Wireless remote brain interfaces
Dr. Polina Anikeeva is an assistant professor of Materials Science and Engineering at MIT and a principle investigator of the Bioelectronics group. Her research lies in the field of neuroprosthetics and brain-machine interfaces. Together with her group she explores optoelectronic, fiber-based and magnetic approaches to minimally invasive neural interrogation. Her group was first to demonstrate multifunctional flexible fibers for simultaneous optical stimulation, electrical recording and drug delivery in the brain and spinal cord, as well as magnetic nanomaterials for wireless magnetic deep brain stimulation.
Science - Magnetic 'rust' controls brain activity
A study in mice points to a less invasive way to massage neuronal activity, by injecting metal nanoparticles into the brain and controlling them with magnetic fields. The technique could eventually provide a wireless, nonsurgical alternative to traditional deep brain stimulation surgery.
Optogenetics has revolutionized how neuroscientists study the brain by allowing them to directly manipulate specific neural circuits. But it isn’t practical for human deep brain stimulation. The technique requires that animals be genetically modified so that their neurons respond to light. Light also scatters in brain tissue. So rodents in optogenetics experiments must remain tethered to a surgically implanted, fiber optic cable that delivers laser beams directly to the brain region of interest.
Unlike light, low-frequency magnetic fields pass straight through brain tissue as if it were "transparent," Anikeeva says. That makes those types of magnetic fields an ideal vehicle for delivering energy into the brain without damaging it. Clinicians have long tried to do just that by placing magnetic field coils near a patient’s head. This so-called transcranial magnetic stimulation (TMS) triggers the flow of small electrical currents in neural circuits beneath the coils. But the magnetic fields used in TMS affect only brain tissue near the brain’s surface. Anikeeva, who is now at the Massachusetts Institute of Technology (MIT) in Cambridge, decided to see if she could use magnetic nanoparticles to go deeper.
Previous cancer studies had shown that by injecting tumors with magnetic nanoparticles made of iron oxide—“essentially rust, with well-tuned magnetic properties," Anikeeva says—then exposing them to rapidly alternating magnetic fields, excited nanoparticles can be used to heat and destroy cancer tumors while leaving surrounding, healthy tissue intact. Anikeeva wondered if a similar method could be used to merely stimulate select groups of neurons deep within the brain.
To find out, she and her MIT colleagues targeted a class of proteins called TRPV1 channels, which are found in neurons that respond to heat and certain chemicals in food. Every time you touch a hot iron or eat a spicy pepper, TRPV1-containing neurons fire. Anikeeva and her colleagues injected custom-made, 20-nanometer iron oxide particles into a region of the rodents' brains called the ventral tegmental area (VTA), a well-studied deep brain structure essential to the experience of reward, which plays a central role in disorders such as addiction and depression in people.
TRPV1-containing neurons are abundant in this region in humans, but sparse in mice. So the team also injected the rodents with a virus that increased cell expression of the channel just within that brain area. Such an approach would not be feasible in people, but made the experiment easier to evaluate, Anikeeva says.
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Dr. Polina Anikeeva is an assistant professor of Materials Science and Engineering at MIT and a principle investigator of the Bioelectronics group. Her research lies in the field of neuroprosthetics and brain-machine interfaces. Together with her group she explores optoelectronic, fiber-based and magnetic approaches to minimally invasive neural interrogation. Her group was first to demonstrate multifunctional flexible fibers for simultaneous optical stimulation, electrical recording and drug delivery in the brain and spinal cord, as well as magnetic nanomaterials for wireless magnetic deep brain stimulation.
Science - Magnetic 'rust' controls brain activity
A study in mice points to a less invasive way to massage neuronal activity, by injecting metal nanoparticles into the brain and controlling them with magnetic fields. The technique could eventually provide a wireless, nonsurgical alternative to traditional deep brain stimulation surgery.
Optogenetics has revolutionized how neuroscientists study the brain by allowing them to directly manipulate specific neural circuits. But it isn’t practical for human deep brain stimulation. The technique requires that animals be genetically modified so that their neurons respond to light. Light also scatters in brain tissue. So rodents in optogenetics experiments must remain tethered to a surgically implanted, fiber optic cable that delivers laser beams directly to the brain region of interest.
Unlike light, low-frequency magnetic fields pass straight through brain tissue as if it were "transparent," Anikeeva says. That makes those types of magnetic fields an ideal vehicle for delivering energy into the brain without damaging it. Clinicians have long tried to do just that by placing magnetic field coils near a patient’s head. This so-called transcranial magnetic stimulation (TMS) triggers the flow of small electrical currents in neural circuits beneath the coils. But the magnetic fields used in TMS affect only brain tissue near the brain’s surface. Anikeeva, who is now at the Massachusetts Institute of Technology (MIT) in Cambridge, decided to see if she could use magnetic nanoparticles to go deeper.
Previous cancer studies had shown that by injecting tumors with magnetic nanoparticles made of iron oxide—“essentially rust, with well-tuned magnetic properties," Anikeeva says—then exposing them to rapidly alternating magnetic fields, excited nanoparticles can be used to heat and destroy cancer tumors while leaving surrounding, healthy tissue intact. Anikeeva wondered if a similar method could be used to merely stimulate select groups of neurons deep within the brain.
To find out, she and her MIT colleagues targeted a class of proteins called TRPV1 channels, which are found in neurons that respond to heat and certain chemicals in food. Every time you touch a hot iron or eat a spicy pepper, TRPV1-containing neurons fire. Anikeeva and her colleagues injected custom-made, 20-nanometer iron oxide particles into a region of the rodents' brains called the ventral tegmental area (VTA), a well-studied deep brain structure essential to the experience of reward, which plays a central role in disorders such as addiction and depression in people.
TRPV1-containing neurons are abundant in this region in humans, but sparse in mice. So the team also injected the rodents with a virus that increased cell expression of the channel just within that brain area. Such an approach would not be feasible in people, but made the experiment easier to evaluate, Anikeeva says.
Read more »
