The left supramarginal gyrus contributes to finger positioning for object use: a neuronavigated transcranial magnetic stimulation study. (2nd December 2017)

• Record Type: Journal Article
• Authors: Andres, Michael; Pelgrims, Barbara; Olivier, Etienne; Vannuscorps, Gilles
• Is Part Of: European journal of neuroscience. Volume 46:Number 12(2017)
• Page Start: 2835
• Page End: 2843
• Publication Date: 2017-12-02
• Subjects: dorsal stream -- grasping -- parietal -- tool -- transcranial magnetic stimulation; Nervous system -- Periodicals; 612.8
• DOI: 10.1111/ejn.13763
• Languages: English
• ISSNs: 0953-816X

Abstract

Abstract: In everyday actions, we grasp dozens of different manipulable objects in ways that accommodate their functional use. Neuroimaging studies showed that grasping objects in a way that is appropriate for their use involves a left‐lateralized network including the supramarginal gyrus (SMG), the anterior intraparietal area (AIP) and the ventral premotor cortex (PMv). However, because previous works premised their conclusions on tasks requiring action execution, it has remained difficult to discriminate between the areas involved in specifying the position of fingers onto the object from those implementing the motor programme required to perform the action. To address this issue, we asked healthy participants to make judgements about pictures of manipulable objects, while repetitive transcranial magnetic stimulation (rTMS) was applied over the left SMG, AIP, PMv or, as a control, the vertex. The participants were asked to name the part of the image where the thumb or the index finger was expected to contact the object during its normal utilization or where a given attribute of the same object was located. The two tasks were strictly identical in terms of visual display, working memory demands and response requirements. Results showed that rTMS over SMG slowed down judgements of finger positions but not judgements of object attributes. Both types of judgements remained unaffected when rTMS was applied over AIP or PMv. This finding demonstrates that, within the parieto‐frontal network dedicated to object use, at least the left SMG is involved in specifying the appropriate position of the thumb and index onto the object. Abstract : One fundamental question in neuroscience concerns how various parts of the brain contribute to object use. Transcranial magnetic stimulation (TMS) of the left supramarginal gyrus (SMG) delayed participants' ability to decide where to place their fingers onto an object. No significant TMS effect was found over the anterior intraparietal area (AIP), the ventral premotor cortex (PMv) or when the task was to locate objects' features. Thus, the SMG contributes to finger positioning for object use.