Magneto-Thermal Genetic Deep Brain Stimulation of Motor Behaviors in Awake, Freely Moving Mice
August 21st, 2017Via: eLIFE:
Establishing how neurocircuit activation causes particular behaviors requires modulating the activity of specific neurons. Here, we demonstrate that magnetothermal genetic stimulation provides tetherless deep brain activation sufficient to evoke motor behavior in awake mice. The approach uses alternating magnetic fields to heat superparamagnetic nanoparticles on the neuronal membrane. Neurons heat-sensitized by expressing TRPV1 are activated with magnetic field application. Magnetothermal genetic stimulation in the motor cortex evoked ambulation, deep brain stimulation in the striatum caused rotation around the body-axis, and stimulation near the ridge between ventral and dorsal striatum caused freezing-of-gait. The duration of the behavior correlated tightly with field application. This approach provides genetically and spatially targetable, repeatable and temporarily precise activation of deep-brain circuits without need for surgical implantation of any device.
I bet that if I showed this to a room of biologists in the area of genetics, they wouldn’t understand this abstract. Neuroscientists already know that electrical stimulation of muscles or different parts of the brain can produce a reaction, which vaguely sounds like what they’re describing here. Genetic stimulation sounds meaningless – there are many biologists who work in the area of cell signaling, or figuring out the purpose of various protein enzymes, or what signal will cause RNA to translate various DNA segments into enzymes. There is no gene translation process that causes immediate muscle behavior.
I think the “genetic” part here has to do with the TRPV1 expression : the receptive neurons are genetically programmed to react to high temperature. And the high temperature is produced under the influence of the external magnetic field by the nanoparticles attached / close to the membrane. So in my mind three mechanisms are involved here : genetic manipulation to ensure certain neurons are activated under heating, injection of nanoparticles at the desired spot in the brain (maybe a high dose is injected in the bloodstream, basically), and emission of a magnetic field.