Active tactile evaluation of surface roughness using a closed loop Brain-Computer Interface with intercranial microstimulation in humans

• Applicant: Robin Lienkämper, Ph.D.
• Subject Area: Human Cognitive and Systems Neuroscience
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 537208836

Invasive Brain-computer interfaces (BCIs) aim to improve the quality of life of severely paralyzed people by decoding movement intentions from brain signals and translating them into control signals that can be used to control robotic devices. These invasive BCIs can be supplemented with intracortical microstimulation (ICMS) systems implanted into the somatosensory cortex to provide artificial sensory feedback. Previous research has shown that ICMS evoked sensations can be reliably localized on the skin surface and that the perceived intensity varies depending on the stimulation parameters. However, past research mostly focused on single-electrode stimulation. In contrast, the natural somatosensory system registers many different qualities of sensations with complex spatial and temporal dynamics, allowing us to identify and discriminate different surface textures. This tactile evaluation of surfaces is one of the most important functions of the somatosensory system and plays a major role in everyday life. Using a BCI to restore this ability in patients with no or limited residual sensations would be hugely beneficial for their use of neuroprosthetic devices. The roughness of a surface has been found to be an important factor for differentiation of surface coatings. When touching a rough surface, the perceived stimulus intensity across the skin reflects the elevation profile of the surface. As the hand is moving across the surface, the stimulus intensity profile moves across the representing area in the somatosensory cortex. Encoding such a stimulus intensity profile for ICMS based artificial somatosensory feedback can therefore be achieved by modulating the stimulus intensity on several electrodes that are associated with different locations on the skin. This stimulation pattern can then be further modulated over time to reflect the movement of the hand in a closed-loop BCI setup. In this proposal, I will outline a set of experiments to further explore and quantify the functional limits of the spatio-temporal resolution of ICMS evoked sensations in three participants implanted with microelectrode arrays in both sensory (S1) and motor areas (M1) for BCI studies. I will then establish a paradigm in which participants can use a closed-loop BCI to actively explore a virtual surface with a simulated roughness.

• DFG Programme: WBP Fellowship
• International Connection: USA
• Host: Professor Robert Gaunt, Ph.D.