Abstract: Bidirectional brain-computer interfaces (BCI) have the potential to improve the lives of many people with incapacitating disorders of the brain, spine, and limbs. Although much recent work has been conducted to address the restoration of motor control, much less work has been conducted on somatosensation. Our lab is uniquely set-up to address this problem: we have implanted electrodes in primary motor cortex and primary somatosensory cortex (S1) of a human participant with a C5/C6 spinal cord injury. We can provide intracortical microstimulation (ICMS) to area 1 of S1 which drives tactile percepts of the hand. One aspect of somatosensation that is especially important for bidirectional BCI is perceived intensity, which is a measure of how intense a sensation feels for the participant. We were interested in seeing how changing the parameters of stimulation could change the participant’s perceived intensity. Using a free magnitude estimation task, we found that increases in amplitude and train duration lead to predictable and consistent increases in intensity. Changes in frequency, however, lead to changes that are electrode specific. This talk will focus on the experiments we have conducted to understand these electrode specific frequency effects, how they relate to other properties of the elicited sensations, and some simple modeling we have explored to explain the observed frequency-intensity relationships.