Left posterior parietal theta burst stimulation affects gestural imitation regardless of semantic content

• Continuous theta burst stimulation (cTBS) over left posterior parietal cortex affects gestural imitation.
• cTBS interfered with gestural imitation regardless of stimulation site (inferior or superior parietal lobe) and semantic content (meaningful versus meaningless).
• The increase of temporal–spatial errors under cTBS fits well with the concept that planning of visuomotor transformations including the appreciation of spatial relationships between body parts may be operative during imitation.

ObjectiveNeuro-imaging studies have suggested that the ability to imitate meaningless and meaningful gestures may differentially depend on superior (SPL) and inferior (IPL) parietal lobule. Therefore, we hypothesized that imaging-guided neuro-navigated continuous theta burst stimulation (cTBS) over left SPL mainly affects meaningless and over left IPL predominantly meaningful gestures.MethodsTwelve healthy subjects participated in this study. High resolution structural MRI was used for imaging guided neuro-navigation cTBS. Participants were targeted with one train of cTBS in three experimental sessions: sham stimulation over vertex and real cTBS over left SPL and IPL, respectively. An imitation task, including 24 meaningless and 24 meaningful gestures, was performed ‘offline’.ResultscTBS over both left IPL and SPL significantly interfered with gestural imitation. There was no differential effect of SPL and IPL cTBS on gesture type (meaningless versus meaningful).ConclusionsOur findings confirm that left posterior parietal cortex plays a predominant role in gestural imitation. However, the hypothesis based on the dual route model suggesting a differential role of SPL and IPL in the processing of meaningless and meaningful gestures could not be confirmed.SignificanceLeft SPL and IPL play a common role within the posterior–parietal network in gestural imitation regardless of semantic content.