Laser Ablation of the Pia Mater for Insertion of High-Density Microelectrode Arrays in a Translational Sheep Model

Abstract

The safe insertion of high density intracortical electrode arrays has been a long-standing practical challenge for neural interface engineering and applications such as brain-computer interfaces (BCIs). Here we describe a surgical procedure, inspired by laser corneal ablation, that can be used in large mammals to thin the pia mater, the innermost meningeal layer encapsulating the brain. This procedure allows for microelectrode arrays to be inserted into the cortex with less force, thus reducing deformation of underlying tissue during placement of the microelectrodes. We demonstrate that controlled pia removal over a small area of cortex allows for insertion of high-density electrode arrays and subsequent acute recordings of spiking neuron activity in sheep cortex. We also show histological and electrophysiological evidence that laser removal of the pia does not acutely affect neuronal viability in the region. This approach suggests a promising new path for clinical BCI with high-density microelectrode arrays.