Human perception of electrical stimulation on the surface of somatosensory cortex

Abstract

Recent advancement in electrocorticography (ECoG)-based brain-computer interface technology has sparked a new interest in providing somatosensory feedback using ECoG electrodes, i.e., cortical surface electrodes. We conducted a 28-day study of cortical surface stimulation in an individual with arm paralysis due to brachial plexus injury to examine the sensation produced by electrical stimulation of the somatosensory cortex. A high-density ECoG grid was implanted over the somatosensory and motor cortices. Stimulation through cortical surface electrodes over the somatosensory cortex successfully elicited arm and hand sensations in our participant with chronic paralysis. There were three key findings. First, the intensity of perceived sensation increased monotonically with both pulse amplitude and pulse frequency. Second, changing pulse width changed the type of sensation based on qualitative description provided by the human participant. Third, the participant could distinguish between stimulation applied to two neighboring cortical surface electrodes, 4.5 mm center-to-center distance, for three out of seven electrode pairs tested. Taken together, we found that it was possible to modulate sensation intensity, sensation type, and evoke sensations across a range of locations from the fingers to the upper arm using different stimulation electrodes even in an individual with chronic impairment of somatosensory function. These three features are essential to provide effective somatosensory feedback for neuroprosthetic applications.

Restored tactile sensation improves neuroprosthetic arm control

“…Without tactile somatosensory feedback, even simple manipulation tasks become clumsy and slow 1–3 . Outside of investigational settings, this source of feedback is rarely provided for prosthetic devices 8 , and in the context of human brain-computer interfaces (BCIs), has only recently become possible 7,9–11 . These studies have begun to describe the perceptual characteristics of cortical stimulation, however, the potential benefits of a bidirectional BCI on function have remained unexplored.…”

Utility and lower limits of frequency detection in surface electrode stimulation for somatosensory brain-computer interface in humans

“…Across both paradigms, when both frequencies were perceived, the higher frequency was described as "faster" (S08), "more intense" (S10), and "faster buzzing" (S14), in line with previous studies (Table 2). 8,9,16 Below 20 Hz, subjects did not report somatosensation, and at 20 Hz, they described the stimulation as "inconsistent." Repeat stimulations and larger frequencies did not alter the dermatomal region that exhibited percepts (Table 2).…”

Long-Term Home-Use of Sensory-Motor-Integrated Bidirectional Bionic Prosthetic Arms Promotes Functional, Perceptual, and Cognitive Changes

“…These methods have proven effective in patient performance of tasks such as precise force generation (De Nunzio et al, 2017), force discrimination , stiffness discrimination Witteveen et al, 2014), stimuli localization (Antfolk et al, 2013), and multi-site sensory discrimination (Antfolk et al, 2013). Other approaches are also being pursued, including electrical stimulation of peripheral nerves (e.g., Christie et al, 2017), electrocutaneous stimulation (e.g., Paredes et al, 2015), and direct cortical stimulation of the primary somatosensory cortex (e.g., Tabot et al, 2013;Hiremath et al, 2017).…”