Artificial Sensory Feedback to the Brain: Somatosensory Feedback for Neural Devices and BCI

Electrical stimulation of the brain is an enabling technology for the fields of neuroscience, clinical medicine, and biomedical engineering. First developed in the late 1800s, neurosurgeons discovered the brain was electrically excitable and both motor and sensory percepts could be elicited from stimulating different cortical regions. In the last 20 years, electrical stimulation has been used to treat a variety of disorders including essential tremor, depression, and various psychiatric conditions. Stimulation has also been used to elicit visual percepts, enhance memory, and recreate somatosensations on the hands, arms, torso, head, and face. These achievements have been primarily driven by fundamental research in rodents, monkeys, and human participants. These studies asked important questions regarding the organization of the brain, identified neural networks responsible for generating physical sensation, and posed engineering questions about building devices which efficiently communicate with neural circuits. In this chapter, we focus on brain-computer interfaces and how to electrically stimulate the brain to recreate somatosensation. We explore the translational motivations for this emerging research, discuss historical mapping experiments of cortical sensory areas, and describe the state-of-the-art achievements in this nascent area. Progress has emerged through simultaneous work by engineers designing stimulation devices to target deep cortical structures or the cortical surface and neuroscientists learning how cortex networks process sensations evoked by the stimulation patterns. Current research is focused on how closely stimulation patterns must mimic existing neural patterns to create "naturalistic" sensations. By exploring these fundamental questions, we aim to lay the ground work for future solutions to restoring sensation via direct brain stimulation.