser,Anouk Van Der Hoorn,Bauke M De Jong

doi:10.1371/journal.pone.0126723

Adriaan R E Potgieser, Anouk Van Der Hoorn + Show 1 more

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https://doi.org/10.1371/journal.pone.0126723

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Abstract

BackgroundWriting is a sequential motor action based on sensorimotor integration in visuospatial and linguistic functional domains. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand. In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing.MethodsSixteen healthy right-handed subjects were scanned during audition-guided writing of short sentences and simple figure drawing without visual feedback. Tapping with a pencil served as a basic control task for the two higher-order motor conditions. Activation differences were assessed with Statistical Parametric Mapping (SPM).ResultsWriting and drawing showed parietal-premotor and posterior inferior temporal activations in both hemispheres when compared to tapping. Drawing activations were rather symmetrical for each hand. Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of particularly the right hemisphere. Writing contrasted to drawing revealed left-sided activations in the dorsal and ventral premotor cortex, Broca’s area, pre-Supplementary Motor Area and posterior middle and inferior temporal gyri, without parietal activation.DiscussionThe audition-driven postero-inferior temporal activations indicated retrieval of virtual visual form characteristics in writing and drawing, with additional activation concerning word form in the left hemisphere. Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway. In this, the left posterior middle temporal gyrus subserves phonological-orthographical conversion, dissociating dorsal parietal-premotor circuitry from perisylvian circuitry including Broca's area.

Highlights

Writing is a complex manual motor skill, gradually acquired during childhood [1]
Activations in left- and right-hand writing were left-hemisphere dominant, while right dorsal premotor activation only occurred in left-hand writing, supporting a spatial motor contribution of the right hemisphere
Similar parietal processing in writing and drawing pointed at a common mechanism by which such visually formatted information is used for subsequent sensorimotor integration along a dorsal visuomotor pathway

Summary

Introduction

Writing is a complex manual motor skill, gradually acquired during childhood [1]. In general, motor skills of the upper extremities are characterized by a combination of fine distal finger and hand movements and more proximal, spatial arm movements. The dorsal premotor cortex (PMd) has a stronger role in proximal arm movements to navigate the arm in surrounding space to a target location [5] This differential contribution of the PMv and PMd to distal and proximal movements is consistent with the somatotopy of the primary motor cortex and the relative positions of the PMv and PMd rostrally to it [6]. To test the hypothesis of lateralized circuitry concerning spatial and language components involved in such action, we employed an fMRI paradigm including writing and drawing with each hand In this way, writing-related contributions of dorsal and ventral premotor regions in each hemisphere were assessed, together with effects in wider distributed circuitry. Given a right-hemisphere dominance for spatial action, right dorsal premotor cortex dominance was expected in left-hand writing while dominance of the left ventral premotor cortex was expected during right-hand writing.

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