Dr Philipp Kuhnke | Adaptive short-term plasticity during conceptual processing - A combined TMS-fMRI study

Conceptual knowledge is central to human cognition. Previous evidence suggests that conceptual processing involves modality-specific perceptual-motor and multimodal brain regions in a task-dependent fashion. However, the capacity of the conceptual system for adaptive short-term plasticity remains unclear. Here, we ask to what extent modality-specific regions can compensate for the disruption of a multimodal hub – the left posterior inferior parietal cortex (pIPL) – by adapting their task-dependent activity and connectivity. 40 young and healthy participants will receive inhibitory TMS over the multimodal pIPL, or ineffective sham TMS, before performing sound and action judgment tasks on written words during fMRI. We hypothesize that task-related activity in the multimodal pIPL will be decreased after pIPL-TMS, as compared to sham stimulation. In contrast, modality-specific regions might increase their activity to compensate for the disruption: Auditory areas should be upregulated during sound judgments, whereas somatomotor regions should be upregulated during action judgments. These activity changes should be related to behavioral changes in a modality-specific fashion. Finally, we expect effective connectivity changes after pIPL-TMS: Inhibitory connectivity may spread from the multimodal pIPL throughout the network, whereas modality-specific areas may increase their excitatory influence onto the multimodal pIPL as a compensatory mechanism. Overall, our study promises to provide novel insights into adaptive short-term plasticity during conceptual processing.