Optogenetics – a method allowing light to be used to control neuron activity via expression of light-activated proteins within cells – is a powerful tool in neurophysiological research. Optogenetics has made significant progress in studies of brain functions in the last decade. Progress in optogenetics depends decisively on the development of new molecular tools, i.e., light-activated proteins. The most widely used molecule for excitation of cells in optogenetics is the natural light-activated cation channelrhodopsin 2 (ChR2). Studies in 2015 identified the natural light-activated chloride channel GtACR2, which in optogenetic experiments can efficiently suppress neuron activity. We identified the unique properties of this channel and showed that not only do GtACR2-expressing neurons r espond to the light signal with strong inhibition, but also that action potentials can be generated, evidently in the axon terminals of the neuron due to changes in the chloride reversion potential is this cell compartment. Our studies used optogenetic methods to investigate the cellular mechanisms of learning and memory. Using channelrhodopsin 2 expression in networks of presynaptic neurons, we employed light stimulation to study the properties of synaptic connections and their plasticity in whole populations of neurons in a single experiment. One potential direction in the clinical use of optogenetics is its use for prosthetization of degenerative retinas. One version of this approach consists of creating an ON/OFF receptor field of retinal ganglion cells by targeted expression of the excitatory light-activated protein in the central part of a ganglion cell and an inhibitory protein in the periphery. Within the framework of this approach, we created a two-layer construct carrying genes for excitatory and inhibitory opsins whose expression was able to lead to restoration of ON/OFF interactions typical of ganglion neurons.
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