Developing an Adaptive Cognitive Prosthetic: Using Large-Scale Electrical Microstimulation to Generate Complex Neural Firing Patterns

Abstract

Over 800,000 individuals in the United States suffer from a stroke or a traumatic brain injury each year. These incidents often leave patients with lasting neurological and neuropsychiatric disorders, which affect their brain function for the rest of their lives. Prosthetic devices can be used to replace some sensory and motor defects. However, a prosthetic for cognitive disorders such as hemispatial neglect has yet to be developed. Previous cognitive prosthetic attempts have only interacted with a small portion of the brain, and only help patients regain function on behaviors that were “prerecorded”. Here, we begin development of an Adaptive Cognitive Prosthetic (ACP) that uses an adaptive learning algorithm paired with multi-site electrical microsimulation and recording techniques to record brain activity from normally functioning regions of the brain, transform this signal to mimic the lost function, and then stimulate a healthy brain region with this signal. This system has two advantages. First, it can use a larger microelectrode array to control many neurons at once, rehabilitating patients more effectively and flexibly. Second, it can learn over time, adapting the prosthetic to the changing needs and environmental conditions of the patient. There are two phases to this project. In the first phase, we develop large-scale electrical microstimulation techniques on mice. In particular, we develop the learning algorithms supporting the ACP. This allows the ACP to guide neural activity towards a target response, often reaching that target within 10 minutes of searching for the correct stimulation pattern. In the second phase of the project, we explore whether control over brain activity can translate to control over behavior. To this end, we use both electrical and visual stimuli to stimulate V1 neural activity in anesthetized mice. Importantly, we find the responses to both electrical and visual stimulation are similar. This similarity is crucial, as the prosthetic must be able to produce neural responses that are similar to neural activity during normal function in order to replace this function. These results will form the basis for behavioral experiments that will test the ACP’s ability to replicate perception.