Ultra Low Power Implantable Platform for Next Generation Neural Interfaces

For over half a century scientists have recorded the tiny electrical potentials generated by neurons in the brains of awake animals performing specific behaviours, using large racks of power-hungry equipment. These experiments have yielded profound insights into how sensory information is represented and transformed by the brain into the signals that control purposeful movements, as well as revealing how this complex system is affected by neurological injuries and disease. However, until recently the therapeutic avenues available to neurologists have been limited to gross interventions such as systemic drug applications and neurosurgical lesions.In recent years, small electronic devices have been developed that deliver specific patterns of stimulation via small electrodes implanted in the nervous system. Devices such as Deep Brain Stimulators and Cochlear Implants have helped many thousands of patients worldwide. The next generation of neural implants will use similar electrodes to detect the activity of neurons, paving the way for new treatments for conditions that currently weigh a heavy clinical burden. For example, by using the activity of neurons in motor areas of the brain to control electrical stimulation of muscles, it is possible that voluntary movements could be restored to patients paralysed by spinal cord injuries. However, despite considerable advances in electrode technologies, our ability to interface digital microelectronics with the brain at the level of individual neurons is at present severely limited. Each electrode detects the signal from multiple cells in its vicinity, and the small, brief 'spike' events they generate can be hard to distinguish beneath the background noise.To solve this problem we have assembled a cross-disciplinary team with expertise in three key areas: the computational algorithms required to detect and sort spike events, low power integrated electronics to perform real-time, reliable spike identification, and the techniques to record long-term activity from the brain using neural implants in order to evaluate real-world performance. The aim is to deliver a platform technology that will convert the raw signal from electrodes into a stream of identified spike events suitable for subsequent processing by conventional digital microelectronics, and be suitable for incorporation into a range of wireless, implantable devices. The availability of such a technology would revolutionise the development of devices to treat a wide variety of nervous system disorders.

The proposed research will have significant economic, clinical and scientific impact. It will be also of large relevance for the participating organizations. In terms of economic impact, a key long-term goal of this research is to develop new technologies to be incorporated into neuroscientific tools and clinical devices such as neural prostheses and Brain-Machine Interfaces (BMIs). Neural devices now constitute a $2 billion/year industry that is predicted to grow twice as fast as the cardiac implant market. The EPSRC has recognised the importance of this area in its initiative 'Developing a Common Vision for UK Research in Microelectronic Design' which describes the interface of electronics to biology and in particular the brain as a Grand Challenge for UK microelectronics. With respect to clinical relevance, the outcomes of this research stand to impact several clinical applications. In the past, treatments for brain disorders have largely been limited to gross psychopharmacological interventions or neurosurgical resections. Our proposed research will deliver an autonomous, implantable platform enabling the next-generation of devices also to monitor the activity of large numbers of individual neurons in the brain. This will significantly increase the scope of neuroprosthetic applications. More significantly, a promising future direction for neuroprosthetics will be to combine neural sensing and stimulation in a single device that can operate 'closed-loop' protocols. Such devices have obvious application as artificial connections between areas that might be disconnected by injury (for example between the motor cortex and the spinal cord). The ability to replace or modify specific connections in the nervous system could revolutionise neurological rehabilitation and impact the lives of a considerable patient population. For example, spinal cord injury affects 35,000 individuals in the UK and is particularly prevalent in young adults (the most common age at injury is just 19 years). Over 300,000 stroke survivors living with moderate to severe disabilities in England alone. The participating organisations (University of Leicester, Imperial College London and Newcastle University) and the project teams will be a significant beneficiary of the proposed research. The project teams will directly benefit from research outcomes through experience gained, papers published and also the availability of new technologies which can filter in to their other research activities. The post-doctoral research associates and PhD students will have valuable interdisciplinary training contributing towards the knowledge economy. This research will generate a stepping stone in the UK's contribution to the field of neural interfaces. The successful completion of this work will make available a technological platform far in excess of the international state-of-the-art. The topic of this proposal is at the forefront of science, as shown by the large number of high profile papers published in this area in the last years, some of them by the investigators of this proposal, and massive media attention. We are therefore confident that results arising from this project will have a large scientific impact leading to high profile journal publications, keynote and public lectures, and media attention.