Electrodes implanted in the brain can help minimize the effects of Parkinson’s disease and other neurological diseases, but implanting and activating these electrodes can be a difficult process. So scientists are currently developing an alternative in the form of small, injectable magnetic disks.
Implanted electrodes are used in a type of therapy known as deep brain stimulation (DBS). As the name suggests, this treatment involves sending electrical signals to specific parts of the brain to selectively stimulate neurons in that area.
Needless to say, brain surgery is required to insert the electrodes into the targeted areas of the brain. Additionally, the electrodes are powered and controlled by a pacemaker-like device that is implanted under the skin in the chest. Subcutaneous wires extend from the device all the way to each electrode.
A number of simpler, less invasive DBS methods have been developed, but many are limited to use on the surface of the brain, stimulate too broadly, or only affect brain tissue that has already been genetically modified. . .
That’s where tiny “magnetoelectric nanodisks” (MEND) come into play.
Developed by scientists at MIT and Germany’s Friedrich-Alexander University, the flat, hexagonal particles are each just 250 nanometers wide and consist of two layers of magnetostrictive cores housed within a piezoelectric shell. . Magnetostrictive materials change shape when magnetized, while piezoelectric materials generate electrical current when subjected to mechanical strain.
When exposed to an externally applied magnetic field, the core responds by changing its shape. This causes distortion in the encasing shell material, which generates electricity. The physical limitations imposed by the flat shape are key to this effect. Previously developed spherical magnetic particles rarely worked well.
When the magnetic field is interrupted, MEND returns to its previous inactive state.
Massachusetts Institute of Technology
The idea is that through small holes drilled in the skull, batches of the device can be injected deep into the brain and into the exact area needed. It can then be activated periodically by an external electromagnet to remain in place permanently.
To test this technique, droplets of MEND (in a carrier solution) were injected into the subthalamic nucleus region of the brains of experimental mice. The subthalamic nucleus is associated with motor control and is therefore the area where electrodes are typically implanted for Parkinson’s disease treatment.
By activating these discs via relatively weak external electromagnets, the scientists were able to generate the same amount of motor control as was possible using implanted electrodes that deliver mild electrical stimulation. It turned out. Researchers are currently working on enhancing the piezoelectric effect to generate more powerful and effective electrical currents.
A paper on the research, led by MIT professor Polina Anikeeva and graduate student Ye Ji Kim, was recently published in the journal Nature Nanotechnology. Last year, South Korean scientists also reported success using injections of particles activated by ultrasound instead of magnetic fields.
Source: MIT
