How is touch represented in the human brain?

• Applicants: Dr. Jonas Bause; Professorin Esther Kühn, Ph.D.
• Subject Area: Human Cognitive and Systems Neuroscience ; Cognitive, Systems and Behavioural Neurobiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 528318902

The sense of touch helps us stabilize our posture, conduct precise motor movements, perceive and recognize objects, relate to our body and ourselves, and experience emotions. Despite the great importance of touch for everyday life, we know surprisingly little about how touch is represented in the human brain. In particular, although we know that human primary somatosensory cortex (S1) comprises somatotopic body maps, for example representing the fingertips, we lack insights into their fine-grained architecture. Although 2D receptive field properties can be quantified at the level of neuronal populations using functional magnetic resonance imaging (fMRI) and population receptive field (pRF) modeling, as has often been done in vision neuroscience, this approach has not been thoroughly applied to the sense of touch. This knowledge is, however, crucial for building models that allow us to infer - across different contexts - what an individual sensed based on fine-grained S1 responsivity. In the project 'HumanTouch', we will apply 2D pRF modeling to fMRI data acquired with a human 9.4T MRI scanner - the highest field strength currently available in Germany - and use novel MRI-compatible tactile stimulation equipment in combination with methods of precision neuroscience to investigate (i) the fine-grained properties of 2D tactile pRFs in human S1 at submillimeter resolution, (ii) how they differ between body parts, and (iii) how we can use them to predict brain responses to novel tactile input and decode what tactile input an individual perceived based on brain activity. In this way, 'HumanTouch' will allow the development of an advanced understanding of the neural population mechanisms underlying our tactile perception of the world, such as the perception of location, distance, form, size, texture, and ultimately whole objects. Besides the critical scientific knowledge that will be gained from 'HumanTouch', we will develop a novel toolbox for tactile pRF modeling, SamSrf-Touch, and will make this and the unique datasets and analysis framework publicly available to ensure transparency, repeatability, reproducibility, and reuse. Especially in light of the recent strong interest in modeling human touch in VR and for the purpose of brain-machine interfaces, we believe 'HumanTouch' is timely and provides novel insights that are likely to excite the (inter)national scientific community as much as the general public.

• DFG Programme: Research Grants
• International Connection: New Zealand
• Cooperation Partner: Professor Dr. Sam Schwarzkopf