Primary Somatosensory contribution to action observation brain activity - combining fMRI and cTBS.

Soc Cogn Affect Neurosci. 2016 Mar 15;

Authors: Valchev N, Gazzola V, Avenanti A, Keysers C

Abstract
Traditionally the mirror neuron system (MNS) only includes premotor and posterior parietal cortices. However, somatosensory cortices, BA1/2 in particular, are also activated during action execution and observation. Here we examine whether BA1/2 and the parieto-frontal MNS integrate information by using fMRI-guided continuous theta-burst stimulation (cTBS) to perturb BA1/2. Measuring brain activity using fMRI while participants are under the influence of cTBS shows local cTBS effects in BA1/2 varied, with some participants showing decreases and others increases in the BOLD response to viewing actions vs. control stimuli. We show how measuring cTBS effects using fMRI can harness this variance using a whole brain regression. This analysis identifies brain regions exchanging action-specific information with BA1/2 by mapping voxels away from the coil with cTBS-induced, action-observation-specific BOLD contrast changes that mirror those under the coil. This reveals BA1/2 exchanges action-specific information with premotor, posterior parietal and temporal nodes of the MNS during action observation. While anatomical connections between BA1/2 and these regions are well known, this is the first demonstration that these connections carry action-specific signals during observation and hence, that BA1/2 plays a causal role in the human MNS.

PMID: 26979966 [PubMed - as supplied by publisher]