From Brain machine interface to Merleau-Ponty
Sensory neuroprostheses offer the promise of restoring perceptual function to people with impaired sensation. Here we developed a paradigm using intracortical microstimulation (ICMS) for encoding the sensation of fingertip motion against texture. Monkeys learned to interpret time-varying ICMS patterns, evoked by the interplay of their voluntary movements and specific object textures, and discriminated texture coarseness relying solely on these pulse trains. As such, variations in exploration strategy directly affected the timing of individual stimulation pulses. Crucially, this was the first attempt of such an encoding in an active exploration task. We propose that this approach could equip upper-limb neuroprostheses with functional access to texture features acquired during active exploration of natural objects. During this task, our monkeys’ brain resonated with the virtual objects; similar to what Merleau-Ponty poetically describes in ‘Eye and mind’:
‘Visible and mobile, my body is a thing among things; it is caught in the fabric of the world and its cohesion is that of a thing’. Hopefully, in the not too distant future, neuroprostheses, equipped with stimulators similar to one we used will permit patients with sensory functions deficiencies to lose themselves in the fabric of the world.