A wireless device for neuronal stimulation in the form of a miniature brain implant is among the most unusual achievements of the modern bionics. The implant is extremely small - with the size of a rice grain - and through it, a team of Stanford scientists has been able to stimulate the brain of mice by means of electrical signals, according to Live Science. This development could help scientists and doctors understand more about brain structure and treat various mental disorders, including depression.
Scientists behind the project explain that the human brain is 'the most powerful computer ever known' - a complex system of natural, living electrical circuits. To expand the existing (and quite limited) knowledge of brain function, a group of neurologists are planning a number of clinical trials to stimulate the brains of animals while they are moving freely and reacting to their surroundings and environment.
This is done by small devices that stimulate the brain without interfering with the movement of the animals tested. Until now, such a test would have been difficult to perform because of the volume and weight of existing batteries used for neurostimulation devices. Now, however, Stanford scientists are feeding these devices wirelessly, using the method of magnetic induction. The energy is transmitted from one metal coil to another through magnetic fields.
According to one of the study's authors, Ada Poon, a Stanford University engineer, wireless neural stimulation allows systems to be developed in a way that allows mice to move undisturbed in larger areas.
Tiny, untethered brain-stimulating devices would permit animals to move, behave and react freely during experiments.
However, previous wireless brain-stimulating devices were limited by their power-harvesting components. If these parts were small, power was lost if the animals moved away from the spot where the energy was focused, which limited how far the animals could roam. On the other hand, if these parts were large, they were typically too big to be implanted.
Other labs either used bulky devices mounted on the skulls of mice, or used complex arrays of coils paired with sensors to locate the mice and deliver power. Now the researchers have created implantable wirelessly powered brain-stimulating devices by essentially using the mouse's body to help collect energy.
The roughly cylindrical device is about 2 millimeters wide, 3 mm long, and 20 mm in weight, making it about 100 times smaller and lighter than previous devices. The bodies of the mice are not used to absorb energy, the researchers said. Rather, the mouse bodies interact with surrounding magnetic fields, helping focus energy like a lens from the transmitter to the receiver in the implant.
About one-thousandth of the energy transmitted at the mice gets absorbed by the devices, an efficiency comparable to previous systems.
The scientists could power the implant as the mice roamed across a 6.3-inch-wide (16 centimeters) chamber lined with a magnetic lattice. The device was implanted in a region of the mouse brain known the infralimbic cortex, which is implicated in animal models of depression and anxiety.
'This will open the door to a range of new experiments to better understand and treat mental health disorders such as depression,' Poon said.
In addition - there is no wire and no protruding structure coming out of the animals - so it will allow experiments with multiple animals in the same space which will help understand social interaction between animals better. Experiments aim at understanding more for the needs of chronic pain treatment and mental disorders.
For the purpose of the study, implants are grafted into a brain region known to be associated with depression and anxiety patterns.
This makes it possible to carry out a number of new experiments that can help to better understand mental disorders such as depression and their more adequate treatment. The team of scientists has published previous research and research results in the Physical Review Applied journal.
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