Light Stimulation Parameters Determine Neuron Dynamic Characteristics

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.

The influence of stimulus duration on olfactory perception

“…The mice had free access to the Safe zone to escape the foot shock. Light stimulation, consisting of a train of ten light pulses of 50 ms duration with an interval of 150 ms, was externally triggered by a Master-8 timer (A.M.P.I, Jerusalem, Israel) [ 42 – 44 ]. The output power of the light pulses was measured and adjusted to 20–22 mw with reference to previous studies [ 45 – 48 ].…”

Functional Relevance of Dual Olfactory Bulbs in Olfactory Coding

“…Light stimulation, consisting of a train of ten light pulses of 50-ms duration with an interval of 150 ms, was externally triggered by a Master-8 timer (A.M.P.I. ; Li et al, 2014 ; Erofeev et al, 2019 ; Quinlan et al, 2019 ). The output power of the light pulses was measured and adjusted to 20–22 mw with reference to previous studies ( Lin, 2011 , 2012 ; Sparta et al, 2011 ).…”

“…The mice had free access to the Safe zone to escape the foot shock. Light stimulation, consisting of a train of ten light pulses of 50 ms duration with an interval of 150 ms, was externally triggered by a Master-8 timer (A.M.P.I, Jerusalem, Israel) (Li et al, 2014;Erofeev et al, 2019;Quinlan et al, 2019). The output power of the light pulses was measured and adjusted to 20-22 mw with reference to previous studies (Lin, 2011a(Lin, , 2011b(Lin, , 2012Sparta et al, 2012b).The mild foot shock (0.65mAmps, 5 s) generated by a stand-alone shock generator (Med Associates, USA) was delivered 2 s after the light stimulation by Master-8 timer.…”

Challenges in Scaling Down of Free-Floating Implantable Neural Interfaces to Millimeter Scale

“…To compare the efficacy of the two stimulation schemes, the maximum achievable stimulation frequencies were calculated. For optogenetic stimulation, with the assumption that 3.3 V and 20 mA were supplied to the stimulating LEDs [201], [202] and 10 ms is the pulse width necessary to achieve a full response [203], the power needed is calculated to be 600 µJ per stimulation. For electrical stimulation, the impedance of Pt electrodes of various sizes are inferred from the theoretical interface This work is licensed under a Creative Commons Attribution 4.0 License.…”