7538015063

C O RT E X III (2019) 16-34

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The temporal involvement of the left supramarginal gyrus in planning functional grasps: A neuronavigated TMS study

Weronika Potok ^a,b,:L, Adam Maskiewicz ^b>1, Gregory Króliczak ^c/ and Mattia Marangon ^c’^{1 2}

^a Cognitive Science Program, Institute ofPsychology, Faculty of Social Sciences, Adam Mickiewicz Uniuersity in Poznań, Poland

^b Psychology, Institute of Psychology, Faculty of Social Sciences, Adam Mickiewicz Uniuersity in Poznań, Poland ^c Action and Cognition Laboratory, Institute of Psychology, Faculty of Social Sciences, Adam Mickiewicz Uniuersity in Poznań, Poznan, Poland

ABSTRACT

ARTICLE INFO

Article history:

Received 10 May 2018 Revised 4 September 2018 Accepted 2 October 2018 Action editor Stephen Jackson Published online 19 October 2018

Keywords:

Praxis representation Tools

Neuromodulation Grasp planning SMG

The left supramarginal gyrus (SMG) is a critical structure in tool use actions, including such simple acts as selection of appropriate grasps and, if necessary, their on-line corrections. Yet, its temporal contribution to initial planning of functional grasps of tools is largely unknown. We used MRI-guided, event-related transcranial magnetic stimulation (TMS) to determine the time point when SMG involvement in processing of tools for functional grasp decision was affected most In Exp. 1, with 15 partidpants, triple-pulse (10 Hz) TMS was applied to either the left anterior-to-mid SMG (amSMG; subdivisions PFt/PF) or vertex at three different time points: startingfrom 17 ms (i.e., delivered at 17/117/217 ms), 117 ms (117/217/317 ms) or 217 ms (217/317/417 ms) after stimulus onset. In Exp. 2, with 12 par-ticipants, we applied single-pulse TMS to either left amSMG or the left rostral middle frontal gurus (rMFG; area 46) at these same time points relative to stimulus onset. Subject-and item-based analyses of response times (RTs) were performed. Whereas the amSMG and vertex stimulation with triple pulse has revealed differential effects on RTs in generał, as well as on tool orientation processing, it gave only vague pointers as to their temporal contributions to the task. Yet, amSMG and rMFG stimulation with single pulse demon-strated that, while the processing in both of these areas can be enhanced at 17 ms and no doubt at 117 ms (as compared to 217 ms), the earliest stimulation facilitated amSMG (vs. rMFG) contribution, and the latest stimulation had the opposite effect, fadlitating rMFG (vs. amSMG) contribution to planning functional grasps. These outcomes demonstrate that the critical role of SMG in tool-related actions can be invoked substantially earlier than pre-viously thought.

© 2018 Elsevier Ltd. Ali rights reserved.

1

Corresponding author. Instytut Psychologii UAM, ul. Szamarzewskiego 89E, 60-568 Poznań, Poland.

2

Corresponding author. Action and Cognition Laboratory, Institute of Psychology, Faculty of Social Sciences, Adam Mickiewicz Uni-versity in Poznań, Poznan, Poland.

E-mail addresses: [e-mail] (G. Króliczak), [e-mail] (M. Marangon).

¹ The authors contributed eąually to this work. https ://doi.or ^10.1016/j. cortex.2018.10.010 0010-9452/© 2018 Elsevier Ltd. Ali rights reserved.