Light Stimulation Parameters Determine Neuron Dynamic Characteristics

Alexander Erofeev,Anastasia Lavrova,Evgenii Gerasimov,Ilya Bezprozvanny,Olga L Vlasova,Anastasia Bolshakova,Eugene Postnikov

doi:10.3390/app9183673

Abstract

Optogenetics is a recently developed technique that is widely used to study neuronal function. In optogenetic experiments, neurons encode opsins (channelrhodopsins, halorhodopsins or their derivatives) by means of viruses, plasmids or genetic modification (transgenic lines). Channelrhodopsin are light activated ion channels. Their expression in neurons allows light-dependent control of neuronal activity. The duration and frequency of light stimulation in optogenetic experiments is critical for stable, robust and reproducible experiments. In this study, we performed systematic analyses of these parameters using primary cultures of hippocampal neurons transfected with channelrhodopsin-2 (ChR2). The main goal of this work was to identify the optimal parameters of light stimulation that would result in stable neuronal activity during a repeated light pulse train. We demonstrated that the dependency of the photocurrent on the light pulse duration is described by a right-skewed bell-shaped curve, while the dependence on the stimulus intensity is close to linear. We established that a duration between 10–30 ms of stimulation was the minimal time necessary to achieve a full response. Obtained results will be useful in planning and interpretation of optogenetic experiments.

Highlights

Large scale neural activity patterns formed due to an interplay between dynamics of neurons and their network interconnections are principal fingerprints of brain functionality
We considered the generation of action potentials because the membrane current changed at all (Figure 3)
We determined the relationship between the light stimulation parameters and neuron activity during repeated light stimulation and defined the optimal parameters for the stable activity of neurons

Summary

Introduction

Large scale neural activity patterns formed due to an interplay between dynamics of neurons and their network interconnections are principal fingerprints of brain functionality. Age and genetic disruption of neuronal connections can lead to neurodegenerative diseases such as Alzheimer’s, Parkinson’s, Huntington’s and others. The number of incidence cases is increasing due to population ageing associated with new advances in medicine and technology. The key problem is the difficult search for mechanisms of neurodegenerative disorders and new approaches to their treatment.

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