Scientists at Ecole Polytechnique Fédérale de Lausanne in Switzerland created a wireless photoelectric implant that allows them to activate or suppress certain neurons in the mouse spinal cord. The flexible implant is controlled through Bluetooth and contains miniaturized LEDs that emit red light, which helps to avoid absorption and reflection by nearby neurons. The researchers hope that the technique could allow for more advanced optogenetics studies, and even pave the way for clinical implants to treat patients with neurological disorders.
Optogenetics is an advanced technique that allows researchers to delve into the inner workings of the nervous system. The approach involves using light to activate specific genetically modified neurons, helping researchers to identify their role and function. While it is currently an experimental tool, the approach may have clinical potential. However, the way that it is conducted at present makes that difficult, with the light source being part of stationary equipment, meaning that experimental animals need to stay in one place while the technique is performed.
A tethered system means that animals are not moving and behaving naturally, potentially limiting the utility of the obtained results and the clinical applicability of the technique. The Swiss researchers are overcoming this by having designed a wireless photoelectric implant that allows the animals to move around freely. The device is small and flexible enough that it can slip in amongst the vertebrae and sits against the spinal cord.
“We found a way to encapsulate miniaturized LEDs in a flexible implant that is thin yet sturdy enough to be applied on the surface of a mouse’s spinal cord by sliding it underneath the vertebrae along the entire lumbar section,” said Stéphanie Lacour, a researcher involved in the study. “Then we worked with our colleagues at ETH Zurich to create a wireless electronic circuit that can be used to switch on one or more LEDs and control the duration and intensity of the emitted light with extreme precision. Finally, through a customized embedded system-on-chip, the light pulses can be managed naturally, for example in response to muscular activity or some other physiological signal.”
The technology brings optogenetics a little closer to clinical reality. In the meantime, the wireless implant lets the Swiss team to probe neural activity in a more natural environment. “That frees us from the wire-based systems that are generally needed for this kind of research,” said Grégoire Courtine, another researcher involved in the study. “Now we can observe mice as they move about freely and examine the role that neurons play in complex movements like walking and swimming, in an ecological environment.”
See a video about the technique below.
Study in Nature Biotechnology: Wireless closed-loop optogenetics across the entire dorsoventral spinal cord in mice