Margherita Marchioro¹, Davide Tabarelli¹, Tommaso Currò¹, Fraser Smith², Carlo Miniussi¹, Luigi Cattaneo¹, Alessandra Dodich¹, Stefania Bracci¹, Luca Turella¹, Simona Monaco¹; ¹Center for Mind/Brain Sciences (CIMeC), University of Trento, ²University of East Anglia

Previous findings have shown that visual presentation of familiar but not unfamiliar objects elicits content-specific activity patterns in the early somatosensory cortex and triggers significant decoding in the mu rhythm response, known to be associated with tactile processing. However, it is not known what aspects of familiarity elicit these effects. Here we explored whether graspability, texture and grip size of viewed objects play a role in cross-modal activation in the somatosensory cortex. We used magnetoencephalography (MEG) to test 18 right-handed participants who viewed visual familiar stimuli presented in a block-design paradigm. The stimuli included graspable and ungraspable items, with graspable items classified by texture (smooth/rough) and grip size (small/large). We assessed graspability, texture, and size contrasts through univariate sensor-level analyses, computing event-related fields (ERFs) and time-frequency representations (TFRs). We hypothesized that early somatosensory effects in central and parietal regions, if reflecting prior experience, would show mu rhythm modulation across all contrasts and beta power variation for graspable items. We found significant ERFs in parietal, temporal, and occipital sensors for graspability (44-148ms) as well as for texture (164-680ms). Significant clusters emerged for size in parietal and occipital regions (34-162ms). The TFRs analysis on graspability showed beta power modulation in parietal and temporal regions, and mu-α power modulation in frontal and occipital sensors. Furthermore, we found mu-α power modulation for size in temporal and frontal sensors, and for texture in temporal and parietal sensors. Our results indicate that graspability of viewed objects activates regions beyond those typically associated with vision, particularly those involved in somatosensory processing, as suggested by mu rhythm modulation for graspable items. This cross-modal activation is likely related to previous experience with object manipulation and concurrent multimodal stimulation, i.e., vision and touch, and might allow retrieving the perceptual representation of prior experience to guide our behaviour.

Acknowledgements: This work was funded by the European Union - Next Generation EU - Mission 4, Component 2, CUP E73C22000490001, ID MSCA 0000051, and by the B2B project SPOKE 4. MNESYS grant PNRR - Next Generation EU.