DBS in the Future
Since its inception, deep-brain stimulation has been a powerful tool for treating neurological disorders. But the invasiveness of the implantation procedure limits DBS to patients who can’t be helped by other therapies and probably repels some who are good candidates.
So we were encouraged to see some ideas for reducing the level of invasiveness of DBS proposed recently. One approach put forward by investigators at Rice University involves carbon nanotube fibers. In a paper published recently in ACS Nano, a team led by Matteo Pasquali described thread-like fibers made of bundles of nanotubes measuring only a few nanometers wide individually. “We developed these fibers as high-strength, high-conductivity materials,” Pasquali said. “Their unique combination of strength, conductivity, and softness makes them ideal for interfacing with the electrical function of the human body.”
Weeks-long tests on cells and then in rats with Parkinson’s symptoms proved the fibers are stable and as efficient as commercial platinum electrodes at only a fraction of the size. The soft fibers caused little inflammation. The highly conductive carbon nanotube fibers also show much more favorable impedance than metal electrodes, and they are amenable to two-way communication, making them a viable option for closed-loop neuromodulation.
Another new approach, published recently in Neuron by a team from the University of Chicago, involves gold nanoparticles conjugated with biological ligands and bound to neurons so as to make them responsive to light and heat. Once bound to a neuron, the particles transduce millisecond light pulses into heat, which depolarizes the neural membrane and elicits action potentials. The approach could offer a more workable alternative to optogenetic stimulation.
Another team at MIT recently described a wireless magnetothermal stimulation technique in Science. They used magnetic nanoparticles to induce minimally invasive and remote neural excitation by activating the heat-sensitive capsaicin receptor TRPV1. Stimulation of the ventral tegmental area of mice evoked excitation in neurons in the targeted brain region and in downstream structures. The nanoparticles persisted in the brain for over a month, thus holding out the promise of chronic stimulation without the need for implants and connectors.
Yet another team from the University of Minnesota proposed a new noninvasive neuromodulation strategy called multimodal synchronization therapy. Writing in Scientific Reports, they described how they could modulate brain activity via precisely timed activation of auditory, visual, somatosensory, motor, cognitive, and limbic pathways.
We expect to see even more proposals for improving DBS in the future and it will be fascinating to watch as the technology evolves.
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