Research into ways to restore brain function has led to the development of an optoelectronic interface that allows interaction between electronic neuron-like generators and living neurons in the brain. Scientists from Lobachevsky University collaborated with scientists from the Technical University of Madrid to create the interface, which consists of an electronic neuron generator, an optical fiber, and a photoelectrical converter. The fiber is placed between the electronic circuit and stimulated neurons and provides galvanic isolation from external electrical and magnetic fields. “Unlike in the known optogenetics methods, there is no need to perform technically difficult and expensive genetic modifications of neurons for stimulation,” said researcher Svetlana Gerasimova. “Stimulation of living neurons is carried out with the help of an electrical signal obtained using photoelectric conversion at the output of the optical fiber.” This is a schematic illustration of an optoelectronic device during the stimulation of synaptic transmission in the mouse hippocampus section. Courtesy of Lobachevsky University. The researchers tested their system in acute hippocampal brain slices obtained from a mouse or a Wistar rat. The optoelectronic system, or hybrid neural circuit, was shown to effectively stimulate electrophysiological living neurons in the hippocampus. Galvanic isolation in the optical fiber prevents breakdowns and electromagnetic effects that could cause electrical damage to brain tissue. The optical fiber also makes it possible to simulate “synaptic plasticity” by adaptive signal transfer through the fiber. According to the researchers, the efficiency of the device could be further increased by implementing an active optical fiber instead of a passive one. “Thus, adaptive stimulation will be possible and its effectiveness will depend on the current state of the fiber optic channel, which reproduces the effects of synaptic plasticity,” said researcher Mikhail Mishchenko. The hybrid neural circuit could be used to develop adaptive systems for restoring brain activity or for replacing individual parts of the brain affected by an injury or a neurodegenerative disease. The research was published in PLOS ONE (https://doi.org/10.1371/journal.pone.0198396).