From wireless charging to seizure forecasting, how are neural implants being updated?
Writer: Omar Khan
Editor: Kaan Suman
Artist: Patrick Marenda
If your patient was presenting with depression, how would you attempt to treat it?
Cognitive behavioural therapy? Antidepressants? Or directly stimulating the ventral striatum with thin wire electrodes inserted into their brain?
Neural implants are devices placed in the body to interact with neurons, cells that transmit electrical impulses – they are often inserted through a process called deep brain stimulation (DBS). Recent advancements in brain implant technology allow conditions like major depressive disorder (MDD) to be treated without chemical or therapeutic intervention. Though DBS is still in its infancy, the procedure has been used widely for the past twenty years to treat epilepsy, Parkinson’s disease, obsessive-compulsive disorder (OCD), and several other conditions.
In recent years, there have been several innovative advancements in brain implant technology. Researchers at UC San Francisco found a way to alleviate treatment-resistant MDD through a process called closed-loop neuromodulation, where the stimulation depends on electroencephalogram (EEG) changes, as opposed to open-loop neuromodulation, where intermittent or continuous electrical stimuli are applied. Other innovations include: the wireless recharging of neurostimulators; the prediction of seizures several days in advance; and the use of sugar to reduce the foreign body response.
Wireless implants eliminate the risks and inconveniences associated with traditional, tethered implants (such as stress and inflammation) and allow patients to lead more comfortable lives. However, there is a simple but major problem associated with wireless neural implants– the battery needs changing. Normally this requires regular, painful surgery but a team at the Korea Advanced Institute of Science and Technology (KAIST) have engineered an implant that can be recharged wirelessly from outside the body, allowing surgery to be avoided altogether. The researchers previously developed an optoelectronic system with a replaceable drug cartridge so researchers could examine the same brain circuits for months without additional drug delivery, all of which can be controlled on a smartphone app.
The KAIST team integrated a low-energy Bluetooth chip with a circuit consisting of a flexible coil antenna and a rechargeable lithium polymer (LiPo) battery. An alternating magnetic field generated by the system induces a current in the device, charging the battery. The lead, Professor Jeong added that this wireless recharging technology can be applied beyond neuroscience, and be used in “cardiac and gastric pacemakers to reduce the burden on patients for long-term use in the body.”
Tomorrow’s Forecast: Light Rain & Possible Seizures
Epilepsy is a neurological condition characterised by, typically idiopathic, disturbances in electrical activity in the brain, called seizures, where a group of neurons begins firing abnormally triggering a depolarising shift. A third of epileptic people worldwide have to live with uncontrollable seizures because no current treatment method works for them. Seizures can result in jerking movements (“fits”), muscle twitching, and a range of non-motor symptoms, such as gastrointestinal sensations, behaviour arrest, and waves of heat or cold. Treatment can involve anti-epileptic drugs, ketogenic diets, or even the surgical removal of affected brain areas.
The NeuroPace RNS system is a neural implant that can study seizure-related activity in the brain, terminate seizures by stimulating the appropriate neurons, and even predict seizures days in advance. Using statistical models, the UC San Francisco team was able to identify when patients were most likely to have a seizure, and in 40% of patients they were able to predict seizures several days in advance. This kind of foresight allows medication to be taken in smaller, targeted doses rather than be administered regularly, thereby lowering the risk of side effects. Although a prediction from the system does not mean that a seizure will definitely occur, these advancements will help reduce the uncertainty harboured by patients — as lead researcher Vikram Rao put it: “currently, patients have absolutely no information about the future”.
Just Add Sugar
All implants suffer the flaw of being harder than the brain tissue itself therefore stress causes inflammation and scar tissue around it. This can reduce the effectiveness of the implant over time and cause harm to the patient. To mitigate the natural immune response to a foreign body, researchers have used silicone polymers to produce a 0.2mm-thick device as soft as the brain itself. Unfortunately, this was so fragile it was practically useless – until they added sugar. Molten sugar is easily moulded and when cooled, the mould contains high-fidelity (ability to accurately replicate a template) features. Why sugar? Sugar is non-toxic and naturally metabolises in the brain. Lead researcher Edward Zhang explained that the technology “could make brain implants a more viable medical treatment.”
It’s A No-Brainer
These advancements offer an exciting opportunity to expand the role of neurotechnology in healthcare, with modern innovations improving the design, functionality, and efficiency of implants. The list of people who could be helped by investing in and expanding research is endless, ranging from the epileptic to the paralysed whose motor functions can be simulated through the brain-computer interface. For the millions suffering from neurological conditions around the world, the future is getting a little brighter thanks to the incredible innovations in neural implant technology.