Neuronal spiking responses to direct electrical microstimulation in the human cortex.

Microstimulation can modulate the activity of individual neurons in order to affect behavior, but the effects of stimulation on neuronal spiking are complex and remain poorly understood. This is especially challenging in the human brain where the response properties of individual neurons are sparse and heterogenous. Here we use micro- electrode array (MEAs) in the human anterior temporal lobe in six participants (3 female) to examine the spiking responses of individual neurons to microstimulation delivered through multiple distinct stimulation sites. We demonstrate that individual neurons can be driven with excitation or inhibition using different stimulation sites, which suggests an approach for providing direct control of spiking activity at the single neuron level. Spiking responses are inhibitory in neurons that are close to the site of stimulation, while excitatory responses are more spatially distributed. Together, our data demonstrate that spiking responses of individual neurons can be reliably identified and manipulated in the human cortex. SIGNIFICANCE STATEMENT: One of the major limitations in our ability to interface directly with the human brain is that the effects of stimulation on the activity of individual neurons remains poorly understood. Here, Youssef et al. examine the spiking responses of neurons in the human temporal cortex in response to pulses of microstimulation. They find that individual neurons can either be excited or inhibited depending on the site of stimulation. These data suggest an approach for modulating the spiking activity of individual neurons in the human brain.