Light-Powered Wires To Modulate Brain’s Electrical Signals

The human brain largely remains a black box: How the network of fast-moving electrical signals turns into thought, movement and disease remains poorly understood. But it is electrical, so it can be hacked—the question is finding a precise, easy way to manipulate electrical signaling between neurons.

A new University of Chicago study shows how tiny, light-powered wires could be fashioned out of silicon to provide these electrical signals. Published Feb. 19 in Nature Nanotechnology, the study offers a new avenue to shed light on—and perhaps someday treat—brain disorders.

Ten years ago, the science world was alive with speculation about a recently discovered technique called optogenetics, which would manipulate neural activity with light. The problem is that it has to be done with genetics: inserting a gene into a target cell that would make it respond to light. Other ways of modulating neurons have since been suggested, but a perfect alternative remains elusive.

A team led by Asst. Prof. Bozhi Tian built minuscule wires previously designed for solar cells. These nanowires are so small that hundreds of them could sit side by side on the edge of a sheet of paper—putting them on the same scale as the parts of cells they’re trying to communicate with.

These nanowires combine two types of silicon to create a small electrical current when struck by light. Gold, diffused by a special process onto the surface of the wire, acts as a catalyst to promote electrochemical reactions.

The rod at top right is positioned to modify electrical signaling between the neurons. The entire image is smaller than the diameter of a single human hair.

When the wire is in place and illuminated, the voltage difference between the inside and outside of the cell is slightly reduced. This lowers the barrier for the neuron to fire an electrical signal to its neighboring cells,” Tian said.


Socializing: Just A Brain Circuit To Stimulate

A team of Stanford University investigators has linked a particular brain circuit to mammals’ tendency to interact socially. Stimulating this circuitone among millions in the brain — instantly increases a mouse’s appetite for getting to know a strange mouse, while inhibiting it shuts down its drive to socialize with the stranger.

The new findings, published June 19 in Cell, may throw light on psychiatric disorders marked by impaired social interaction such as autism, social anxiety, schizophrenia and depression, said the study’s senior author, Karl Deisseroth, MD, PhD, a professor of bioengineering and of psychiatry and behavioral sciences.

People with autism, for example, often have an outright aversion to social interaction,” says Deisseroth, a practicing psychiatrist who sees patients with severe social deficits. They can find socializing — even mere eye contactpainful.

Deisseroth pioneered a brain-exploration technique, optogenetics, that involves selectively introducing light-receptor molecules to the surfaces of particular nerve cells in a living animal’s brain and then carefully positioning, near the circuit in question, the tip of a lengthy, ultra-thin optical fiber (connected to a laser diode at the other end) so that the photosensitive cells and the circuits they compose can be remotely stimulated or inhibited at the turn of a light switch while the animal remains free to move around in its cage.