Different facets of object-use pantomime: online TMS evidence on the role of the supramarginal gyrus

Elsevier

Available online 3 September 2022

CortexHighlights•

TMS over the left supramarginal gyrus (SMG) interferes with pantomime of tool use.

Studies suggest a direct link between an object and the respective pantomime.

A novel task assessed the recognition and comprehension of object-use pantomimes’ meaning.

Online TMS over left SMG revealed that SMG supports both facets of pantomime.

AbstractBackground

A key question in apraxia research is which specific cognitive processes in pantomiming the parietal cortex supports. The manipulation-based hypothesis and the technical-reasoning hypothesis ascribe different roles to the inferior parietal lobule (IPL).

Objective

We elucidated the role of the left supramarginal gyrus (SMG, i.e., part of IPL) during the processing of different aspects of object-use pantomime.

Methods

Thirty-one healthy participants matched pantomimes with the corresponding object (PO) or the corresponding situation (PS) during online transcranial magnetic stimulation (TMS) interference applied to left SMG, compared to a control stimulation (vertex). Notably, the object corresponding to a given pantomime was explicitly not shown in the PS task, excluding the possibility to analyse a physical object. Matching an object to the corresponding situation (OS) served as a control task.

Results

TMS interference with left SMG significantly affected response times for both investigated pantomime tasks (PO and PS); the effect in the PO task significantly correlated with the PS task. As expected, no TMS effect was observed in the control task (OS).

Conclusion

Left SMG does not only establish a link between pantomime and a manipulable object but is also involved in pantomime recognition and comprehension. That TMS interfered with both pantomime tasks supports the manipulation-based hypothesis, assuming that the IPL recruits stored gesture engrams whenever pantomimes are processed.

Keywords

apraxia

manipulation knowledge

action knowledge

parietal cortex

transcranial magnetic stimulation (TMS)

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© 2022 Published by Elsevier Ltd.

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