The Neural Engine: A Reprogrammable Low Power Platform for Closed-Loop Optogenetics

Abstract

Brain-machine Interfaces (BMI) hold great potential for treating neurological disorders such as epilepsy. Technological progress is allowing for a shift from open-loop, pacemaker-class, intervention towards fully closed-loop neural control systems. Low power programmable processing systems are therefore required which can operate within the thermal window of 2O C for medical implants and maintain long battery life. In this work, we have developed a low power neural engine with an optimized set of algorithms which can operate under a power cycling domain. We have integrated our system with a custom-designed brain implant chip and demonstrated the operational applicability to the closedloop modulating neural activities in in-vitro and in-vivo brain tissues: the local field potentials can be modulated at required central frequency ranges. Also, both a freely-moving non-human primate (24-hour) and a rodent (1-hour) in-vivo experiments were performed to show system reliable recording performance. The overall system consumes only 2.93mA during operation with a biological recording frequency 50Hz sampling rate (the lifespan is approximately 56 hours). A library of algorithms has been implemented in terms of detection, suppression and optical intervention to allow for exploratory applications in different neurological disorders. Thermal experiments demonstrated that operation creates minimal heating as well as battery performance exceeding 24 hours on a freely moving rodent. Therefore, this technology shows great capabilities for both neuroscience invitro/in-vivo applications and medical implantable processing units.

A Miniaturized Closed-Loop Optogenetic Brain Stimulation Device

“…Table 3 compares features of the different components of this device with existing clOBS devices. These other clOBS devices were reported by Turcotte et al [20], Liu et al [45], Ramezani et al [46,47] and Mendrela et al [48]. While most of these devices are tetherless, the current work is the first device to use on-device processing of neural signals using an AI-based algorithm, along with miniaturization and tetherless operation.…”

A scalable data transmission scheme for implantable optogenetic visual prostheses

“…Using gene therapy to target specific types of neurons to be sensitive to particular optical wavelengths has significant potential in neuroprosthetics as a whole. We have previously explored optogenetic approaches to retinal prosthesis [32,33] and Luo et al [34] recently demonstrated how are technology could be used for closed-loop control methodologies. A similar approach could potentially be used to improve visual prosthetics.…”